ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The influence of gallamine, metocurine, pancuronium, and tubocurarine on depolarization of a mammalian muscle end-plate region was examined to determine whether the antagonists given in combination exerted a degree of block consistent with the simple classical competitive model. Depolarization was produced by carbachol in isolated guinea pig lumbrical muscles and recorded by the moving fluid electrode technique. The dose–response values obtained were fitted to a regression embedded in a split plot factorial experimental design such as both to control and to measure effects of variation among preparations, order of administration, time, and level of block. Of the six possible pairings of the four drugs, four showed the simple additivity expected from a competitive mechanism, while two (pancuronium plus metocurine and metocurine plus gallamine) showed potentiation beyond additivity. In these latter two pairs the combination shifted the carbachol dose-response curve, respectively, 41 and 21% further than predicted from the classical model. The significance of this deviation in the light of alternative receptor models is discussed, and a model consistent with the observed results is outlined.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To compare the effect of halothane and enflurane on an atracurium-induced neuromuscular blockade, the authors studied 40 patients during elective surgery. During 1.25 MAC enflurane–nitrous oxide (n = 20) or halothane–nitrous oxide (n = 20) (MAC value includes contribution from 60% nitrous oxide), the doses depressing twitch tension 50% (ED50s) for atracurium were 70 and 77 μg/kg, respectively. The difference was not significant. Time from injection to peak effect did not differ between groups. However, the duration of action of atracurium (expressed as durations50or the duration of a 50% blockade) was longer during enflurane–nitrous oxide anesthesia (34.2 min) than during halothane–nitrous oxide anesthesia (25.5 min) (P< 0.05). The authors conclude that the potency of atracurium does not differ during halothane-nitrous oxide and enflurane-nitrous oxide anesthesia. Combining the results of this study with a previous study (atracurium ED50= 68 μg/kg and 83 μg/kg during isoflurane–nitrous oxide and fentanyl–nitrous oxide anesthesia respectively), the potency of atracurium does not differ by more than 20% among the four anesthetic techniques studied. The background anesthetic appears to have less effect on an atracurium-induced neuromuscular blockade than on one produced by other longer-acting nondcpo-larizing muscle relaxants (e.g., pancuronium andd-tubocurarine).

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The respiratory effects of two postoperative analgesic regimens were compared in two groups of 16 patients each, recovering from general anesthesia and major surgery. One group received a pain-relieving dose of iv morphine (mean, 18.1 mg), with the same dose repeated as a continuous intravenous infusion over the subsequent 24 h. The other group received regional anesthesia using bupivacaine. The patients were monitored for 16 h after surgery. The two analgesic regimens provided patients with comparable analgesia throughout the study period, but there were quite different respiratory effects in the two groups. Ten patients receiving morphine infusions had a total of 456 episodes of pronounced oxygen desaturation (SaO2< 80%). These occurred only while the patients were asleep, and all were associated with disturbances in ventilatory pattern, namely, obstructive apnea (144 episodes in eight patients), paradoxic breathing (275 episodes in six patients), and period of slow ventilatory rate (37 episodes in one patient). In contrast, in patients receiving regional anesthesia, oxygen saturation never decreased below 87%. Central apnea, obstructive apnea, and paradoxic breathing occurred more frequently in patients in the morphine group (12, 10, and 10 patients, respectively) than patients in the regional anesthesia group (4, 3, and 5 patients, respectively). The interaction of sleep and morphine analgesia produced disturbances in ventilatory pattern, causing profound oxygen destruction. These results suggest that postoperative pain relief using regional anaesthesia has a greater margin of safety in terms of respiratory side effects than does the continuous administration of opiates.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of enflurane on three epilepsy models were studied in cats. The models used were seizures in amygdaloid kindled cats and those induced by bicuculline and penicillin. The authors found that not only a subconvulsive (1.5%) but a convulsive (3.5%) dose of enflurane suppressed the seizures in all models. There was no sign of activation by enflurane of the epileptic focal activities in the dose range studied: the penicillin-induced cortical seizure was suppressed completely, and the threshold dose of bicuculline required to induce seizure in normal cats and the threshold current required to induce seizure in amygdaloid-kindled cats were both increased by both the subconvulsive and convulsive dose of enflurane. The pattern of suppression was, however, dissimilar in each model. It was dose dependent in the case of penicillin-induced seizure, while it was biphasic in several aspects in the seizures of bicuculline-induced and amygdaloid kindled models. For the subconvulsive dose the degrees of increase in the thresholds required to induce seizure in bicuculline-induced and amygdaloid-kindled models were both greater than those for the convulsive dose of enflurane. In spite of such a definite suppression of the excitability of focus, the propagation of amygdaloid after-discharge was facilitated by the convulsive dose. The intensity of convulsion induced by suprathreshold dose of bicuculline was depressed in a dose-related manner. The intensity of the convulsion in the amygdaloid-kindled model was also suppressed when it was estimated by visual inspection of behavior and the degree of activation of the brain electrical activities. The authors conclude that there is little, if any, exacerbation by enflurane of preexisting epileptic foci, the only exception possibly being the case of certain myoclonic type epilepsies such as progressive myoclonic epilepsy and photosensitive epilepsy. This anesthetic probably can be used with a considerable degree of safety for epileptic patients.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The design and implementation of a computer-assisted continuous infusion (CACI) system to rapidly attain and maintain a constant plasma fentanyl concentration (PFC), as well as a CACI system that allowed the anesthesiologist to change the plasma level of fentanyl during cardiac anesthesia, were developed. In 30 patients (three groups of 10 patients each) these two automated methods of fentanyl infusion were compared with a manual fentanyl administration method. There was excellent agreement in the measured/predicted PFC ratios with the CACI stable fentanyl level system (ratio = 0.99, n = 91) and in the CACI variable fentanyl level system (ratio = 1.08, n = 79). The stable fentanyl level group of patients received significantly more (P< 0.05) fentanyl than did the other groups. The CACI variable fentanyl level group of patients had greater hemodynamic stability, required significantly (P< 0.05) fewer adjuvant drug interventions and experienced significantly (P< 0.05) fewer hypotensive and hypertensive episodes than the manual, bolus fentanyl (control) group. These data show that a computer-assisted automated infusion of fentanyl is safe and as good as manual methods. CACI has greater potential as a new method of intravenous anesthesia administration.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Thiopental was used in long-term infusion (3–4.5 mg · kg−1· h−1during 4–8 days) to protect the brain from injury following trauma. Thiopental plasma concentrations were measured during infusion (48 patients) and after infusion (14 patients) to determine the kinetics of the drug in continuous infusion. All mean values were mean ± SD. Steady state concentrations (C18) were 31.8 ± 10.7 mg/1 for an infusion rate of 3.05 ± 0.37 mg · kg−1· h−1and 48.9 ± 14.6 mg/1 for a rate of 4.2 ± 0.3 mg · kg−1· h−1. Corresponding steady state clearance decreased when C18increased, indicating possible saturation of the metabolic enzymatic system. Michaelis-Menten kinetics were confirmed by postinfusion data that give, for higher C18, a nonlinear decay of log Cversustime. First-order kinetics were only obtained with C18, below 30 mg/1. The maximum rate of elimination (Vm) was 1.76 ± 1.15 mg · I−1· h−1(n = 11), and the Michaelis constant (Km) was 26.7 ± 22.9 mg/1 (n = 11). Hepatic enzyme saturation was between 35 and 85%. The volume of distribution at steady state was 4.35 ± 1.83 1/kg (n = 11). Apparent half-lives of elimination were between 18 and 36 h at the end of infusion, and predicted terminal half-lives were 10.15 ± 5.43 h (n = 11). Phases of burst-suppression were observed on electroencephalographic traces for concentrations greater than 40 mg/1. The authors' results suggest that a continuous infusion at a dose of 4 mg · kg−1· h−1induces EEG changes consistent with a near-maximum reduction in cerebral metabolism. Because of the thiopental Michaelis-Menten kinetics at doses above 4 mg · kg−1· h−1, the authors suggest that thiopental plasma concentrations be measured and/or the drug effect be measured with the EEG to prevent excessive thiopental overdosage, causing a prolonged recovery time.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The author studied in conscious rats the local spinal blood flow (SCBF) and metabolic effects of intrathecally administered bupivacaine. Fourteen rats received 0.75% bupivacaine, 15 μ1, through a chronically implanted lumbar subarachnoid catheter. Twelve control animals were treated identically, except that they received only an equal volume of saline intrathecally. Ten minutes after intrathecal drug injection, either local SCBF or glucose utilization was measured in the lumbar spinal cord of seven experimental and six control animals with the quantitative autoradiographic iodo-[14C]antipyrine or 2-[14C]deoxyglucose methods, respectively.Intrathecal bupivacaine produced a limp tail, absent hindlimb withdrawal to pinch, and 25–30 min of analgesia on the tail-flick test. Mean arterial blood pressure decreased 14% (P< 0.01) after bupivacaine was administered, but there was no change in arterial blood gases,pH, or rectal temperature. Subarachnoid bupivacaine reduced both local SCBF and glucose utilization, but the SCBF effect was larger. Local SCBF decreased 27–34% (P< 0.01) in all five spinal gray and three white matter areas measured, and there was little regional variability in the response. The reduction in spinal glucose utilization was regionally selective and less marked. For example, glucose utilization decreased 15% (P< 0.05) and 21% (P< 0.05) in lateral and anterior spinal white matter, respectively, but only decreased approximately 3% in laminae I–III and dorsal white matter (P> 0.1). A trend toward metabolic depression was also evident in laminae VIII (-15%, P = 0.06), VII (-13%,P= 0.09), and IV-VI (-11%,P> 0.1). These results indicate that, regardless of whether it acts on the spinal cord itself or on extraspinal cord sites (e.g., spinal roots) to produce anesthesia, intrathecal bupivacaine alters the circulatory and metabolic state of the spinal cord.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The benzodiazepine antagonist Ro 15–1788 was administered in a 10-mg intravenous bolus dose to seven healthy young adult volunteers to evaluate the drug's efficacy and duration of action against midazolam. A steady state serum concentration of midazolam was obtained by an initial fast infusion rate of 6.0 mg/min (duration: 10 min) and a maintenance infusion rate of 0.275 mg/min. After administering the antagonist, all subjects opened their eyes without any command in a median time of 36 s (range: 28–48 s). Their personal, temporal and local orientation was reestablished within 54–120 s (median time: 65 s). The subjects fell deeply asleep, again in a median time of 145 min (range: 115–150 min), which was interpreted as an indication of the returning action of midazolam, which was infused for a total period of 210 min. Ro 15–1788 deserves further study as an antagonist, since it could prove useful in the management of benzodiazepine overdosage and in the reversal of benzodizepine action following surgical anesthesia and in the intensive care.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The relation between fiber size and safety of conduction was testedin vitroon individual afferent axons of rabbit vagus nerve by lowering the external sodium ion concentration and noting the effect on threshold excitability and conduction velocity. Conduction safety of myelinated axons was found to be independent of fiber size and slightly less than among unmyelinated axons. The results are consistent with previous data from the same model, where blocking concentration and diffusion time of lidocaine to the excitable membrane of individual axons also were independent of myelinated axonal size. The evidence from these single-unit studies implies that the differential blocks of functional modalities observed with spinal and epidural anesthesia probably do not arise from fiber size-related differences in susceptibility to block: possible alternatives are mentioned briefly.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID