摘要:

This study was performed to study the effects of acute pulmonary embolization (injection of autologous muscle) on global and regional (ultrasonic dimension technique) right ventricular (RV) performance, coronary hemodynamics (electromagnetic flow probes), and gas exchange during underlying critical stenosis (cuff occluder) of the right coronary artery (RCA) in eight open-chest dogs. Resting coronary blood flow (CBF) and regional myocardial performance remained unaffected by the induction of RCA stenosis. Following embolization pulmonary artery (PA) pressure, pulmonary vascular resistance, end-diastolic dimensions and pressure increased, and PA flow, stroke volume (SV), and aortic pressure (AoP) decreased (P< 0.05). There was a marked decline (60%) in CBF accompanied by severe myocardial dysfunction suggestive of ischemia (akinesis, systolic lengthening, postsystolic shortening) in the area supplied by the stenosed RCA. Gas exchange, lung compliance, andpH worsened. Release of the RCA constriction led to a fourfold increase in CBF, return of PA flow, SV, and AoP to baseline values, and disappearance of regional myocardial dysfunction despite continued pulmonary hypertension. These data indicate that RV function may deteriorate in response to even small increases in afterload if coronary vascular reserve is absent and aortic pressure is allowed to decrease.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The aim of this study was to investigate direct cytotoxicity to human and rat hepatocytes in primary culture from halothane and compare it with that of isoflurane, which is known to be minimally metabolized and less toxicin vivo.Both human and rat parenchymal cells were isolated by the two-step collagenase perfusion method and after attachment to plastic were incubated with either volatile anesthetic for 24 h. All the cultures were maintained in 20% O2condition and were not induced prior to anesthetic treatment. Temperature, atmosphere conditions, and anesthetic concentrations were kept constant during the study period. Evaluation of cytotoxicity was based on morphologic, biologic (determination of both extracellular and intracellular lactate dehydrogenase activity), and metabolic (protein synthesis and secretion) end points. Protein synthesis and secretion rates were found to be the most sensitive parameters in hepatocyte cultures from both species. Protein synthesis was inhibited by 18% and protein secretion by 50% in the presence of 1 and 1.25 mM halothane, respectively, in human cell cultures (P< 0.05). With 1.25 mM halothane intracellular lactate dehydrogenase was also decreased; lactate dehydrogenase leakage and morphologic alterations were detected only beyond 5 mM halothane. By contrast, in rat hepatocyte cultures protein secretion was inhibited by 26% and protein synthesis by 20% in the presence of 0.1 and 0.75 mM halothane, respectively, whereas morphologic alterations and a 37% lactate dehydrogenase leakage increase were observed with the concentration of 1 mM (P< 0.05). However, isoflurane was found to be less cytotoxic because lactate dehydrogenase leakage and morphology were not altered at concentrations as high as 2.35 mM and 5.5 mM in rat and human hepatocyte cultures, respectively. All of these observations show that halothane can be cytotoxic to adult hepatocytes maintained in standard culture conditions at concentrations much higher than those used in the clinical setting and that the degree of sensitivity of both cells is different.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Experiments were designed to determine the effects of fentanyl on coronary vascular tone and energetic state of the heart. Both arterial and arteriolar responses were assessed; particular attention was directed to epicardial vessels. Four experimental methods and three animal species were used. Isolated canine coronary artery rings with and without endothelium were suspended in organ chambers, and changes in their tension were measured. Fentanyl (100 ng/ml) had noeffect on resting tension of unstimulated rings on a contraction evoked by serotonin 10−3to 10−4M. In rings with endothelium, the opioid had a minimal depressant effect on the contractile response to phenylephrine. Tension of vessels precontracted with serotonin (3 × 10−7M), or phenylephrine (10−5M) was unchanged following fentanyl at 10, 30, 70, or 150 ng/ml. Computerized quantitative angiography was used in intact pigs anesthetized with ketamine to determine the effects of fentanyl on coronary artery diameters of vessels with or without endothelium. Intravenous fentanyl 50 and 250 μg/kg had no effect on vessel diameters. Isolated perfused rat hearts were used to assess fentanyl effects upon coronary flow and arteriolar tone and upon myocardial energy state. Coronary blood flow was not altered by fentanyl (100 ng/ml) and was unchanged following washout of the drug. The heart maintained a normal energy status prior to and following fentanyl treatment. These data demonstrate that, under the conditions tested, fentanyl is devoid of major effects on the coronary circulation and upon myocardial metabolism.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Metallic tapes have been shown to protect combustible endotracheal tubes from the CO2laser; however, no adequate means of protecting such tubes from the Nd-YAG laser has yet been found. In this investigation, five different metallic tapes were evaluated as protection for red rubber endotracheal tubes from an Nd-YAG laser set to 50 W. Radio Shack no. 44–1155 and 3M no. 1430 were quickly perforated by the laser. Laser contact with the adhesive side of 3M no. 433 resulted in combustion. The nonadhesive side of the Venture copper tape was not affected by the laser; however, when its adhesive side was struck, a fire occurred. 3M no. 425 tape provided the best protection: no effect was seen when the laser was aimed at its nonadhesive side for 1 min, with only smoking of the tape evident when its adhesive side was tested. Finally, 3M no. 425 and Venture copper foil tapes were shown to be resistant to an Nd-YAG laser set to 110 watts in an atmosphere of 98% O2.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Few studies have examined the possible adverse effects that epidural injection of depot corticosteroid preparations may have on meningeal membranes and nervous tissue. Thirty-six healthy adult white rabbits received 0.3 ml/kg epidural injections of either lactated Ringer's solution (negative control group), 1% lidocaine containing methylprednisolone acetate (study group), or normal saline containing talc (positive control group). Animals were killed either 4 or 10 days after injection and stained sections of the spinal cord and meningeal membranes were examined by light microscopy. In all animals that received either lactated Ringer's solution or lidocaine with methylprednisolone acetate, microscopic examination of specimens taken from the L5-L6 interspace revealed no white cell infiltrates and no fibroblastic activity. All animals that received epidural injections of normal saline containing talc had marked infiltration of tissue macrophages in the epidural space. There was no thickening of the meningeal membranes or nerve roots in any animal. The complete lack of inflammatory changes and meningeal thickening demonstrated in this pilot study helps to confirm the safety of methylprednisolone acetate when injected into the epidural space.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID