ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The effects of local anesthetics on the synthesis, release, and degradation of γ-aminobutyric acid (GABA) in rat brains were investigated. The addition of procaine, lidocaine, cocaine, or tetracaine did not alter either glutamic acid decarboxylase (GAD) activity or GABA transaminase (GABA-T) activityin vitro. Neither did the enzyme activities in rats with local anesthetic-induced convulsions differ from control values. Tetracaine inhibited high K+-evoked [2,3-3H]GABA release from synaptosomes of rat brain in a dose-dependent manner with a minimal effective concentration of 10-4M. Cocaine, lidocaine, and procaine also reduced the release, although they were less potent than tetracaine. The GABA release inhibitors in order of potency are tetracaine, cocaine, lidocaine, and procaine which correlates well with their relative toxicity as convulsants. These results suggest that local anesthetics reduce GABAergic activities by inhibiting the release of the neurotransmitter from the nerve terminals, and that inhibition of the GABA system may be involved in the mechanism of local anesthetic-induced convulsions.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

This study was designed to determine in postcesarean patients whether in addition to superior analgesic effects, epidural morphine administration results in secondary benefits in maternal well-being and maternal-infant interaction. Following elective cesarean section with bupivacaine epidural anesthesia, 40 healthy mothers received 5 mg preservative-free morphine sulfate in 10 ml of saline, either by the epidural (Group 1, n = 20) or the intravenous (Group 2, n = 20) route, in a randomized, double blind fashion. Each received a simultaneous injection of saline by the alternate route. Analgesia in Group 1 lasted significantly longer (16.1 ± 8.8vs. 4.4 ± 2.4 h, mean ± SD;P <0.001), and morphine requirements in the first 24 h were significantly less (12.5 ± 20 mgvs. 36 ± 21 mg,P <0.001) than in Group 2. Seventy-four per cent of patients who received epidural morphine reported excellent analgesia, compared with only 32% of those who received intravenous morphine (P <0.05). Although Group 1 mothers ambulated 6 h earlier than those in Group 2 (P <0.02), there was no difference between the groups in time of first voiding, number of hours mothers slept, or duration of hospital stay. Mothers in both groups interacted with their infants equally well and for the same duration of time. Itching occurred in 58% of Group 1 patients and only 16% of Group 2 patients (P <0.01); the incidences of nausea, vomiting, and urinary retention were not statistically different between the groups. No respiratory depression was observed. Benefits of epidural morphine in this patient population appear limited to the provision of improved analgesia and earlier mobility.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

To determine the effects of cardiopulmonary bypass (CPB) and hypothermia on the neuromuscular blockade produced by pancuronium, this relaxant was infused intravenously into 10 anesthetized patients to produce and maintain 90% depression of the twitch tension of the adductor pollicis muscle following supramaximal ulnar nerve stimulation. Infusion rates, plasma concentration of pancuronium, and adductor pollicis temperature were measured every 15 min. During the normothermic period preceding the start of CPB, the pancuronium requirement, the pancuronium plasma concentration, and muscle temperature were (mean ± SEM): 238 ± 12 μg·m-2.15 min-1, 0.31 ± 0.01 μg/ml, and 33.9 ± 0.1 ° C, respectively. At the beginning of CPB, the pancuronium infusion rate increased to 362 ± 32 μg·m-215 min-1(P <0.001) despite a decrease in the muscle temperature to 29.2 ± 0.9° C (P <0.001) and in pancuronium plasma concentration to 0.22 ± 0.02 μg/ml. During sustained muscle hypothermia to 28.3 ± 0.4° C the pancuronium plasma concentration remained constant at 0.22 ± 0.01 μg/ml (P <0.001) while the requirement decreased to 94 ± 15 μg·m-2·15 min-1(P <0.001). After the muscle temperature was returned to 34 · 0.6° C, the plasma pancuronium concentration and requirements increased to 0.35 · 0.05 μg/ml and 392 · 32 μg·m-215 min-1(P <0.001), respectively. After CPB, these values were 0.39 · 0.04 μg/ml and 239 · 25 μg·m-2*15 min-1. These results demonstrate that pancuronium requirements are increased at the beginning of CPB because of circulatory volume changes and again during rewarming of the patient once muscle temperature reaches about 34° C.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The present study examined the influence of spinally administered fentanyl on the spontaneous and noxiously evoked activity of wide dynamic range (WDR) neurons in the dorsal horn of decere-brate, spinal cord-transected cats. This work was performed in order to evaluate the dose-response relationship, time course, and naloxone reversibility of fentanyl suppression of neurons that are involved with the transmission of information about pain. Extracellular single neuron recordings were obtained from 18 WDR neurons in the lumbar enlargement. These neurons were activated by a radiant heat stimulus on the footpads of the hindpaw. Fentanyl (10, 15, 25 μg in 0.5 ml of physiologic saline) was placed on the spinal cord following control studies of each neuron and the effect was observed. In 12 cats, 31 min after fentanyl administration, naloxone (0.1 mg) was administered intravenously, and its effect on the fentanyl suppression was determined. All three doses of fentanyl suppressed both the spontaneous and evoked activity of all the neurons studied. Thirty minutes after fentanyl the mean evoked activity was reduced to 47, 23, and 11% of control values by 10, 15, and 25 4mUg, respectively. The spontaneous activity was reduced to similar levels. Intravenous naloxone (0.1 mg) caused a significant reversal of the fentanyl suppression.The results of the present study indicate that fentanyl causes a naloxone-reversible, dose-dependent suppression of noxiously evoked WDR neuron activity. Such results support the concept that fentanyl is acting through a specific drug-receptor interaction. The onset of neuronal suppression occurred more rapidly, and the duration of the suppression was longer following fentanyl than that seen following spinal morphine. The onset and duration of this suppression correlates well with human clinical data, providing further evidence that alterations of WDR neuronal activity may be important in the production of spinal opioid analgesia.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The hemodynamic effects of nitroglycerin (TNG) and sodium nitroprusside (SNP) were studied in a canine model of pulmonary hypertension. Oleic acid administration resulted in pulmonary hypertension with a 133% increase in pulmonary vascular resistance (PVR), a 40% increase in mean pulmonary artery pressure (MPAP), and a 28% decrease in cardiac output (CO). In this model, subsequent TNG administration increased CO 40%, decreased PVR 43%, and decreased MPAP 12%; pulmonary hemodynamics during TNG administration were not significantly different from those prior to oleic acid administration. SNP produced systemic hypotension but did not alter either PVR or MPAP and increased CO only 14%. The efficacy of TNG in this model may relate to its ability to dilate preferentially the pulmonary vascular bed.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The authors determined the neuromuscular effects of vecuronium (ORG NC45, NorcuronTM) during anesthesia with nitrous oxide and 0.9 MAC halothane. To determine potency, they administered vecuronium (15, 20, or 25 μg/kg) to 18 infants (<1 year old) and 18 children (1–8 years old). They then compared these dose-response relationships with values obtained for adults (>18 years old) under comparable anesthetic conditions. The ED50s (dose producing 50% depression of adductor pollicis twitch tension) of 16.5, 19.0, and 15.0 μg/kg for infants, children, and adults, respectively, did not differ significantly. To determine the time course of neuromuscular blockade, the authors administered vecuronium, 70 μg/kg, to six infants, six children, and six adults. Onset time (time to maximal effect) was shortest for infants (1.5 ± 0.6 min, mean ± SD) compared with that for children (2.4 ± 1.4 min) and adults (2.9 ± 0.2 min). Duration (time from injection to 90% recovery) was longest for infants (73 ± 27 min) compared with that for children (35 ± 6 min) and adults (53 ± 21 min). The authors conclude that vecuronium can be used in infants and children in doses similar to those recommended for adults. The time interval for supplemental doses will be longest in infants and shortest in children.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The nitrous oxide withdrawal syndrome in mice was used as an experimental model to examine some of the factors which may play a role in postanesthetic excitation. Predisposition to nitrous oxide withdrawal convulsions as judged by duration of susceptibility was decreased significantly after pretreatment with the cholinesterase inhibitors, physostigmine and galanthamine, or with the opiate receptor blocking agent naloxone. Results are discussed in relation to the central anticholinergic syndrome, endorphin release, and disturbances which follow nitrous oxide anesthesia in humans and animals.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Following establishment of total spinal anesthesia, the cerebral metabolic effects of progressive hypothermia (37, 28, 18, and 14° C) were studied initially in six awake dogs. The EEG became iso-electric at temperatures below 18° C. At 14° C, CMROlwas reduced to 7% of control. Thereafter, 40 mg/kg thiopental, iv, was given and the dogs were rewarmed while an isoelectric EEG was maintained by a continuous thiopental infusion. The CMROlwas then compared at the different temperatures with and without thiopental. The CMRO, was unaffected by the barbiturate at 14 and 18° C. At 28 and 37° C the CMRO, was significantly reduced by the barbiturate (at 37° C to 55% of the 37° C value without thiopental). The change in CMROlwith temperature in the absence of EEG activity (due to barbiturates) closely approximated an Arrhenius curve (relating log CMRO, to the reciprocal of absolute temperature). In the presence of EEG activity (no barbiturates) such a simple relationship was less apparent. The results support the following conclusions: barbiturates only affect CMRO, in the presence of neuronal electrical activity; the combined effect of hypothermia and barbiturates on CMROlcannot be expressed as a simple additive relationship; and in the presence of electrical activity, the relationship between temperature and CMRO, cannot be denned by any simple mathematical function.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Cerebral blood volume (CBV) and intracranial pressure (ICP) were examined in dogs during 3.5 h anesthesia with halothane (0.8%) or enflurane (2.2%), and after decreasing the concentration of halothane to <0.1% or enflurane to <0.2%. As compared with animals breathing N2O and O2, halothane (0.8%) increased CBV 11–12%, while ICP remained increased (4–5 cmH2O) for 3.5 h. Both at 0.8% and <0.1% ICP correlated positively with changes in CBV. Enflurane (2.2%) increased CBV by 8–10%, and while ICP correlated with changes in CBV during the initial 30 min, ICP increased independently of CBV thereafter.

ISSN:0003-3022    

出版商:OVID    

年代:1983

数据来源: OVID