ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

This paper relates research on anesthetic effects on lipid membrane systems to mechanisms of neural function. A unitary theory of anesthesia based on anesthetic-induced changes in fluid-solid-phase separations in the lipid region of nerve membranes is presented. It is suggested that anesthetics act by fluidizing nerve membranes to a point where critical lipid regions no longer contain phase separations. As a consequence, the membranes are less able to facilitate the conformational changes in proteins that may be the basis for such membrane events as ion gating, synaptic transmitter release, and transmitter binding to receptors. It is proposed that the anesthetic-modified phase separation behavior of the membrane may alter neural function by a combination of the following effects: inhibition of conformational changes of intrinsic membrane proteins; prevention of the association of protein subunits to form polymeric ion channels; depression of transmitter release by preventing fusion of vesicles containing synaptic transmitter with the membrane of the presynaptic terminal.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The effects of equipotent concentrations of enflurane, isoflurane, and halothane on isolated human uterine muscle have been evaluated. Three anesthetic concentrations (0.5, 1.0, and 1.5 MAC) were studied. Specimens included myometrial strips from 45 non-gravid and seven gravid uteri. Both groups of muscle strips showed significant (P < 0.05) and progressive depression of contractility with all anesthetics. However, the extents of depression at each anesthetic level studied were similar with all drugs. Enflurane, isoflurane, and halothane are equally depressing to isolated human uterine muscle.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Strips of myometrium were obtained at operation from eight nonpregnant and ten pregnant patients. The tissues were immediately suspended in a muscle bath and induced to contract isometrically with K2SO4in the presence and absence of halothane (0.5 to 2.0 vol per cent). The anesthetic produced significant dose-related depression of developed tension and rates of increase and decrease of tension in both pregnant and nonpregnant muscles. Time to peak tension was increased in the nonpregnant but not in the pregnant muscles. The depressant effect of the lower halothane concentrations (<1.1 vol per cent) was significantly greater in the pregnant muscles.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Recovery from anesthesia was assessed in a controlled manner in 34 healthy student volunteers, using a psychomotor test battery 1 and 5 hours and a driving simulator 2, 4.5, and 7 hours after 3.5 minutes of anesthesia with halothane or enflurane combined with nitrous oxide and oxygen. Psychomotor performances remained significantly (P < 0.05 to P < 0.001) worse than in an unanesthetized control group for 5 hours after both halothane and enflurane. However, impairment of driving skills 4.5 hours after anesthesia was measurable only after halothane (P < 0.05). It is concluded that after even brief periods of halothane or enflurane anesthesia patients should not drive or operate machinery for at least 7 hours. The magnitudes and durations of the residual effects of both agents on psychomotor performance were, however, less than those previously found after thiopental, methohexital, or diazepam.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The relationship between cerebral oxygen consumption (CMRO2) and anesthetic concentration has been assumed (based upon isolated measurements) to be approximately linear at concentrations less than 1 MAC. The shapes of the anesthetic dose-response curves for both CMRO2and cerebral blood flow (CBF) were examined by multiple measurements made at small, progressive concentration increments from 0 to 2 MAC halothane (six dogs), enflurane (six dogs), and isoflurane (six dogs), and during a constant 23 mg/kg/hr infusion of thiopental (six dogs). The EEG was continuously recorded and changes in EEG patterns from “awake” to “anesthetic” were correlated with changes in anesthetic concentration, CBF, and CMRO2. The significance of changes in the slopes of regression lines for CMRO2, before, during and after changes in EEG patterns from “awake” “anesthetic” were then determined.Contrary to previous inferences, CMRO2, dose–response curves were found to be nonlinear at anesthetic concentrations less than 1 MAC for all anesthetics studied. CMRO2, decreased precipitously until a stable “anesthetic” pattern was observed on the EEG; thereafter, CMRO2, decreased at a markedly reduced rate. The onset of this change occurred at concentrations well below MAC for the inhalational anesthetics. With the thiopental infusion, CMRO2decreased most rapidly during the first 25 minutes.With halothane and enflurane, CBF was maximal during the period of transition in the EEG from an “awake” to an “anesthetic” pattern. CBF was elevated at all concentrations of isoflurane studied. CBF decreased rapidly during thiopental infusion until the EEG pattern changed from “awake” to “anesthetic” and then more slowly. The results demonstrate that the change in the EEG to an “anesthetic” pattern, which occurs at concentrations well below MAC, is accompanied by an abrupt metabolic depression. It is speculated that these events coincide with the onset of functional depression.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

A new method for monitoring the effect of muscle relaxants on the myoneural junction was tested in unanesthetized volunteers. Evoked electromyographic responses to stimulation, sweeping exponentially from 1 to 100 Hz over 10 seconds, were recorded from the hand and abdominal muscles.d-Tubocurarine (dTc) was given intravenously in incremental doses until head lift was abolished. Thumb twitch tension, vital capacity, peak expiratory flow, maximal inspiratory force, and hand grip strength were recorded during partial paralysis and recovery. The frequency sweep electromyogram (FS-EMG) of the musculus rectus abdominis was more depressed than the FS-EMG of the musculus abductor digiti V at the time head lift was abolished. The abdominal muscle recovered faster fromdTc paralysis than did the hand muscle. The latter failed to respond normally to the highest frequencies of stimulation during the entire period of observation lasting 72 minutes afterdTc injection. At the time of maximal neuromuscular blockade, respiratory function showed less depression than the FS-EMG of the abdominal muscle.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

In dogs anesthetized with pentobarbital–chloralose, cardiac output and blood flows of four regional vascular beds (superior mesenteric, left renal, left circumflex coronary and left femoral) were continuously monitered with electromagnetic flowmeters. Arterial blood pressure and heart rate were also measured. Hypotension was induced with intravenous infusions of sodium nitroprusside and trimethaphan for 5–16 min to produce comparable reductions of mean arterial pressure (32 mm Hg or 26 per cent with nitroprusside and 37 mm Hg or 31 per cent with trimethaphan). Cardiac output also decreased, but to a lesser extent (11.5 per cent with nitroprusside and 12.5 per cent with trimethaphan). Thus, total peripheral resistance was consistently decreased. Nitroprusside caused slight tachycardia, while trimethaphan produced bradycardia. Both drugs decreased mesenteric blood flow and increased mesenteric vascular resistance. Renal blood flow was maintained or increased with nitroprusside; thus, renal vascular resistance decreased; with trimethaphan, renal blood flow decreased and renal vascular resistance did not change. Both nitroprusside and trimethaphan reduced coronary blood flow; the reduction was more pronounced with the latter. Nitroprusside affected femoral blood flow minimally, with a slight reduction of femoral vascular resistance. In contrast, trimethaphan increased femoral blood flow and markedly decreased femoral vascular resistance. Redistribution of cardiac output favoring the dilated skin and muscle vascular beds appears to be an important undesirable effect of trimethaphan.

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1977

数据来源: OVID