摘要:

Pulmonary compliance and shunt were evaluated preoperatively, 30 minutes after cardiopulmonary bypass, and two hours postoperatively in 132 calves undergoing open-heart surgery with halothane and oxygen anesthesia. The calves were divided into 11 groups with respect to maintenance of the lungs during bypass. In Group 1 the lungs were collapsed during bypass. In all other groups the lungs were mechanically ventilated, statically inflated, or both, with either pure oxygen or nitrous oxide, 50 per cent, in oxygen. All groups had similar compliance and shunt values before operation and sustained significant decreases in compliance and increases in shunt 30 minutes after bypass. Calves exposed to positive-pressure breathing during bypass had higher shunt and lower compliance values after bypass and postoperatively than those not exposed to mechanical ventilation, irrespective of the inflating gas or presence or absence of any amount of static airway pressure. Animals not ventilated during bypass had compliance and shunt values that were not significantly different from preoperative values, while calves that were ventilated had compliance and shunt values that were still significantly altered two hours postoperatively. These data demonstrate that positive-pressure breathing during bypass decreases pulmonary compliance after bypass and postoperatively and increases intrapulmonary shunt, but that the gas inflating the lungs during bypass does not influence either of these variables. The findings also suggest that static pulmonary inflation during bypass offers no advantage over allowing the lungs to remain collapsed.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Using radioimmunoassay, d-tubocurarine (dTc) was found in the cerebrospinal fluid (CSF) of man after intravenous injection. When dTc was administered in a single dose (0.3 mg/kg) to nine patients, small quantities, 3.5 ±.26 ng/ml (mean ± SE), appeared in the lumbar CSF within 5 minutes. The concentration of dTc in the CSF remained constant for the next 25 minutes, but then began to increase with time to 9.3 ± 4.4 ng/ml 30 minutes after injection, 14.5 ± 4.4 ng/ml at one hour, and 24.9 ± 6.5 ng/ml at six hours. In another group of six patients, three doses of dTc (0.3 mg/kg) were given at 90-minute intervals. Concentration of dTc in the CSF increased after each injection. The quantities of dTc found in the CSF are unlikely to produce any pharmacologic or adverse effect (e.g., convulsion) in man.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

To determine the site and mechanism of action underlying the inhibition of adrenal medullary catecholamine release by enflurane, the authors measured the effects of enflurane on catecholamine secretion evoked by various secretagogues in isolated bovine adrenals perfused with Locke's solution. Cate-cholamine concentrations in the perfusate were measured spectrofluorometrically. Enflurane caused concentration-dependent inhibition of catecholamine release in response to activation of the nicotinic receptors in the chromaffin cells with acetylcholine or dimethylphenylpiperazinium (DMPP). An enflurane concentration of 0.88 mM caused 50 per cent inhibition of the DMPP-induced secretion. The inhibition induced by enflurane was shown to be noncompetitive. The catecholamine release evoked by activation of the muscarinic receptors with pilocarpine was only slightly decreased by 3.74 mM enflurane. At this concentration the release in response to KCl, 56 mM, was partially inhibited, whereas the output in response to tyramine (from glands perfused with calcium-free Locke's solution) was unaffected. It is concluded that the site of action of enflurane is the cell membrane. At concentrations above 1 mM, enflurane may impair calcium ion influx, but at lower concentrations it probably interacts with hydrophobic regions of the nicotinic receptor.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The contractile response of helically-cut strips of rabbit ascending aorta to transmural electrical stimulation was attenuated in a dose-dependent manner by treatment for 20 min with fentanyl, 10–6to 10–5M. Fentanyl also shifted the dose-response curve of the contractile response of aorta to norepinephrine to the right. The response to transmural stimulation was more resistant to fentanyl than was the response to an equipotent dose of norepinephrine. The inhibitory effect of fentanyl was neither prevented nor reversed by naloxone, but was partially reversed by repeated washing of the preparations. The contractile responses to histamine and serotonin were not significantly altered by fentanyl. Treatment with fentanyl as well as phentolamine protected alpha-adrenergic receptors from persistent blockade by phenoxybenzamine. Morphine to 10–3M failed to influence the dose-response curve of norepinephrine significantly. It may be concluded that fentanyl reversibly blocks alpha-adrenergic receptors in a competitive manner in vascular smooth muscle, and the potency of fentanyl is approximately 1/30 that of phentolamine.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Halothane depresses myocardial blood flow and metabolism in the dog, but no studies in man have been published. However, the coronary circulation of the pig is remarkably similar to that of man. The authors investigated the effects of halothane-nitrous oxide anesthesia on cardiac function and metabolism in piglets. Thermodilution cardiac output, catheter-tip-manometer measurement of left ventricular function, electromagnetic flowmeter measurement of coronary blood flow, and blood and tissue measurements of gases and metabolites were made during 0.04 (control), 0.46 (low concentration) and 1.04 (high concentration) per cent halothane vaporized in nitrous oxide, 60 per cent: oxygen, 40 per cent. Compared with control, the low concentration decreased cardiac output (CO) by 10 per cent, left ventricular systolic pressure (LVSP) by 30 per cent, peak contractile element velocity (Vmax) by 34 per cent, coronary blood flow (CBF) by 36 per cent, and cardiac oxygen uptake (±o2) by 55 per cent. Compared with control, the high concentration decreased CO by 32 per cent, LVSP and Vmaxby 53 per cent, CBF by 63 per cent and ±o2by 62 per cent. This indicates that the dose-related depression in left ventricular function produced by halothane was accompanied by equivalent decreases in coronary blood flow and oxygen consumption. There was minimal evidence of anaerobic metabolism in these depressed ventricles. Tissue levels of the high-energy phosphates, adenosinetriphosphate and creatine phosphate, and glycogen were unchanged. It is concluded that changes in cardiac oxygenation and metabolism in the pig during halothane anesthesia result from the changes in ventricular function.

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

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

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