Can you tell me about guidelines concerning anesthetic criteria that would exclude patients from ambulant surgery? —andreas.koch@koeln.de

Dr. Beverly Philip responds:

Criteria for acceptability for Ambulatory Surgery fall into two categories- medical and psychosocial. Medical criteria are that patients' disease processes, if any, must be stable and in good control. After the surgery and anesthesia, patients must be able to return to their normal functional state by the end of the day. In general, this includes patients in ASA physical status categories 1-3. Surgical complexity is also a factor- more major and lengthy surgery can be done on healthy patients, while more limited procedures with less attendant physiologic disruption are appropriate for patients with more complex medical conditions. The psychosocial criteria are that patients must be willing and able to participate in the preparation for and recovery from their anesthesia and surgery. Alternatively, patients need to identify an individual who can work with them to enable this- such as a parent for a child.

What practice guidelines exist regarding maintenance of labor epidural analgesia in a community hospital setting? I'm aware of the ACOG and ASA guidelines regarding availability of anesthesia support for emergent operative delivery; however, I'm not aware of any guidelines regarding management of routine uncomplicated labor epidurals. Specifically, can the anesthesia provider safely remain "readily" available without staying in the hospital (in a laboring patient with a functioning epidural catheter)? Please reference any known studies. —hholbrooks@kscable.com

Dr. Peter Dwane responds:

In 1988 the American Society of Anesthesiologists produced the Guidelines for Regional Anesthesia in Obstetrics, and amended this document in 1991. From this document, guideline number 8 states: " A physician with appropriate privileges should remain readily available during the regional anesthetic to manage anesthetic complications until the patient's postanesthesia condition is satisfactory and stable."

It is my understanding that this statement does not require the anesthesiologist to be "in hospital", in a community hospital setting.

I see a lot of drug users come in for accidents that require surgery. What are the possible affects/dangers of a person undergoing anesthesia for emergency surgery after using street drugs- crystal meth/cocaine/hallucinogenics/etc.? Do these drugs alter the amount of anesthesia administered to the patient? —smith@vertibrae.com

Dr. David Lubarsky responds:

There is some increased risk as each drug has a unique profile. Stimulants cause the most concern. They raise the adrenaline level in the body, and may predispose to cardiac arrhythmias as the body is also increasing its adrenaline in response to stress/the accident. Chronic use of street drugs may also create cross tolerance to the effects of anesthetics.

What are the minimal lag tests needed for patients on chronic hemodialysis who are scheduled for surgery such as hysterectomy? Is serum K needed before surgery? Please outline reference articles. —bashiti@hotmail.com

Dr. Ron Olson responds:

The underlying concerns are that we not miss worsening anemia, coagulation, uremia, glycemia, acidemia, or hyperkalemia. Let's assume that a preoperative history, ROS, and physical exam reveals that, aside from the renal failure, there are no other significant co-morbidities, no medications that predispose to hyperkalemia, and that the patient is generally feeling well. Documentation within the last 2-4 weeks that Hgb, plt, glucose, and electrolytes are stable should be adequate. If there have been some changes, then the tests should be repeated after the last dialysis. If the patient is diabetic, then obviously a preop glucose is needed. A calcium and magnesium within the last 6 months would be reasonable. The minimum preoperative tests would then be potassium and an ECG.

Hyperkalemia is the most common perioperative complication in renal failure patients [1]. Cardiac arrhythmias are the most common serious complication. Unfortunately, different patients will be symptomatic at different serum K levels. Because the ECG is a window on the electrophysiology, it is a sensitive indicator of hyperkalemic toxicity, and a normal one is reassuring. However it will not reliably show changes for K levels under 6.5 mmol/L [1] and is not foolproof at any level [2].

What level of K is acceptable? There is little evidence on which to base this. Internal medicine literature generally states that levels below 6.5 mmol/L are rarely life threatening [1]. For low risk surgery in an asymptomatic patient with no ECG changes of hyperkalemia, many anesthesiologists will proceed at a K of up to about 5.6 mmol/l. This is an arbitrary level. There is little published evidence on which to base it. The rationale is that either blood transfusions or administration of succinylcholine which might be emergently necessary will not push the K above a truly dangerous level. We will present a poster at the ASA describing 11 cases of renal vascular access surgery which proceeded with K levels > 6 mmol/l, with no complications.

Prolonged fasting (greater than 16 hours) causes hyperkalemia, so don't let these or any other patients languish in preop holding without allowing clear fluids.

References:

1. DS Prough. Anesthesia and Renal Consideratons: Physiological acid-base and electrolyte changes in acute and chronic renal failure patients. Anesthesiology Clinics of North America 2000;18.
2. J Yee, R Parasuraman, RG Narins. Selective review of key perioperative renal-electrolyte disturbances in chronic renal failure patients. Chest 1999;115;149S-157S.
3. Pinson CW et al. Surgery in long-term dialysis patients. Am J of Surg 1986;151:567-71
4. Surawicz B. Relationship between elcetrocariogram and electrolytes. Am Heart J 1967;73:814-34.
5. Wrenn KD et al. The ability f physicians to predict hyperkalemia from the ECG. Annals of Emergency Medicine 1991;20:1229-32.
6. Paice B et al. Hyperkalemia in patients in hospital. BMJ 1983;286:1189-92.
7. Gifford JD et al. Control of serum potassium during fasting in patients with end-stage renal disease. Kidney Int 1989;35:90-4.

What is your opinion about autodonation of one pack of blood just before coronary bypass and transfusion after bypass?

Dr. Richard Prielipp responds:

"Autodonation" refers to the elective withdrawal of whole blood prior to cardiopulmonary bypass (CPB), with the concurrent administration of a crystalloid or colloid solution to maintain normal circulating blood volume. This blood is stored, and then retransfused after separation from CPB and the timely administration of protamine. This is a variant of intraoperative isovolemic hemodilution, with the goals of:

• Decreasing the need for postoperative erythrocyte transfusion,
• Restoring normal concentrations of clotting factors and platelet function, by decreasing the exposure of the harvested blood to the foreign extracorporeal membrane surfaces, and
• And perhaps, to just lower the hematocrit (Hct) in those rare cases where the preoperative Hct exceeds 46%. [There is ample evidence from the British literature that Hct values > 46% increase the risk of myocardial thrombosis and stroke].

Does EEG monitoring improve outcome after carotid endarterectomy? Do you perform GA for carotid endarterectomy if EEG monitoring isn't available? —stav_m@internet-zahav.net

Dr. David Lubarsky responds:

There is no evidence that EEG monitoring affects outcome. However, that may be related to either inadequate studies, or the inherent limitations of the EEG (looking at superficial gray matter and not deep structures). We routinely perform GA for CEA at Duke without EEG, but our surgeon almost always uses a shunt. In the absence of shunting, I prefer to use compressed spectral analysis (a processed EEG). Although imperfect, and without strong evidence, it certainly makes me feel like I am doing everything possible to titrate my therapy to avoid cerebral ischemia. Should an abnormailty occur, I would not consider increasing blood pressure further and/or hyperventialting, and/or suggesting a shunt be placed without an EEG monitor in place.

What are the anesthetic techniques used for endoscopic sinus surgery in E.N.T? Please explain the potential problems involved in such procedures & care to be taken by anaesthesiologist. —lata789@rediffmail.com

Dr. Kathryn McGoldrick responds:

Endoscopic sinus surgery can be accomplished under either general anesthesia or, depending upon the circumstances, monitored anesthesia care. Typically, the problems encountered pertain more to dramatic (sometimes fatal) surgical complications rather than anesthesia complications. (Major hemorrhage and injury to brain anatomy have been reported). For more detail I would suggest referring to the ENT chapter in either the Miller or the Barash et al anesthesia textbooks.

I have a question about regional anesthesia, anticoagulation and ambulatory patients. The patient should be covered against thromboembolism during the operation and I should not have problems with my spinal anesthesia. I give normal Liquemin 5000 U s.c. with the premedication and when the patient goes home Liquemin 5000 U s.c. about 8 hours later when he is leaving. When the patient is staying O/N at the hospital I give low liquemin in the evening. Is this a good technique? Does it make a difference when doing a spinal or an epidural? What if the patient is taking aspirin? Is the technique I mentioned above still possible or too dangerous? Does it make a difference if doing a spinal or epidural? —bdomb@bluewin.ch

Dr. Kathryn McGoldrick responds:

It is thought that subcutaneous heparin appears to add little risk to spinal anesthesia [1]. However, systemic anticoagulation may occur, and spinal hematoma has been described with subcutaneous heparin and EPIDURAL block. Risk of neurologic complications may be reduced by giving the heparin after spinal puncture. Spinal puncture of course should be avoided if the patient is currently systemically anticoagulated with heparin. The heparin should then be stopped for 2-4 hr, and an activated partial thromboplastin time checked to verify normal coagulation before spinal puncture.

Although expert opinion considers risk of antiplatelet agents to be minimal, caution and judgment should be exercised when patients are receiving other anticoagulants in addition to antiplatelet agents because of increased anticoagulation effects.

An excellent review article dealing with your questions is:

1. Liu SS, McDonald SB. Current issues in spinal anesthesia. Anesthesiology 95(5), 888-906, 2001.
   This article appears in the May issue of Anesthesiology and is highly recommended to you.

1. Liu SS, Mulroy MF. Reg Anesth Pain Med 1998;23:140-5)

I am interested in dreaming while under general anesthesia… Are there any books or sites you could recommend to further investigate this topic?

Dr. Beverly Philip responds:

At what INR values would you defer from administering spinal and epidural anesthetic? —airwayman@yahoo.com

Dr. David Lubarsky responds:

Reference:

1. Wu CL: Regional anesthesia and anticoagulation. J Clin Anesth 13:49-58, 2001

Do you know of any herbals that affect coagulation?

Dr. Douglas Coursin responds:

Yes. Ginger inhibits thomboxane A2 synthetase and may alter platelet aggregation and increase the bleeding time. Echinacea - may be associated with liver toxicity, especially if used with other hepatotoxic drugs. This could result in an elevation of the INR from decreased vitamin K dependent factor synthesis.

• Ginkgo - may increase INR or increase effect of NSAIDs, heparin or coumadin
• Garlic - will increase INR and may potentiate coumadin
• Feverfew - can inhibit platelet activity and increase bleeding. Avoid in patients on coumadin.
• Ginseng - may decease INR and decrease effectiveness of coumadin.
• For more info go to the ASA website and see their info
  • http://www.asahq.org/homepage2.html or
  • http://www.asahq.org/PublicEducation/herbal.html.

  Also see; Eisenberg DM, et al. JAMA 1998; 280:1569-75.

I am undertaking a study of anaesthesia for insulin dependent diabetic patients, looking at management of both pre and post surgery. Can you please forward any information on guideline issues or any other relevant information?

Dr. Douglas Coursin responds:

For general reviews, please see the ASA refresher course from 2000 annual meeting by DB Coursin on the perioperative care of the diabetic patient or Angelini, Ketzler, and Coursin. Periop care of the diabetic. ASA Refresher Courses in Anesthesiology 2001 - in press (chapter 1).

Key issues are to differentiate types of diabetic. Type I absolutely need insulin intra and perioperatively to avoid ketosis. Type 2 diabetics need insulin if they are already on it and if they are undergoing longer, more major surgery. Experts vary in opinion as to best administration techniques. WE favor combined regular insulin and glucose infusions for type I DM with hourly glucose monitoring. For our type 2 we often give 1/2 of their intermediate acting insulin (NPH or lente) and hold their regular. WE then supplement with subq regular as needed with careful glucose follow up. The goal is to maintain the blood glucose at 110 - 200 mg/dL to avoid risk of periop hypoglycemia and hyperglycemia. Hypo is hard to identify under general anesthesia or analgesia and sedation. The sequalae of even short term severe hypoglycemia (glucose <20 - 30 mg/dl can be devastating to the CNS.

On the other end, blood sugars over 200 are associated with increased osmotic diuresis, decreased white blood cell function (and increased infection risk), and worsening of CNS ischemia if the patient has a cerebral insult.

WE hold oral agents at least the day of surgery and do not restart metformin until we are sure that post op renal and hepatic function are adequate.

Diabetics have a higher incidence of post op infection, MI, renal insufficiency, and death. Therefore, it is important to sort out baseline cardiovascular, cerebral vascular, and renal vascular disease. If indicated, these patients should be on periop beta-blockers (prior MI, known or suspected myocardial ischemia) or ACEI (if they have baseline proteinuria or renal insufficiency as long as renal artery stenosis is excluded). Beta blockers have been felt to be relatively contraindicated in diabetics, but a study in the NEJM in 1998 (Gottleib, et al. NEJM 1998; 339:489-497) showed that post MI diabetics have better survival if treated long-term with beta blockers.

Diabetics often have autonomic dysfunction and may be at greater risk for gastroparesis and blood pressure lability. Type I diabetics have an increased incidence of "stiff joint" syndrome. Upwards of 30 - 40% may be difficult to intubate due to immobility.

Diabetics who have a post op MI have a greater morbidity and mortality. They should receive conventional therapy, but may not be as responsive to some interventions as others. Diabetics should have tight control (with insulin, potassium and glucose infusion) of their glucose if they have an MI, short and long term control of sugar improves survival .

Here are some additional potentially useful references.

• Levetan C: Controlling hyperglycemia in the hospital: a matter of life and death. Clin Diab 18(1): 2000.
• Pomposelli JJ, Baxter JK et al: Early postoperative glucose control predicts nosocomial infection rate in diabetic patients. J Parenteral and Enteral Nutr 22(2): 77-81, 1998.
• Rassias AJ: Insulin infusion improves neutrophil function in diabetic cardiac surgery patients. Anesth Analg 88(5):1011-6, 1999. Click here for abstract
• Furnary AP: Continuous intravenous insulin infusion reduces the incidence of deep sternal wound infection in diabetic patients after cardiac surgical procedures. Ann Thor Surg 69(2):667-8, 2000.
• Zerr KJ: Glucose control lowers the risk of wound infection in diabetics after open heart operations. Ann Thor Surg 63(2):356-61, 1997.
• Golden SH et al: Perioperative glycemic control and the risk of infectious complications in a cohort of adults with diabetes. Diab Care 22(9):1408-14, 1999.
• Watts et al: Postoperative management of diabetes mellitus: steady-state glucose control with bedside algorithm for insulin adjustment. Diab Care 10(6): 722-28, 1987.
• Peters A and Kerner W: Perioperative management of the diabetic patient. Exp Clin Endocrinol 103:213-18, 1995.
• Malmberg K et al: Glycometabolic state at admission: important risk marker of mortality in conventionally treated patients with diabetes mellitus and acute myocardial infarction: long-term results from the DIGAMI study. Circulation 99(20):2626-32, 1999.
• Miller LG. Arch Intern Med 1998; 158:2200-2211.

We aim for reasonable control, realize that we want to avoid low sugars under anesthesia, but want to avoid ischemic exacerbations and increased risk of dehydration with osmotic diuresis and WBC dysfunction with high sugars. Hopefully better guidelines will be forthcoming along the lines of periop myocardial risk assessment and management.

Does the anesthesia method affect kidney function after transplantation. Which is better to use during the procedure, general or regional? — fsoltan@hotmail.com

Dr. David Lubarsky responds:

There is no evidence that anesthetic technique affects renal transplantation outcome. The most important thing is appropriate fluid loading, regardless of technique.

What are your thoughts on using tetracaine spinals routinely for total joint surgery?— mmessieh@aol.com

Dr. David Lubarsky responds:

Tetracaine has a higher failure rate than other local anesthetics. There is nothing wrong with it, per se. Other than that, choosing the local is just a matter of matching the timing of the drug to the speed of the surgeon.

Does EEG monitoring improve outcome following and after carotid endarterectomy? Should one perform GA for carotid endarterectomy if EEG monitor isn't available? — stav_m@internet-zahav.net

Dr. David Lubarsky responds:

EEG has never been shown to affect outcome - mostly due to inadequate studysize. As a matter of fact, NOTHING has been shown to make a difference.As Chief of Vascular Anesthesia at Duke for a decade, here's my opinion. Common sense dictates careful attention to hemodynamics. Most complications in our experience occurs with severe emergence hypertension. With general anesthesia, I think (with no proof) that lacking an EEG or processed EEG (i.e. compressed spectral analysis), that one should shunt, thereby providing the "cure" to an EEG change prophylactically. If one is shunting, there is no real need for an EEG once sufficient back bleeding after carotid clamping is noted (signifies patent collateral circulation). If one is not shunting, I believe (with little proof) that monitoring forsigns of cerebral ischemia is in the patient's best interest as it allows intervention if an abnormality is detected - shunting, increasing BP, hyperventilation - and allows for monitoring the effectiveness of thatintervention.

Should you deny a patient a general anesthetic if no monitoring isavailable and the surgeon will not shunt prophylactically? No good answer. In that case, however , a regional anesthetic can be considered. It is an excellent technique (deep and superficial cervical plexus blocks) if you are familiar with it, and prepared to deal with the occasional unruly or claustrophobic patient.

What guidelines/rules are there governing the use of droperidol being used in a procedure room by nonanesthesia personnel? An anesthesiologist is in the building at all times but not directly in the procedure room.— Mebruja@aol.com

Dr. Kathryn McGoldrick responds:

Your question is a complex one that cannot be answered easily. I would refer you to an excellent article that appeared in Anesthesiology 84:459-71, 1996. This article is titled "Practice Guidelines for Sedation and Analgesia by Non-Anesthesiologists." It contains a wealth of valuable information that should be extremely useful to you.

Dr. David Lubarsky responds:

This is an emerging procedure with very little human experience, and some question as to the long term viability of the current technique. There was no expert on anesthesia for this procedure known. Optimal treatment in general for patients with GERD is described in all major textbooks.

1. Rao RB. Ely SF. Hoffman RS. Deaths related to liposuction [see comments]. New England Journal of Medicine. 1999 May 13 340(19):1471-5.
   Click here for abstract
2. Tsai RY. Lai CH. Chan HL. Evaluation of blood loss during tumescent liposuction in Orientals. Dermatologic Surgery. 24(12):1326-9, 1998 Dec.
   Click here for abstract
3. Letter to the Editor: Pitman, Gerald H. M.D.
   Click here for abstract
4. Hanke CW. Bullock S. Bernstein G. Current status of tumescent liposuction in the United States. National survey results [see comments]. Dermatologic Surgery. 1996 Jul 22(7):595-8.
   Click here for abstract
5. Klein JA. Tumescent technique for local anesthesia improves safety in large-volume liposuction [see comments]. Plast. Reconstr. Surg. 92: 1085, 1993
   Click here for abstract
6. Letter to the Editor: An article in this journal, "The Role of Subcutaneous Infiltration inSuction-Assisted Lipoplasty: A Review,"
   • contained several dangerous errorsconcerning intravascular fluid homeostasis with tumescent liposuction. Theauthors state that tumescent liposuction is unsafe, but offer onlymisrepresentations and misquotes to support this claim. They assert thatliposuction using general anesthesia, bupivacaine, and the infusion ofsignificant volumes of intravenous fluids is safer than liposuction performedtotally under local anesthesia.
   • I disagree.
     Click here for full text
7. Letter to the Editor:
   • Dr. Klein is an acknowledged innovator and leader in the field of liposuction. Although we appreciate his comments, we feel that his conclusions are erroneous and he totally misinterpreted our intentions in publishing "The Role of Subcutaneous Infiltration in Suction Assisted Lipoplasty" (Plast. Reconstr.Surg. 99: 514, 1997). Our aims in this article were to clarify and help standardize the often confusing nomenclature of subcutaneous infiltration, tostimulate discussion, and to provide some guidance concerning the role of subcutaneous infiltration.
     Click here for full text
8. Letter to the Editor:
   • I have been asked to respond to two issues raised in Dr. Klein's letter: namely, (1) the safety of general anesthesia for liposuction and (2) the safety ofbupivacaine as a local anesthetic.
     Click here for full text
9. Butterwick KJ. Goldman MP. Sriprachya-Anunt S. Lidocaine levels during the first two hours of infiltration of dilute anesthetic solution for tumescent liposuction: rapid versus slow delivery. Dermatologic Surgery. 25(9):681-5, 1999 Sep.
   Click here for abstract
10. Craig SB. Concannon MJ. McDonald GA. Puckett CL. The antibacterial effects of tumescent liposuction fluid [see comments]. Plastic & Reconstructive Surgery. 103(2):666-70, 1999 Feb.
    Click here for abstract

Additional Answer From SCOTT002@mc.duke.edu:

We have done approximately 200 outpatient liposuctions at the Duke Center for Aesthetic Services. All patients have been discharged in 1.5 hours or less. Most are done with deep sedation/MAC anesthesia. Some have involved general anesthesia depending on the number of areas involved and whether they are included as part of another procedure. The medications used has been geared toward early ambulation and discharge. They include fentanyl, midazolam, and propofol. Patient selection and surgeon discretion are very important. Possible complications include hypovolemia from third space shifts which can occur up to4 hours post op; fat embolism; hypothermia; fluid overload; blood loss; local anesthetic toxicity. We limit the liposuction aspirate to 2000ml. The tumescent injection is limited to 4000ml. This solution contains very dilute local anesthetic. Fluid replacement with crystalloid is 2:1. To date, we have not had any anesthetic or surgical complications.

Dr. Katherine Grichnik responds:

Injury (clinically apparent and subclinical) to the brachial plexus mayoccur in up to 87% of patients after CABG using symmetric and asymmetric sternalretraction. Clinical plexopathy has been reported to be between 12 and 37.5% of patients. Studies have revealed conflicting results, in part due to the methods used to assess brachial plexus injury. Studies have used detail edneurological examinations, somatosensory evoked potentials (SSEPs), and electromyogram examination. Patients thought be more at risk include those with diabetic neuropathies, those with preexisting neurological disorders elderly patients, those who had repeated internal jugular cannulation attempts, the use of an automated blood pressure cuff, those who had a long cardiopulmonary bypasstime and those patients who are significantly over ideal body weight. Injury occurs with both symmetric sternal retraction and asymmetric sternal retraction(used for internal mammary harvest) and occurs bilaterally. Reasons postulated for the nerve bundle injuries include nerve stretch, nerve compression and nerve injury due to penetration of the nerves by a fractured first rib after sternotomy. Various interventions have been tried to reduce the incidence of brachialplexus injury. A hands-up (HU) position (arms behind the head and elevated above the level of the table) as opposed to an arms at the side (AAS) position has been investigated (1). The authors found that both positions resulted in decline of SSEPs, but that the AAS position resulted in a higher incidence of postoperative ulnar symptoms. Various types of retractors (Ankeney, Pittman,Favalaro, Canadian, Rultract, etc) are also used clinically, with the goal of reducing brachial plexus injury. In the above referenced study, the HU positionwith the Pittman sternal retractor offered a modest decrease in brachial plexusinjury. Other interventions would be to try to modify the risk factorsidentified above.

1. Jellish WS, Blakeman B, Warf P, Slogoff S. Hands-Up Positioning During Asymmetric Sternal Retraction for Internal Mammary Artery Harvest: A PossibleMethod to Reduce Brachial Plexus Injury. Anesth Analg 1997 Feb;84(2):260-5
   Click here for abstract

Dr. Francine D’Ercole responds:

The decision may need to be based on a Benefit versus Risk scale. I agree peripheral neurologic states may not afford you with accurate patient feed back necessary to identify a parathesia. However, alternative regional techniques may include isobaric spinal anesthesia (assuming agents such as lovenox, plavix, pletal are not part of the patients regime). The benefit may be reducing morbidity in a patient who may not tolerate general anesthesia.

Reference

1. Roger A, Walker N, et al. Reduction of postoperative mortality and morbidity with epidural or spinal anesthesia: results from overview of randomized trials. BMJ 2000; 321: 1-12.

Dr. Beverly Philip responds:

• Schirmer BD. Laparoscopic bariatric surgery. Surg Clin North Am. 2000 Aug;80(4):1253-67, vii. Review.
• Schauer PR, Ikramuddin S, Gourash W, Ramanathan R, Luketich J. Outcomes after laparoscopic roux-en-Y gastric bypass for morbid obesity. Ann Surg. 2000 Oct;232(4):515-29.
  Click here for abstract
• Sarr MG, Felty CL, Hilmer DM, Urban DL, O'Connor G, Hall BA, Rooke TW, Jensen MD. Technical and practical considerations involved in operations on patients weighing more than 270 kg. Arch Surg. 1995 Jan;130(1):102-5
  Click here for abstract

Dr. Katherine Grichnik responds:

Dr. Peter DeBalli responds:

PEEP stands for positive end expiratory pressure [1]. The benefits of PEEP are multiple and include improvements in arterial oxygenation, decrease in the work of breathing and improvement in ventilation-perfusion abnormalities. With a lung injury, PEEP can improve the functional residual capacity, end expiratory lung volume, decrease shunting, decrease dead space ventilation and decrease venous admixture. It can open collapsed alveoli and prevent further airway closure. Compliance can be increased and lung volume can be increased. An adequate arterial oxygen level may be able to be obtained with a lower inspired oxygen level.

The level of PEEP to choose may be difficult to ascertain. A useful approach is to add PEEP in increments of 3-5 cm H₂0 and follow arterial oxygenation, alveolar to arterial oxygen gradient, shunt fraction, lung compliance and oxygen delivery. Watching for the adverse effects of PEEP listed below is also important.

The risks of PEEP are also multiple. PEEP can cause complex hemodynamic changes. Increased airway pressure is transmitted to the great vessels and the heart within the thorax. Consequences of PEEP can include decreased venous return, decreased ventricular filling, increased pulmonary vascular resistance, interference with subendocardial blood flow, reduced LV afterload, and altered configuration /compliance of the RV and LV. Other adverse effects include the potential for barotrauma including interstitial emphysema, pneumothorax, and pneumomediastinum. PEEP may also alter ICP, renal function, hepatic function and gastrointestinal function.

PEEP is used in the critical care setting to improve oxygenation. It is often added at a low level routinely to mechanically ventilated patients to prevent atelectasis of lung units. In the OR, it may be used to prevent or correct a problem with oxygenation due to ventilation-perfusion mismatching. This may especially occur when the patient is in an abnormal position (such as lateral), with a patient with preexisting abnormal physiology (patient with ARDS) or with a patient with abnormal anatomy such as extreme obesity. Care should be taken when using PEEP with emphysema, however. Dynamic pulmonary hyperinflation and barotraumas can occur.

Reference:

1. Clinical Anesthesia 3^rd Edition. Barash PG, Cullen BF, Stoelting RK eds Lippincott-Raven, Philadelphia 1997

Dr. Francine D’Ercole responds:

Related References:

1. D'Ercole F, et al. A teaching model for resident training in regional anesthesia. Regional Anesthesia and Pain Medicine. 1998; 23:112.
2. D'Ercole F, et al. High Performance Teams in the Operating Roon System: A model for Orthopedic Surgical Procedured with Regional Anesthesia. Anesthesiology. 1998; 90:A1346.

Dr. David Lubarsky responds:

To my knowledge there is no literature. I would suggest a literature review using Medline.

Dr. David Lubarsky responds:

I would refer you to the AANA and ASA sites for a discussion of this issue. In addition, HCFA (via the HHS) is in a comment period regarding repeal of the requirement that an MD supervise the provision of anesthesia. States vary in their laws regarding this issue.

Dr. David Lubarsky responds:

For patients with known hypersensitivity (for example to contrast agents), there are several published regimens in textbooks involving steroids, and H1/H2 receptor blockade. Generally pre-treatment with steroids for 24 hours insures that the steroids are working prior to exposure to the allergic item.

Obviously, the best choice is to avoid the exposure by using an alternative. Minor allergic symptoms (like hay fever) usually do not require pretreatment. Asthmatic attacks obviously require cancellation and optimization of pulmonary function.

Dr. David Lubarsky responds:

In our practice, it is the physiologic status, not the timing of dialysis that is the final determinant of readiness for anesthesia. We do recommend dialysis within 24 hours, but as long as the K is < 6.5, there are no symptoms or peakedT waves and a reliable surgeon is doing an access procedure under local, we willproceed. We are currently tabulating our experience for publication as this is above the recommended cut-off of 5.5 meq/L for K. We do insist on a K of 5.5 ifthere is any chance of not being able to abort the procedure, any possibility of transfusion (given K in the stored blood) or any chance of doing a regional or general anesthetic. This has been our practice (safely) for the 12 years I have been running vascular/transplant anesthesia at Duke. There is no exponential increase in K of which I am aware. If there is a reference, please forward itso we can discuss it on the website. In any event, the absolute K is less important than the chronicity and magnitude of the intracellular:extra cellular gradient.

Dr. Katherine Grichnik responds:

Note: most of the information in this response is from reference 1.

Laparoscopy is not a benign process. A third of complications with this procedure relate to the cardiopulmonary system. Cardiac arrhythmias are a well-known occurrence during laparoscopy. Many of the of cardiopulmonary effects result from hypercarbia and increased intraabdominal pressure. Intraabdominal pressure may range from 5-25 mm Hg.

Hypercarbia is induced by CO₂ insufflation. Increased ventilatory dead space, reduced diaphragmatic movement and decreased pulmonary CO₂ excretion can occur. On average, PaCO₂ increases by 10 mm Hg and pH decreases by 0.1. Hyperventilation is stimulated in spontaneously breathing patients. CO₂ can accumulate in the body and it may take several hours for PaCO₂ to return to normal. Significant hypercarbia (55-70 mm Hg) can increase HR, BP, CVP, CO, SV and a decrease in peripheral vascular resistance.

Hemodynamic effects induced by CO2 insufflation and resultant increases in intraabdominal pressure (IAP). An IAP of 15 mm Hg increases SVR, MAP, PAP, inferior vena caval pressure, with resultant falls in stroke volume. At an IAP of 20 mm Hg, right atrial pressure and intracranial pressure can rise. The inferior vena cava can be compressed with reduced venous return at an IAP of 40 mm Hg. A rise in afterload can occur also. All of these factors can reduce cardiac output. All of these effects are exacerbated in the hypovolemic patient.

Arrhythmias occur often but are often transient and without adverse effects. In one study, 47% of patients had arrhythmias [2]. Ventricular ectopic beats are the most common arrhythmias. Bradydysrhythmias are also common and may result in sinus arrhythmia and asystole. Atropine and reduction in the rate of CO₂ insufflation are effective. Arrhythmias were also shown to occur in infants who underwent laparoscopic procedures [3].

Some patients are unsuited for laparoscopy due to the hemodynamic effects of laparoscopy. These may include patients with severe cardiomyopathy, untreated CHF, and moderate to severe myocardial ischemia. Cardiac decompensation may occur 1.5 to 3 hours after CO₂ insufflation and thus usually occurs in the first postoperative hour.

Other complications which may ultimately result in cardiac dysrhythmias include pneumothorax, pneumomediastinum, pneumopericardium, gas embolus and significant hypoxemia.

Total IV anesthesia versus inhalational anesthesia have been examined and no difference in arrhythmias found [4].

References:

1. Sharma, KC et al. Laparoscopic Surgery and its potential for medical complications. Heart and Lung, The Journal of Acute and Critical Care. 1999;26:52-67
2. Myles PS. Bradyarrthymias and laparoscopy: A prospective study of heart rate changes with laparoscopy. Aust N Z J Obstet Gynaecol 1991 May;31(2):171-3.
   Link to abstract
3. Bozkurt P, et al. The cardiorespiratory effects of laparoscopic procedures in infants. Anaesthesia 1999;54:831-4.
   Link to abstract
4. Goodwin AP, et al. Day Case Laparoscopy. A comparison of two anaesthetic techniques using the laryngeal mask during spontaneous breathing. Anaesthesia 1992;47:892-5.
   Link to abstract

Dr. Beverly Philip responds:

A good way to know is to keep a record of what the surgeon has required in his recent operations, and do the same. If s/he has often required blood be transfused, then be prepared. Inexpert surgeons can have problems other than blood loss.

Dr. Richard Rosenquist responds:

Evaluation of pain in patients that are unable to communicate is difficult. As an initial attempt, the use of simplified pain measurement tools such as faces that range from happy to sad is one way to approach this problem. Changes in heart rate, blood pressure, sweating, restlessness, inability to rest or sleep, crying or grimacing are others. There are no perfect measures for evaluating pain in patients that have difficulty communicating for any reason. It is also useful to obtain input from family members that may have a better idea of the individuals baseline and any variations from that baseline. This is an issue that continues to attract the attention of healthcare providers but does not have a good answer at the present time.

Dr. David Lubarsky responds:

The best way to follow this is to attend/read the ASA review lectures on these topics. In a nutshell, new endovascular techniques are making open AAA repair less common. An arterial line for invasive monitoring and an epidural are all that are required. For open AAAs, an arterial line and CVP are minimal requirements. PA catheters, which we only employ on patients with poor LVEF or valvular disease, are optional, as are epidurals for post op pain relief, which we employ on >95% of our patients, usually using a T9-10 thoracic epidural and dilaudid. Aggressive beta-blockade is usually employed based on the results of the NEJM article by Poldermans et. al. (reviewed by me in an earlier issue of AWEB, and archived here. This short answer obviously is not all-inclusive as many issues - ischemia prevention/detection, renal protection, thoracic aneurysm spinal cord protection, etc. - are all chapters unto themselves.

Dr. Francine D’Ercole responds:

Based on a survey at our institution the following opinion regarding anti-platelet agents and regional anesthesia resulted in this statement:

We do not know of any case reports describing new anti-platelet agents. We do not perform neuraxial or peripheral nerve blockade on patients receiving Plavix or Ticlid or any other new generation platelet inhibitors unless the patient is extremely high risk (and the anesthesia providers are willing to accept the risk). However, regional anesthesia is performed on patients receiving such agents as aspirin, NSAIDs. The conservative approach for newer anti-platelet agents has been reinforced most likely because of the (hard lesson learned) tragic outcomes associated with the LMWH, Lovenox and neuraxial blockade.

Dr. Francine J. D’Ercole responds:

I strongly recommend acquiring the April 2000 issue of Techniques in Regional Anesthesia and Pain Management. This issue has a series of reviews/updates describing Combined Regional and General Anesthesia. Techniques in Regional Anesthesia and Pain Management 4(2): April 2000.Editor: William Urmey, MD

Dr. Katherine Grichnik responds:

I am not sure that there are legal issues concerning intraoperative use only of beta blockade. It is certainly the choice of the physician caring for the patient postoperatively as to whether to continue beta blockade or not. There are many good reasons to use beta blockade intraoperatively, especially to control hypertension and tachycardia with the stimulus of surgery. If you are concerned that the patient will/should not get beta blockade postoperatively, then a short-acting beta blocker such as esmolol can be used intraoperatively if you deem it indicated. If the patient is on beta blockers preoperatively and the plan is for postoperative use, then use of a longer acting beta blocker intraoperatively may be indicated. Of course, one must always review the patient's history for contraindications to beta blockade.

Dr. Giuditta Angelini responds:

I think the best information to help you make a decision about residency programs is not found in published lists. These are always based on criteria like reputation, prominent physicians, publications, etc. They don't necessarily reflect good training. The best source of information is from Anesthesiology residents and staff in your own institution. I would solicit their opinions about programs that they would recommend and why. You are more likely to get information that is practical.

There are areas that many programs may be lacking, yet you are required to fulfill a certain amount of experience by ACGME requirements. Most places have problems in regional and pain. These include the following:

• of lumbar epidurals
• of thoracic epidurals
• of pump cases
• of regional blocks
• of ambulatory cases
• of pediatric cases

These need to be in the range of 50-100, and the last two even more.

• Do they have a meaningful Pain Clinic experience?
• Do they have an Acute Pain Service?
• Do they have fellowship trained staff in the different subspecialties such as cardiac, neuro, pain, critical care, obstetrics, regional, pediatrics, ambulatory--this will allow you a balanced experience.
• What kind of teaching experience do you receive (conferences)?
• Do you have reading days?
• What is the ratio of resident to staff on average on a typical day? (More than 2 residents to one staff makes accessibility more dubious)
• Are you single staffed in the beginning while you become accustomed to being in the OR?
• Are you expected to respond to airway calls by yourself?
• What is the frequency of call? Who is on call with you? Is there a staff in house at all times?
• When you are senior, are you expected to run the OR board (deciding who gets to do what surgery and when)?

I would recommend checking out the website below, which has information on residency programs by state and also has some literature about getting into a residency for medical students: http://www.healthadvisor.com/resinfo.htm

Dr. Katherine Grichnik and Dr. Beverly Philip respond:

We have no knowledge about the preferred order of procedures to investigate the GI tract. The question should be referred to a gastroenterologist.

Dr. Katherine Grichnik responds:

Please refer to the excellent chapter in Clinical Anesthesia (3d Edition) on obesity from which most of this discussion was derived [1]. Obesity affects every major organ system, causing deviations from the norm in the anatomic, physiologic and biochemical properties of the body. Obesity is defined as greater than 20% above ideal body weight (IBW) or having a body mass index (BMI) of greater than 28. Morbid obesity is defined as being more than 45 kg over IBW or having a BMI >35. In the United States, 33% of the population can be defined as obese and of these, 3-5% are morbidly obese. Obese people have an increased risk of premature death due to the pathophysiology of being obese and they also have a higher risk of perianesthetic and perioperative complications. Most studies on obese people were done on obese people without other clinically identifiable concurrent disease processes. This may be unlike the population of obese people who are presenting for a surgical procedure; these obese people may have an increased likelihood of having comorbid systemic diseases in addition to the problems inherent to being obese as outlined below. The type of obesity also matters for risk assessment. Android obesity (truncal) is associated with a higher incidence of cardiovascular diseases and is associated with higher resting oxygen consumption. Gynecoid obesity (buttocks and thighs primarily) is less associated with significant increases in oxygen consumption and less associated with cardiovascular disease.

A partial review of the organ system alterations follows:

• Respiratory: Increased oxygen consumption, increased carbon dioxide production, decreased resting lung volumes which fall even more in a supine position, decreased chest wall compliance, tidal volumes may be close to closing capacity leading to V/Q mismatch and perhaps right to left shunting. Severe pulmonary problems may be manifested by obesity hypoventilation syndrome or Pickwickian syndrome.
• Cardiovascular: Increased blood volume, increased plasma volume, increased cardiac output (via increased stoke volume not increased heart rate), increased splanchnic blood flow, hypertension, abnormal exercise or stress response which can be characterized by abrupt increased in cardiac output and can be accompanied by increased LVEDP and PCWP. Clearly if the patients also have concurrent CAD, the stress of the operation may be poorly tolerated.
• Endocrine: Increased incidence of glucose intolerance, hyperlipidemia.
• GI: Hiatus hernia, increased intrabdominal pressure, high residual gastric fluid volume with low pH, increased incidence of fatty liver (may have liver dysfunction post-intestinal bypass procedures), increased risk of aspiration.
• Airway: May be challenged, with limited flexion and extension, smaller mouth opening due to fatty tissue beneath chin, and redundant tissue within mouth limiting visualization.

Further useful information pertinent to caring for the obese patient:

• Pharmacology: Water-soluble drugs are less affected by increased volume of distribution than lipophilic drugs. Hepatic phase one metabolism should be unaffected, but phase two metabolism may be increased. Renal excretion may be increased. Benzodiazepines and thiopental may have increased volume of distribution and increased elimination half-life.
• OR preparation: Ensure adequately sized equipment (beds, BP cuffs, etc). Ensure adequate padding of extremities. Plan for difficulty in IV access. May consider intra-arterial BP measurement, as cuff may not be accurate nor reliable.
• Postop: Monitor for cardiac and pulmonary dysfunction. Postop hypoxia can last 4-6 days after an abdominal procedure so supplemental oxygen and oxygen monitoring are indicated. Beware of the risk of pulmonary embolism. Watch for hypoventilation with opioids.

In summary, there is no particular protocol for caring for the obese patient who presents for a gastroplasty at our institution. Careful preoperative assessment, careful planning of the OR setup, attention to the details of fluid and electrolyte shifts during an abdominal procedure and increased monitoring in the postoperative period are all important.

Reference:

1. Barash PG, Cullen BF, and Stoelting RK, Editors. Clinical Anesthesia, 3rd Edition Philadelphia, Lippincott-Raven: 1997.

Dr. Katherine Grichnik responds:

Note: most of the information in this response is from reference 1.

Laparoscopy is not a benign process. A third of complications with this procedure relate to the cardiopulmonary system. Cardiac arrhythmias are a well-known occurrence during laparoscopy. Many of the of cardiopulmonary effects result from hypercarbia and increased intraabdominal pressure. Intraabdominal pressure may range from 5-25 mm Hg.

Hypercarbia is induced by CO₂ insufflation. Increased ventilatory dead space, reduced diaphragmatic movement and decreased pulmonary CO₂ excretion can occur. On average, PaCO₂ increases by 10 mm Hg and pH decreases by 0.1. Hyperventilation is stimulated in spontaneously breathing patients. CO₂ can accumulate in the body and it may take several hours for PaCO₂ to return to normal. Significant hypercarbia (55-70 mm Hg) can increase HR, BP, CVP, CO, SV and a decrease in peripheral vascular resistance.

Hemodynamic effects induced by CO2 insufflation and resultant increases in intraabdominal pressure (IAP). An IAP of 15 mm Hg increases SVR, MAP, PAP, inferior vena caval pressure, with resultant falls in stroke volume. At an IAP of 20 mm Hg, right atrial pressure and intracranial pressure can rise. The inferior vena cava can be compressed with reduced venous return at an IAP of 40 mm Hg. A rise in afterload can occur also. All of these factors can reduce cardiac output. All of these effects are exacerbated in the hypovolemic patient.

Arrhythmias occur often but are often transient and without adverse effects. In one study, 47% of patients had arrhythmias [2]. Ventricular ectopic beats are the most common arrhythmias. Bradydysrhythmias are also common and may result in sinus arrhythmia and asystole. Atropine and reduction in the rate of CO₂ insufflation are effective. Arrhythmias were also shown to occur in infants who underwent laparoscopic procedures [3].

Some patients are unsuited for laparoscopy due to the hemodynamic effects of laparoscopy. These may include patients with severe cardiomyopathy, untreated CHF, and moderate to severe myocardial ischemia. Cardiac decompensation may occur 1.5 to 3 hours after CO₂ insufflation and thus usually occurs in the first postoperative hour.

Other complications which may ultimately result in cardiac dysrhythmias include pneumothorax, pneumomediastinum, pneumopericardium, gas embolus and significant hypoxemia.

Total IV anesthesia versus inhalational anesthesia have been examined and no difference in arrhythmias found [4].

References:

1. Sharma, KC et al. Laparoscopic Surgery and its potential for medical complications. Heart and Lung, The Journal of Acute and Critical Care. 1999;26:52-67
2. Myles PS. Bradyarrthymias and laparoscopy: A prospective study of heart rate changes with laparoscopy. Aust N Z J Obstet Gynaecol 1991 May;31(2):171-3. Link to abstract http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1834052&dopt=Abstract
3. Bozkurt P, et al. The cardiorespiratory effects of laparoscopic procedures in infants. Anaesthesia 1999;54:831-4. Link to abstract http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10460552&dopt=Abstract
4. Goodwin AP, et al. Day Case Laparoscopy. A comparison of two anaesthetic techniques using the laryngeal mask during spontaneous breathing. Anaesthesia 1992;47:892-5. Link to abstract http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1443487&dopt=Abstract

Dr. Beverly Philip responds:

A good way to know is to keep a record of what the surgeon has required in his recent operations, and do the same. If s/he has often required blood be transfused, then be prepared. Inexpert surgeons can have problems other than blood loss.

Dr. Richard Rosenquist responds:

Evaluation of pain in patients that are unable to communicate is difficult. As an initial attempt, the use of simplified pain measurement tools such as faces that range from happy to sad is one way to approach this problem. Changes in heart rate, blood pressure, sweating, restlessness, inability to rest or sleep, crying or grimacing are others. There are no perfect measures for evaluating pain in patients that have difficulty communicating for any reason. It is also useful to obtain input from family members that may have a better idea of the individuals baseline and any variations from that baseline. This is an issue that continues to attract the attention of healthcare providers but does not have a good answer at the present time.

Dr. David Lubarsky responds:

The best way to follow this is to attend/read the ASA review lectures on these topics. In a nutshell, new endovascular techniques are making open AAA repair less common. An arterial line for invasive monitoring and an epidural are all that are required. For open AAAs, an arterial line and CVP are minimal requirements. PA catheters, which we only employ on patients with poor LVEF or valvular disease, are optional, as are epidurals for post op pain relief, which we employ on >95% of our patients, usually using a T9-10 thoracic epidural and dilaudid. Aggressive beta-blockade is usually employed based on the results of the NEJM article by Poldermans et. al. (reviewed by me in an earlier issue of AWEB, and archived here. This short answer obviously is not all-inclusive as many issues - ischemia prevention/detection, renal protection, thoracic aneurysm spinal cord protection, etc. - are all chapters unto themselves.

Dr. Francine D’Ercole responds:

Based on a survey at our institution the following opinion regarding anti-platelet agents and regional anesthesia resulted in this statement:

We do not know of any case reports describing new anti-platelet agents. We do not perform neuraxial or peripheral nerve blockade on patients receiving Plavix or Ticlid or any other new generation platelet inhibitors unless the patient is extremely high risk (and the anesthesia providers are willing to accept the risk). However, regional anesthesia is performed on patients receiving such agents as aspirin, NSAIDs. The conservative approach for newer anti-platelet agents has been reinforced most likely because of the (hard lesson learned) tragic outcomes associated with the LMWH, Lovenox and neuraxial blockade.

Dr. Francine J. D’Ercole responds:

I strongly recommend acquiring the April 2000 issue of Techniques in Regional Anesthesia and Pain Management. This issue has a series of reviews/updates describing Combined Regional and General Anesthesia. Techniques in Regional Anesthesia and Pain Management 4(2): April 2000.Editor: William Urmey, MD

Dr. Katherine Grichnik responds:

I am not sure that there are legal issues concerning intraoperative use only of beta blockade. It is certainly the choice of the physician caring for the patient postoperatively as to whether to continue beta blockade or not. There are many good reasons to use beta blockade intraoperatively, especially to control hypertension and tachycardia with the stimulus of surgery. If you are concerned that the patient will/should not get beta blockade postoperatively, then a short-acting beta blocker such as esmolol can be used intraoperatively if you deem it indicated. If the patient is on beta blockers preoperatively and the plan is for postoperative use, then use of a longer acting beta blocker intraoperatively may be indicated. Of course, one must always review the patient's history for contraindications

Dr. Giuditta Angelini responds:

I think the best information to help you make a decision about residency programs is not found in published lists. These are always based on criteria like reputation, prominent physicians, publications, etc. They don't necessarily reflect good training. The best source of information is from Anesthesiology residents and staff in your own institution. I would solicit their opinions about programs that they would recommend and why. You are more likely to get information that is practical.

There are areas that many programs may be lacking, yet you are required to fulfill a certain amount of experience by ACGME requirements. Most places have problems in regional and pain. These include the following:

• of lumbar epidurals
• of thoracic epidurals
• of pump cases
• of regional blocks
• > of ambulatory cases
• of pediatric cases

These need to be in the range of 50-100, and the last two even more.

• Do they have a meaningful Pain Clinic experience?
• Do they have an Acute Pain Service?
• Do they have fellowship trained staff in the different subspecialties such as cardiac, neuro, pain, critical care, obstetrics, regional, pediatrics, ambulatory--this will allow you a balanced experience.
• What kind of teaching experience do you receive (conferences)?
• Do you have reading days?
• What is the ratio of resident to staff on average on a typical day? (More than 2 residents to one staff makes accessibility more dubious)
• Are you single staffed in the beginning while you become accustomed to being in the OR?
• Are you expected to respond to airway calls by yourself?
• What is the frequency of call? Who is on call with you? Is there a staff in house at all times?
• When you are senior, are you expected to run the OR board (deciding who gets to do what surgery and when)?

I would recommend checking out the website below, which has information on residency programs by state and also has some literature about getting into a residency for medical students: http://www.healthadvisor.com/resinfo.htm

Dr. Katherine Grichnik and Dr. Beverly Philip respond:

We have no knowledge about the preferred order of procedures to investigate the GI tract. The question should be referred to a gastroenterologist.

Dr. Katherine Grichnik responds:

Please refer to the excellent chapter in Clinical Anesthesia (3d Edition) on obesity from which most of this discussion was derived [1]. Obesity affects every major organ system, causing deviations from the norm in the anatomic, physiologic and biochemical properties of the body. Obesity is defined as greater than 20% above ideal body weight (IBW) or having a body mass index (BMI) of greater than 28. Morbid obesity is defined as being more than 45 kg over IBW or having a BMI >35. In the United States, 33% of the population can be defined as obese and of these, 3-5% are morbidly obese. Obese people have an increased risk of premature death due to the pathophysiology of being obese and they also have a higher risk of perianesthetic and perioperative complications. Most studies on obese people were done on obese people without other clinically identifiable concurrent disease processes. This may be unlike the population of obese people who are presenting for a surgical procedure; these obese people may have an increased likelihood of having comorbid systemic diseases in addition to the problems inherent to being obese as outlined below. The type of obesity also matters for risk assessment. Android obesity (truncal) is associated with a higher incidence of cardiovascular diseases and is associated with higher resting oxygen consumption. Gynecoid obesity (buttocks and thighs primarily) is less associated with significant increases in oxygen consumption and less associated with cardiovascular disease.

A partial review of the organ system alterations follows:

• Respiratory: Increased oxygen consumption, increased carbon dioxide production, decreased resting lung volumes which fall even more in a supine position, decreased chest wall compliance, tidal volumes may be close to closing capacity leading to V/Q mismatch and perhaps right to left shunting. Severe pulmonary problems may be manifested by obesity hypoventilation syndrome or Pickwickian syndrome.
• Cardiovascular: Increased blood volume, increased plasma volume, increased cardiac output (via increased stoke volume not increased heart rate), increased splanchnic blood flow, hypertension, abnormal exercise or stress response which can be characterized by abrupt increased in cardiac output and can be accompanied by increased LVEDP and PCWP. Clearly if the patients also have concurrent CAD, the stress of the operation may be poorly tolerated.
• Endocrine: Increased incidence of glucose intolerance, hyperlipidemia.
• GI: Hiatus hernia, increased intrabdominal pressure, high residual gastric fluid volume with low pH, increased incidence of fatty liver (may have liver dysfunction post-intestinal bypass procedures), increased risk of aspiration.
• Airway: May be challenged, with limited flexion and extension, smaller mouth opening due to fatty tissue beneath chin, and redundant tissue within mouth limiting visualization.

Further useful information pertinent to caring for the obese patient:

• Pharmacology: Water-soluble drugs are less affected by increased volume of distribution than lipophilic drugs. Hepatic phase one metabolism should be unaffected, but phase two metabolism may be increased. Renal excretion may be increased. Benzodiazepines and thiopental may have increased volume of distribution and increased elimination half-life.
• OR preparation: Ensure adequately sized equipment (beds, BP cuffs, etc). Ensure adequate padding of extremities. Plan for difficulty in IV access. May consider intra-arterial BP measurement, as cuff may not be accurate nor reliable.
• Postop: Monitor for cardiac and pulmonary dysfunction. Postop hypoxia can last 4-6 days after an abdominal procedure so supplemental oxygen and oxygen monitoring are indicated. Beware of the risk of pulmonary embolism. Watch for hypoventilation with opioids.

In summary, there is no particular protocol for caring for the obese patient who presents for a gastroplasty at our institution. Careful preoperative assessment, careful planning of the OR setup, attention to the details of fluid and electrolyte shifts during an abdominal procedure and increased monitoring in the postoperative period are all important.

Reference:

1. Barash PG, Cullen BF, and Stoelting RK, Editors. Clinical Anesthesia, 3rd Edition Philadelphia, Lippincott-Raven: 1997.

Dr. Katherine Grichnik and Dr. Beverly Philip respond:

We have no knowledge about the preferred order of procedures to investigate the GI tract. The question should be referred to a gastroenterologist.

Dr. Katherine Grichnik responds:

Please refer to the excellent chapter in Clinical Anesthesia (3d Edition) on obesity from which most of this discussion was derived [1]. Obesity affects every major organ system, causing deviations from the norm in the anatomic, physiologic and biochemical properties of the body. Obesity is defined as greater than 20% above ideal body weight (IBW) or having a body mass index (BMI) of greater than 28. Morbid obesity is defined as being more than 45 kg over IBW or having a BMI >35. In the United States, 33% of the population can be defined as obese and of these, 3-5% are morbidly obese. Obese people have an increased risk of premature death due to the pathophysiology of being obese and they also have a higher risk of perianesthetic and perioperative complications. Most studies on obese people were done on obese people without other clinically identifiable concurrent disease processes. This may be unlike the population of obese people who are presenting for a surgical procedure; these obese people may have an increased likelihood of having comorbid systemic diseases in addition to the problems inherent to being obese as outlined below. The type of obesity also matters for risk assessment. Android obesity (truncal) is associated with a higher incidence of cardiovascular diseases and is associated with higher resting oxygen consumption. Gynecoid obesity (buttocks and thighs primarily) is less associated with significant increases in oxygen consumption and less associated with cardiovascular disease.

A partial review of the organ system alterations follows:

• Respiratory: Increased oxygen consumption, increased carbon dioxide production, decreased resting lung volumes which fall even more in a supine position, decreased chest wall compliance, tidal volumes may be close to closing capacity leading to V/Q mismatch and perhaps right to left shunting. Severe pulmonary problems may be manifested by obesity hypoventilation syndrome or Pickwickian syndrome.
• Cardiovascular: Increased blood volume, increased plasma volume, increased cardiac output (via increased stoke volume not increased heart rate), increased splanchnic blood flow, hypertension, abnormal exercise or stress response which can be characterized by abrupt increased in cardiac output and can be accompanied by increased LVEDP and PCWP. Clearly if the patients also have concurrent CAD, the stress of the operation may be poorly tolerated.
• Endocrine: Increased incidence of glucose intolerance, hyperlipidemia.
• GI: Hiatus hernia, increased intrabdominal pressure, high residual gastric fluid volume with low pH, increased incidence of fatty liver (may have liver dysfunction post-intestinal bypass procedures), increased risk of aspiration.
• Airway: May be challenged, with limited flexion and extension, smaller mouth opening due to fatty tissue beneath chin, and redundant tissue within mouth limiting visualization.

Further useful information pertinent to caring for the obese patient:

• Pharmacology: Water-soluble drugs are less affected by increased volume of distribution than lipophilic drugs. Hepatic phase one metabolism should be unaffected, but phase two metabolism may be increased. Renal excretion may be increased. Benzodiazepines and thiopental may have increased volume of distribution and increased elimination half-life.
• OR preparation: Ensure adequately sized equipment (beds, BP cuffs, etc). Ensure adequate padding of extremities. Plan for difficulty in IV access. May consider intra-arterial BP measurement, as cuff may not be accurate nor reliable.
• Postop: Monitor for cardiac and pulmonary dysfunction. Postop hypoxia can last 4-6 days after an abdominal procedure so supplemental oxygen and oxygen monitoring are indicated. Beware of the risk of pulmonary embolism. Watch for hypoventilation with opioids.

In summary, there is no particular protocol for caring for the obese patient who presents for a gastroplasty at our institution. Careful preoperative assessment, careful planning of the OR setup, attention to the details of fluid and electrolyte shifts during an abdominal procedure and increased monitoring in the postoperative period are all important.

Reference:

1. Barash PG, Cullen BF, and Stoelting RK, Editors. Clinical Anesthesia, 3rd Edition Philadelphia, Lippincott-Raven: 1997.

Dr. Katherine Grichnik responds:

This answer is mostly taken from Goldman's article: "Cardiac Risk in Noncardiac Surgery: An Update" [1]. This is an article which addresses your questions well. Briefly, up until the 1970�s, elective noncardiac surgery was avoided for 3-6 months in patients who had suffered a myocardial infarction. This is because the risk of perioperative MI or cardiac death was thought to be 30% within 3 months of a MI and 15% within 6 months of a MI. However, subsequent data suggest far lower risks after elective noncardiac surgery especially in those with aggressive intraoperative and postoperative monitoring. Of note, the risks remained high for vascular surgery within 6 months of a MI. Thus the type of elective noncardiac surgery is important, as is the vigilance during the perioperative period. Little data is available about the risks to patients after a MI who have had TPA or PTCA. The range of risks for surgery after MI and the studies to support this data are presented in Dr. Goldman's article.

• Emergent and/or potentially life-saving surgery: Surgery needs to be done regardless of cardiac risk.
• Purely elective surgery: Delay for 3 months when the infarction is likely to be healed within that time and the patient is back to baseline functional status. Delay for 6 months if patient not fully recovered at 3 months. Consider noninvasive cardiac testing preoperatively.
• Urgent surgery which can be delayed but not for 3-6 months (severe vascular disease, resectable tumors, etc.): Undergo usual evaluation and rehabilitation after infarctions.

Patient without persistent signs and symptoms may have necessary noncardiac surgery 6 weeks to 3 months after MI if at their baseline functional status and if noninvasive cardiac evaluation allows. Persistent symptoms should be investigated; PTCA may be an option for these patients to achieve some revascularization without inordinate delay. Of course surgical intervention can be considered for those with persistent symptoms after which the necessary noncardiac surgery can be done.

Reference:

1. Goldman L. Cardiac Risk in Noncardiac Surgery: An Update. Anesthesia and Analgesia 1995;80(4) 810-20.

Dr. Richard Rosenquist responds:

I have no experience with this type of manipulation. I personally would be very hesitant to be involved with this group of health care practitioners performing manipulations under anesthesia, but this is not based on data. I have never seen this done at any of the 20 hospitals I have worked in during my career.

Dr. Katherine Grichnik responds:

I agree with Richard on this subject - I would not give anesthesia for a "manipulation". One cannot predict whether an adverse neurological or physical outcome may occur; such an event could possibly be blamed on the anesthetic when in fact it was due to the "manipulation". The patient loses the ability to voice severe pain or neurological abnormalities with an anesthestic, thus decreasing the "safety" of the "manipulation". I have never seen an anesthetic given for a chiropractic procedure.

Dr. Katherine Grichnik responds:

Renal disease can alter the concentration of plasma and tissue proteins, change protein binding, and change free drug concentrations. Further, many drugs and their metabolites are eliminated through the kidneys. This can result in an alteration of effect to a standard dose of a given drug and well as an altered duration of effect. Also, there can be marked inter-patient variability for a given drug, due to individual variability in protein binding, aging, coexisting disease states, temperature, and concurrently administered drug effects. Keep in mind as well that, since metabolic pathways can become saturated, longer effects will occur with infusions. Thus one must use with care any drug which is metabolized or excreted via a renal mechanism. Narcotics in particular may have an unanticipated prolonged effect in a patient with renal failure including undesired effects such as sedation, apnea, "narcosis," and seizures (with meperidine).

Some specific examples:

• Morphine undergoes glucuronidation to active metabolites, which are eliminated by the kidney. Renal failure patients have an unusual sensitivity to morphine and the metabolites may not be cleared well.
• Meperidine is metabolized to normeperidine, which is eliminated by the kidney. The accumulation of normeperidine can lead to seizures.
• Methadone is extensively protein bound (90%) and long acting respiratory depression can occur.
  

In summary, titration of narcotics to desired effects would seem appropriate. If you choose to use an infusion, beware of accumulation and saturation of the metabolic pathways. Avoidance or careful use of long-acting narcotics and those with active metabolites, which are cleared by the kidney, may also be considered.

References:

1. Barash PG, Cullen BF and Stoelting RK eds. Clinical Anesthesia 3rd Edition 1997, Lippincott-Raven, Philadelphia

I am currently a student at Southwest Missouri School of Anesthesia. I am writing a paper on the effects of hypotension intraoperatively and acute renal failure. Any suggestions on some good articles or resources? — Dean Losee

Dr. Katherine Grichnik responds:

Logically, maintenance of normal hemodynamic and volume status will be the most important methods for preventing acute renal failure. Avoidance of nephrotoxic drugs is also important. Of course, there are special circumstances such as cardiopulmonary bypass and supra-renal aortic cross-clamping, which can also lead to renal dysfunction.

I did do a literature search on this subject. The results are as follows:

1. Kribben A, et al. Pathophysiology of acute renal failure. Journal of Nephrology 1999;12S:S142-51
2. Bertolissi M. Prevention of acute renal failure in major vascular surgery. Minerva Anestesiologica 1999;65:867-77. Link to Abstract
3. Galley HF. Can Acute Renal Failure be prevented? Journal of the Royal College of Surgeons of Edinburgh 2000;45:44-50 Link to Abstract
4. Haller M and Schelling G. Acute kidney failure: Physiopathology, clinical diagnosis therapy. Anaesthesist 2000;49:349-52 Link to Abstract
5. Kohli HS, et al. Treatment-related acute renal failure in the elderly: a hospital-based prospective study. Nephrology, Dialysis and Transplantation. 2000;15:212-7
6. Evans TW and Smithies M. ABC of intensive care: Organ dysfunction. British Medical Journal. 1999;318:1606-9 Link to Abstract
   

As an orthopedic surgeon, I often become frustrated in the variability of the spinals administered for total joint replacements in my hospital. There are over 10 anaesthesiologists on staff. A few questions:

1. Are there any tricks to speed up the onset of action of a bupivacaine
   spinal. What factors are considered for judging the dose and concentration of bupivacaine? Is concomitant administration of epinephrine for a more dense spinal worthwhile?
   
   
2. When a patient exhibits motor function within 2 hours of a spinal, what went wrong? What is the optimal remedy when this occurs? My patients often gets Diprivan which often causes confusion and restlessness if not dosed well.
   
   
3. Why do some bupivacaine spinals result in a more sensory than motor
   block? What are the most common causes of failure of a bupivacaine spinal? In my humble opinion, the amount of residual motor function after a spinal can influence the outcome of a total joint procedure. When assessing the neck length for a total hip, we use the chuck test to determine stability of the hip joint. I've often found that this test is variable depending on when the test is performed. If the patient can move their ankle, the test usually shows that the hip is tight and vice versa. How can the SURGEON easily determine motor tone intraoperatively to help balance the tightness of the joint implanted? I am convinced that muscle tone during surgery and joint stability/instability has been poorly studied. Maybe a significant number of hip dislocations occur because the surgeon feels that the joint is tight intraoperatively but was fooled because there was excessive muscle tone.
   
   
4. When I do a knee scope, a general is administered but no muscle relaxant is usually given. If the knee joint is tight, I ask for a muscle relaxant but by that time the tourniquet has been inflated. Isn't this a problem? —Dr. Mike Messieh

Dr. Francine D'Ercole responds:

My institution has no requirements for OR temperature and the ASA has no standard for OR temperature. I don't know of any standards for this. I included an answer to a similar question on OR temperature posted previously.

Operating room temperature is critical because heat is lost by radiation and convection from the skin and surgical incisions. Unfortunately, I could find no consensus about and ideal temperature for an OR. In our facility, when it is imperative to keep a patient as close to a normal body temperature as possible (vascular surgical cases, off-pump cardiac bypass cases, pediatric cases, etc), the operating room temperature is kept well above 70 degrees F (21 degrees C), or as warm as necessary to prevent hypothermia in the patient. All measures are taken to prevent hypothermia including warming IV fluids, forced air heating, and heated/humidified inspiratory gases. Certainly age, extent of surgery, extent of exposed tissue and comorbid disease states all should influence the amount of hypothermia a patient is at risk of and thus the aggressiveness of the measures needed to prevent hypothermia. Despite the knowledge that significant hypothermia is detrimental to many patients, so far as I know there is not a set temperature which is standard for the operating rooms. Three interesting studies are briefly presented below. Roizen et al. [1] examined OR temperature and its relationship to patient temperature and/or shivering the vascular surgery patient. They examined the effect of a cold room versus a warm room prior to draping, but subsequently treated all patients with warm IV fluids, and a heating blanket. There were no differences in temperature in the recovery room, shivering, and other morbidity. They concluded that with active warming efforts, the OR temperature could be kept at a temperature comfortable for the OR personnel without detriment to patient care.

Frank et al. [2] attempted to examine the effect of room temperature and type of anesthesia on patient temperature. They major correlates of a greater intraoperative decrease in temperature were:

• general anesthesia
• cold ambient OR temperature
• advancing patient age

There was a greater decrease in body temperature with general versus epidural anesthesia in a cold OR but similar decreases between the two groups in a warm OR. Borms et al. [3] studied the effect of forced air warming versus reflective insulation in patients undergoing total hip arthroplasty. Those with forced air warming increased their temperatures during surgery and those with reflective insulation continued to decline with respect to core temperature.

References:

1. Roizen MF, et al. Operating room temperature prior to surgical draping: effect on patient temperature in recovery room. Anesthesia and Analgesia 59:852:1980
   
2. Frank SM et al. Epidural versus general anesthesia, ambient operating room temperature, and patient age as predictors of inadvertent hypothermia. Anesthesiology 77:252; 1992
   
3. Borms SF, et al. Bair hugger forced-air warming maintains normothermia more effectively than thermolite insulation

Toradol: What would be the "upper limit dosage" for healthy orthopedic analgesia post-operative IV? The literature says 30 mg IV, but 60 seems to work much better. What do you say?
--Merlyn Erickson, CRNA

Dr. Katherine Grichnik responds:

I do not know of any differences in efficacy between the two doses but 60 mg is far too toxic. Most practitioners now only use 30 mg in young healthy individuals for a short time. Five days of 30mg q 6 will result in 79% having significant gastric erosions.

Also, anyone performing interscalene block for shoulder surgery should know the following reference. The authors reported a 4% frequency of neurologic injury following total shoulder arthroplasty reviewing 368 patients. The article identifies various risk factors associated with neurologic injury. The presumed mechanism of injury was traction on the plexus during surgery:

Dr. Grichnik responds:

Here are several good references:

These articles point out that you must understand the pharmacology of heparin. It has a greater bio-availability when given IV vs SC. The dose of heparin has a profound effect on the duration of the clinical effect. And there is a significant variability of patients? responses to a given dose of heparin. For instance, up to 15% of patients given 5000 U of heparin SC will have up to a 50% increase in their aPPT, and about 2% of patients will become therapeutically anticoagulated if given this dose q12h.

To date in the literature, there are only four cases reported of epidural hematoma in patients concurrently receiving low dose SC heparin (LDSCH) thromboprophylaxis and continuous epidural analgesia/anesthesia. And it is unknown whether the risk of epidural hematoma is increased with LDSCH. However, the American Society of Regional Anesthesia (ASRA) consensus guidelines suggests delaying the administration of heparin until one hour AFTER the placement of a neuraxial block.

In addition they state that prolonged therapeutic anticoagulation does appear to increase the risk of spinal hematoma formation.

As you can see, there is significant concern about the combination of heparin and neuraxial blockade. So, without knowing the heparin-dosing schedule, nor the resultant anticoagulant effect, it is difficult to answer your questions specifically. However, I wish to restate that the proof of safety clearly rests with the physician who wishes to introduce this relatively uncommon IV heparin therapy into your epidural practice.

  -- Nancy Montgomery

Dr. Dwane responds:
As I understand the political process, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) outlines the requirements for hospital accreditation on a national level and specifies that hospitals' governing bodies provide for collaboration of leaders in developing, reviewing, and revising policies and procedures.

To facilitate this process for their members, various professional organizations have published guidelines/standards:

…to mention a few.
Then each state licensing body may also issue standards, guidelines, or statements which may impact on the policies and procedures of their licensees.

Finally, the local hospital committee dealing with the specific policies and procedures would look to local practice standards of their colleagues and to local teaching and non-teaching hospitals to define the specific requirements of their patients for their specific health care unit.

Were I on such a committee in California I would refer to the ASA guidelines for Anesthesia and Obstetrics as well as the AWHONN standards and guidelines with specific reference to monitoring of the patient before, during and after the establishment of epidural analgesia for labor. I would also be aware of any state regulations which might impact the policy.

References:

1. Horlocker TT, Wedel DJ. Spinal and epidural blockade and perioperative low molecular weight heparin: smooth sailing on the Titanic. Anesth Analg. 1998:86:1153-6.

2. Horlocker TT, Wedel DJ, Schlichting JL. Postoperative epidural analgesia and oral anticoagulant therapy. Anesth Analg. 1994; 79:89-93.

3. Wu CL, Perkins FM: Oral anticoagulant prophylaxis and epidural catheter removal. Regional Anesth. 1996; 21: 517-24.

4. Vandermeulen EP, Van Aken H, Vermylen J. Anticoagulants and spinal-epidural anesthesia. Anesth Analg. 1994;79:1165-77.