Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026916 (MAC)
 5,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the effects of vecuronium neuromuscular blockade on O2 consumption (VO2) during isoflurane anaesthesia 12 patients were studied. 12 patients (ASA-PS I-II, 37.1 +/- 12.1 yr, 173 +/- 8 cm, 70.1 +/- 8.6 kg), scheduled for urological lower abdominal surgery, received isoflurane-N2O-O2-anaesthesia under steady-state conditions (1.3 MAC). Duration of anaesthesia was 169 +/- 32 min and 0.057 +/- 0.016 mg/kg/h vecuronium were needed. The desired level of neuromuscular transmission was set to 10% of control. This level of neuromuscular blockade was kept constant for 60 min by a negative feedback controlled infusion of vecuronium. VO2 was measured by an indirect calorimetry device (MMC Horizon, STPD). During and after recovery of neuromuscular function anaesthesia was maintained and oxygen measurements were continued. Preanaesthetic values of VO2 were in the predicted range for basal metabolism. Steady-state general anaesthesia lead to an 26-28% reduction of VO2 (Range: 144-232 ml/min) compared to the preanaesthetic values (202-288 ml/min, p < 0.01). Neuromuscular blockade showed no significant effect on O2 uptake. We conclude that in patients with adequate depth of anaesthesia vecuronium-induced neuromuscular blockade does not lead to a further reduction of oxygen consumption, since muscular tone is already reduced by general anaesthesia.
 ...
PMID:[Muscle relaxation with no effect on oxygen uptake during isoflurane anesthesia?]. 148 70

The aims of this study were firstly, to determine the effect of various concentrations of isoflurane on cerebrovascular circulation and secondly, to examine the time-response characteristics of the drug on cerebral blood flow velocity in anaesthetized children. Thirty-two ASA physical status I or II patients aged one to eight years and scheduled for urological surgery were studied. Anaesthesia was induced with thiopentone 5 mg.kg-1 and fentanyl 2 micrograms.kg-1. Muscle relaxation was provided with vercuronium 0.1 mg.kg-1. Tracheal intubation was performed in all cases. Anaesthesia was maintained with isoflurane in a mixture of air and oxygen to produce an inspired oxygen fraction (FIO2) of 0.3. Ventilation was adjusted to maintain normocapnia. A caudal or lumbar epidural catheter was inserted before skin incision and a continuous bupivacaine, without epinephrine, infusion established. During the first part of this study, the initial isoflurane concentration for 24 patients was randomized and age-adjusted to 0.5 MAC, 1.0 MAC, or 1.5 MAC. After steady-state was reached, the subsequent isoflurane MAC concentration was randomized by either raising or lowering it from the initial concentration. In the second part of this study, the time-response effect of isoflurane was examined. Eight patients received 1.0 MAC isoflurane over 90 to 150 min. Temperature, heart rate, and systolic blood pressure were unchanged throughout the study. Cerebral blood flow velocity (CBFV) and resistance index (RI+), a measure of cerebrovascular resistance, were measured in the M1 segment of the middle cerebral artery (MCA) with a 2 MHz transcranial Doppler monitor.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cerebrovascular stability during isoflurane anaesthesia in children. 154 94

The temperatures in the aural canal (core), skeletal muscle and skin surface were measured during anaesthesia and surgery in 32 healthy females undergoing total abdominal hysterectomy and for 4 h after operation. The patients were allocated randomly to one of four groups according to the end-tidal concentration of volatile anaesthetic: 1 MAC isoflurane, 1 MAC enflurane, 1.8 MAC isoflurane and 1.8 MAC enflurane. The lungs were ventilated with an air-oxygen mixture. Neuromuscular block was produced with pancuronium. Room temperature and i.v. fluid administration were standardized. Aural canal, muscle and mean skin temperatures decreased significantly in all groups during surgery (P less than 0.001). The decrease in core and muscle temperatures, and mean body heat was significantly greater in the 1.8 MAC groups than in the 1 MAC groups for both volatile agents (P less than 0.001). However, there was a significantly greater decrease in core temperature and mean body heat in the isoflurane compared with the enflurane group (P less than 0.026). Body temperature returned to preoperative values during the recovery period. There was a significantly greater rate of rewarming during the first 1 h of recovery in the 1.8 MAC groups compared with the 1 MAC equivalent (P less than 0.001), and this was independent of the volatile agent used. The present results are compared with those reported previously in which nitrous oxide was added to the volatile agents. The decrease in body temperature depends upon the concentration of vapour used. However, it appears that isoflurane, without nitrous oxide, caused greater loss of body heat than enflurane.
 ...
PMID:Effects of enflurane and isoflurane in air-oxygen on changes in thermal balance during and after surgery. 226 44

Neuromuscular blocking effects of pipecuronium bromide 0.04 mg.kg-1 were compared those of vecuronium bromide 0.08 mg.kg-1 in a double blind study. Fifty surgical patients (ASA I or II) were allocated randomly to two groups of each 25 cases and they were anesthetized with nitrous oxide 4 l.min-1, oxygen 2 l.min-1 and isoflurane 1 MAC. Neuromuscular blockade was monitored by using mechanical twitch responses of the thumb to electrical stimulations of the ulnar nerve. Adequate neuromuscular relaxation for surgery of 85.8% to 100% block was obtained by this dose of pipecuronium. The duration of action and recovery time from 75% to 25% block were longer than those produced by twice the dosage of vecuronium (62.3 +/- 37.15 vs. 40.4 +/- 16.09 min, and 48.1 +/- 22.0 vs. 19.9 +/- 10.8 min, P < 0.05). The blocks by both drugs responded to neostigmine. Cardiovascular side effects of the both agents were not found. From these results, it is concluded that pipecuronium is a useful nondepolarizing relaxant with a long duration of action and negligible side effects.
 ...
PMID:[A comparison between neuromuscular blocking effects of pipecuronium and vecuronium; a double blind controlled study in collaboration with 5 departments of anesthesiology]. 781 11

We evaluated the effect of different concentrations of isoflurane in a nitrous oxide/oxygen mixture on the infusion requirements of mivacurium in 60 adult surgical patients. Anaesthesia was induced with thiopentone and fentanyl, and intubation was facilitated with mivacurium 0.15 mg.kg-1. The patients were randomly assigned to one of four study groups. The control group received nitrous oxide in oxygen (2:1) anaesthesia supplemented with fentanyl. In the other groups, isoflurane was administered at different end-tidal concentrations: 0.29%, 0.58% and 1.15%, corresponding to 0.25, 0.5 and 1.0 MAC of isoflurane, respectively. Neuromuscular block was maintained at 95% with a computer-controlled infusion of mivacurium and monitored with electromyography. The mean (SD) steady-state infusion requirements of mivacurium in patients receiving nitrous oxide-fentanyl anaesthesia or isoflurane 0.25-0.5 MAC were similar, ranging from 6.1 (2.2) to 5.1 (2.1) micrograms.kg-1.min-1. Isoflurane 1.0 MAC reduced mivacurium infusion requirements by 32% (p < 0.01). Interindividual differences in mivacurium infusion requirements were large.
 ...
PMID:Quantifying the effect of isoflurane on mivacurium infusion requirements. 877 67

We have studied the potency and onset and duration of action of rocuronium in patients anaesthetized with 1 MAC of desflurane or isoflurane (in 66% nitrous oxide). Potency was estimated using the single bolus dose technique. Neuromuscular block was measured by stimulation of the ulnar nerve and recording the force of contraction of the adductor pollicis muscle. The ED50 and ED95 of rocuronium were estimated as 138 (95% confidence limits 117-162) micrograms kg-1 and 281 (241-328) micrograms kg-1, and 126 (105-151) micrograms kg-1 and 283 (236-339) micrograms kg-1 during desflurane and isoflurane anaesthesia, respectively. The mean times to onset of maximum block after rocuronium 0.6 mg kg-1 were 1.0 (SD 0.10) min and 1.1 (0.15) min, respectively, during anaesthesia with desflurane and isoflurane. The respective times to recovery of T1 (the first response in the train-of-four (TOF) stimulation) to 25% and 90% were 36 (8.3) min and 54 (15.4) min during desflurane anaesthesia and 31 (8.2) min and 45 (12.7) min during isoflurane anaesthesia. The times to recovery of the TOF ratio to 0.7 were 66 (13.4) min and 52 (16.3) min and the 25-75% recovery indices 14 (5.3) min and 10 (3.2) min, respectively, in the desflurane and isoflurane groups. There were no differences in the estimated potency or onset of action of rocuronium during desflurane and isoflurane anaesthesia. However, duration of action tended to be longer curing desflurane anaesthesia although only the differences in times to TOF ratio of 0.7 and the recovery indices were close to being significantly different (P = 0.0503 and 0.0560).
 ...
PMID:Potency and time course of action of rocuronium during desflurane and isoflurane anaesthesia. 894 33

The dose-response and concentration-response relation of rocuronium infusion was studied in 20 adult surgical patients during propofol-nitrous oxide and isoflurane (1 MAC)-nitrous oxide anaesthesia. Neuromuscular block was kept constant, initially at 90% and then at 50% with a closed-loop feedback controller. At 90% block the steady-state infusion of rocuronium was 0.55 +/- 0.16 mg kg-1 h-1 and the corresponding concentration 1714 +/- 281 ng mL-1 in patients receiving propofol. At 50% block the corresponding infusion rate was 0.27 +/- 0.11 mg kg-1 h-1 and the concentration 1077 +/- 244 ng mL-1, respectively. At 50% block isoflurane reduced the rate of infusion by 52% (P < 0.005) and the concentration by 59% (P < 0.001); at 90% block both the mean infusion rate and the concentration of rocuronium were reduced by 35% (P < 0.005). The mean rocuronium clearance at 50% block was unaffected by the type of anaesthesia; it was 4.1 +/- 1.6 and 4.9 +/- 2.7 mL kg-1 min-1 in the groups receiving propofol and isoflurane anaesthesia, respectively. We conclude that isoflurane reduces the infusion requirements of rocuronium by changing the pharmacodynamic behaviour.
 ...
PMID:Dose-response and concentration-response relation of rocuronium infusion during propofol-nitrous oxide and isoflurane-nitrous oxide anaesthesia. 930 85

The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.
 ...
PMID:[Effects of thiopental and sevoflurane on hemodynamics during anesthetic management of electroconvulsive therapy]. 945 79