ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

To study the effect of halothane on the coronary circulation, the circumflex diastolic coronary vascular resistance was measured in the working heart and total mean coronary resistance (TCR) in the isolated nonworking heart of the dog during administration of 100 per cent oxygen and during administration of 2–3 per cent halothane in oxygen. In the working heart, when the diastolic aortic pressure was kept at a nearly control level, halothane induced decreases of 12 per cent in circumflex diastolic coronary vascular resistance and 18 per cent in left ventricular arteriovenous oxygen content difference and no significant change in diastolic coronary blood flow. This effect occurred in spite of the absence of any significant change of myocardial oxygen consumption. In the nonworking beating, urrested or fibrillnting heart, halothane induced a decrease of 24 per cent in total mean coronary resistance. Since the decrease in circumflex diastolic coronary vascular resistance in the working heart cannot be attributed to myocardial hypoxia and since the results in the isolated nonworking heart eliminate the influences of mechanical and neurohumoral factors on coronary resistance, it is concluded that the observed decrease in resistance is probably due to vasodilation produced by a direct action of halothane on the coronary vessels. This effect was not modified by beta-adrenergic blockade.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The effect of naloxone, a narcotic antagonist, on the response of animals to painful stimuli during anesthesia was studied. Bats were anesthetized with cyclopropane, halothune, or enflurane in groups of 12. Following induction, inspired anesthetic concentration was gradually reduced to a point at which 35–60 per cent of animals responded to tail clamping. Thereafter the anesthetic concentration was held constant for 30 minutes. Bats in each group then received saline solution or naloxone, 10 mg/kg, given intravenously. The response to tail clamping was retested 5 minutes later. In additional experiments EEG's were recorded from rats anesthetized with one of these anesthetics. After a stable light plane of anesthesia had been attained, each animal was given naloxone, 10 mg/kg, iv, and the EEG recorded for an additional 5 minutes. In the tail-clomping experiments, naloxone approximately doubled the number of rats responding during cyclopropane, halothane, or enflurane anesthesia. The EEC patterns of several animals anesthetized with either cyclopropane or halothane changed to patterns consistent with lighter planes of anesthesia after naloxone administration. That naloxone alters the depth of inhalational anesthesia suggests that anesthetics may release an endogenous morphine-like factor (MLF) in the central nervous system.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Changes in pulmonary hemodynamics and acid-base balance were recorded during induction of anesthesia using either intravenous administration of a barbiturate (28 patients) or inhalation of N2O-O2-halothane (12 patients). The two types of induction resulted in equal elevations of pressures within the pulmonary circulation. The increase, proportional on the two sides of the heart, was most pronounced immediately before endotracheal intubation. Cardiac index decreased before and during intubation but subsequently increased to levels above control values. Systemic blood pressure increased more during barbiturate than during inhalation induction. Changes in acid-base balance were similar during the two types of induction: arterial blood Pco2, and Po2increased,pH decreased, and standard bicarbonate remained unchanged. Changes in pulmonary arterial mean pressure and central venous pressure were correlated with changes in Paco2Pulmonary capillary filtration pressure (i.e., pulmonary capillary wedge pressure minus plasma colloid osmotic pressure) was negative in every patient before anesthesia. During induction of anesthesia, filtration pressures became positive in half the patients. Observed changes in circulation may have been caused by hypercapnia alone or by a combination of hypercupnia and vascular reflexes associated with instrumentation during intubation. The increased strain on the heart during induction of anesthesia may lead to cardiac failure in patients with diminished cardiac reserve.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

EEG amplitude dominance in awake man is posterior. During EEC monitoring in patients, the authors observed the abrupt appearance of anterior amplitude dominance during induction of anesthesia with halothane, enflurane, or thiopental. This EEG change is coincident with loss of eyelid reflex and loss of ability to respond to command. This EEG change was studied with several anesthetics in five Java monkeys to determine alveolar anesthetic concentrations at which it occurred and to observe the effects of various stimuli on it. EEG recordings were obtained after equilibration at each level with increasing concentrations of halothane, enflurane or isoflurane in oxygen and each agent again in 30 per cent N2O, in separate experiments in the same animals. EEG amplitude dominance became anterior in each animal with each anesthetic and combination at concentrations less than MAC, which was also determined in the some experiments. At lower concentrations, stimulation at equilibrated anesthetic concentrations resulted in abrupt EEG return to posterior amplitude dominance. The end-tidal anesthetic concentration at which persistence of anterior EEG dominance was seen after stimulation was approximately 0.4 MAC for each anesthetic and combination tested. This is interpreted as support for physical solution-lipid solubility theories of anesthetic action. In addition, an EEG change common to various anesthetics may increase the clinical usefulness of EEG monitoring. It is speculated that this EEG change may signal loss of awareness. If so, observance of sustained anterior EEG amplitude dominance may provide assurance of obliteration of awareness during anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Methoxyflurane is capable of producing high-output renal failure in some patients and animal models, probably through metabolic liberation of free fluoride. The tubular site of action of fluoride was examined in Fischer 344 rats using clearance techniques. Free water reabsorption (TcH2O) and free water excretion (CH2O) were measured during mannitol or water diuresis in control rats and in rats given methoxyflurane or pre-treated with sodium fluoride. Pretreatment produced statistically significant increases in urinary flow (from 10.5 ± 1.4 to 20.1 ± 1.9 μl/min/100 g b. wt.), in glomerular filtration rate (from 814 ± 31 to 1,039 ± 53 μl/min/100 g b. wt.), in per cent sodium excretion (from 0.107 ± 0.008 to 0.155 ± 0.015 per cent), and in per cent water excretion (from 1.27 ± 0.15 to 2.00 ± 0.20 per cent). Free water excretion remained relatively unaltered in rats pretreuted with fluoride, perhaps due to elevated glomerular filtration rate and/or reduced proximal tubular reabsorption combined with inhibition of reabsorption in the ascending loop. Percentage free wuter reubsorption, on the other hand, was markedly reduced by the pretreatment, from 2.66 ± 0.21 to 0.66 ± 0.09 per cent. The observations are consistent with the hypothesis that fluoride inhibits tubular reabsorption primarily in the medullury portion of the ascending limb of Henle's loop, perhaps by inhibition of an active chloride pump located in this nephron segment.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The effects of prolonged enflurane and halothane administration on urine-concentrating ability were determined in volunteers by examining their responses to vasopressin before anesthesia and on days 1 and 5 after anesthesia. A significant decrease in maximum urinary osmolality of 264 ± 34 mOsm/kg (26 per cent of the preanesthetic value) was present on day 1 after enflurane anesthesia, whereas subjects anesthetized with halothane had a significant increase in maximum urinary osmolality of 120 ± 44 mOsm/kg. Serum inorganic fluoride level peaked at 33.6 μM and remained above 20 μM for approximately 18 hours. Thus, the threshold level for inorganic fluoride nephrotoxicity is lower than previously suspected.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Medical gases and water were sampled and tested for purity prior to the opening of a 176-bed addition to a 450-bed general hospital. Contamination was found. In delivered oxygen, compressed air, and nitrous oxide, this consisted of a volatile hydrocarbon at an initial concentration of 10 parts per million and a dust of fine gray particulate matter. In water from new taps bacterial contamination with as many as 400,000 organisms per 100 ml was present. All these contaminants were considered potential hazards to patient safety. Studies were done to help delineate the nature and origin of these contaminants. Each contaminant was eventually largely eliminated by purging the respective pipeline systems with continuous flows. Planners, builders, and responsible medical personnel must be aware of the potential for such hazards in a new hospital building.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID