Anesthesia and analgesia
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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 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
The degradation, absorption, and solubility of volatile anesthetics in soda lime depend on water content.
Absorption of anesthetic into soda lime may delay induction of anesthesia and degradation by soda lime may produce toxic products. We determined whether the moisture content of soda lime influences the mechanisms underlying absorption (saturable uptake), degradation, and solubility (nonsaturable uptake). We placed liquid anesthetic (sevoflurane, isoflurane, halothane, enflurane, or desflurane) in 581-mL equilibration flasks containing soda lime of various water contents (0%-15.1% H2O) and sampled the vapor concentrations repeatedly for 24-35 h. ⋯ We also found that soda lime in absorbers may dry from H2O contents of 15% to 4%-8.5% in routine clinical use. Our observations suggest that during induction of anesthesia a portion of the delivered anesthetic may be lost to the soda lime, rather than delivered to the patient. In addition, the potential for production of toxic products may be increased when volatile anesthetics are used with dry soda lime.
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Anesthesia and analgesia · Feb 1994
Pulse oximetry monitoring can change routine oxygen supplementation practices in the postanesthesia care unit.
Routine use of supplemental oxygen (O2) in the postanesthesia care unit (PACU) traditionally has been used to minimize the incidence of hypoxemia. However, with the advent of continuous noninvasive monitoring by pulse oximetry, is routine administration of O2 necessary? We hypothesized that administering O2 as needed, based on pulse oximetry data, would effect considerable cost savings without compromising patient care. Five hundred adult (> or = 18 yr) patients breathing room air when arriving in the PACU were enrolled in the study. ⋯ Cost savings to the 307 patients in one study not receiving O2 was $31,928 if it had been billed separately from the PACU global charge. The annualized figure for patients in our hospital (approximately 10,000 cases) would be an additional $623,272. Inasmuch as pulse oximetry monitoring is now standard in the PACU, perhaps it is time to apply the objective data it supplies, thereby creating cost savings while maintaining patient care standards.
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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.