摘要:

Intravenous cannulation by an epidural catheter may complicate epidural anesthesia. Local anesthetic solutions containing epinephcine produce tachycardia and hypertension when given intravenously and may identify intravenous placement. The authors studied the Maternal and fetal effects of intravenous epinephrine-containing solutions in ten chronically instrumented gravid ewes. While continuously monitoring maternal and fetal effects, epinephrine 5, 10, or 20 μg iv bolus was injected. Solutions of bupivacaine 5 mg and bupivacaine 5 mg combined with epinephrine 10 μg given iv were also examined. All epinephrine-containing solutions produced a significant increase (P < 0.001) in maternal mean arterial pressure, which returned to baseline after 1 min. Maternal heart rates decreased transiently and returned to baseline after 1 min. All epinephrine-containing solutions decreased uterine blood flow (UBF) (P < 0.001), and, for doses of 10 to 20 μg, this decrease lasted more than 3 min. Fetal heart rate and mean arterial blood pressure did not change following any test solution, nor did maternal or fetal arterial blood of values. The authors conclude that small intravenous boluses of epinephrine decreased UBF in these animals.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The purpose of this study was to test the hypothesis that bleomycin administration enhances the toxic effects of oxygen on the respiratory system. Twenty-one rabbits, with no evidence of respiratory disease, received intravenous injections of 45 units of bleomycin (Blenoxane), twice a week, for a total dose of 300 units. Fifteen rabbits received an equal volume of saline and served as controls. Treatment with bleomycin resulted in failure to thrive, weight loss, and 30% mortality from nonpulmonary causes, as indicated by the lack of respiratory distress or cyanosis, during or shortly after the injection period. The remainder of the animals were allowed to recover for 21 days following the last injection. At that time, no differences were found between the experimental and the control groups with respect to arterial blood gases, total lung capacity, compliance, and hydroxyproline content. Histologic examination of lung tissue revealed normal lung architecture. When exposed to 100% O2, bleomycin-treated rabbits developed arterial hypoxemia and died from respiratory failure at the same rate as the controls. It was concluded that pretreatment of healthy rabbits with 300 units of intravenous bleomycin did not result in the development of significant amounts of lung fibrosis or enhance the toxic effects of oxygen on the respiratory system.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Depressant effects of halothane and isoflurane on isolated right ventricular guinea pig papillary muscle bathed in Tyrode's solution at 37°C were examined. Contractions were elicited by stimulation through external field electrodes while tension was recorded continuously and the intracellular cardiac action potential (AP) was monitored simultaneously by microelectrodes. The time differential of tension (dT/dt) and of membrane potential (V) was determined electronically and recorded also. Contractions after rest and at stimulation rates of 0.1, 0.25, 0.5, 1, 2, and 3 Hz were studied. With normal APs, isoflurane (1.3 and 2.5%) depressed peak tension significantly less at high frequencies than did equivalent doses of halothane (0.75 or 1.5%). Isoflurane depressed dT/dt max less than halothane at all frequencies. At 0.3 Hz stimulation, isoflurane (1–4%) significantly increased the normal AP duration by 7–11%. Slow calcium-dependent APs and accompanying contractions were studied in partially depolarized muscles (−40 to −45 mV resting potential in 26mM K+Tyrode's solution) stimulated with 0.1 M isoproterenol. Following rest and at 0.1, 0.25, 0.5, 1, 2, and 3 Hz, both isoflurane (1.3% or 2.5%) and enflurane (1.7% or 3.5%) markedly depressed the late-peaking slow AP contraction observed with low-frequency stimulation. Halothane (0.75% or 1.5%) caused a similar contractile depression (40–60%) at all frequencies. In contrast, isoflurane depressed early peaking tension and the dT/dt max at frequencies greater than 1 Hz significantly less than did halothane or enflurane. At 0.3 Hz, 2% and 4% isoflurane caused 9% and 17% depression of slow AP maximum rate of depolarization (Vmax), but significantly prolonged the AP duration. Isoflurane altered the pattern of tension development in a different manner than halothane, suggesting differing mechanisms of myocardial depression by these anesthetics.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Myocardial ischemia results when halothane is administered to animals with severe coronary stenosis. This study was done to separate the effect of halothane,per se, on myocardial ischemia from indirect cardiovascular effects, primarily hypotension, that might cause ischemia by altering the oxygen supply-demand balance. Eight dogs underwent sterile surgery for implantation of sonomicrometer crystals and atrioventricular (A-V) heart block. One week later, each dog was anesthetized with morphine and chloralose. Heart rate was controlled by ventricular pacing and altered in five steps from 50 to 150 beats/min. Arterial blood pressure was controlled by blood withdrawal or phenylephrine infusion at four levels of arterial pressure (60 to 120 mm Hg). Regional myocardial contraction was measured at each of the resulting 20 points as an indicator of myocardial ischemia. Twenty points were collected under each of four conditions in each animal: control, halothane (1% inspired), stenosis, halothane plus stenosis. Systolic thickening in the presence of stenosis was divided, on a point-by-point basis, by values obtained in the absence of stenosis to obviate the direct effects of blood pressure and heart rate on thickening. A separate normalization was done for data obtained in the presence of halothane. The normalized data demonstrate impaired systolic contraction at low arterial pressures and high heart rates. Multiple regression analysis failed to demonstrate a significant effect of halothane on systolic contraction once the effects of blood pressure, heart rate, and the negative inotropic effect of halothane were taken into account. Thus, the contraction failure that occurred during halothane and severe stenosis was mediated by changes in hemodynamics. Halothane,per se, did not cause myocardial ischemia in this nonfailing canine model of acute coronary artery stenosis.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID