Anesthesia and analgesia
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Anesthesia and analgesia · May 2003
Randomized Controlled Trial Comparative Study Clinical TrialRecovery of neuromuscular function after cardiac surgery: pancuronium versus rocuronium.
The use of pancuronium in fast-track cardiac surgical patients may be associated with delays in clinical recovery. Our objective in this study was to evaluate the incidence and severity of residual neuromuscular blockade after cardiac surgery in patients randomized to receive either pancuronium (0.08-0.1 mg/kg) or rocuronium (0.6-0.8 mg/kg). Eighty-two patients undergoing cardiopulmonary bypass were randomized to a pancuronium (n = 41) or rocuronium (n = 41) group. Intraoperative and postoperative management was standardized. In the intensive care unit, train-of-four (TOF) ratios were measured each hour until weaning off ventilatory support was initiated. Neuromuscular blockade was not reversed. After tracheal extubation, patients were examined for signs and symptoms of residual paresis. When weaning of ventilatory support was initiated, significant neuromuscular blockade was present in the pancuronium subjects (TOF ratio: median, 0.14; range, 0.00-1.11) compared with the rocuronium subjects (TOF ratio: median, 0.99; range, 0.87-1.21) (P < 0.05). Patients in the rocuronium group were more likely to be free of signs and symptoms of residual paresis than patients in the pancuronium group. Our findings suggest that the use of longer-acting muscle relaxants in cardiac surgical patients is associated not only with impaired neuromuscular recovery, but also with signs and symptoms of residual muscle weakness in the early postoperative period. ⋯ The use of long-acting muscle relaxants in fast-track cardiac surgical patients is associated with significant residual neuromuscular block in the intensive care unit, including signs and symptoms of residual paresis.
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Anesthesia and analgesia · May 2003
Clinical TrialStroke volume variation as an indicator of fluid responsiveness using pulse contour analysis in mechanically ventilated patients.
Assessment of cardiac performance and adequate fluid replacement of a critically ill patient are important goals of a clinician. We designed this study to evaluate the ability of stroke volume variation (SVV), derived from pulse contour analysis, and frequently used preload variables (central venous pressure and pulmonary capillary wedge pressure) to predict the response of stroke volume index and cardiac index to volume replacement in normoventilated cardiac surgical patients. We studied 20 patients undergoing elective coronary artery bypass grafting. ⋯ Except for heart rate, all hemodynamic variables changed significantly (P < 0.01) after volume loading. Linear regression analysis between SVV at baseline (T1) and DeltaSVV after volume application showed a significant correlation (r = -0.97; P < 0.01), whereas linear regression analysis between SVV (T1) and percentage changes of stroke volume index (r = 0.19) and cardiac index (r = 0.17) did not reveal a significant relationship between variables. The results of our study suggest that SVV derived from pulse contour analysis cannot serve as an indicator of fluid responsiveness in normoventilated cardiac surgical patients.
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Anesthesia and analgesia · May 2003
Case ReportsExtrapyramidal reactions to ondansetron: cross-reactivity between ondansetron and prochlorperazine?
Ondansetron can rarely induce extrapyramidal reactions in susceptible individuals. Our patient had a history of drug-induced dystonic reaction; therefore, these patients may be susceptible to extrapyramidal adverse reactions after ondansetron.
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Anesthesia and analgesia · May 2003
Low baseline Bispectral Index of the electroencephalogram in patients with dementia.
The baseline value of the Bispectral Index (BIS) is 96-99 in the awake state. Patients with Alzheimer's disease or vascular dementia may show an increase in slow wave and a decrease in fast wave activity of the electroencephalogram (EEG). BIS is presumed to decrease with EEG slowing. We hypothesized that the baseline "awake" BIS is lower in dementia than in normal elderly patients. We studied 36 patients with Alzheimer's disease or multiinfarct dementia and 36 control patients aged >75 yr. Both groups were assessed with a Mini-Mental State Test. BIS (version 3.4) was recorded from a frontal derivation using an Aspect A-2000 EEG monitor. Off-line data analysis was also performed with the newer version 4.0 of the BIS algorithm. Fourteen of 36 (38%) dementia patients and 4 of 36 (11%) controls had mean baseline BIS 3.4 <93 (P = 0.006). Eighteen of 36 (50%) dementia patients and 8 of 36 (22%) controls had mean BIS 4.0 <93 (P = 0.026). Mean (95% confidence interval) BIS 3.4 was 92.9 (91-95) in the dementia and 96.1 (95-97) in the control group (P = 0.02). Values with BIS 4.0 were, respectively, 89.1 (86-92) and 94.7 (93-96) (P = 0.002). No significant difference was found in age, sex, activity from the electromyogram, and signal quality index. As expected, the difference in Mini-Mental State Test scores was significant (P < 0.0001). A significant proportion of patients with dementia shows a low baseline BIS. The utility of the BIS monitor in detecting dementia warrants further investigation. ⋯ This prospective, controlled, observational study demonstrates that electroencephalogram slowing associated with dementia affects the Bispectral Index of the electroencephalogram. A significant proportion of patients with dementia have a lower than normal "awake" Bispectral Index.
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Anesthesia and analgesia · May 2003
Halothane and isoflurane have additive minimum alveolar concentration (MAC) effects in rats.
Studies suggest that at concentrations surrounding MAC (the minimum alveolar concentration suppressing movement in 50% of subjects in response to noxious stimulation), halothane depresses dorsal horn neurons more than does isoflurane. Similarly, these anesthetics may differ in their effects on various receptors and ion channels that might be anesthetic targets. Both findings suggest that these anesthetics may have effects on movement in response to noxious stimulation that would differ from additivity, possibly producing synergism or even antagonism. We tested this possibility in 20 rats. MAC values for halothane and (separately) for isoflurane were determined in duplicate before and after testing the combination (also in duplicate; six determinations of MAC for each rat). The sum of the isoflurane and halothane MAC fractions for individual rats that produced immobility equaled 1.037 +/- 0.082 and did not differ significantly from a value of 1.00. That is, the combination of halothane and isoflurane produced immobility in response to tail clamp at concentrations consistent with simple additivity of the effects of the anesthetics. These results suggest that the immobility produced by inhaled anesthetics need not result from their capacity to suppress transmission through dorsal horn neurons. ⋯ Despite differences in their capacities to inhibit spinal dorsal horn cells, isoflurane and halothane are additive in their ability to suppress movement in response to a noxious stimulus.