摘要:

The visual evoked response (VER) was monitored in eight women intraoperatively during anesthesia with halothane in oxygen administered via endotracheal tube. Control measurements were made prior to anesthetic induction in these unpremedicated patients. The latency of the positive peak designated PI increased progressively from a mean of 113 ± 10 (SD) msec in the awake state to the following values at indicated end-tidal halothane concentrations: 123 ± 10 msec at 0.75 per cent; 130 ± 9 msec at 0.90 per cent; 134 ± 9 msec at 1.13 per cent. The differences among mean latency values at these anesthetic concentrations were insufficient to conclude that VER latency would be a useful monitor of anesthetic depth. However, significant effects were seen at clinical levels of halothane anesthesia, and the prolongation caused by anesthesia must be considered when using VERs to monitor central nervous system function during neurosurgery.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The incidence, time course, and magnitude of hypothermia following apparently adequate rewarming from hypothermic cardiopulmonary bypass (defined as a nasopharyngeal temperature [NPT] of 37 C) were studied in 20 adult patients (Group I). In each patient a decrease in NPT (averaging 2.6 ± .2 C) occurred during the 80-min intraoperative postbypass period. The NPT had stabilized approximately 45 min after the end of bypass. Eight additional patients (Group II) received pharmacologic vasodilation with nitroprusside during the rewarming period. Pump flow was increased as nitroprusside was infused to maintain mean arterial pressure ≥ 70 torr. Group II patients maintained NPT significantly better in the postbypass period than did Group I patients (NPT decrease of 1.5 ± .4 C,P< 0.01, a 42 per cent improvement). As in Group I, NPT in Group II had stabilized 45 min after bypass. Ambient air temperatures between 18 and 23 C had no effect on NPT decrease. Presumed peripheral heat delivery was found to be greater in Group II. It is concluded that postbypass NPT decreases occurred in all patients, but that these decreases were significantly lessened by pharmacologic vasodilation plus deliberately increased pump flow during rewarming on bypass.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Droperidol antagonizes postsynaptic α-adrenoceptors in blood vessels, yet clinical doses of this drug can induce hypertension when a pheochromocytoma is present. Whether droperidol can block presynaptic α-adrenoceptors, causing increased release of norepinephrine from adrenergic nerve endings, was examined in isolated canine saphenous vein segments using standard superfusion techniques. The helical strips of vein were first incubated in [7-3H]dl-norepinephrine (2 × 10−7M), then mounted for superfusion and isometric tension recording. [3H]Norepinephrine and its metabolites were measured in superfusate collected during basal conditions and during release of [3H]norepinephrine evoked by electrical stimulation (10 V; 2 msec duration; 1 or 2 Hz). In unstimulated veins, droperidol (3.9 × 10−7M) increased the efflux of total radioactivity and of the norepinephrine metabolite, 3,4-dihydroxyphenylglycol; in addition to these changes, 3.9 × 10−6M droperidol increased the efflux of norepinephrine and 3,4-dihydroxymandelic acid. Tension did not change. The increased efflux of norepinephrine and its metabolites was due to droperidol-induced nonexocytotic release of norepinephrine from intraneuronal storage vesicles. When electrically stimulated veins were exposed to droperidol (3.9 × 10−6M), tension decreased, although [3H]norepinephrine efflux was not different. During electrical stimulation of veins, addition of unlabeled norepinephrine to the superfusing fluid inhibited the overflow of total radioactivity; treatment of veins with droperidol (3.9 × 10−6M) did not alter this effect. These studies indicate that droperidol, in the concentrations used, is an antagonist of the postsynaptic, but not of the presynaptic, α-adrenoceptor. Moreover, droperidol promotes a leakage of norepinephrine from intraneuronal storage vesicles. Indeed, this may be the mechanism by which this agent produces hypertension in patients who have pheochromocytoma.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The objectives of this study were to determine the effects of enflurane on cell division and incorporation of macromolecular precursors into nucleic acid ofTetrahymena pyriformis, to determine the effects of both enflurane and halothane on incorporation of amino acids into proteins ofT. pyriformis, and to compare the effects of these two anesthetics using these data and data previously reported for halothane. After exposure for three hours, cell division was inhibited 66 and 81 per cent by enflurane, 2.2 and 4.3 per cent, respectively. Similarly, exposure for three hours resulted in 25 and 81 per cent inhibition ofl4C-thymidine incorporation and 74 and 98 per cent inhibition of14C-uridine incorporation by enflurane, 2.2 and 4.3 per cent, respectively. Enflurane, as previously shown for halothane, did not inhibit DNA or RNA synthesis in isolated nuclei (assayed using3H-labeled nucleoside triphosphates as precursors). Finally, incorporation of14C-amino acids was inhibited 17 and 60 per cent by exposure for three hours to halothane (1.2 and 2.4 per cent, respectively) and 49 and 77 per cent by exposure for three hours to enflurane (2.2 and 4.3 per cent, respectively). The comparison of halothane and enflurane was made to determine whether the effects onT. pyriformiswere proportional to the absolute (per cent or molar) anesthetic concentration, or to MAC (minimum alveolar concentration). It was found that inhibition of cell division is proportional to MAC (i.e., equivalent inhibition is observed when the anesthetic concentration in the culture medium is the same as that in blood exposed to either 1 MAC halothane or 1 MAC enflurane), and that inhibition of macromolecular precursor incorporation (in intact cells) is proportional to the absolute (per cent or molar) anesthetic concentration. It is concluded that inhibition of cell division by the anesthetics is not due to direct inhibition of nucleic acid synthesis, nor is it directly related to inhibition of thymidine, uridine, or amino acid incorporation in intact cells.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The authors compared the effects of naloxone and saline solution on the respiratory changes following diazepam in a double-blind crossover trial in six subjects. Following baseline measurements of respiration, each subject was given diazepam, 15 mg, intravenously. Sixty and ninety-five minutes later each subject received either two doses of naloxone, 15 mg, intravenously, or two doses of the equivalent volume of saline solution. Forty-five minutes after diazepam administration the slopes of the curves of the ventilatory responses to rebreathing carbon dioxide (&OV0312;E/PetCO2) were depressed to 53 per cent of control (P< 0.05). Following the two doses of naloxone, the slopes of &OV0312;E/PetCO2, recovered, until, 120 minutes after the second dose of naloxone, slopes had returned to control values. After saline solution, however, slopes remained depressed at 68 per cent of control (P< 0.05). A similar recovery following naloxone was observed in the PetCO2intercept of the &OV0312;E/PetCO2response curve and in the slope of the mouth-occlusion-pressure response curve to rebreathing carbon dioxide. End-tidal carbon dioxide during quiet breathing and during inspiratory resistive-loaded breathing (80 cm H2O/l/s) showed small increases after diazepam, which were not significantly reduced by naloxone. The results of this study show that diazepam produces respiratory depression, and that this may be relieved by large doses of naloxone.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The purpose of this investigation was to clarify in a laboratory model the sites of action of epidurally administered local anesthetics. This report describes such a model, which is capable of monitoring sites of altered electrophysiologic activity induced by epidural anesthetic agents. Evoked potential response alterations measured from electrodes positioned along the conducting pathways were assessed in six monkeys following epidural injections of 0.5 per cent bupivacaine, 3 per cent chloroprocaine, and 1 per cent etidocaine. Bupivacaine in ten studies was found to cause its major effects at the dorsal root entry zone and the long tracts of the spinal cord white matter, associated with variable peripheral nerve alterations. Chloroprocaine effects in six studies were limited to alteration of responses recorded from the dorsal root entry zone and peripheral nerve. In contrast, etidocaine in eight studies caused marked attenuation of the responses recorded from the long tracts of the spinal cord white matter, associated with only minimal corresponding changes at the dorsal entry zone or peripheral nerve levels. These findings illustrate the capability of this experimental model to demonstrate relatively selective effects along the sensory and motor pathways for epidurally injected local anesthetic agents.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

A rapid, reliable method for the determination of 2-chloroprocaine in serum was developed. The method, using double-beam ultraviolet spectroscopy, provides rapid, accurate analysis of 2-chloroprocaine in the range of 5.5 to 111 µM (1.5µ30 µg/ml), as documented by comparison with the accepted gas chromatographic procedure. The contribution of 4-amino-2-chlorobenzoic acid, the principal metabolite of 2-chloroprocaine, to the total absorbance at 300 nm was examined and found to be negligible. Using the ultraviolet spectrophotometric method, values of the Michaelis-Menton constant (Km) and maximal reaction velocity (Vmax) for hydrolysis of procaine and 2-chloroprocaine by homozygous typical, heterozygous, and homozygous atypical plasma cholinesterases were determined. The Kms for the three genotypes were 5.0, 6.2, and 14.7 µM, respectively, for procaine, and 8.2, 17, and 103 µM, respectively for 2-chloroprocaine. The Vmaxs for the three genotypes were similar for all esters. Vmaxfor procaine was 18.6 ± 0.9 nmol/min/ml serum, while Vmaxfor 2-chloroprocaine was 98.4 ±2.1 nmol/min/ml serum. At high concentrations, 2-chloroprocaine acts as an inhibitor of its hydrolysis. The inhibitory effects of lidocaine, bupivacaine, neostigmine, and succinyldicholine on 2-chloroprocaine hydrolysis for homozygous typical and atypical variants, respectively, were studied. Competitive inhibition was demonstrated for all four drugs. However, at clinically significant concentrations, only neostigmine and bupivacaine produced high degrees of inhibition. The competitive inhibition constants (KI) for the typical and atypical variants, respectively, were 3.3 ± 0.3 µM and 15.1 ± 4.8 µM for neostigmine, and 4.2 ± 0.3 µM and 36.9 ± 9.8 µM for bupivacaine.

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

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