Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1994
Comparative Study Clinical TrialThe effect of hypothermia on adductor pollicis twitch tension during continuous infusion of vecuronium in isoflurane-anesthetized humans.
The effect of total body cooling on force of contraction of the adductor pollicis was determined during a constant rate infusion of vecuronium. Anesthesia was induced with thiopental and maintained with isoflurane/nitrous oxide in eight volunteers (study group) and seven surgical patients (control group). After train-of-four (TOF) stimulation of the ulnar nerve, we measured the amplitude of the first response (T1) in the train and the ratio of the fourth-to-first response (TOF ratio). ⋯ In the study group, core temperature was then reduced (using circulating-water blankets) by a mean of 2.6 degrees C, decreasing the T1 and TOF ratio, respectively, by 19% and 18% per degrees C reduction in adductor pollicis temperature. Normothermia was maintained in the control group for a mean of 111 min, with no significant change in T1 and TOF responses. We conclude that, during a constant-rate infusion of vecuronium, the magnitude of neuromuscular block increases significantly when adductor pollicis temperature decreases secondary to core cooling.
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Anesthesia and analgesia · Feb 1994
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of lumbar epidural and general anesthesia on plasma catecholamines and hemodynamics during abdominal aortic aneurysm repair.
Twenty-four patients undergoing abdominal aortic aneurysm (AAA) repair were studied to compare the effects of lumbar epidural anesthesia (LEA) and general anesthesia (GA) on plasma catecholamine levels and hemodynamics before and during infrarenal aortic cross-clamping. Patients received either a high dose of opioid anesthetic (GA group, n = 12), or lumbar epidural anesthesia to T4 sensory level with a light general anesthetic (LEA group, n = 12). Systemic vascular resistance (SVR) and norepinephrine (NE) and epinephrine (E) levels were measured before anesthetic induction (before epidural activation in the LEA group, and before general anesthesia induction in the GA group), 15 min before cross-clamping, and 1,5, and 10 min after cross-clamping. ⋯ After clamping, SVR increased in both groups, but the increase occurred after 1 min in the GA group and took 5 min to become significant in the LEA group. There was no significant correlation between changes in NE or E and changes in SVR in either group. This study shows that epidural anesthesia to T4 prevents NE and E increases in response to abdominal surgery.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Feb 1994
Comparative StudyAlfentanil pharmacokinetics in cardiac surgical patients.
There is growing interest in early tracheal extubation and intensive care unit. (ICU) discharge of cardiac surgical patients. Among the opioids currently available, alfentanil seems to be particularly suited to these goals because of its pharmacokinetic and pharmacodynamic characteristics. However, the pharmacokinetics of alfentanil after cardiopulmonary bypass (CPB) have not been fully characterized. ⋯ There was no substantial change in the concentration of free alfentanil at the start of CPB. The clearance of total alfentanil was not affected significantly by CPB. We conclude: 1) Alfentanil pharmacokinetics in CABG patients before CPB are similar to those found in noncardiac surgical patients and volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Feb 1994
Comparative StudyThe effects of epidural anesthesia on uterine vascular resistance, plasma arginine vasopressin concentrations, and plasma renin activity during hemorrhage in gravid ewes.
In an earlier study, epidural anesthesia increased uterine vascular resistance and fetal acidosis during hemorrhage in gravid ewes. But, it is unclear whether epidural anesthesia modifies the uterine vascular resistance response during hemorrhage, independent of changes in arterial blood pressure. The purpose of this study was to determine the effects of epidural anesthesia on: 1) the mean arterial pressure/uterine vascular resistance relationship; and 2) arginine vasopressin concentrations and plasma renin activity during hemorrhage in gravid ewes. ⋯ At that time, uterine vascular resistance was similar in both groups despite lower (P = 0.0001) mean arterial pressure in the epidural group. Between H and H + 60 min, uterine vascular resistance was lower (P = 0.045) in the epidural group than in the control group. Also, fetal PCO2 was lower (P = 0.020) in the epidural group than in the control group, but fetal pH and PO2 did not differ significantly between groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Feb 1994
Blood volume redistribution during cross-clamping of the descending aorta.
We tested the hypothesis that occlusion of the descending aorta is associated with blood volume redistribution resulting in a relative hypervolemia in organs and tissues proximal to the level of occlusion. The study was performed on splenectomized dogs anesthetized with pentobarbital. Whole body scintigraphy with a Sophy DSX rectangular large field of view gamma-camera equipped with a high resolution collimator was used; Tc99m was used to label plasma albumin. ⋯ The aortic cross-clamping at diaphragmatic level was associated with significant increases in the gamma-emission in all organs and tissues above the level of aortic occlusion by 8%-38%. Thus, the present study supports the hypothesis by demonstrating that cross-clamping of the aorta at diaphragmatic level is associated with an increase in blood volume in the organs and tissues proximal to the level of cross-clamping. Such an increase might represent the mechanism for well-documented increases in preload and blood flow above aortic occlusion, resulting in an additional (in addition to an increase in afterload) burden to the heart.