SAMBA Talks eNewsletter

Volume 3, Issue 3

S A M B A T A L K S

August, 2003

JOIN THE DISCUSSION: NOW AVAILABLE HERE! - TOP

To optimize the educational experience and encourage more extensive discussion among practitioners involved with anesthesia for ambulatory surgery, the Professional Discussion has been moved from the SAMBA website to SAMBA TALKS. To enter the Discussion with a question, reply, or other comment, click here. Your question/reply/comment will be published in this section of the next edition of SAMBA TALKS. Initials and location (city and state) will be included, unless you request otherwise.

?? - PREVIOUS QUESTIONS AND REPLIES - ??

QUESTION:

"A woman has been on lithium for 10 years. Her mother states that she cannot be off it for more than 3 days, but her surgeon requests that she be off it for 2 weeks. What is the safe time frame to be off this medication before surgery?"

-- From L.S., Louisiana

REPLY:

"While the surgeon should be commended for taking a conservative course, this may a case of "mother knows best". Although some authorities recommend discontinuing lithium for 2 weeks before ECT because it may interfere with the therapeutic effectiveness of the ECT, and increase the incidence and severity of memory loss, I am aware of no literature which supports discontinuing the drug before elective surgery. Indeed, for the patient with a severe manic-depressive disorder, maintaining the drug may be critical in preventing life-threatening actions potentially associated with relapse into a manic state."

"Nevertheless, there are several considerations which one must be aware of when providing anesthesia to patients receiving lithium therapy: potential prolongation of neuromuscular blockade (established for succinylcholine and pancuronium; not studied for the newer agents); possible potentiation of the action of sedative/hypnotics (established for barbiturates and diazepam; not studied for propofol, midazolam, or other newer agents); potential cardiac arrhythmias and conduction abnormalities (documented in lithium toxicity; one case report of atropine-resistant bradycardia during anesthesia with propofol and fentanyl); and the possibility of hypothyroidism and nephrogenic diabetes insipidus precipitated by the lithium therapy."

"In the case described above, I would suggest that these anesthetic considerations be discussed with the mother so that she is aware of the importance of the situation, and then the mother's opinion of the maximum duration her daughter can have the lithium discontinued before surgery should be followed. (Manic-depressive patients themselves are notoriously unreliable in assessing their own need for therapy and should not be relied upon to make this decision). "

-- From D.D., Houston, TX

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QUESTION:

"I am being besieged by the morbidly obese with diagnosed or suspected sleep apnea. I am familiar with Dr. Benumof's ASA Refresher Course article and several letters to the editor. I am also aware that this subject will be discussed at the upcoming SAMBA meeting. I am having difficulty putting together a policy re: sleep apnea. Does anyone have anything that might help me?"

-- From S.R., Dallas, TX

REPLY 1:

"Unfortunately there is very little data available which helps us develop evidence-based protocols for the management of OSA patients. The vast majority of published information is either retrospective reviews, case reports, or opinion. We do know that the number of patients with OSA is expected to increase 5-10 fold over the next decade so this problem is not going away. It is estimated that 4% of middle-aged males and 2% of females have OSA and 80-90% of patients have not been diagnosed."

"Patients with OSA are at increased risk for perioperative problems including difficult intubation, postoperative hypoxia, hypercarbia, ischemia and reintubation. There are 19 cases of patients with OSA in the ASA closed claims database. In 18/19 cases, the patient sustained brain damage or death related to adverse respiratory system events. There is a recent report in the Anesthesia Patient Safety Foundation Newsletter (Lofsky APSF Newsletter 2002;17:24-5) describing 8 cases of "unexplained" postoperative cardiopulmonary arrests. All patients received parenteral narcotics and were ultimately diagnosed with OSA."

"Treatment of OSA with nCPAP may dramatically improve BP control and symptoms of heart failure. None of the case reports of sudden death or cardiorespiratory arrest involved patients wearing nCPAP. One study (Rennotte et al Chest 1995;107:367-74) described 14 consecutive patients effectively treated with nCPAP for 3 weeks preop, nearly continuously postop for 24 hrs and then for all sleep periods. There were no major complications despite the use of opioid analgesics. This highlights the importance of screening patients for symptoms of OSA preoperatively so they can be studied and treated before surgery."

"Although there is no data correlating severity of OSA with complications, most authors feel it is reasonable to consider severity of OSA when formulating a management plan. Similarly, the anesthetic technique has not been studied to determine its influence on complications. Regional anesthesia may have advantages by circumventing airway difficulties and limiting the need for sedative and analgesic medications. However, the type of surgery and need for postoperative opioid analgesics is probably more important than the type of anesthetic."

"It is not known which OSA patients can safely undergo ambulatory surgery. The recent paper in A&A (Sabers et al Anesth Analg 2003;96:1328-35) found no difference in unexpected admission rates or complications between OSA and weight-matched controls. However, there are several problems with this retrospective study. There was a very high unanticipated admission rate (24%), the controls were obese and not screened for symptoms of OSA, the OSA group was a mixture of treated and untreated and there was no information about complications for patients who were sent home. There are several papers expressing opinions (Tung and Rock Curr Opin Anaesth 2001;14:671-678 and Benumof J Clin Anesth 2001;13:144-156) and one paper that proposes a protocol for management of OSA patients (Deutscher et al APSF Newsletter 2002;17:58). Ultimately, each institution needs to develop guidelines for management of these patients. I think it is imperative that patients are screened preoperatively for symptoms of OSA and elective surgery postponed until they can be assessed and treated. Adequately treated OSA patients may be considered for ambulatory surgery if they are having minor surgery with minimal need for postoperative analgesics, are alert and are willing and able to use nCPAP themselves at home for all sleep periods."

-- From Janet van Vlymen, MD, FRCPC, Kingston, Ontario, Canada

REPLY 2:

"Any discussion really depends on the type of facility you practice in. I would not allow surgery involving the airway in these patients if I worked in a free standing unit. I feel that these patients should be admitted over-night after general anesthesia and airway surgery. As you know they can be difficult intubations. Most are not. But when these patients are difficult intubations they can be very difficult. Our policy is to approach these patients very cautiously. When in doubt, admit overnight. Their recovery from general anesthesia is often stormy. Sitting them up immediately after extubation helps. Expect lower oxygen saturations early. They usually improve with time. These patients can die in the postoperative period. They are especially sensitive to morphine."

"We do surgery on several of these patients every week. Most do well. However, some are challenging postop problems. If you don't want to get hung up in the PACU occasionally, don't do them."

-- From: Grover R. Mims, MD, Winston-Salem, NC

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?? - THIS MONTH'S QUESTION - ??

"I am an anesthesiologist in New Orleans at an outpatient center. A surgeon in the group where I work is starting to do thyroid surgery there. This includes both subtotal and total thyroidectomies where the patient goes home the same day (not a 23 hr. stay). What are your views on outpatient thyroid surgery?"

-- From D.M., New Orleans, LA

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SAMBA TALKS: SPANISH VERSION - TOP

SAMBA TALKS is now available in Spanish! You may view the Spanish version on the SAMBA website. If you would like to subscribe to the Spanish SAMBA TALKS and receive notice by email when the current edition is available, please click here. SAMBA TALKS is available to SAMBA members, as well as nonmembers. If you have a colleague in Latin America whom you believe would benefit from this electronic newsletter, please forward this copy of SAMBA TALKS to them.

FROM THE LITERATURE: - TOP

CANADIAN JOURNAL OF ANESTHESIA - TOP

Absence of adverse outcomes in hyperkalemic patients undergoing vascular access surgery
Ronald P. Olson, MD, Adam J. Schow, MD, Richard McCann, MD, David A. Lubarsky, MD MBA and Tong J. Gan, MD
Canadian Journal of Anesthesia 50:553-557 (2003)

Purpose: The decision to cancel vascular access surgery because of hyperkalemia requires knowledge of the risks vs benefits. This study sought to identify and characterize cases where surgery had been performed in patients with uncorrected hyperkalemia.
Methods: One thousand four hundred and seventy-two consecutive cases of vascular access surgery at an academic medical centre between 1995 and 2000 by a single surgeon were analyzed retrospectively.
Results: Eight cases had clear documentation that the case proceeded with hyperkalemia. Anesthesia techniques were one general anesthetic, one regional block, five monitored anesthesia care (MAC), and one local infiltration only. Mean potassium was 6.9 mmol•L^-1 (range 6.1–8.0). In this series of selected asymptomatic hyperkalemic patients undergoing low risk surgery, no adverse results occurred.
Conclusion: While this review of eight cases (only one receiving general anesthesia) cannot be used to prove the safety of proceeding to surgery with uncorrected hyperkalemia, it does suggest that asymptomatic hyperkalemia may not be an absolute contraindication to vascular access surgery.

Use of a new videolaryngoscope (GlideScope®) in the management of a difficult airway
Richard M. Cooper, BSc MSc MD FRCPC
Canadian Journal of Anesthesia 50:611-613 (2003)

Purpose: To describe the clinical use of a new videolaryngoscope in a patient who had repeatedly been difficult or impossible to intubate by conventional direct laryngoscopy. This device provided excellent glottic visualization and permitted easy endotracheal intubation.
Clinical features: A 74-yr-old male presenting for repeat elective surgery had a history of failed intubations by direct laryngoscopy and pulmonary aspiration with a laryngeal mask airway. He refused awake flexible fibreoptic intubation. After the induction of general anesthesia, laryngoscopy was performed using a GlideScope®. This provided complete glottic exposure and easy endotracheal intubation.
Conclusion: This new videolaryngoscope provided excellent laryngeal exposure in a patient whom multiple experienced anesthesiologists had repeatedly found to be difficult or impossible to intubate using direct laryngoscopy. The clinical role of this device awaits confirmation in a large series of difficult airways.

BRITISH JOURNAL OF ANAESTHESIA - TOP

The upper airway during anaesthesia (Review Article)
D. R. Hillman, P. R. Platt and P. R. Eastwood
Br J Anaesth 2003; 91: 31–9

Upper airway obstruction is common during both anaesthesia and sleep. Obstruction is caused by loss of muscle tone present in the awake state. The velopharynx, a particularly narrow segment, is especially predisposed to obstruction in both states. Patients with a tendency to upper airway obstruction during sleep are vulnerable during anaesthesia and sedation. Loss of wakefulness is compounded by depression of airway muscle activity by the agents, and depression of the ability to arouse, so they cannot respond adequately to asphyxia. Identifying the patient at risk is vital. Previous anaesthetic history and investigations of the upper airway are helpful, and a history of upper airway compromise during sleep (snoring, obstructive apnoeas) should be sought. Beyond these, risk identification is essentially a search for factors that narrow the airway. These include obesity, maxillary hypoplasia, mandibular retrusion, bulbar muscle weakness and specific obstructive lesions such as nasal obstruction or adenotonsillar hypertrophy. Such abnormalities not only increase vulnerability to upper airway obstruction during sleep or anaesthesia, but also make intubation difficult. While problems with airway maintenance may be obviated during anaesthesia by the use of aids such as the laryngeal mask airway (LMA ), identification of risk and caution are keys to management, and the airway should be secured before anaesthesia where doubt exists. If tracheal intubation is needed, spontaneous breathing until intubation is an important principle. Every anaesthetist should have in mind a plan for failed intubation or, worse, failed ventilation.

ANESTHESIA AND ANALGESIA - TOP

The Effects of Common Airway Maneuvers on Airway Pressure and Flow in Children Undergoing Adenoidectomies
Heinz Bruppacher, MD, Adrian Reber, MD PhD, Jürg P. Keller, PhD, Jeremy Geiduschek, MD, Thomas O. Erb, MD MHS, and Franz J. Frei, MD
Anesth Analg 2003;97:29-34

Obstruction of the upper airway occurs frequently in anesthetized, spontaneously breathing children, especially in those with adenoidal hyperplasia. To improve airway patency, maneuvers such as chin lift (CL), jaw thrust (JT), and continuous positive airway pressure (CPAP) are often used. In this study, we examined the comparative efficacy of these maneuvers in children scheduled to undergo adenoidectomy. Sixteen children aged 2–9 yr were anesthetized with sevoflurane. During spontaneous breathing, the flows and pressures in the mask (ma), oropharynx (op), and esophagus (es) were measured simultaneously, and maximal pressure differences during inspiration (P) were calculated. After baseline recording, CL and JT maneuvers were performed in random order without and with CPAP (5 cm H₂O). The observed P_ma - P_es of 12.3 ± 3.4 cm H₂O at baseline decreased with all airway maneuvers (P < 0.05). This resulted from decreases of P_ma - P_op (P < 0.05) and P_op - P_es (P < 0.05) in all interventions except CL, in which P_ma - P_op remained similar. In contrast, significant improvements of minute ventilation and maximal inspiratory peak flow (P > 0.05) were observed only with JT (with and without CPAP). We conclude that CL may improve airway patency and ventilation, whereas JT with or without CPAP was the most effective maneuver to overcome airway obstruction in children with adenoidal hyperplasia.
IMPLICATIONS: Airway maneuvers are often used in anesthetized children to relieve airway obstruction during spontaneous ventilation. Compared with chin lift and continuous positive airway pressure, the jaw thrust maneuver was the most effective to improve airway patency and ventilation in children undergoing adenoidectomy.

Consensus Guidelines for Managing Postoperative Nausea and Vomiting
Tong J. Gan, MD, Tricia Meyer, MS FASHP, Christian C. Apfel, MD, Frances Chung, FRCPC, Peter J. Davis, MD, Steve Eubanks, MD, Anthony Kovac, MD, Beverly K. Philip, MD, Daniel I. Sessler, MD, James Temo, CRNA MSN, MBA, Martin R. Tramèr, MD DPhil, and Mehernoor Watcha, MD
Anesth Analg 2003;97:62-71

IMPLICATIONS: We present evidence-based guidelines developed by an international panel of experts for the management of postoperative nausea and vomiting.

Subarachnoid Small-Dose Bupivacaine Versus Lidocaine for Cervical Cerclage
Yaakov Beilin, MD, Jeffrey Zahn, MD, Sharon Abramovitz, MD, Howard H. Bernstein, MD, Sabera Hossain, MS, and Carol Bodian, DrPH
Anesth Analg 2003;97:56-61

Cervical cerclage is often performed as an outpatient procedure under subarachnoid anesthesia. Lidocaine was historically the drug of choice for short procedures but has fallen out of favor because of concerns of transient neurologic symptoms (TNS). We performed this study to determine whether small-dose bupivacaine is an acceptable alternative to lidocaine for cervical cerclage. We randomized 59 women to receive either subarachnoid isobaric lidocaine 30 mg or hyperbaric bupivacaine 5.25 mg. Fentanyl 20 mcg was added to both local anesthetics, and the total volume was diluted to 3 mL with 0.9% saline. Onset and highest dermatomal level of sensory block; quality of anesthesia; hypotension; and times until T12 regression, return of lower extremity motor function, ambulation, and micturition were recorded. Symptoms of TNS were evaluated by telephone interview 24 h after surgery. We did not find any significant difference in onset or recovery times between the groups, with the exception of a longer duration until return of lower extremity motor strength in the lidocaine group. Symptoms consistent with TNS that resolved spontaneously within 48 h were reported by two women in the lidocaine group but by none in the bupivacaine group. We conclude that subarachnoid bupivacaine offers a satisfactory alternative to subarachnoid lidocaine for cervical cerclage.
IMPLICATIONS: We found that small-dose subarachnoid bupivacaine (5.25 mg) with fentanyl 20 mcg provides reliable anesthesia for cervical cerclage and exhibits a pharmacodynamic profile similar to that of small-dose lidocaine.

ANESTHESIOLOGY - TOP

Effect of Prophylactic Bronchodilator Treatment with Intravenous Colforsin Daropate, a Water-soluble Forskolin Derivative, on Airway Resistance after Tracheal Intubation
Zen'ichiro Wajima, M.D., Ph.D.; Toshiya Shiga, M.D., Ph.D.; Tatsusuke Yoshikawa, M.D., Ph.D.; Akira Ogura, M.D., Ph.D.; Kazuyuki Imanaga, M.D.; Tetsuo Inoue, M.D., Ph.D.; Ryo Ogawa, M.D., Ph.D.
Anesthesiology 2003; 99(1):18-26

Background: After induction of anesthesia, lung resistance increases. The authors hypothesized that prophylactic bronchodilator treatment with intravenous colforsin daropate, a water-soluble forskolin derivative, before tracheal intubation would result in decreased lung resistance and increased lung compliance after tracheal intubation when compared with placebo medication.
Methods: Forty-six adult patients were randomized to placebo or colforsin daropate treatment. Patients in the control group received normal saline; patients in the colforsin group received 0.75 mcg · kg^-1 · min^-1 colforsin daropate intravenously until the study ended. Thirty minutes after the study began, the authors administered 5 mg/kg thiamylal and 5 mcg/kg fentanyl for induction of general anesthesia and 0.3 mg/kg vecuronium for muscle relaxation. A 15-mg · kg^-1 · h^-1 continuous infusion of thiamylal followed anesthetic induction. Four, 8, 12, and 16 min after tracheal intubation, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured.
Results: Patients in the colforsin group had significantly lower Rawm and Rawe and higher Cdyn after intubation than those in the control group. Differences in Rawm, Rawe, and Cdyn between the two groups persisted through the final measurement at 16 min. At 4 min after intubation, smokers had a higher Rawm and a lower Cdyn than nonsmokers in the control group. After treatment by intravenous colforsin daropate, Rawm, Rawe, and Cdyn values were similar for smokers and nonsmokers after tracheal intubation.
Conclusions: Prophylactic treatment with colforsin daropate produced lower Rawm and Rawe and higher Cdyn after tracheal intubation when compared with placebo medication. Pretreatment before intubation may be beneficial and advantageous for middle-aged smokers.

Narcotrend Monitoring Allows Faster Emergence and a Reduction of Drug Consumption in Propofol-Remifentanil Anesthesia
Sascha Kreuer, M.D.; Andreas Biedler, M.D.; Reinhard Larsen, M.D.; Simone Altmann, B.S.; Wolfram Wilhelm, M.D., D.E.A.A.
Anesthesiology 2003; 99(1):34-41

Background: The Narcotrend is a new electroencephalographic monitor designed to measure depth of anesthesia, based on a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages. This study was designed to investigate the impact of Narcotrend monitoring on recovery times and propofol consumption in comparison to Bispectral Index® (BIS®) monitoring or standard anesthetic practice.
Methods: With institutional review board approval and written informed consent, 120 adult patients scheduled to undergo minor orthopedic surgery were randomized to receive a propofol-remifentanil anesthetic controlled by Narcotrend, by BIS®, or solely by clinical parameters. Anesthesia was induced with 0.4 mcg · kg^-1 · min^-1 remifentanil and a propofol target-controlled infusion at 3.5 mcg/ml. After intubation, remifentanil was reduced to 0.2 mcg · kg^-1 · min^-1, whereas the propofol infusion was adjusted according to clinical parameters or to the following target values: during maintenance to D0 (Narcotrend) or 50 (BIS®); 15 min before the end of surgery to C1 (Narcotrend) or 60 (BIS®). Recovery times were recorded by a blinded investigator, and average normalized propofol consumption was calculated from induction and maintenance doses.
Results: The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS® monitoring needed significantly less propofol (standard practice, 6.8 ± 1.2 mg · kg^-1 · h^-1 vs. Narcotrend, 4.5 ± 1.1 mg · kg^-1 · h^-1 or BIS®, 4.8 ± 1.0 mg · kg^-1 · h^-1; P < 0.001), opened their eyes earlier (9.3 ± 5.2 vs. 3.4 ± 2.2 or 3.5 ± 2.9 min), and were extubated sooner (9.7 ± 5.3 vs. 3.7 ± 2.2 or 4.1 ± 2.9 min).
Conclusions: The results indicate that Narcotrend and BIS® monitoring are equally effective to facilitate a significant reduction of recovery times and propofol consumption when used for guidance of propofol titration during a propofol-remifentanil anesthetic.

Psoas Abscess Complicating Femoral Nerve Block Catheter
Frédéric Adam, M.D.; Souhail Jaziri, M.D.; Marcel Chauvin, M.D.
Anesthesiology 2003; 99(1):230-231

CONTINUOUS three-in-one blockade is widely used for providing postoperative analgesia after knee surgery. Distinct serious complications have been described after femoral nerve block: neurologic injury as well as hematoma compressive and epidural anesthesia. We report a case of psoas abscess complicating a continuous three-in-one blockade.
Discussion: The main infectious complication reported after a regional nerve block technique is the uncommon but potentially deleterious epidural abscess. Recently, it was shown that after 48 h, 57% of femoral nerve catheters had positive bacterial colonization; however, no patient developed an abscess. In our patient, a culture was not performed on the catheter because on the day of removal the patient reported no discomfort. Yet S. aureus found with computed tomographic scan puncture is the most common causative organism cultured from epidural abscess after epidural anesthesia. Pyogenic psoas abscesses are most often associated with vertebral osteomyelitis or Crohn disease. In our patient, the abscess probably resulted from catheter colonization at a superficial site and subsequently wicked the infection from the skin to the psoas space. This case illustrates the importance of the golden aseptic rules during puncture and catheter insertion for regional anesthesia. In any patient who shows an infectious syndrome and has or has had a continuous nerve block, the possibility of a complication of regional anesthesia should be considered until proof of the contrary, even if the patient had no evidence of superficial infection at the catheter insertion site.

ACTA ANAESTHESIOLOGICA SCANDINAVICA - TOP

ACE inhibition does not exaggerate the blood pressure decrease in the early phase of spinal anaesthesia
C. Höhne, L. Meier, W. Boemke and G. Kaczmarczyk
Acta Anaesthesiologica Scandinavica Volume 47 Issue 7 Page 891-6

Background: This study investigates whether long-term treatment with an angiotensin converting enzyme inhibitor (ACEI) impairs the hemodynamic regulation during the early phase of spinal anaesthesia.
Methods: Forty-two patients undergoing minor surgery were studied. Twenty-one patients were long-term treated (ACEI group), while the other patients served as controls (nonACEI group). All patients received a balanced electrolyte solution(6 ml kg -1) 20 min before spinal anaesthesia.
Results: Mean arterial blood pressure decreased 19% in both groups within 20 min after spinal anaesthesia. Heart rate did not change in either group. Plasma renin concentration increased from 7.3 ± 2.1 to 12.8 ± 4 pg ml ^-1 during spinal anaesthesia in nonACEI patients (P < 0.05), whereas an elevated plasma renin level remained unchanged in the nonACEI group. The angiotensin II concentration increased in both groups during spinal anaesthesia (P < 0.05). The vasopressin concentration did not change during spinal anaesthesia in the ACEI group, but increased from 1.2 ± 0.3 to 2.2 ± 0.5 pg ml ^-1 in patients with ACEI treatment (P < 0.05). The norepinephrine concentration increased transiently 5 min after spinal anaesthesia in both groups, and returned to baseline levels within 15 min.
Conclusion: Long-term ACEI treatment does not further exaggerate the blood pressure decrease in the early phase of spinal anaesthesia. The increase in vasopressin concentrations in ACEI treated patients seems to be sufficient to compensate for the inhibited renin-angiotensin system. In addition, the transient increase in plasma norepinephrine, which occurs independent of preoperative ACEI treatment, seems to be involved in blood pressure regulation during spinal anaesthesia.

Cardiac arrest after interscalene brachial plexus block with ropivacaine and lidocaine (Case Report)
M. Reinikainen, A. Hedman, O. Pelkonen and E. Ruokonen
Acta Anaesthesiologica Scandinavica Volume 47 Issue 7 Page 904 -6

Serious adverse reactions to ropivacaine and lidocaine are rare. In this report, we describe a case of sudden cardiac arrest after an interscalene brachial plexus block with a mixture of 150 mg of ropivacaine and 360 mg of lidocaine in a previously healthy, 34-year-old, 97-kg man. Severe hypotension occurred after successful resuscitation, necessitating an infusion of epinephrine. The patient developed pulmonary oedema, and was mechanically ventilated for 22 h. He eventually made a good recovery. We conclude that although ropivacaine and lidocaine are often considered relatively safe local anesthetics, serious cardiovascular complications can occur after the use of these drugs.

Dexamethasone is as effective as ondansetron for the prevention of postoperative nausea and vomiting following breast surgery
M. Wattwil, S-E. Thörn, Å. Lövqvist, L. Wattwil, A. Gupta and G. Liljegren
Acta Anaesthesiologica Scandinavica Volume 47 Issue 7 Page 823-827

Introduction: Postoperative nausea and vomiting remain a common problem following breast surgery. This study assesses whether dexamethasone is as effective as ondansetron in the control of postoperative nausea and vomiting (PONV).
Methods: Eighty ASA I-III patients undergoing breast surgery for carcinoma of the breast were included in the study. Following premedication with diazepam 5-10 mg, patients were induced with fentanyl 50 µg and propofol 2-2.5 mg kg ^-1. A larynx mask was inserted and anesthesia maintained with sevoflurane in oxygen and nitrous oxide. Patients were then randomly divided into two groups: Group D (dexamethasone) was given 4 mg dexamethasone i.v. after induction and Group O (ondansetron) was given 4 mg ondansetron at the same time point. Postoperatively, nausea, vomiting and pain were recorded at 1-h intervals during 4 h, and thereafter every 4 h during 24 h.
Results: The incidence of PONV during 24 h was 37% and 33% in Group D and Group O, respectively (NS). No differences were found between the groups in the incidence of postoperative nausea, vomiting or pain at the different time intervals. No differences were found in the incidence of PONV in smokers vs. non-smokers. No side-effects of these drugs were observed.
Conclusions: Ondansetron 4 mg or dexamethasone 4 mg are equally effective in the prevention of postoperative nausea and vomiting following breast surgery. Other factors being similar, the difference in cost between these drugs would favor the use of dexamethasone instead of ondansetron when monotherapy against PONV is used.

Use of the laryngeal tube in 100 patients
T. Asai, K. Shingu and T. Cook
Acta Anaesthesiologica Scandinavica Volume 47 Issue 7 Page 828-32

Background: The laryngeal tube has a potential role during anaesthesia, but there have been only a few studies assessing its efficacy during the entire course of anaesthesia, and all previous studies used prototypes. We studied 100 patients to assess the efficacy of a new laryngeal tube during the entire course of anaesthesia.
Methods: After induction of anaesthesia, the laryngeal tube was inserted (up to two times) and adequacy of ventilation was assessed. The airway pressure at which gas leaked around the device was measured. The device was used during anaesthesia, while ventilation was controlled. The device was removed after the patient had opened the mouth to verbal command. Any complications during and after anaesthesia were recorded.
Results: Ventilation was possible at the first attempt in 90 patients, at the second attempt in another seven patients, and adequate ventilation failed after two attempts in three patients. Median (interquartile range) leak pressure was 28 (22-30) cmH₂O. In all 97 patients, the laryngeal tube was used until the end of surgery. However, in two of the 97 patients the airway was partially obstructed during anaesthesia and it was necessary to reposition the device. The laryngeal tube was tolerated well during emergence from anaesthesia. No hypoxia, regurgitation, vomiting or laryngospasm occurred in any patient. On removal of the laryngeal tube, no blood was detected on the device and no apparent ischaemic changes to the tongue were observed in any patient. Post-operatively, six patients complained of a mild sore throat, and no patient complained of difficulty in swallowing or numbness of the oropharynx.
Conclusion: The laryngeal tube can be useful for maintaining a patent airway during anaesthesia.

PUB MED - TOP

Adverse events with outpatient anesthesia in Massachusetts
D'eramo EM, Bookless SJ, Howard JB.
J Oral Maxillofac Surg. 2003 Jul;61(7):793-800; discussion 800

PURPOSE: This retrospective study documented the frequency of various complications associated with outpatient anesthesia.
PATIENTS AND METHODS: A questionnaire was mailed to the 157 active members of the Massachusetts Society of Oral and Maxillofacial Surgeons (MSOMS) and all members responded. Morbidity data were obtained for the calendar year 1999. Mortality data included 1999 and the preceding 4 years. This continues our long-term survey of ambulatory oral surgical office deaths in Massachusetts since 1984. The data include anesthesia-related complications and all office deaths for the patients treated by these oral and maxillofacial surgeons.
RESULTS: The most common complication in our survey continues to be syncope, which occurred in 1 in 160 patients receiving local anesthesia. The incidences of other specific anesthetic problems are given. Two treatment-related deaths occurred among approximately 1,706,100 patients treated during the 5-year period of 1995 through 1999, for a mortality rate of 1/853,050.
CONCLUSIONS: The results of this retrospective practitioner survey documented the specific incidence of untoward anesthetic events with outpatient anesthesia and found a mortality rate consistent with the 6 similar mortality studies since 1980. These 7 retrospective reviews found 34/28,399,193 outpatient deaths for an overall dental anesthesia mortality rate of 1/835,000.

Patient outcomes following ambulatory anesthesia
Deutsch N, Wu CL.
Anesthesiol Clin North America. 2003 Jun;21(2):403-15

As the number and type of surgeries performed in the ambulatory setting have increased, outcomes research has allowed for better analysis of the safety and efficacy of care given to patients. Though this once involved measures of clinical morbidity and mortality alone, researchers have begun to focus their attention beyond these end points and take into account patients' postoperative functional status and satisfaction as a way to assess the overall quality of patient care. Also key in this move to a more global assessment of health care interventions has been an increased focus on economic outcomes. As new anesthetic drugs and techniques continue to develop, outcomes research will continue to evolve in new directions, providing further information for improvements in patient care.

Postoperative recovery and discharge
McGrath B, Chung F
Anesthesiol Clin North America. 2003 Jun;21(2):367-86

Ambulatory surgery provides quality care that is cost-effective. The use of innovative surgical and anesthetic techniques will allow larger numbers of patients to take advantage of the benefits of undergoing an elective operation on an ambulatory basis. Anesthesiologists will be faced with more complex surgery, which will require careful selection and assessment of patients to ensure continuity of the excellent safety record of ambulatory anesthesia. Minor adverse events, such as pain and PONV, are still common. The occurrence of these minor adverse advents is now the major area of quality assessment and an area where improvement could be targeted. Fast tracking facilitates earlier discharge, but we must ensure this has benefit to the patient as speedy discharge may mask the true incidence of adverse minor symptoms. This can lead to patient dissatisfaction and a poor impression of ambulatory surgery.

Controversial issues in ambulatory anesthesia
Chikungwa M, Smith I
Anesthesiol Clin North America. 2003 Jun;21(2):313-27, ix

Many controversies surround ambulatory anesthesia, but this article concentrates on two major areas: monitoring devices and airway management. Being able to monitor the depth of anesthesia has been a long-term goal with the aim of avoiding awareness during surgery. As monitoring devices are developed, they are being used to reduce anesthetic delivery and reduce costs, possibly increasing the risk of awareness. Management of the airway has been revolutionized by the laryngeal mask, and this article reviews some controversial uses. Several other airway devices that have been developed and promoted as suitable alternatives also are evaluated.

Current issues in pediatric ambulatory anesthesia
Fishkin S, Litman RS
Anesthesiol Clin North America. 2003 Jun;21(2):305-11, ix

This article summarizes current guidelines in pediatric ambulatory anesthesia and surgery. The reader is provided with our department's current outpatient guidelines at Children's Hospital of Philadelphia and the rationale behind them. Whenever possible, the differences in anesthetic management for the freestanding surgicenter will be discussed. Appropriate patient and procedure selection, preoperative assessment, intraoperative and postoperative considerations, and protocols for follow-up are discussed.

Intravenous techniques in ambulatory anesthesia
Tesniere A, Servin F
Anesthesiol Clin North America. 2003 Jun;21(2):273-88

The growing importance of ambulatory surgery during the past decade has led to the development of efficient anesthetic techniques in terms of quality and safety of anesthesia and recovery. In these challenging objectives, intravenous techniques have played an important role, as they provide safe, efficient, and cost-effective anesthesia in the ambulatory setting. Among the numerous intravenous drugs, propofol, with its fast and smooth onset of action, short duration of action, and low incidence of postoperative side effects appears to be the anesthetic of choice in this situation. The recent development of new techniques of administration (such as TCI, monitored anesthesia care, or patient-controlled sedation) and monitoring (such as the BIS and the availability of "hit and run" drugs such as remifentanil) will optimize intraoperative conditions and recovery, thus allowing faster home readiness in the ambulatory setting.

Inhalational techniques in ambulatory anesthesia
Joshi GP
Anesthesiol Clin North America. 2003 Jun;21(2):263-72

In the current health care environment, anesthesia practitioners are frequently required to reevaluate their practice to be more efficient and cost-effective. Although IV induction with propofol and inhalational induction with sevoflurane are both suitable techniques for outpatients, patients prefer IV induction. Maintenance of anesthesia with the newer inhaled anesthetics (ie, desflurane and sevoflurane) provide for a rapid early recovery as compared with infusion of propofol (ie, TIVA), while allowing easy titratability of anesthetic depth. Titration of hypnotic sedatives using BIS monitoring may reduce the time to awakening and thereby may facilitate fast tracking (ie, bypassing the PACU) and reduce hospital stay. Inhalational anesthesia is associated with a higher incidence of PONV, but no differences have been demonstrated with respect to late recovery (eg, PACU stay and home readiness). Although clinical differences between desflurane and sevoflurane appear to be small, desflurane may be associated with faster emergence, particularly in elderly and morbidly obese patients. Balanced anesthesia with IV propofol induction and inhalation anesthesia with N2O for maintenance, and an LMA for airway management, may be an optimal technique for ambulatory surgery. Inhalational anesthesia may have an economic advantage over a TIVA technique.

The development of ambulatory anesthesia and future challenges
Pregler JL, Kapur PA.
Anesthesiol Clin North America. 2003 Jun;21(2):207-28

It is difficult to predict the future but foolish to ignore the past. The history of ambulatory anesthesia is one of many trends and societal or economic forces that have provided the impetus for the growth of the specialty. By understanding the events of the past one can have a greater understanding of the present and some insight into the possible trends of the future. Financial and societal forces will continue to drive the growth of ambulatory anesthesia. New technology, surgical techniques, and progress in anesthesiology will be financed and supported by society so long as ambulatory surgery continues to decrease the costs of health care. Although new technology may increase the direct costs of providing care in the operating room, the overall costs to society should be reduced by a decrease in lost productivity and individual suffering on the part of the patients. Regardless of future changes, the anesthesiologist must remain dedicated to the safety and comfort of the patient first and foremost. If that happens, then the future of ambulatory anesthesiology and surgery will continue to be bright.

Management of postoperative nausea and vomiting in ambulatory surgery
Cameron D, Gan TJ.
Anesthesiol Clin North America. 2003 Jun;21(2):347-65

The management of PONV has improved significantly over the years but remains a frequent occurrence in postoperative patients. Evaluation of individual patient risk and the consideration for prophylactic antiemetic in high-risk populations should reduce these unpleasant symptoms and help direct appropriate clinical strategies. Treatment following failure of prophylactic antiemetic therapy requires knowledge of previously used antiemetics and the time of their administration.

Effective analgesic modalities for ambulatory patients
Redmond M, Florence B, Glass PS.
Anesthesiol Clin North America. 2003 Jun;21(2):329-46

The introduction of government-mandated standards for pain management has focused our attention on postoperative pain. With the recent JACHO standards' for ambulatory surgery, it is imperative that all health care workers who care for these patients are familiar with appropriate pain management. Developments in our understanding of the pathophysiology of acute pain have further enhanced our ability to improve pain management for postoperative ambulatory patients. This has led to the concept of preventive analgesia (inhibition of physiological and pathological secondary inflammatory pain). Extensive work has shown that this is best achieved using a multimodel approach usually consisting of an NSAID, opioid, and local anesthetic. NMDA antagonists (ketamine, dextromethorphan) and alpha-2 agnoists (clonodine) show potential supplements to further enhance pain management, especially if given preemptively. Nonpharmacological intervention such as cold therapy or acupuncture may also be considered. The armanentarium for effective pain management has improved substantially over the past few years. The challenge is for health care workers to implement these therapies to obtain optimum pain management in ambulatory surgical patients.

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