摘要:

The effect of ketamine on the functional residual capacity (FRC) was measured in nine ASA class I children prior to elective surgery. FRC was determined by the closed-circuit helium dilution method on the day prior to surgery in the awake state and also following induction of anesthesia on the day of the operation. Anesthesia consisted of ketamine by continuous intravenous infusion following preanesthetic sedation with atropine and triclofos or flunitrazepam. There were no significant differences in FRC between the measurements in the awake state and anesthetized (392 ± 43 SEM ml, and 411 ± 53 SEM ml, respectively), and the authors conclude that ketamine does not affect resting lung volume in young children.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Reversal of the usual relationship between aortic and radial artery pressure can occur in patients following cardiopulmonary bypass. Radial systolic (and often radial mean) pressures were lower, relative to aortic pressure, after cardiopulmonary bypass than before bypass in all 18 patients studied. The systolic pressure difference (aortic minus radial) was large enough to be of clinical concern (12–32 mmHg) in 13 patients. The change persisted for 10–60 min, gradually returning toward normal. The change temporally was associated with warming at the end of cardiopulmonary bypass and lowered forearm vascular resistance. Relative forearm vascular resistance (x) predicted the systolic aortic minus radial pressure difference (y) by the equation y = −0.34x + 17 for all patients (r = −0.49,P< 0.001). The authors conclude that radial artery pressure does not accurately reflect central aortic pressure in the immediate postbypass period.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Because of lack of direct evidence of histamine release by trimethaphan, the authors determined serum histamine levels and hemodynamic responses to trimethaphan administration in 19 consecutive patients. Group 1 patients (n = 7) received a single intravenous injection of trimethaphan, 0.5 mg · kg−1, while awake and again during stable halothane-nitrous oxide anesthesia. Group 2 patients (n = 6) were pretreated with intravenous H1(chlorpheniramine, 0.1 mg · kg−1) and H2(cimetidine, 4 mg · kg−1) receptor antagonists administered 15 min before trimethaphan, 0.5 mg · kg−1, in the awake and anesthetized states. In Group 3 (n = 6), the effects of infusion of trimethaphan, 3 mg · min−1for 15 min, were studied during halothane-nitrous oxide anesthesia. In Group 1, bolus doses of trimethaphan were associated with maximal increases in serum histamine from 0.56 ± 0.14 to 2.56 ± 0.35 ng · ml−1(P< 0.01) and from 0.60 ± 0.11 to 2.58 ± 0.33 ng · ml−1(P< 0.01) 2 min after drug administration in the awake and anesthetized states, respectively; there were also clinical manifestations of histamine release. Mean arterial pressure decreased maximally after 5 min in the awake (from 92.0 ± 3.4 to 69.9 ± 2.2 mmHg;P< 0.01) and anesthetized (from 82.6 ± 3.7 to 57.3 ± 2.5 mmHg;P< 0.01) states, and was associated with increases in cardiac output and heart rate; stroke volume increased in the awake state only. Pretreatment with H1and H2receptor antagonists did not modify the hemodynamic response to trimethaphan, despite increases in serum histamine levels comparable to Group 1. In contrast to Group 1, although trimethaphan infusion caused a significant (P< 0.05) increase in serum histamine concentration from 0.72 ± 0.1 to 1.1 ± 0.1 ng · ml−1, the hypotension achieved was not associated with significant alterations in heart rate or cardiac output. In all patients, trimethaphan-induced hypotension was associated with a significant decrease in systemic vascular resistance, an effect that probably was related to the ganglionic blocking, direct vasodilating and alpha-adrenergic blocking action of trimethaphan. The authors conclude that histamine release by trimethaphan does not play an important role in the hemodynamic effects of the drug in humans.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Despite the increasing use of rectal methohexital as a premedicant-induction agent in pediatric anesthesia, there are no data to confirm the assumption that low plasma methohexital concentrations are the cause of inadequate sedation of children and that high concentrations are associated with the loss of consciousness. Plasma methohexital concentrations were determined in 20 ASA Class I children, ages 2–7 yr, after the rectal administration of methohexital (25 mg/kg). Seventeen of the 20 children in this study fell asleep after receiving the drug and achieved peak plasma concentrations greater than 2 μg/ml. The maximum plasma methohexital concentration in children that did not fall asleep was less than 2 μg/ml. The mean time to the onset of sleep after drug administration was 8.3 min (at which time the mean plasma concentration was 4.4 μg/ml). The mean peak plasma concentration and the mean time to peak plasma concentration were 4.7 μg/ml and 13.9 min, respectively. Loss of consciousness after rectal administration of methohexital correlates well with the plasma concentration of the drug.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Critical changes in left and right ventricular function immediately after myocardial revascularization may affect the success of the procedure, morbidity, and mortality. To delineate these changes and identify vulnerable patient populations and times of highest risk, ventricular function was studied for 24 h in 22 patients undergoing myocardial revascularization. Preoperative ejection fractions ranged from 0.26 to 0.81. For each patient, eight left and eight right ventricular function curves (LVFC and RVFC) were generated by altering preload during the 24-h perioperative period. Central venous pressure ranged from 0 to 19 mmHg and pulmonary capillary wedge pressure from 0 to 31 mmHg. In all patients, significant (P< 0.05) left and right ventricular dysfunction occurred at 15 min following bypass, LVFCs and RVFCs being depressed 35–75% of control. The degree of depression and the pattern of recovery could be predicted best (stepwise logistic regression) by two preoperative indices: the ejection fraction and degree of dyssynergy. Patients with ejection fractions greater than 0.55 and no significant dyssynergy (n = 11) had postbypass LVFCs and RVFCs that were 75% and 60% of control, respectively. However, these depressions were transient, and recovery to 90% of control occurred within 4 h of revascularization. In contrast, patients having preoperative ejection fractions less than 0.45 or dyssynergy (n = 11) had more severely depressed ventricular function (LVFC = 40% and RVFC = 30% of control) that persisted for 24 h after revascularization, resulting in only 60% recovery of ventricular function. In conclusion, the preoperative indices—ejection fraction and degree of dyssynergy—best identified patients most likely to have significant and prolonged biventricular dysfunction after revascularization.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To study the effects of anesthesia on respiratory function of the neonate, the authors investigated the effect of breathing 100% oxygen and of breathing oxygen plus 0.75 MAC halothane on functional residual capacity, lung and airway resistance, expired minute volume, work of breathing, lung compliance, and blood gases andpH in nine 5–8-day-old, 4.6–7.7-kg lambs. Breathing 100% oxygen increased PaO2but had no effect on PaCO2, minute ventilation, or lung mechanics. Three-fourths MAC halothane depressed minute ventilation 34% ± 13% (P< 0.05) and increased PaCO250% ± 5% (P< 0.05). Lung and airway resistance increased 59% ± 26% (P< 0.05); work of breathing decreased (P< 0.05); and lung compliance was unchanged. Functional residual capacity was reduced 32% ± 6% (P< 0.05), which may be due to loss of diaphragm and intercostal muscle function and to an inability to take deep breaths. The authors conclude that 0.75 MAC halothane significantly impairs the pulmonary function of lambs who breathe spontaneously. Similar changes in human infants could account for the hypoxemia and hypercarbia that often are seen during anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Variation in thepH of biologic fluids parallels modifications in the neutral point of water, which is temperature dependent. Therefore,pH adjustment, when organs from homeotherms are subjected to hypothermia as presently practiced in cardiac surgery or organ preservation, appears to be justified. The present study evaluated, during moderate hypothermia (26° C), the effect of variations in perfusatepH on hemodynamic performance of isolated working rat hearts in conditions of increased workload. Perfusates of blood with apH corrected according to thepH-temperature relationship of neutral water, and blood withpH maintained at 7.4 were used. Hemodynamic function was unaltered by respiratory modifications in bloodpH (normalpH blood:pH = 7.59 ± 0.01; PCO2= 20 ± 1 mmHg; blood maintained atpH 7.4:pH = 7.39 ± 1; PCO2= 37 ± 1 mmHg) and the hypothermic heart perfused with blood atpH 7.4 maintained its ability to do work in response to increased workload. The authors conclude that isolated heart at this degree of hypothermia has the capacity to resist noticeable changes in bloodpH with no deleterious effect on its functional characteristics even at high workloads. The results suggest that the range of optimum extracellularpH value is relatively large at a given temperature. Such good tolerance could be related to tissue buffering efficiency and no conclusion concerning the relationship between tolerance of cellular function and intracellularpH changes can be made.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The authors studied the effect of halothane in a canine model of coronary collateral circulation secondary to chronic occlusion of a coronary artery. Two sets of experiments were performed. In the first experiments, Ameroid® constrictors were placed around the left anterior descending coronary artery to produce complete occlusion in three weeks. An inflatable occluder was placed around the circumflex coronary artery in order to apply a mild stenosis to the artery supplying the collateral vessels to produce vasodilation distal to the stenosis. Regional myocardial blood flows were measured using radioactive microspheres. Blood flows to normal and collateralized myocardium were decreased significantly during halothane anesthesia, but perfusion of the subendocardium in both regions was maintained even in the presence of mild stenosis of the circumflex coronary artery supplying the collateral vessels, as indicated by unchanged endocardial/epicardial blood flow ratios. In the second experiments, chronic occlusions of both circumflex and right coronary arteries were produced using Ameroid constrictors. In these animals, sedated using xylazine, pacing-induced tachycardia produced a marked but reversible decrease in blood flow to the collateralized subendocardium. During halothane anesthesia at normal heart rate, blood flow to the collateralized subendocardium was well maintained, but tachycardia produced marked decrease in blood flow to the collateralized subendocardium, leading to the demise of four of seven dogs. The authors conclude that in this chronic canine model, in which control measurements were made during sedation using xylazine, coronary collateral blood flow is well maintained during halothane anesthesia at normal heart rate, but tachycardia during halothane anesthesia severely limits blood flow to the collateralized subendocardium.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effect of prior administration of reserpine on fentanyl dose-response curves for loss of the righting reflex and prevention of purposeful movement response to noxious stimulation was studied in rats. It was found that reserpine (5 mg · kg−1, 3 h before the tests) antagonized the effect of fentanyl on purposeful movement response to the tail clamp and, at the same time, strengthened its effect on the righting reflex. As a result, reserpine pretreatment reversed the order of fentanyl potency regarding these two effects. Reserpine changed fentanyl ED50values for the purposeful movement response from 8.2 to 20.3 μg · kg−1(P< 0.0001) and for the righting reflex from 20.5 to 13.7 μg · kg−1(P< 0.0001). The results suggest that reserpine dissociates the analgesic action of fentanyl from its anesthetic action, defined as a loss of the righting reflex. This may be regarded as an indication that the analgesic action of narcotics may not adequately reflect their anesthetic potency.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To evaluate the effect of liver cirrhosis on the pharmacokinetics and the pharmacodynamics of vecuronium, 12 patients with cirrhosis, aged (mean ± SD) 52 ± 12 yr, and 14 control patients, 42 ± 15 yr, undergoing elective surgery under general anesthesia were studied. The simultaneous time courses of the plasma concentration of vecuronium and of the neuromuscular blockade were studied after the administration of a bolus dose of 0.2 mg · kg−1. Vecuronium plasma concentration declined biexponentially in both groups. Vecuronium plasma clearance was reduced significantly (P< 0.01) from 4.26 ± 1.38 ml · min−1· kg−1in the controls to 2.73 ± 1.19 ml · min−1· kg−1in the patients with cirrhosis. The elimination half-life was 58 ± 19 min in the controls and was prolonged significantly to 84 ± 23 min (P< 0.01) in the patients with cirrhosis. The total apparent volume of distribution was unchanged in patients with cirrhosis (0.253 ± 0.086 1 · kg−1vs.0.246 ± 0.092 1 · kg−1in the controls). Cirrhosis caused a prolongation of the neuromuscular blockade induced by vecuronium: the duration of effect from injection to 50% recovery of the twitch height was prolonged by 100% (P< 0.01) from 62 ± 16 min in the controls to 130 ± 52 min in patients with cirrhosis. The recovery rate (TH 25–75) also was prolonged (P< 0.05) from 21 ± 7 min in the controls to 44 ± 18 min in patients with cirrhosis. Vecuronium plasma concentration measured during recovery from paralysis indicates that cirrhosis did not alter the sensitivity to the relaxant, the plasma concentration corresponding to 50% of recovery (Cp 50) being unchanged between the two groups: 247 ± 60 ng · ml−1in the controlsversus281 ± 129 ng · ml−1in the cirrhotic patients. Thus, vecuronium seems to exert a prolonged neuromuscular blockade in patients with cirrhosis, and this change is mediated through its delayed elimination.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID