ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To determine if a relationship exists between perioperative myocardial ischemia (ST segment depression ± 0.1 mV) and post-operative myocardial infarction (PMI), nonparticipating observers recorded all ECG, hemodynamic, and other events between arrival of patients in the operating room and onset of cardiopulmonary bypass during 1,023 elective coronary artery bypass operations (CABG). The roles of preoperative patient characteristics, quality of the operation limited by disease as rated by the surgeon and duration of ischemic cardiac arrest as risk factors for PMI also were quantified. ECG ischemia occurred in 36.9% of all patients, with almost half the episodes occurring before induction of anesthesia. PMI was almost three times as frequent in patients with ischemia (6.9% vs. 2.5%) and was independent of when ischemia occurred. Ischemia was related significantly to tachycardia but not hypertension nor hypotension and was frequent in the absence of any hemodynamic abnormalities. The anesthesiologist whose patients had the highest rate of tachycardia and ischemia had the highest rate of PMI. Although neither single nor multiple preoperative patient characteristics related to PMI, suboptimal quality of operation and prolonged ischemic cardiac arrest increased the likelihood of PMI independent of the occurrence of myocardial ischemia. The authors conclude that perioperative myocardial ischemia is common in patients undergoing CABG, occurs randomly as well as in response to hemodynamic abnormalities, and is one of three independent risk factors the authors identified as related to PMI. PMI is unrelated to preoperative patient characteristics such as ejection fraction and left main coronary artery disease, and its frequency will relate primarily to perioperative management rather than patient selection.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of anesthetic drugs on lipid order were evaluated by the fluorescence polarization of the probe molecule, 1,6-diphenyl-1,3,5-hexatriene (DPH) incorporated into vesicles of dimyristoyl-phosphatidylcholine (DMPC) and DMPC with 10 mol% ganglioside (GDL2). Anesthetics (enflurane, chloroform, diethylether, pentobarbital, ethanol, butanol, hexanol) decreased the fluorescence polarization of DPH in vesicles of DMPC, but relatively large concentrations were required. Addition of gangliosides to DMPC enhanced the lipid disordering effects of anesthetics by several fold. The potencies of these anesthetics in decreasing fluorescence polarization of DPH in DMPC-ganglioside was well correlated with their potencies as anesthetics, and significant decreases in fluorescence polarization occurred at pharmacologically relevant concentrations. These results indicte that gangliosides can enhance the sensitivity of membrane lipids to the disordering effects of anesthetics and suggest that the large ganglioside content of the outer leaflet of the lipid bilayer of neuronal membranes may render this membrane region unusually sensitive to anesthetic agents.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To determine whether electrical stimulation of the periaqueductal gray region decreases anesthetic requirement, the authors studied the effect of such stimulation on the MAC of halothane and 60% nitrous oxide in 33 patients. These patients, who were undergoing implantation of a radio-frequency-coupled receiver and connection of that receiver to electrodes previously implanted in the periaqueductal gray area, were assigned randomly to receive (n = 16) or not receive (n = 17) electrical stimulation 1 h before surgery. The mean value (±SEM) for the minimum alveolar concentration of halothane combined with 60% nitrous oxide was significantly less (P, < 0.001) for patients who were stimulated preoperatively (0.15 ± 0.05%) than for those who were not (0.51 ± 0.02%). The authors conclude that stimulation of the periaqueductal gray region decreases anesthetic requirements and believe that at least three mechanisms are possible: a nonspecific narcotic-like effect, a specific effect on a pain pathway, or an effect on specific neural pathways that affect anesthetic requirements secondary to changes in regional concentrations of neurotransmitters.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Human leukocyte and skin mast cell preparations were incubated with morphine sulfate in concentrations ranging from 1.5 × 10−5. M to 4.5 × 10−5M. Skin mast cells also were incubated with oxymorphone and fentanyl in the same concentrations. Human leukocytes did not release histamine in response to any concentration of morphine. In skin mast cells, histamine release by morphine first was detected at 1.5 × 10−4M. Histamine release further increased at 5.0 × 10−4M with no incremental increase at higher concentrations. Oxymorphone and fentanyl failed to release histamine at any concentration. Histamine release by morphine required calcium but was not influenced by changes in the 1–4 nM range. Skin mast cell preparations were pretreated for 30 min in naloxone 5 × 10−4M and then morphine 5 × 10−4M was added for 30 min without removing naloxone. Naloxone neither released histamine nor inhibited morphine-induced histamine release. The release of histamine by morphine but not equimolar concentrations of fentanyl and oxymorphone indicates that histamine release by narcotics is not a nonspecific effect of high drug concentration. The failure of naloxone to inhibit morphine-induced histamine release suggests that histamine release by morphine is not dependent on opiate receptor binding or activation. These results indicate that this human mast cell preparation will be useful in further understanding the mechanism of histamine release induced by morphine and other agents.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To determine the influence of background vasomotor tone on the effectiveness of sodium nitroprusside in decreasing total peripheral resistance, experiments were performed on 12 open-chest dogs under halothane anesthesia. In the first experiment, the vasomotor condition of six dogs was changed by altering the background infusion rate of phenylephrine (0, 40, and 0 μg/min). Increasing background phenylephrine infusion from 0 to 40 μg/min significantly enhanced the effectiveness of nitroprusside in decreasing total peripheral resistance. In contrast, the effectiveness of nitroprusside in decreasing arterial pressure was not altered significantly. In a second experiment on six other dogs, phenylephrine was infused continuously at 40 μg/min, and the vasomotor condition was changed by the infusion of phentolamine (0, 60–100, 0 μg/min). Phentolamine significantly diminished the effectiveness of nitroprusside in decreasing peripheral resistance. In contrast, the effectiveness of nitroprusside in decreasing arterial pressure was not altered significantly. Stepwise linear regression analysis indicated that the background peripheral resistance was the hemodynamic variable that could account partially for the changes in nitroprusside effectiveness. Increasing background total peripheral resistance significantly enhanced the effectiveness of nitroprusside in decreasing total peripheral resistance.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of halothane and isoflurane on hypocapnic increases in pulmonary collateral resistance were studied in dogs. A bronchoscope with a double lumen catheter in the suction port obstructed a peripheral airway and allowed gas to flow out of the isolated segment of lung only via collateral channels. The collateral gas flow (&OV0312;coll) was measured with a flowmeter and delivered through one lumen of the catheter, while the other lumen measured distal pressure (Pb). At FRC, the resistance to collateral ventilation (Rcoll) was calculated as Rcoll = Pb/Vcoll. The rest of the lung was ventilated with air, while air (hypocapnia), 10% CO2in air, or air and halothane or isoflurane were delivered to the isolated segment. A measurement of resistance was made after 4 min of test gas flow. For each segment, when air replaced 10% CO2, the average increase in Rcoll was calculated and called Rmax. When 10% CO2in air was infused into segments the mean Rcoll (n = 50) was 0.0196 ± 0.0022 cmH2O·ml−1· min. This increased to 0.0285 ± 0.0031 cmH2O · ml−1· min (mean ± E) when air was infused, a mean increase in resistance of 52 ± 3%. When halothane or isoflurane was added to air the hypocapnic increase in Rcoll was attenuated with a 50% decrease at 1.3% (1.4 MAC and 0.8 MAC, respectively). These two inhalational anesthetics reduce active changes in the flow resistance to collateral ventilation. When collateral resistance acts to adjust ventilation perfusion deviations, this action of halothane and isoflurane may make this regulation less effective.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The microvascular effects of varying concentrations of lidocaine were evaluated with the use of videomicroscopy in anin vivorat cremaster muscle preparation. Animals were anesthetized with chloralose and urethane and breathed room air spontaneously. Mean areterial pressure and heart rate were measured via a carotid artery cannula. The cremaster muscle was suffused with a balanced electrolyte solution andpH, temperature, Po2, Pco2, and osmolarity were controlled. Internal diameters of fourth-order arterioles in the cremaster muscle were measured with an electronic vernier system. In one group of animals (n = 7), arteriolar diameters were measured every 30 s during a 10-min control period, a 10-min period of topical application of lidocaine hydrochloride, and a 10-min recovery period. Lidocaine hydrochloride, 100, 101, 102, 103, or 104μg·ml−1, produced changes in arteriolar diameters to 88.9 ± 0.9, 79.0 ± 1.3, 67.5 ± 2.4, 60.1 ± 3.4, and 127.1 ± 7.2 per cent of control, respectively (P< 0.001). In a second group of animals (n = 4), fourth-order arteriolar diameters were measured during administration of intravenous lidocaine, 1.2 mg·kg−1bolus plus 0.3 mg·kg−1· min−1. Vasoconstriction to 91.3 ± 0.9% of control was observed (P< 0.001). These results demonstrate a biphasic dose-dependent response to lidocaine. At lesser concentrations, including those that occur in the plasma of patients during intravenous infusion or nerve blocks, dose-related vasoconstriction occurred. Lidocaine, 104μg · ml−1, a concentration similar to that which occurs at the site of injection during infiltration, nerve block, or epidural anesthesia, produced vasodilation. It appears likely that the observed effects are a result of peripheral rather than central actions of the drug.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The purpose of this study was to examine the effects of ketamine and pentobarbital on venous capacitance in rats. Venous capacitance was assessed by measuring the mean circulatory filling pressure (MCFP) at three levels of blood volume in conscious rats as well as during anesthesia with ketamine (125 mg/kg, ip) or pentobarbital (50 mg/kg, ip). MCFP was measured during brief periods of circulatory arrest produced by inflating an indwelling balloon in the right atrium. MCFP was maintained during ketamine anesthesia at a level similar to that measured in conscious animals, while it was decreased (P< 0.01) during pentobarbital anesthesia both at normal blood volume and following hemorrhage. These results suggest that ketamine did not alter but pentobarbital increased venous capacitance. The slope of the regression line relating MCFP and blood volume was not altered by ketamine but was increased (P< 0.05) by pentobarbital, which suggests that ketamine did not alter but pentobarbital decreased total vascular compliance. These results suggest that ketamine maintains but pentobarbital decreases venous tone.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Cardiovascular responses to acute hemodilution and controlled hypotension were studied in mongrel dogs anesthetized with halothane and paralyzed with pancuronium. Regional blood flows were determined by microsphere injections. Hemodilution to an hematocrit of 23% was produced by removal of whole blood and simultaneous infusion of Ringer's lactate solution. Subsequently, hypotension to a mean arterial pressure of 55 mmHg was produced for 90 min by intravenous infusion of trimethaphan. The hypotension resulted entirely from a 55% decrease in total peripheral resistance. Thirty minutes after initiation of controlled hypotension, there were significant increases in blood flow to the brain, liver, skeletal muscles, and diaphragm. However, at 30 min, calculated oxygen delivery had decreased to brain (−16%), renal cortex (−51%), heart (−45%), and retina (−44%). By 90 min, retinal, adrenal, and renal cortical blood flows were decreased significantly relative to control, and cerebral blood flows had returned to control levels. Absence of changes in acid-base status during the period of hemodilution and hypotension may indicate that whole body oxygen delivery was maintained at adequate levels. However, major decreases in calculated oxygen delivery after 90 min to critical tissue beds such as renal cortex (−67%) and retina (−78%) indicate that extension of the procedure past 30 min may involve risks that are not warranted by the benefits.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID