摘要:

The anesthetic requirements of chronic alcoholics for induction of anesthesia with thiopental were investigated using an electroencephalographic (EEG) measure of thiopental's CNS drug effect and pharmacodynamic modeling to relate thiopental serum concentrations to drug effect. Eleven patients with a history of excessive alcohol intake were studied from an inpatient alcohol rehabilitation program and compared with nine control patients or volunteers who were social drinkers. The alcoholic population had consumed ethanol 9–17 days prior to the study. They had no evidence of acute intoxication or acute withdrawal at the time of the study. Five of the 11 alcoholic patients were restudied after 1 month of abstinence from alcohol consumption. Each study consisted of a thiopental infusion until EEG burst suppression (1–3s of isoelectric signal) was achieved. Timed arterial and then venous blood samples were obtained for measurement of thiopental serum concentrations for up to 36 h. Pharmacokinetic differences between groups were analyzed using a three-compartment model. Power spectral analysis of the EEG allowed determination of spectral edge frequency. An inhibitory sigmoid Emaxpharmacodynamic model combined with an effect compartment was used to analyze concentration-response relationships and to provide an estimate of brain sensitivity to thiopental in the study populations. The thiopental anesthetic dose requirement using the EEG was not different between alcoholics and nonalcoholics. The mean dose requirement (± SD) of alcoholics was 823 ± 246 mg and the mean dose requirement of nonalcoholics was 733 ± 218 mg. There were no differences in thiopental pharmacokinetic and pharmacodynamic parameters between alcoholics and nonalcoholics. In the subgroup of five alcoholics who were studied approximately 1 month later, thiopental dose requirement, pharmacokinetics, and pharmacodynamics had not changed. These findings suggest that thiopental induction doses should not be routinely increased in chronic alcoholic patients.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The peripheral vascular effects of isoflurane and halothane were compared in five critically ill patients in whom a Jarvik-7 artificial heart had been implanted. The lungs of all patients were mechanically ventilated in the postoperative period and the patients were monitored with an arterial catheter and with catheters that had been surgically inserted into the right and left atria and into the pulmonary artery. Noreperinephrine and epinephrine plasma concentrations were measured using a radioenzymatic assay. The Jarvik-7 settings were modified to render the artificial heart “preload independent” and to maintain cardiac output constant. Each patient was anesthetized twice using halothane and isoflurane at two different MAC levels, 1 and 1.5 (Datex vapour analyzer), with the interval between each anesthetic ranging from 12 to 26 h. Both anesthetics significantly decreased mean arterial pressure (from 100 ± 11 mmHg to 66 ± 13 mmHg for halothane and from 102 ± 17 mmHg to 48 ± 11 mmHg for isoflurane; mean ± SD) and systemic vascular resistance index (from 27 ± 11 Wood units/m2to 18 ± 6 Wood units/m2for halothane and from 30 ± 6 Wood units/m2to 13 ± 3 Wood units/m2for isoflurane; mean ± SD), but with isoflurane to a significantly greater extent than with halothane (P< 0.01). Both anesthetics induced significant and comparable decreases in right atrial pressure (from 15 ± 2 mmHg to 13 ± 4 mmHg for halothane and from 16 ± 3 mmHg to 11 ± 2 mmHg for isoflurane; mean ± SD), mean pulmonary arterial pressure (from 22 ± 10 mmHg to 17 ± 11 mmHg for halothane and from 19 ± 9 mmHg to 14 ± 8 mmHg for isoflurane; mean ± SD), and left atrial pressure (from 14 ± 6 mmHg to 11 ± 7 mmHg for halothane and from 11 ± 5 mmHg to 6 ± 5 mmHg for isoflurane, mean ± SD) without changing catecholamine plasma concentrations (from 474 ± 586 pg/ml to 206 ± 390 pg/ml for norepinephrine concentrations and from 100 ± 172 pg/ml to 96 ± 71 pg/ml for epinephrine concentrations during halothane, from 356 ± 92 pg/ml to 512 ± 269 pg/ml for norepinephrine concentrations and from 121 ± 118 pg/ml to 129 ± 95 pg/ml for epinephrine concentrations during isoflurane; mean ± SD). Because cardiac output was maintained constant throughout the anesthetic, these results suggest that halothane and isoflurane reduced vascular tone of veins, pulmonary vessels, and systemic arteries.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The plasma protein binding of sufentanil has been studied in newborns, infants (0.5 ± 0.3 yr), children (6.8 ± 3.0 yr), and adults (39.5 ± 9.0 yr). Binding of sufentanil was determinedin vitroby equilibrium dialysis, and radioactive tritiated sufentanil was used for the determination of drug concentrations in plasma and buffer. The free fraction of sufentanil was significantly higher in the newborn (19.5 ± 2.7%;P< 0.01) than in the other age groups. The free fraction was also significantly higher in infants (11.5 ± 3.2%;P< 0.01) than in children (8.1 ± 1.4%) or in adults (7.8 ± 1.5%) but did not differ significantly between children and adults. The free fraction of sufentanil was strongly correlated with the α1-acid glycoprotein plasma concentration (r = −0.73;P< 0.001) whereas it was weakly correlated with albumin plasma concentration (r = −0.35;P< 0.05). These data suggest that the lower concentration of α1-acid glycoprotein in newborns and infants probably accounts for the decrease in protein binding of sufentanil in these age groups when compared with that in older children or adults. The increased free fraction in the neonate might contribute to the enhanced effects of lipophilic opioids in the neonate.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The use of the laryngeal mask airway, a new form of airway, is described in infants and young children receiving radiotherapy under general anesthesia. The laryngeal mask airway consists of a tube, at the distal end of which is attached an elliptically shaped cuff resembling a miniature face mask. The laryngeal mask is inserted blindly into the pharynx, and its cuff forms a low pressure seal around the larynx through which the patient can breathe spontaneously. No complications occurred during use of the laryngeal mask in 25 children who received 312 anesthetics. This experience suggests that the laryngeal mask airway has a valuable role in this situation and may contribute to the safety of anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To determine if age, height, weight, body mass index, or vertebral column length significantly influence the distribution of sensory analgesia or anesthesia after subarachnoid injection of hyperbaric bupivacaine, 52 women presenting for cesarean section were studied. All received 15 mg hyperbaric bupivacaineviasubarachnoid injection at L-2 or L-3. Fifteen minutes after injection, while the women lay supine on a horizontal operating table, the maximum cephalad extent of sensory analgesia (loss of sensation of sharpness to pin prick) and anesthesia (loss of sensation of light touch) was determined. Age (20–42 yr), height (146.9–174.0 cm), weight (55.5–136.4 kg), body mass index (19.2–50.0 kg/m2), and vertebral column length (49.6–67.0 cm) did not correlate with the spread of sensory blockade. In conclusion, in parturients of age, height, weight, body mass index, and vertebral column length within the aforementioned ranges, it is not necessary to vary the dose of injected hyperbaric bupivacaine with changes in any of the patient variables studied.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The fetal uptake of lidocaine was measured continually and quantitatively during and after a constant rate intravenous (iv) maternal infusion into five chronically prepared pregnant ewes. Lidocaine, 6 mg/kg (base), was infused at a constant rate for 1 h and measurements continued to 5 h. Rate of fetal uptake was determined from the product of the umbilical venous (UV) and fetal aortic (FA) concentration difference and umbilical blood flow (&OV0422;u). Total fetal uptake was determined by integrating fetal uptake rate with respect to time. Maternal and fetal protein binding was determined, and its effect on fetal blood concentrations was evaluated. Mean total fetal uptake as it related to time and infused dose increased linearly (r= 0.998,P< 0.001) with a constant, weight-normalized fetal-maternal dose fraction of 0.45 during the infusion. Despite rapidly declining blood concentrations after the infusion, uptake increased an additional 17%. The sevenfold variation in uptake appeared to be inversely related to the biodegradation rate of lidocaine. Fetalmaternal concentration ratios (F/M) increased during declining blood concentrations. Protein binding determinations for maternal and fetal blood were 43.6 ± 2.48% and 26.9 ± 1.59%, respectively. These values were used to calculate the F/M in conjunction with the maternal and fetalpH. At maternal-fetal equilibrium the calculated F/M, 1.0 ± 0.05, closely approximated the observed, 1.0 ± 0.03. Variations in lidocaine concentrations among the vital organs 4 h after the infusion were small, but high concentrations of metabolites were found in the lungs and kidneys. The results challenge the validity of placental transfer estimates commonly based on the F/M and umbilical cord blood concentrations.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of increased intracranial pressure (ICP) and increased cardiac output (&OV0422;T) on the pulmonary vascular response to regional alveolar hypoxia were compared in pentobarbital-anesthetized, closed-chested dogs. A bronchial divider was inserted, the right lung (RL) was continuously ventilated with 100% O2, and the left lung (LL) was ventilated with either 100% O2(hyperoxia) or a hypoxic gas mixture (hypoxia). Sulfur hexafluoride (SF6) was used to measure differential lung blood flow and the multiple inert gas technique assessed gas exchange. The response to LL alveolar hypoxia (hypoxic pulmonary vasoconstriction, HPV) was studied in each animal prior to, during, and after the ICP was increased by infusing mock cerebrospinal fluid (CSF) into a lateral ventricle so that cerebral perfusion pressure was 25 mmHg. During both control periods, &OV0422;Twas randomly altered by opening (high &OV0422;T) or closing (normal &OV0422;T) two arteriovenous fistulas. Increasing ICP significantly increased &OV0422;T(P< 0.01), pulmonary artery pressure (PAP) (P< 0.05), and mixed venous oxygen tension (Pvo2) (P< 0.05), compared with normal &OV0422;Tcontrols. Opening the arteriovenous fistulas achieved similar increases in &OV0422;T(P< 0.01), PAP (P< 0.05), and P, (P< 0.05). The percentage of blood flow to the LL(&OV0422;L/&OV0422;T%) during hyperoxia was 43.9 ± 0.8% (mean ± SE) and did not vary with manipulation of &OV0422;Tor ICP. &OV0422;L/&OV0422;T% during LL hypoxia was significantly increased by both increased ICP (24.6 ± 3.5%) and high &OV0422;T(23.1 ± 1.0%) compared with normal &OV0422;T(16.8 ± 2.1) controls (P< 0.05). Therefore, flow diversion with HPV was reduced equally by both increasing ICP and increasing &OV0422;T(P< 0.05). Ventilation-perfusion matching was unchanged by increased ICP. These results suggest that impaired oxygenation with increased ICP may be partly secondary to an attenuation of regional HPV, caused by increased cardiac output.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Single-channel recording techniques have been used to examine interactions between anticholinesterases and ion channels activated by acetylcholine. Single-channel currents activated by 200 nM acetylcholine were recorded from cell-attached patches of BC3Hl mouse tumor cells grown in culture. Channels were recorded in the absence and presence of edrophonium (1–20 μM), neostigmine (2–20 μM), or pyridostigmine (10–200 μM). All three drugs shortened channel open time but did not alter single-channel current amplitude. Effects on channel open time were not secondary to inhibition of cholinesterase but appeared to involve direct interactions between anticholinesterase drugs and acetylcholine-activated channels. Drug concentrations calculated to reduce the time constant of open time distributions by 50% were 3.8 μM edrophonium, 4.6 μM neostigmine, or 97 μM pyridostigmine. Channel open time was decreased by edrophonium at concentrations comparable to those occurring during reversal of neuromuscular block, but it was reduced by neostigmine and pyridostigmine only at levels higher than those encountered clinically. Differences in interactions between anticholinesterases and acetylcholine-activated channels at the end plate may possibly account for some of the clinical differences between these drugs.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study provides direct evidence that in hepatocytes, intracellular Ca++is released from internal stores by halothane, enflurane, and isoflurane. Hepatocytes isolated from rat livers were used fresh or treated with saponin and then incubated in45Ca++media. The uptake of45Ca++by hepatocytes was maximal following 13–16 min of incubation (untreated or saponin-treated) and the effects of various agents on the release of45Ca++was studied following maximal loading. The agents used included halothane, enflurane, isoflurane, and several putative intracellular second messengers. The anesthetics, to various degrees, all stimulated a significant release of45Ca++from internal stores at concentrations that were at or less than clinical concentrations. The release of intracellular45Ca++by each of the anesthetic agents was dose-dependent with halothane and enflurane being equally potent at concentrations equivalent to 1 MAC exposure. The halothane-induced release was only somewhat suppressed by preincubation in either 2 mM LaCL5or 10 μM dantrolene, both suggested Ca++channel blockers. Transient increases in intracellular Ca++regulates a number of enzyme systems, including glycogenolysis, while prolonged elevation in Ca++concentrations have been implicated in the mechanism of hepatotoxicity.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Changes in oxygen consumption (&OV0312;o1and oxygen delivery (&OV0312;o2) were compared in three groups of paralyzed, sedated dogs: 1) a group (n = 5) cooled to 29° C and immediately rewarmed to 37° C; 2) a group (n = 5) cooled to and maintained at 29° C for 24 h, and then rewarmed; and 3) a group (n = 5) maintained at 37° C for 24 h. During the cooling phase, in both the acute and prolonged hypothermia animals, Vo2and Do2decreased significantly from control values (P< 0.05). The decrease in Do2occurred as a result of a similar decrease in cardiac index (CI;P< 0.05) that was associated with a significant increase in systemic vascular resistance index (SVRI;P< 0.05). Arteriovenous oxygen content difference (C(a-v)o2), O2extraction ratio, mixed venous oxygen tension (P&OV0312;o2),pH, and base deficit (BD) were not different from control values even during prolonged hypothermia. Normothermic control dogs also demonstrated a significant decrease in CI (P< 0.05) at 24 h. Surface rewarming increased &OV0312;o2back to control values in the acute hypothermia group and to values above control (P< 0.05) in the prolonged hypothermia group. Do2remained below control in both groups, resulting in a significant increase in O2extraction (P< 0.05) and a decrease in P&OV0312;o2(P< 0.05) in the prolonged hypothermia animals. Following rewarming administration of sodium nitroprusside returned Do2, CI, and SVRI to control values but did not increase &OV0312;o2. All animals survived the study without need for inotropic support. The heart and peripheral vasculature appear to be responsive to direct vasodilation when, with rewarming, residual excess afterload prevents oxygen delivery from matching oxygen requirement.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID