ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

Cerebral oxygen utilization and blood flow were measured by the washout of oxygen-15 isotopes injected into the internal carotid artery in baboons during hypotension produced by acute hemorrhage, trimethaphan, and sodium nitroprusside. Acute hemorrhage, trimethaphan, and sodium nitroprusside lowered the mean arterial blood pressure to 52 per cent, 55 per cent, and 47 per cent, respectively, of control values. There were corresponding decreases in cerebral blood flow to 76 per cent (P< 0.01), 81 per cent (P< 0.05), and 79 per cent (P< 0.01) of control values. When the mean arterial blood pressure was decreased 11 per cent with hemorrhage, autoregulation of the cerebral vasculature was preserved and cerebral oxygen utilization increased 10 per cent (P< 0.01). When cerebral autoregulation was lost with acute hemorrhage, cerebral oxygen utilization declined 17 per cent (P< 0.05). When cerebral autoregulation was lost with pharmacologic hypotension, cerebral oxygen utilization was preserved with trimethaphan and increased 17 per cent (P< 0.05) with sodium nitroprusside. The increase in cerebral oxygen utilization seen with sodium nitroprusside and hemorrhagic (autoregulation preserved) hypotension may be due to stimulation of the sympathetic nervous system with release of circulating catecholamines. However, the mechanism by which circulating catecholamines mediate an increase in cerebral oxygen metabolism during hypotension is not clear.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

A carcinogen bioassay of enflurane was performed in Swiss/ICR mice. Two groups of weanling mice, each of 125 males and 125 females, were exposed to either a maximum tolerated dose of enflurane, 3000 ppm (0.3 per cent v/v) or compressed air for 4 hs per day, 5 days per week. After 52 weeks exposure, 25 males and 25 females from each group were killed. After 78 weeks exposure, a 4-week period without treatment was allowed before the remaining mice were killed. Mice killed at the scheduled periods and those killed or dying at other times throughout the study, underwent extensive gross and histologic examinations unless autolysis or cannibalism precluded examination. After 78 weeks exposure, male mice in the enflurane-treated group had a 36 per cent incidence of liver tumors compared with 24 per cent in the control group; however, the difference was not statistically significant. The incidence of lung tumors was about 20 per cent in all groups. Other neoplastic lesions occurred in small numbers and were unrelated to treatment. It was concluded that under the conditions of the present experiment, chronic administration of enflurane at its maximum tolerated dose did not lead to an increased incidence of neoplasia in Swiss/ICR mice.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

Halothane anesthesia administered to enzyme-induced animals in a hypoxic atmosphere consistently produces hepatic necrosis. Rats pretreated with phenobarbital were exposed to hypoxia at varying intervals after administration of halothane, enflurane, or isoflurane anesthesia. Anesthetics were administered at 1 MAC for 2 h. For each agent, hypoxia consisting of 8 per cent oxygen-balance nitrogen for 1 h was imposed at the end of anesthesia. In other groups of rats, we also used a 15-, 30-, 60-, and 120-min interval of 100 per cent oxygen between 2 h of halothane anesthesia and the imposition of hypoxia. Controls included enzyme-induced animals with and without hypoxia, hypoxia alone, and cage controls. Hepatic injury was graded by histologic examination of the livers. Injury was greater when hypoxia followed halothane anesthesia than when it followed enflurane, isoflurane, or enzyme-induction alone. A difference in injury score existed between control animals and those anesthetized with halothane who received a 15-min interval of oxygen before hypoxia. Combined results from the 15− and 30-min delay groups also were different from control. There was no difference between control and halothane groups when the oxygen interval was 60 or 120 min. The injury score of the enflurane and isoflurane groups were comparable to that of controls. We conclude that a potential for hypoxia-induced liver injury during recovery exists after halothane anesthesia. Neither enflurane nor isoflurane anesthesia produced significant hepatic injury in this model.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

A selective breeding process designed to produce mice resistant (HI mice) and susceptible (LO mice) to nitrous oxide anesthesia was continued through 10 generation. At the tenth generation, the nitrous oxide requirements of the HI and LO mice (as measured by the partial pressure of nitrous oxide required to abolish the righting reflex) were separated by more than 0.7 atm. The HI mice also had a higher anesthetic requirement for cyclopropane, enflurane, isofluranc, halothane, and methoxyflurane, as measured by response to a tail-clamp stimulus. HI mice given an intraperitoneal injection of ethanol (4 g/kg) had 44 per cent shorter sleep times and 12 per cent higher blood alcohol levels upon awakening than did LO mice. For nitrogen, argon, cyclopropane, isoflurane, enflurane, halothane, and methoxyflurane, we determined the doses at which the righting reflex was abolished in HI and LO mice. The separation in righting-reflex ED50s between these two lines was inversely related to the lipid solubility of the anesthetic. For the most lipid-soluble anesthetic, methoxyflurane, no significant differences in potency, as measured by the righting-reflex ED50, could be detected between the HI and LO mice. In contrast, the separation in anesthetic requirements, as measured by the tail-clamp ED50, was approximately the same for each of the anesthetics tested.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

To test the possibility that mice selectively bred for resistance (HI mice) and susceptibility (LO mice) to nitrous oxide anesthesia have general differences in central nervous system excitability, we examined the effects of six convulsant agents in these two lines of mice. Using high-pressure helium, flurothyl, pentylenetetrazol, strychnine, (+)-bicuculline, and picrotoxin, we induced convulsions in HI and LO mice. For all of the agents tested, HI mice were significantly more susceptible to convulsions than LO mice. LO mice convulsed at a 13 to 25 per cent higher dose of convulsant agent than did HI mice. In contrast, nitrous oxide requirements (as measured by the partial pressure of nitrous oxide required to abolish the righting reflex), were 49 to 65 per cent higher in HI mice. Therefore, the higher nitrous oxide requirement in HI mice is probably due, at least in part, to a generalized increase in central nervous system excitability.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

The effect of sodium nitroprusside (SNP)-induced hypotension on the sensitivity of the baroreflex was studied in 11 informed patients anesthetized with morphine (M) or halothane (H). PaCO2was controlled at 28 to 32 mmHg with a respirator. Baroreflex sensitivity was assessed with a depressor test using a small dose of SNP (4–6 μg/kg, iv) to decrease the systolic pressure (SP) rapidly by about 30 mmHg. The slope of the regression line (in ms/mmHg) relating SP and the succeeding pulse interval (PI, R-R interval) was used as an index for the sensitivity of baroreflex control of heart rate. In control measurements, SP-PI slopes were 6.4 ms/mmHg for the morphine group and 3.2 ms/mmHg for the halothane group, indicating that baroreflex sensitivity is greater during morphine than during halothane anesthesia. This difference in baroreflex sensitivity might explain the differences in dose requirements for SNP in patients anesthetized with either morphine or halothane. Following a control test, SNP was infused at a rate adjusted to maintain the mean arterial pressure between 55 and 60 mmHg. The duration of hypotension was in accordance with surgical needs. SNP infusion was then discontinued and SP was allowed to recover spontaneously. When SP recovered to its control level, PI was significantly prolonged by 18 per cent in patients anesthetized with morphine and by 13 per cent in those anesthetized with halothane over the respective control values. Immediately after the recovery of SP following the discontinuation of SNP infusion, another baroreflex sensitivity test was made; the SP-PI slopes increased markedly by 105 per cent in patients anesthetized with morphine and by 179 per cent in those with halothane over the respective control values, indicating a resetting of the baroreflex. These changes may have significant implications in hemodynamic adjustments following induced hypotension in patients during general anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

Twenty-eight elderly patients (>75 years old) and 43 younger patients (25 to 60 years old) were studied to evaluate the effect of aging on the pharmacokinetics and pharmacodynamics of pancuronium. The pancuronium dose-response relationship and the duration of neuromuscular blockade after the administration of a single dose (70 to 100 μg/kg) were compared in the two groups. The plasma concentration-response relationship was established during recovery from paralysis. The pharmacokinetics of pancuronium were characterized after a single bolus dose by measuring plasma and urine concentrations of pancuronium fluorimetrically. The dose–response and plasma concentration–response relationships in elderly patients were comparable to that of the control group. The dose that caused 50 per cent paralysis averaged 39 ± 10 and 44 ± 12 μg/kg in control subjects and elderly patients, respectively. The plasma concentrations corresponding to a fixed degree of neuromuscular blockade were similar between the two groups. The time for recovery of the twitch tension to 25 per cent of the control value was prolonged from 44 ± 10 to 73 ± 22 min in the elderly patients. The recovery rate of the twitch from 25 to 75 per cent of the control value also was prolonged from 39 ± 13 to 62 ± 30 min in the elderly patients. The plasma clearance was decreased by 35 per cent in the elderly patients and caused a prolongation of the elimination half-life to 201 min as compared with 107 min in the younger adults. Urinary excretion of pancuronium was delayed in the elderly patients. It is concluded that pancuronium exerts a prolonged effect in elderly patients because of delayed elimination; the pharmacodynamics of pancuronium are not altered by aging.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

The effect of 80 per cent nitrous oxide on motility of human neutrophils obtained from six volunteers was studiedin vitro.In every case, random migration through the pores of 3 μm-millipore filter paper was reduced (mean value 16 per cent). Chemotaxis toward casein also was reduced in every case (mean value 22 per cent). These results contrast with a previous study in which mean rates of migration were found to increase following exposure to 2 per cent halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1982

数据来源: OVID