Anesthesia and analgesia
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Anesthesia and analgesia · May 1999
Comparative StudyComparison between the European and North American protocols for diagnosis of malignant hyperthermia susceptibility in humans.
We compared the diagnostic outcome of in vitro contracture tests for diagnosis of malignant hyperthermia susceptibility performed according to the European Malignant Hyperthermia Group protocol and the North American Malignant Hyperthermia Group protocol. The aim of the study was to compare the two major diagnostic tests of malignant hyperthermia susceptibility to have basic data for a common worldwide protocol. We evaluated 156 patients and 17 control individuals. The accordance in diagnostic outcome was 87%. The diverging outcomes between the two protocols were found in a group of patients reacting in few muscle strips and close to the cutoff limits. A 100% accordance in diagnostic outcome was found in individuals with contractures in at least five of six tested muscle strips. In both protocols, contractures close to the cutoff limits in a few muscle strips in scientific studies should be considered as unknown results. ⋯ We compared the two major protocols for investigating malignant hyperthermia susceptibility. There was 87% accordance in diagnostic outcome. The diverging outcomes were seen in individuals with less reproducible test results near the cutoff limits. In scientific studies, such results should be considered as unknown.
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Anesthesia and analgesia · May 1999
S(+)-ketamine, but not R(-)-ketamine, reduces postischemic adherence of neutrophils in the coronary system of isolated guinea pig hearts.
Polymorphonuclear neutrophils (PMN) play a crucial role in the initiation of reperfusion injury. In a previous study, we found that ketamine reduced the postischemic adherence of PMN to the intact coronary system of isolated guinea pig hearts. Because ketamine is a racemic mixture (1:1) of two optical enantiomers, we looked for possible differences in action between the stereoisomers. Seventy-six guinea pig hearts were perfused in the "Langendorff" mode under conditions of constant flow (5 mL/min) using modified Krebs-Henseleit buffer. After 15 min of global warm ischemia, freshly isolated human PMN (10(6)) were infused as a bolus into the coronary system during the second minute of reperfusion. PMN adhesion was expressed as the numeric difference between PMN recovered in the effluent and those applied. Series A hearts received 5 microM S(+), 5 microM R(-), or 10 microM racemic ketamine starting 20 min before ischemia and during reperfusion. In Series B hearts, 10 microM nitro-L-arginine, an inhibitor of NO synthase, was added to the perfusate. In Series C, PMN were preincubated for 15 min with 5 microM S(+)- or R(-)-ketamine. Coronary vascular leak was assessed by measuring the rate of formation of transudate on the epicardial surface. Ischemia/reperfusion without anesthetics increased coronary PMN adherence from 25.5% +/-2.3% (basal) to 35.3%+/-1.5% of the number applied. S(+)-ketamine reduced postischemic adherence in each series (A, 25.5%+/-5.1%; B, 22.5%+/-1.7%; C, 25.3%+/-7.7%), as did racemate (A, 26.4%+/-3.7%). Although 5 microM R(-)-ketamine had no effect on adhesion (A, 30.5%+/-6.7%; B, 34.3%+/-5.1%; C, 34.3%+/-4.3%), it significantly increased vascular leak in the presence of NOLAG. These findings indicate stereoselective differences in biological action between the two ketamine isomers: S(+)-ketamine inhibited PMN adherence, R(-)-ketamine worsened coronary vascular leak in reperfused isolated hearts. ⋯ In this study, we demonstrated stereoselective differences in the biologic action of the two ketamine isomers in an animal model of myocardial ischemia. Polymorphonuclear neutrophil adherence to the coronary vasculature after ischemia was inhibited by S(+)-ketamine, whereas R(-)-ketamine increased coronary vascular fluid leak.
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Anesthesia and analgesia · May 1999
Computer simulation to determine how rapid anesthetic recovery protocols to decrease the time for emergence or increase the phase I postanesthesia care unit bypass rate affect staffing of an ambulatory surgery center.
Ambulatory surgery centers (ASC) are implementing new anesthetic techniques and rapid recovery protocols in the postanesthesia care unit (PACU) to achieve earlier discharge after general anesthesia. Using computer simulation, we addressed two questions. First, what is the decrease in an ASC's operating room (OR) staff if the time from which the surgery is finished to the time the patient leaves the OR is decreased? Second, what is the decrease in PACU nursing staffing if patients bypass phase I PACU (i.e., proceed from the OR directly to the phase II PACU)? The decrease in labor costs from rapid emergence or fast-tracking depends on how staff are compensated, how many ORs routinely run concurrently, and what percentage of patients undergo general anesthesia. The results show potential decreases in ASCs' labor costs ($7.39 per case) from technologies (e.g., new anesthetics or Bispectral Index [Aspect Medical Systems, Natick, MA] monitoring) to decrease emergence times or increase the phase I bypass rates. ⋯ Decreases in operating room and postanesthesia care unit labor costs resulting from faster emergence and phase I postanesthesia care unit bypass vary depending on the amount of routine overtime, how the staff are compensated, and how many patients are routinely anesthetized each day.
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Anesthesia and analgesia · May 1999
Cardiovascular autonomic dysfunction and hemodynamic response to anesthetic induction in patients with coronary artery disease and diabetes mellitus.
Autonomic neuropathy is a major complication of diabetes mellitus and is reported to be associated with increased perioperative hemodynamic instability. We investigated the relationship between autonomic dysfunction and hemodynamic response to anesthetic induction in diabetic and nondiabetic patients with coronary artery disease. We studied 60 patients scheduled for coronary artery surgery, 30 suffering from diabetes mellitus. Preoperative evaluation included traditional cardiovascular autonomic function tests (coefficient of variation of 150 beat-to-beat intervals in heart rate at rest, heart rate response to deep breathing, and heart rate and arterial blood pressure response to standing), spectral analysis of blood pressure and heart rate variability (HRV), and the computation of spontaneous baroreflex sensitivity. After premedication with clorazepate, anesthesia was induced with sufentanil (0.5 microg/kg), etomidate (0.1-0.2 mg/kg), and vecuronium (0.1 mg/kg). Heart rate and blood pressure before anesthetic induction and before and after tracheal intubation were compared between groups. Autonomic function tests, spectral analysis of HRV, and spontaneous baroreflex sensitivity revealed significant differences between patient groups. Most diabetic patients (n = 23) had one or more abnormal test results, in contrast to most nondiabetic patients, who did not show signs of autonomic neuropathy (n = 23). There was no relationship between cardiovascular autonomic function and hemodynamic behavior during anesthetic induction. The blood pressure response to anesthetic induction was not different between patient groups, even when comparing the subgroups with and without abnormal autonomic function tests. These findings indicate that increased hemodynamic instability during anesthetic induction is not obligatory in patients with diabetes mellitus and autonomic dysfunction. ⋯ This study indicates that increased hemodynamic instability during anesthetic induction is not obligatory in patients with coronary artery disease and autonomic dysfunction.
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Anesthesia and analgesia · May 1999
Intraoperative localization of an epileptogenic focus with alfentanil and fentanyl.
We evaluated the effectiveness of alfentanil and fentanyl in stimulating epileptogenic activity during surgery for intractable temporal lobe epilepsy under general anesthesia. Ten patients received a standardized anesthetic induction with i.v. fentanyl 5 microg/kg, propofol 3-5 mg/kg, and atracurium 0.5 mg/kg. Maintenance was with isoflurane, 70% N2O/30% O2, and an atracurium infusion. After dural opening, droperidol 0.02 mg/kg was administered i.v.. Both inhaled anesthetics were discontinued and verified to be at 0 end-tidal concentration before the study. Baseline electrocorticography over the surface of the temporal lobe and depth electrode recordings in the amygdala and hippocampus were obtained, followed by 10 min of recording before and after the i.v. administration of both alfentanil 50 microg/kg and fentanyl 10 microg/kg. Any changes in cardiovascular variables were documented. The number of interictal epileptiform spikes at the most active site for each patient was tabulated before and after the administration of each drug. Both alfentanil and fentanyl induced an increase in spike activity in all patients. Alfentanil was more potent, increasing the median number of spikes per epoch from 18 to 58, compared with fentanyl (20 to 42 spikes) (P < 0.05). Alfentanil had a shorter duration of action (4.9+/-1.3 min) compared with fentanyl (8.5+/-2 min) (P < 0.009). In nine patients, the most active site was the hippocampus or amygdala. There was a decrease in mean blood pressure, but only after the administration of alfentanil (P < 0.05). Two patients had electrographic evidence of seizure activity. These opioids can be used to assist in the localization of the epileptogenic focus during surgery. ⋯ Both alfentanil and fentanyl activate epileptiform activity in patients with temporal lobe epilepsy. These opioids can be used to assist in the localization of the epileptogenic focus during surgery.