ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The effects of reversible sympathetic neural blockade of the canine myocardium under control conditions and in the presence of decreased coronary blood flow and after myocardial infarction were investigated in 17 dogs. A multiple-microsphere technique was used to measure distribution of blood flow in the myocardium. Epidural blockade was associated with the following changes in the ratio of endocardial to epicardial blood flow: under control conditions, no change; after 50 per cent decrease in coronary flow, 18 per cent increase in endocardial/epicardial ratio; after myocardial infarction at unrestricted coronary flow, 43 per cent ratio increase; after myocardial infarction and 50 per cent decrease in coronary flow, 76 per cent increase of endocardial/epicardial ratio. These effects appear to be independent of systemic factors, and may result from alterations in tone of transmural resistance vessels. In addition, cervicothoracic epidural blockade resulted in a decrease in systemic pressure and an increase in coronary vascular resistance as myocardial oxygen demand decreased. When systemic pressure was restored these effects were abolished. In the presence of myocardial infarction, epidural blockade had less effect on systemic pressure and left ventricular filling pressure was decreased. With decreased coronary flow, sympathetic blockade redistributed coronary blood flow, favoring the endocardium in both the normal and the infarcted heart.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Nitrous oxide labeled with a stable heavy nitrogen isotope was used forin-vitrostudies of nitrous oxide metabolism in man and rat. At 5 per cent oxygen tension, which is comparable to normal oxygen tension in the intestinein vivo, each gram of intestinal contents during a 16-hrin-vitroincubation produced 47 ± 13 nmol of molecular nitrogen for the rat and 103 ± 17 nmol for man. Active reductive metabolism of nitrous oxide by intestinal contents was significantly inhibited by antibiotics and by 20 per cent oxygen tension. It is suggested that the reduction of nitrous oxide to nitrogen may proceed through a single-electron transfer process with formation of free radicals. Under these circumstances, metabolism of nitrous oxide could produce toxic intermediates, even though the end-metabolite is inert.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The purpose of this study was to evaluate the analgesic contribution of intravenously administered lidocaine and to correlate it with blood levels of the drug. In a double-blind manner, 14 healthy male volunteers received saline solution or lidocaine, 0.2 per cent, at three increasingly greater rates of infusion on two separate days. Experimental pain was produced by means of the submaximal tourniquet-induced ischemia test of Beecher and Smith. The times to the onset of ischemic (threshold) and unbearable (tolerance) pain were recorded for three control trials to two tests for the same end points during each infusion rate. Between the two ischemic trials, while the test solution continued to be infused, venous blood samples were drawn and analyzed for lidocaine by gas chromatography. No statistically significant difference in analgesia between the control and lidocaine values for threshold or tolerance was observed at blood levels from 1 to 3 μg/ml. The data suggest that lidocaine at these blood levels produces sedation but not analgesia.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Arrhythmogenic doses of epinephrine were determined in six mongrel dogs anesthetized at 1.4 MAC halothane initially in the absence of local anesthetics and then at increasing arterial plasma levels of lidocaine, bupivacaine, and etidocaine. The authors gave epinephrine intravenously at 5 μg/kg/min and calculated the arrhythmogenic dose as a function of time until two or more premature ventricular contractions occurred within a 10-sec period. The control arrythmogenic dose of epinephrine was 4.66 ± 0.46 μg/kg (mean ± SEM). Arrythmogenic doses of epinephrine were increased significantly after each dose of lidocaine, bupivacaine, and etidocaine. With the largest doses studied, local anesthetic plasma levels were frequently in the toxic range. The data show that lidocaine, bupivacaine, and etidocaine equally protect against epinephrine-induced arrhythmias in dogs anesthetized with halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To determine the effects of endotracheal intubation on airway mechanics in healthy individuals, measurements of pulmonary function were made while semirecumbent subjects performed dynamic respiratory maneuvers. Eight healthy male volunteers were studied under three test conditions: 1) breathing through a 25-mm ID mouthpiece (control); 2) with an 8.0-mm ID endotracheal tube adaptor in the mouthpiece (external resistance); 3) with an 8.0-mm ID endotracheal tube 25 cm long in place. Decreases in peak inspiratory flow and peak expiratory flow during flow–volume loops were the only significant changes seen with the external resistance. Peak flows were also decreased by intubation, but to a significantly greater extent (P< 0.01). Forced vital capacity (FVC) decreased significantly with tracheal intubation to 89 ± SEM 2 per cent of control. Forced expiratory volume in 1 sec (FEV1) was also decreased significantly, whether expressed as actual volume or as FEV1/FVC. Compliance of the lung was unchanged after intubation, but flows below mid-vital capacity during maximal expiratory flow-volume (MEFV) curves were decreased significantly from control. Responses to breathing helium were abnormal with intubation in many subjects, although mean responses did not differ significantly from control. Mean values for closing volume and slope of Phase III (ΔN2per cent/1) were likewise not significantly different from control, but in at least three subjects were indicative of peripheral airway obstruction. The decreased peak flows and FEV1with intubation reflect the tube's behavior as a significant fixed upper-airway resistance. The decreased FVC and expiratory flows below mid-vital capacity indicate that with intubation many subjects showed diffuse airway constriction superimposed on the fixed resistance of the tube.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The relationship of the frequency of motor-nerve stimulation to the dose-response tod-tubocurarine was studied in 45 adult patients during nitrous oxide–oxygen–morphine-thiopental anesthesia. One of five stimulus frequencies, 0.1, 0.15, 0.25, 0.5, and 1.0 Hz, was employed in each of five groups of nine patients. Cumulative dose–response curves for inhibition of evoked thumb adduction were constructed at each frequency on log probit scales and the ED50and ED95values were determined. The apparent potencies ofd-tubocurarine at 0.5 and 1.0 Hz were significantly different from that at 0.1 Hz; for example, at 0.1 Hz the ED50and ED95were 0.25 and 0.52 mg/kg, respectively. The corresponding values at 1.0 Hz were 0.07 and 0.15 mg/kg, respectively, or approximately 3.5 times less. The durations of recoveries of the twitch from 5–25 per cent of control at 1.0 and 0.5 Hz were 13 ± 2 min (mean ± SE) and 20 ± 2 min, respectively. These durations were significantly different from that at 0.1 Hz (30 ± 2 min). These results emphasize the importance of defining the stimulus frequency for meaningful interpretation of the dose-response relationships for nondepolarizing relaxants in man. Slow stimulus rates (0.1–0.15 Hz) are most useful clinically, since all levels of clinical relaxation can be achieved at these rates without abolishing the evoked twitch response.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Sodium nitroprusside (SNP) is frequently used to decrease afterload in patients who have vasoconstriction with low cardiac output. Often, these patients are concomitantly oliguric or anuric, conditions suggested to be likely to increase the risk of SNP-induced cyanide (CN) toxicity. Previously, the authors determined in normal dogs that SNP, 0.5 mg/kg/hr, was tolerated for 48 hours without CN toxicity, whereas 0.75 mg/kg/hr resulted in toxicity and death. In the present study, dogs rendered anuric by bilateral ureteral ligation were again maintained for 48 hours or until death in a simulated intensive-care situation, and were given various doses of SNP. CN toxicity, as evidenced by near-linear increases in blood CN, metabolic acidosis, and increases of mixed venous blood P±2with time, did not occur in animals given SNP at either 0.5 or 0.75 mg/kg/hr (n = 8), and was the cause of death in only two of seven dogs given SNP, 1.0 mg/kg/hr. In all five dogs given SNP 1.25 mg/kg/hr, cyanide toxicity developed, with death occurring at an average of 21 hours. Comparisons between the anuric dogs studied herein and the normal dogs studied previously with SNP, 1.0 mg/kg/hr, indicated that CN levels were significantly higher in the normal dogs at 36 hours and that thiocyanate (SCN) levels were significantly lower in the normal dogs at 24 and 36 hours. The observed resistance to SNP-induced CN toxicity in anuric dogs was probably secondary to decreased sulfate and thiosulfate excretion, resulting in greater availability of thiosulfate donor, which in turn enabled greater rates of detoxification of CN to SCN to be catalyzed by hepatic rhodanase. It is concluded that anuriaper sedoes not increase the risk of SNP-induced CN toxicity, probably because of increased availability of endogenous sulfur donor. Based on this study in dogs, the authors would not arbitrarily decrease SNP dosage limits in anuric or oliguric patients because of the possibility of cyanide toxicity.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The authors studied three groups of patients undergoing elective cesarean section during lumbar epidural anesthesia with bupivacaine, 0.75 per cent (15 patients), chloroprocaine, 3 per cent (15 patients) or etidocaine, 1 per cent (ten patients). Excellent sensory and motor block were obtained with chloroprocaine and bupivacaine; sensory anesthesia was inadequate with etidocaine in most patients. Onset of anesthesia, induction–delivery interval, and stay in the recovery room were all longer with bupivacaine when compared with chloroprocaine. Fetal outcomes, as determined by Apgar scores, acid-base status and neurobehavioral testing, were equally good in all groups. At delivery, fetal/maternal concentration ratio of bupivacaine was 0.31 and that of etidocaine, 0.25. The umbilical artery–umbilical vein blood concentration difference for etidocaine was significantly higher than that for bupivacaine. Excellent clinical results were obtained using either bupivacaine, 0.75 per cent, alone, or chloroprocaine, 3 per cent, for induction and maintenance of anesthesia, supplemented with bupivacaine, 0.25 per cent, before removal of the catheter.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID