Anesthesia and analgesia
-
Anesthesia and analgesia · Sep 1997
Comparative StudyThe impact of choice of muscle relaxant on postoperative recovery time: a retrospective study.
To test the hypothesis that the use of long-acting muscle relaxants is associated with prolonged postoperative recovery when compared with the use of shorter-acting relaxants, we undertook a retrospective study of 270 patients with induced paralysis recovering from general anesthesia. We calculated the mean recovery time associated with each muscle relaxant used. Regression analyses were performed to control for potential confounding of the results by length and type of surgery, as well as age and sex. Taking these into account, the adjusted difference in mean recovery time between patients receiving short- and intermediate-acting relaxants (mivacurium, atracurium, and vecuronium) versus those receiving long-acting relaxants (d-tubocurarine, pancuronium, and pancuronium and d-tubocurarine combination) was 30 min (95% confidence interval [CI] 8-53). The adjusted difference in mean recovery time between patients receiving vecuronium and those receiving pancuronium (i.e., the single most frequently used drug in each category) was 33 min (95% CI 1-66). Shortened recovery time accounted for an estimated average $37.95 decrease in recovery room charge per patient when vecuronium was used instead of pancuronium, versus a $22.84 increase in drug cost. Our data and analyses support the hypothesis that the use of long-acting muscle relaxants is associated with prolonged recovery after surgery and provide preliminary evidence that restricting the use of the more expensive, shorter-acting muscle relaxants may represent a false economy. ⋯ In this retrospective study, the use of old-fashioned, inexpensive, long-acting paralyzing drugs was found to be associated with prolonged postoperative recovery. This has implications when deciding whether, as an economic measure, to restrict the use of the more expensive, shorter-acting paralyzing drugs, because prolonged recovery also has a price.
-
Anesthesia and analgesia · Sep 1997
Comparative StudyThe effects of sevoflurane on recovery of brain energy metabolism after cerebral ischemia in the rat: a comparison with isoflurane and halothane.
Isoflurane is an appropriate anesthetic for neuroanesthesia. We evaluated whether the effect of sevoflurane is similar to that of isoflurane or halothane on brain energy metabolism after cerebral ischemia followed by reperfusion using 31P-magnetic resonance spectroscopy. Wistar rats (n = 21) were divided into three groups: isoflurane-, sevoflurane-, or halothane-treated. After anesthesia induction and surgical preparation, each anesthetic concentration was adjusted to 1 minimum alveolar anesthetic concentration. Cerebral ischemia was induced with bilateral carotid occlusion and reduction of mean arterial blood pressure to 30-40 mm Hg by blood withdrawal. Magnetic resonance measurements were performed during ischemia and for 120 min of reperfusion. Intracellular pH in the isoflurane-treated, sevoflurane-treated, and halothane-treated groups decreased to 6.180 +/- 0.149, 6.125 +/- 0.134, and 6.027 +/- 0.157, respectively, at the end of ischemia. There were no differences in the change of phosphorous compounds and intracellular pH between the isoflurane-treated and the sevoflurane-treated groups during ischemia and reperfusion. However, in the halothane-treated group, we observed a significant delay in the recovery of adenosine triphosphate and intracellular pH (0.038 +/- 0.013 pH unit/min compared with 0.064 +/- 0.011 in the isoflurane-treated group and 0.058 +/- 0.008 in the sevoflurane-treated group) until 24 min of reperfusion (P < 0.05). We conclude that sevoflurane has effects similar to isoflurane on brain energy metabolism during and after cerebral ischemia. ⋯ It is important to know whether anesthetics adversely effect brain metabolism during ischemia and reperfusion. A new anesthetic, sevoflurane, affected the brain in a manner similar to isoflurane, which has been used for many years as an anesthetic.
-
Anesthesia and analgesia · Sep 1997
Antithrombin III during cardiac surgery: effect on response of activated clotting time to heparin and relationship to markers of hemostatic activation.
This study was designed to determine if, and to what extent, antithrombin III (AT) levels affect the response of the activated clotting time (ACT) to heparin in concentrations used during cardiac surgery, and to characterize the relationship between AT levels and markers of activation of coagulation during cardiopulmonary bypass (CPB). After informed consent, blood specimens obtained from eight normal volunteers (Phase I) were used to measure the response of the kaolin and celite ACT to heparin after in vitro addition of AT (200 U/dL) and after dilution with AT-deficient plasma to yield AT concentrations of 20, 40, 60, 80, and 100 U/dL. In Phase II, blood specimens collected before the administration of heparin and prior to discontinuation of CPB, were used to measure the response of the kaolin ACT to heparin (preheparin only), AT concentration, and a battery of coagulation assays in 31 patients undergoing repeat or combined cardiac surgical procedures. In Phase I, strong linear relationships were observed between kaolin (slope = 1.04 AT - 2, r2 = 0.78) and celite (slope = 1.36 AT + 6, r2 = 0.77) ACT slopes and AT concentrations below 100 U/dL. In the pre-CPB period of Phase II, only factors V (partial r = -0.49) and VIII (partial r = -0.63) were independently associated with heparin-derived slope using multivariate analysis; an inverse relationship was observed between AT and fibrinopeptide A levels (r = -0.41) at the end of CPB. Our findings indicate that the responsiveness of whole blood (ACT) to heparin at the high concentrations used with CPB is progressively reduced when the AT concentration decreases below 80 U/dL. Because AT is variably, and sometimes extensively, reduced in many patients before and during CPB, AT supplementation in these patients might be useful in reducing excessive thrombin-mediated consumption of labile hemostatic blood components, excessive microvascular bleeding, and transfusion of blood products. ⋯ Heparin, a drug with anticoagulant properties, is routinely given to patients undergoing cardiac surgery to prevent clot formation within the cardiopulmonary bypass circuit. However, when levels are reduced, heparin is not as effective. Findings within this study indicate that administration of antithrombin III may help to preserve the hemostatic system during cardiopulmonary bypass.
-
Anesthesia and analgesia · Sep 1997
Context-sensitive half-times and other decrement times of inhaled anesthetics.
The length of anesthetic administration influences the rate at which concentrations of anesthetics decrease after their discontinuation. This is true for both intravenous (I.V.) and inhaled anesthetics. This has been explored in detail for I.V. anesthetics using computer simulation to calculate context-sensitive half-times (the time needed for a 50% decrease in anesthetic concentration) and other decrement times (such as the times needed for 80% or 90% decreases in anesthetic concentration). However, decrement times have not been reported for inhaled anesthetics. In this report, published pharmacokinetic parameters and computer simulation were used to compare the context-sensitive half-times and the 80% and 90% decrement times of the expected central nervous system concentrations for enflurane, isoflurane, sevoflurane, and desflurane. The context-sensitive half-times for all four anesthetics are small (<5 min) and do not increase significantly with increasing duration of anesthesia. The 80% decrement times of both sevoflurane and desflurane are also small (<8 min) and do not increase significantly with duration of anesthesia. However, the 80% decrement times of isoflurane and enflurane increase significantly after approximately 60 min of anesthesia, reaching plateaus of approximately 30 and 35 min. The 90% decrement time of desflurane increased slightly from 5 min after 30 min of anesthesia to 14 min after 6 h of anesthesia. It remained significantly less than the 90% decrement times of sevoflurane, isoflurane, and enflurane, which reached values of 65 min, 86 min, and 100 min, respectively, after 6 h of anesthesia. ⋯ The major differences in the rates at which desflurane, sevoflurane, isoflurane, and enflurane are eliminated occur in the final 20% of the elimination process.