Jochen Schulte am Esch

Multicenter Randomized Comparison of the Efficacy and Safety of Xenon and Isoflurane in Patients Undergoing Elective Surgery

Background All general anesthetics used are known to have a negative inotropic side effect. Since xenon does not have a negative inotropic effect, it could be an interesting future general anesthetic. The aim of this clinical multicenter trial was to test the hypothesis of whether recovery after xenon anesthesia is faster compared with an accepted, standardized anesthetic regimen and that it is as effective and safe. Method A total of 224 patients in six centers were included in the protocol. They were randomly assigned to receive either xenon (60 ± 5%) in oxygen or isoflurane (end-tidal concentration, 0.5%) combined with nitrous oxide (60 ± 5%). Sufentanil (10 &mgr;g) was intravenously injected if indicated by defined criteria. Hemodynamic, respiratory, and recovery parameters, the amount of sufentanil, and side effects were assessed. Results The recovery parameters demonstrated a statistically significant faster recovery from xenon anesthesia when compared with isoflurane–nitrous oxide. The additional amount of sufentanil did not differ between both anesthesia regimens. Hemodynamics and respiratory parameters remained stable throughout administration of both anesthesia regimens, with advantages for the xenon group. Side effects occurred to the same extent with xenon in oxygen and isoflurane–nitrous oxide. Conclusion This first randomized controlled multicenter trial on the use of xenon as an inhalational anesthetic confirms, in a large group of patients, that xenon in oxygen provides effective and safe anesthesia, with the advantage of a more rapid recovery when compared with anesthesia using isoflurane–nitrous oxide.

The Effects of Propofol on Brain Electrical Activity, Neurologic Outcome, and Neuronal Damage Following Incomplete Ischemia in Rats

This study compares the effects of propofol and fentanyl/N2O on spontaneous brain electrical activity, neurologic outcome, and neuronal damage due to incomplete cerebral ischemia in rats. Thirty Sprague-Dawley rats were assigned to one of three groups: group 1 (n = 10) received 70% N2O in O2 plus fentanyl (bolus 10 micrograms.kg-1, infusion 25 micrograms.kg-1.h-1); group 2 (n = 10) received 70% N2 in O2 and propofol (infusion 0.8-1.2 mg.kg-1.min-1) adjusted to maintain EEG burst suppression during ischemia; group 3 (n = 10) was anesthetized with propofol and received 6 ml.kg-1 10% glucose intraperitoneally 15 min before the start of ischemia. Incomplete cerebral ischemia was produced by right common carotid artery occlusion combined with hemorrhagic hypotension (35 mmHg) for 30 min. Arterial blood gases, pH, and rectal temperature were kept constant in all groups. Plasma glucose was lower during ischemia in propofol-anesthetized rats compared to that in fentanyl/N2O- (P = 0.009) and glucose-loaded propofol-treated rats (P = 0.008). Neurologic outcome and brain tissue injury were significantly better in propofol-anesthetized compared to fentanyl/N2O-anesthetized rats (P less than 0.05). Elevated plasma glucose in propofol-treated rats resulted in similar neurologic outcome and histopathologic injury as seen in propofol-anesthetized rats given no glucose. Recovery of EEG theta-alpha activity after ischemia was inversely correlated to neurologic deficit (fentanyl/N2O: r = -0.71; propofol: r = -0.83; P less than 0.01). These results show that propofol improves neurologic outcome and decreases neuronal damage from incomplete cerebral ischemia when compared to fentanyl/N2O. This effect is not dependent on plasma glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for Susceptibility to Malignant Hyperthermia in Patients with Exercise-induced Rhabdomyolysis

BackgroundMalignant hyperthermia (MH), heat stroke, and exercise-induced rhabdomyolysis (ER) were suspected to be related syndromes. However, it is not known whether individuals with history of ER have an increased incidence of susceptibility to MH. To establish an association between ER and susceptibility to MH, the authors determined the MH status in patients with a history of MH-like episodes induced by physical stress. MethodsTwelve unrelated patients with ER, 18 patients with anesthesia-induced MH, and 28 controls were investigated with the in vitro contracture test (IVCT) according to the European MH Group protocol and the ryanodine contracture test. In addition, all patients were screened for genetic mutations, and histology was performed on muscle specimens. ResultsTen ER patients had positive IVCT results, one patient had a negative test result, and one patient showed equivocal responses. Samples from patients with positive IVCT results showed pronounced contractures after exposition to ryanodine, as opposed to specimens from patients with negative IVCT results, which developed contractures slowly. Three ER patients had mutations at the ryanodine receptor gene. All anesthesia-induced MH patients had positive IVCT results, two of them presented the C1840T mutation. The control patients had normal contracture test results and no typical MH mutations. Histologic examination determined no specific myopathies in any patient. ConclusionsRegarding these results, the authors recommend performing muscle biopsies for histologic examination and IVCT in patients with ER. In addition, the patient should be seen by a neurologist and screened for genetic abnormalities to shed light on the genetics of MH.

Living donor for liver transplantation

Since living related liver transplantation was first performed in 1989, more than 150 cases have been performed worldwide, mostly in the United States and Japan. This paper reports the first series of living related liver transplantation in Europe. Twenty living related liver transplantation surgeries were performed over a 13‐mo period, with an overall patient survival of 85%. For patients who underwent elective transplantation (n=13), the survival rate was 100%. Technical complications included one arterial thrombosis necessitating retransplantation and five bile leaks requiring surgical revision. The technical improvements that permit avoidance of these complications are discussed. A detailed description of the living related liver procurement is given. All procurements yielded grafts of excellent quality. No intraoperative complications occurred, and no reoperations were necessary. No heterologous blood transfusion was needed. In two patients, incisional hernias developed after wound infection. Living related liver transplantation does not absolve the transplant community of efforts to promote cadaveric organ procurement. Nevertheless, living related liver transplantation does have the advantage of a readily available graft of excellent quality, permitting transplantation with optimal timing under elective conditions. Several centers are now preparing living related segmental liver transplants, following the model of our protocol, for three reasons: (a) to obtain superior results compared with cadaveric liver transplantation; (b) to overcome cadaveric organ shortage and further reduce pretransplantation mortality and (c) to provide viable organs in countries where cadaveric organ procurement is not established. When performed by a team experienced in pediatric liver transplantation and in adult liver resection, living related liver transplantation is an excellent modality for the treatment of end‐stage liver disease in children. (Hepatology 1994;20:49S‐55S.)

Comparative evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index monitor during propofol-remifentanil anesthesia.

Background:Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index® monitor (BIS®; Aspect Medical Systems, Newton, MA) during propofol–remifentanil anesthesia. Methods:The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 &mgr;g/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 &mgr;g · kg−1 · min−1) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability. Results:SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate. Conclusion:SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.

Active warming during cesarean delivery.

We tested the hypothesis that 15 min of forced-air prewarming, combined with intraoperative warming, prevents hypothermia and shivering in patients undergoing elective cesarean delivery. We simultaneously tested the hypothesis that maintaining maternal normothermia increases newborn temperature, umbilical vein pH, and Apgar scores. Thirty patients undergoing elective cesarean delivery were randomly assigned to forced-air warming or to passive insulation. Warming started 15 min before the induction of epidural anesthesia. Core temperature was measured at the tympanic membrane, and shivering was graded by visual inspection. Patients evaluated their thermal sensation with visual analog scales. Rectal temperature and umbilical pH were measured in the infants after birth. Results were compared with unpaired, two-tailed Student’s t-tests and &khgr;2 tests. Core temperatures after 2 h of anesthesia were greater in the actively warmed (37.1°C ± 0.4°C) than in the unwarmed (36.0°C ± 0.5°C;P < 0.01) patients. Shivering was observed in 2 of 15 warmed and 9 of 15 unwarmed mothers (P < 0.05). Babies of warmed mothers had significantly greater core temperatures (37.1°C ± 0.5°C vs 36.2°C ± 0.6°C) and umbilical vein pH (7.32 ± 0.07 vs 7.24 ± 0.07).

Effects of Sufentanil on Cerebral Hemodynamics and Intracranial Pressure in Patients with Brain Injury

Background The current study investigates the effects of sufentanil on cerebral blood flow velocity and intracranial pressure (ICP) in 30 patients with intracranial hypertension after severe brain trauma (Glasgow coma scale < 6).

Physostigmine Prevents Postanesthetic Shivering As Does Meperidine or Clonidine

BackgroundPostanesthetic shivering develops in as many as one half of patients recovering from isoflurane anesthesia. Cholinergic stimulation of the hypothalamic-pituitary-adrenal axis and adrenal medulla by physostigmine enhances secretion of arginine vasopressin, epinephrine, and norepinephrine. B

Surgical stimulation induces changes in brain electrical activity during isoflurane/nitrous oxide anesthesia. A topographic electroencephalographic analysis.

Background:The aim of this study was to investigate topographic changes in electroencephalographic (EEG) power and frequency induced by abdominal surgery during anesthesia with 0.6% or 1.2% isoflurane in 66% nitrous oxide. Methods:Forty-six patients (aged 41 ± 13 yr) scheduled for elective abdominal surgery were studied. The trachea of each patient was intubated and the lungs ventilated. Patients were randomly assigned to one of four groups: anesthesia was maintained with 0.6% (group 1, n = 12; group 2, n = 11) or 1.2% end-tidal isoflurane (group 3, n = 12; group 4, n = 11) in 66% nitrous oxide. Data were recorded over 20 min. Groups 1 and 3 were studied without surgery (as controls). In groups 2 and 4 recording was started 6 min before skin incision. The EEG was acquired via 17 scalp electrodes placed in standard International 10–20 locations (reference C2). Absolute and relative power densities were calculated in selected frequency bands. EEG maps of spectral power densities were coded according to a continuous color spectrum. Results:During baseline recordings, alpha activity was dominant at frontal areas in groups 1 and 2. In comparison, in groups 3 and 4, delta and theta activities were dominant at frontal leads. In group 2, the start of surgery resulted in increases in delta activity and decreases in alpha activity that were most dominant frontally (delta +181% and alpha −61%, F3). The delta shift was attenuated at 1.2% isoflurane (group 4, delta +44%, F3), but decreases in alpha activity (-53%, F3) were comparable to those in group 2. The EEG response in all frequency bands was attenuated at parietotemporal recording sites at both isoflurane concentrations. Conclusions:The current data demonstrate graded EEG responses induced by abdominal surgery during anesthesia with 0.6% or 1.2% isoflurane in 66% nitrous oxide. Spatial heterogeneities in absolute spectral power densities were reflected by color changes in the EEG maps. The topographic EEG analysis indicates that these changes were most dominant at frontal areas. The increases in delta and decreases in alpha activities may be related to intraoperative “paradoxical” electro-physiologic arousal phenomena.

Multicenter randomized comparison of xenon and isoflurane on left ventricular function in patients undergoing elective surgery

Background: Volatile anesthetics are commonly used for general anesthesia. However, these can induce profound cardiovascular alterations. Xenon is a noble gas with potent anesthetic and analgesic properties. However, it is uncertain whether xenon alters myocardial function. The aim of this study was therefore to investigate left ventricular function during anesthesia with xenon compared with isoflurane. Methods: The authors performed a randomized multicenter trial to compare xenon with isoflurane with respect to cardiovascular stability and adverse effects in patients without cardiac diseases scheduled for elective surgery. Two hundred fifty-nine patients were enrolled in this trial, of which 252 completed the study according to the protocol. Patients were anesthetized with xenon or isoflurane, respectively. Before administration of the study drugs and at four time points, the effects of both anesthetics on left ventricular function were investigated using transesophageal echocardiography. Results: Global hemodynamic parameters were significantly altered using isoflurane (P < 0.05 vs. baseline), whereas xenon only decreased heart rate (P < 0.05 vs. baseline). In contrast to xenon, left ventricular end-systolic wall stress decreased significantly in the isoflurane group (P < 0.05 vs. baseline). Velocity of circumferential fiber shortening was decreased significantly in the xenon group but showed a more pronounced reduction during isoflurane administration (P < 0.05 vs. baseline). The contractile index (difference between expected and actually measured velocity of circumferential fiber shortening) as an independent parameter for left ventricular function was significantly decreased after isoflurane (P < 0.0001) but unchanged using xenon. Conclusions: Xenon did not reduce contractility, whereas isoflurane decreased the contractile index, indicating that xenon enables favorable cardiovascular stability in patients without cardiac diseases.