Cardiac Arrhythmias in Non-intubated Children during Adenoidectomy. A Comparison between Enflurane and Halothane Anaesthesia

The incidence of cardiac arrhythmias, heart rate, blood pressure, capillary perfusion and end-tidal CO2 tension were studied in 167 healthy children 1-12 years of age undergoing adenoidectomy (n = 82) and myringotomy (n = 85) during enflurane and halothane anaesthesia. The incidence of cardiac arrhythmias was significantly lower during myringotomy than during adenoidectomy. In children undergoing adenoidectomy the incidence of arrhythmias was 38.9% during enflurane anaesthesia and 86.6% during halothane anaesthesia (P less than 0.001). In the halothane group ventricular arrhythmias were observed in 19 patients (41.3%) but only in one child (2.8%) in the enflurane group. The ventricular arrhythmias seen during halothane anaesthesia were unifocal in six patients and multifocal in five and classified as ventricular tachycardia in eight children. Heart rate was increased by about 40% at the onset of ventricular arrhythmias. The heart rate remained unchanged with enflurane anaesthesia during surgery, which may reflect a decreased sympathomimetic activity. It is suggested that the low incidence of ventricular arrhythmias during enflurane anaesthesia may be explained by the combination of a reduced sympathomimetic activity and a lowered susceptibility of the myocardium to the actions of endogenous catecholamines.     

Cardiac Arrhythmias in Intubated Children During Adenoidectomy. A Comparison Between Enflurane and Halothane Anaesthesia

In 75 children undergoing adenoidectomy, occurrence of cardiac, arrhythmias and influence of anaesthesia on respiration were studied during halothane and enflurane anaesthesia. All the children were intubated orally. In 25 children halothane, and in another 25 children enflurane was used during spontaneous ventilation. Twenty-five children were also followed during halothane anaesthesia with manually controlled ventilation. The overall incidence of cardiac arrhythmias was higher during halothane anaesthesia (72% at spontaneous breathing and 68% with controlled ventilation) than during enflurane anaesthesia (32%, P <0.05). Ventricular arrhythmias were noted in 20% of the spontaneously breathing children and in 12% of those with controlled ventilation during halothane anaesthesia. Three children breathing spontaneously during halothane anaesthesia developed ventricular tachycardia. During enflurane anaesthesia the incidence of ventricular arrhythmias was lower (8 %) in spite of higher end-tidal CO₂ tensions and an anaesthetic depth that was only just the level needed to allow intubation. The incidence of ventricular arrhythmias during halothane anaesthesia was shown to be influenced by the anaesthetic technique used, which was not found with enflurane anaesthesia. The greater stability in cardiac rhythm with enflurane indicates a more favourable effect of this agent on the myocardium as well as a decreased sympathetic response to anaesthesia and surgery as compared with halothane anaesthesia.     

Esmolol prevents and suppresses arrhythmias during halothane anaesthesia in dogs

The antiarrhythmic effect of esmolol, a selective beta 1 adrenoreceptor blocker, was evaluated in the presence of epinephrine induced arrhythmias in dogs (n = 6). The arrhythmogenic dose of epinephrine (ADE) during 1.2 MAC halothane in dogs was increased from 3.23 +/- 0.25 (mean +/- SD) to 30.90 +/- 3.56 micrograms.kg-1.min-1 (P less than 0.001) by the prior administration of esmolol 0.5 microgram.kg-1 bolus followed by an infusion at the rate of 150 micrograms.kg-1.min-1. Higher esmolol infusion doses of 200 micrograms.kg-1.min-1 further increased ADE to 99.0 +/- 2.92 micrograms.kg-1.min-1 (P less than 0.001). After discontinuation of esmolol and during continued halothane anaesthesia, ventricular tachycardia was induced by increasing the infusion rate of the 100 micrograms.ml-1 solution of epinephrine. In all dogs ventricular tachycardia was restored to sinus rhythm by a bolus dose of esmolol (1 microgram.kg-1). We conclude that esmolol pretreatment increases the ADE during halothane anaesthesia in dogs. Our data suggest that esmolol may be useful as an antiarrhythmic agent in the management of epinephrine-related ventricular arrhythmias during anaesthesia in man.     

Halothane Anaesthesia and Suxamethonium III. Atropine 30 s Before a Second Dose of Suxamethonium During Inhalation Anaesthesia: Effects and Side-Effects

The protection against bradycardia afforded by atropine given intravenously just prior to a second dose of suxamethonium during halothane inhalation anaesthesia was studied in 100 healthy, adult patients randomly allocated to one of five groups characterized by dosage of atropine.
ECG monitoring was continuous, and regular determinations were made of serum potassium, Paco₂, Pao₂, and blood pressure.
Slowing of the heart rate was seen in more than 50% of patients in each group, but bradycardia (heart rate <60 beatslmin) was seen only in patients receiving the lowest dose of atropine - 0.0075 mg/kg. In the other four groups (atropine 0.01 mg/kg-0.02 mg/kg), bradycardia prophylaxis was effective, but at the cost of serious ventricular arrhythmias in 15% of the patients. The incidence of these arrhythmias seemed to increase with increasing atropine dosage. Marked tachycardia was also seen.
Because of the incidence of side effects in this and other studies, no absolute recommendation can be made about suxamethonium bradycardia prophylaxis during halothane inhalation anaesthesia, but our present experience suggests that atropine in a dose not exceeding 0.01 mg/kg, given 30 s prior to a second dose of suxamethonium is best.     

Heart rate response to atropine in humans anaesthetized with five different techniques

Atropine, 0.01 mg.kg-1, was given intravenously before the start of surgery to 169 patients who were anaesthetized with one of five different techniques; halothane, enflurane, cervical epidural, lumbar epidural or narcotic anaesthesia in addition to nitrous oxide and oxygen. Atropine produced a significant increase in heart rate (HR) within 1 min in all patients studied; the HR increases in patients anaesthetized with halothane (37 +/- 11 beats.min-1, n = 37) or narcotic (34 +/- 12 beats.min-1, n = 30) were significantly greater than in those anaesthetized with enflurane (25 +/- 10 beats.min-1, n = 35; P less than 0.01) or epidural anaesthesia. Because of the presence of an acute cardiac sympathectomy, the patients who received cervical epidural anaesthesia were expected to have different responses to the atropine. However, there was no significant difference in the HR increases between the patient groups with cervical (19 +/- 12 beats.min-1, n = 32) and lumbar (22 +/- 8 beats.min-1, n = 35) epidural anaesthesia. Atropine also produced a small but significant increase in arterial pressure in all five groups of patients. These results suggest that the cardiac responses to atropine may differ depending on the individual anaesthetic agent used, and are likely dependent upon the agent's effect on autonomic nervous system activity.     

Halothane, enflurane and isoflurane anaesthesia for adenoidectomy in children, using two different premedications

In 48 children subjected to adenoidectomy, comparisons of airway problems, heart rates, cardiac arrhythmias, ventilation and stress hormone reactions were studied during halothane, enflurane and isoflurane anaesthesia. Sixteen children were anaesthetized with either of the three agents and eight patients in each group received diazepam 0.25 mg kg-1 and atropine 0.015 mg kg-1 rectally (DA) as premedication and the remainder diazepam 0.5 mg kg-1, morphine 0.15 mg kg-1 and scopolamine 0.01 mg kg-1 (DMS) rectally. All children were intubated and breathing spontaneously. Equianaesthetic inspired concentrations of halothane, enflurane and isoflurane were used. Airway problems were of the same magnitude during halothane and isoflurane anaesthesia but were less frequent with both agents compared with enflurane anaesthesia. DMS reduced the number of airway reactions in all groups. Respiratory rates were uninfluenced by anaesthesia, intubation and surgery during enflurane anaesthesia. Cardiac arrhythmias were less frequent with enflurane and isoflurane than with halothane. Plasma ACTH and cortisol were similar with all three agents. During induction of anaesthesia in the DA-premedicated halothane group, however, plasma catecholamines were higher than in the group which received DMS, in contrast to the findings during enflurane and isoflurane anaesthesia. The DMS premedication decreased the response of plasma ACTH, cortisol and plasma catecholamines to surgery.     

Induction characteristics of thiopentone/suxamethonium, propofol/alfentanil or halothane alone in children aged 1-3 years.

The aim of this study was to compare the effect of three different induction techniques, with or without neuromuscular block, on tracheal intubation, haemodynamic responses and cardiac rhythm. Ninety children, aged 1-3 years, undergoing day-case adenoidectomy were randomly allocated to three groups: group TS received thiopentone 5 mg kg-1 and suxamethonium 1.5 mg kg-1, group H 5 Vol.% halothane and group PA alfentanil 10 micrograms kg-1 and propofol 3 mg kg-1 for induction of anaesthesia. No anti-cholinergics were used. Holter-monitoring of the heart rate and rhythm was started at least 15 min before induction of anaesthesia and continued until 3 min after intubation. Tracheal intubation was performed by an anaesthetist blinded to the induction method and judged as excellent, moderate or poor according to ease of laryngoscopy, position of vocal cords and incidence of coughing after intubation. Tracheal intubation was successful at the first attempt in all children in groups TS and H and but only in 80% in group PA (P = 0.001). Intubating conditions were excellent in 22 (73%), 22 (73%) and one (3%) of the patients in groups TS, H and PA, respectively (P = 0.001). Cardiac dysrhythmias (supraventricular extrasystole or junctional rhythm) occurred in two (7%) patients in groups PA and H each (NS). Bradycardia occurred in 0 (0%), four (14%) and six (21%) children in groups TS, H and PA, respectively (P = 0.007 PA vs. TS, P = 0.03 H vs. TS). In conclusion, induction of anaesthesia with propofol 3 mg kg-1 and alfentanil 10 micrograms kg-1 without neuromuscular block did not provide acceptable intubating conditions in children 1-3 years, although it preserved arterial pressure better than thiopentone/suxamethonium or halothane. Cardiac dysrhythmias were few regardless of the induction method.     

Effects of dose and concentration of rectal methohexitone for induction of anaesthesia in children

To investigate the effect of dose and concentration of rectal methohexitone for induction of anaesthesia, 60 children (ASA physical status 1 or 2) undergoing outpatient surgery were studied. Each child was randomly assigned to receive one of three rectal solutions (each containing atropine 0.02 mg X kg-1): Group A - ten per cent methohexitone, 25 mg X kg-1 (n = 20); Group B - ten per cent methohexitone, 15 mg X kg-1 (n = 20); or Group C - one per cent methohexitone, 15 mg X kg-1 (n = 20). After induction of anaesthesia, or a maximum period of 20 minutes following rectal administration of methohexitone, halothane, nitrous oxide, and oxygen were administered by mask. The time to induction of anaesthesia, complications, postanaesthetic recovery scores, and recovery time did not differ significantly among the three groups. The incidence of failed inductions did not differ significantly between Group A (zero per cent) and Group C (ten per cent) but both were significantly less than Group B (45 per cent) (p less than 0.05). Heart rate increased significantly between 10 and 30 minutes after rectal administration of methohexitone and atropine. The authors conclude that ten per cent rectal methohexitone 25 mg X kg-1 and one per cent rectal methohexitone 15 mg X kg-1 are equally effective for induction of anaesthesia in children and both are significantly more effective than ten per cent methohexitone 15 mg X kg-1.     

Rocuronium attenuates oculocardiac reflex during squint surgery in children anesthetized with halothane and nitrous oxide

BACKGROUND: The oculocardiac reflex (OCR) may be activated during squint surgery. The aim of this study was to test whether rocuronium 0.4 mg kg(-1) could reduce the frequency of OCR, and also whether a single dose of succinylcholine 1 mg kg(-1) could affect the frequency of OCR during anesthesia with halothane in a nitrous oxide/oxygen mixture. METHODS: A total of 161 ASA I children, 3-10 years old, undergoing elective surgery of the medial rectus muscle (MRM) were randomly assigned to three groups. Group R (n = 51), received 0.4 mg kg(-1) of rocuronium intravenously before endotracheal intubation. Group S (n = 58) received 1 mg kg(-1) of succinylcholine. Group C (controls, n = 52) received no relaxant. Oculocardiac reflex was defined as a reduction in heart rate (HR) > or = 15% and/or the appearance of any other arrhythmias, during manipulation of the MRM. Analysis of variance (anova), chi-squared, Kruskal-Wallis, and Student's t-tests were used for statistical analysis; P< 0.05 was considered statistically significant. RESULTS: In group R, OCR occurred in 15/51 (29%) of children, in group S in 31/58 (53%), and in group C in 23/52 (44%) (chi2 = 6.46, P = 0.049). In group R, the incidence of arrhythmias such as nodal rhythms, supraventricular and ventricular premature beats was 6%, compared with 22% in group S and 19% in group C (chi2 = 6.01, P = 0.040). However, there was no reduction in the occurrence of bradycardia (chi2 = 0.16, P = 0.924). CONCLUSION: Rocuronium reduced the frequency of OCR, mainly by reducing the incidence of supraventricular and ventricular premature beats.     

Comparison of sevoflurane and halothane for outpatient dental anaesthesia in children

In a prospective, randomized, double-blind clinical study, we have studied 100 children, aged 2-12 yr, to compare halothane and sevoflurane in outpatient dental anaesthesia. All patients were unpremedicated and received inhalation induction using nitrous oxide in oxygen supplemented with either halothane (maximum inspired concentration 5%) or sevoflurane (maximum inspired concentration 8%). Time to loss of the eyelash reflex was more rapid using sevoflurane although time to adequate anaesthesia (to allow insertion of a mouth prop) was slower in the sevoflurane group. The incidence of cardiac arrhythmia was higher during halothane (62%) than during sevoflurane anaesthesia (28%) (P < 0.005) and the arrhythmias were more often ventricular in origin. The two agents were comparable in terms of ease of use and quality of anaesthesia, and times to eye opening and satisfying discharge criteria were similar. We conclude that sevoflurane has qualities that have made halothane the most used inhalation agent for children, and that it is superior to halothane in dental outpatients where cardiac arrhythmias are a particular problem.      

Effects of halothane on arrhythmias induced by myocardial ischaemia

The effect of halothane on arrhythmias induced by ischaemia was investigated in rats, isolated perfused rat hearts, and pigs. Responses to the occlusion of the left anterior descending coronary artery were determined in groups (n = 9) of chronically prepared rats treated with no halothane, 0.5, or 1.0 per cent halothane immediately after occlusion; in isolated rat hearts (n = 10) treated with no halothane, 0.5, 1.0, 2.0, or 4.0 per cent halothane for 15 min before and after occlusion; and 20–25 kg pigs (n = 11) anaesthetised with halothane or pentobarbital. The ECG, arrhythmias, blood pressure (BP), heart rate (HR) and extent of infarction were determined in each model. In pigs, left ventricular pressure, dp/dt_max and cardiac output were also measured. In chronically prepared rats, halothane anaesthesia started after occlusion was antiarrhythmic and decreased the incidence of ventricular fibrillation and resulting mortality. In isolated rat hearts, 0.5 or 1.0 per cent halothane had little effect on occlusion-induced arrhythmias. The highest concentration of halothane increased the incidence of ventricular fibrillation both before and after occlusion. Halothane decreased developed ventricular pressure in a dose-dependent manner. In acutely prepared pigs, halothane pre-treatment had no appreciable effect upon occlusion-induced arrhythmias when compared with pentobarbital anaesthesia. Thus, halothane is antiarrhythmic when treatment is initiated after occlusion in the rat but this action is not seen in isolated hearts or intact pigs. The antiarrhythmic action of halothane is, therefore, species and model dependent.     

Comparison of Electrocardiographic Changes during Microlaryngoscopy under Balanced Anaesthesia Induced by Althesin or Thiopentone

Electrocardiographic (ECG) changes during microlaryngoscopy were studied with three methods of anaesthesia. In the two main groups, balanced anaesthesia was induced by Althesin (=Althesin I group) in 98 patients or by thiopentone (=thiopentone group) in 68 patients. In 23 patients, halothane anaesthesia was induced by Althesin (= Althesin II group). During the procedure, the most common ECG changes in all groups were sinus tachycardia (54–78%), junctional rhythm (28–57%), ventricular ectopic beats (12–26%), T-wave changes (9–22 %) and supra ventricular ectopic beats (7–17%). There was no statistically significant difference in the total number of ECGchanges between the groups. There was, however, significantly more sinus tachycardia in the Althesin II group (78%) than in the thiopentone group (54%). Junctional rhythm occurred significantly more often in the Althesin II group (57%) than in the Althesin I group (31 % ) or in the thiopentone group (28%). Upper junctional rhythm was most common in the Althesin I group, whereas middle junctional rhythm dominated in the Althesin II group. Ischaemic S-T segment depression did not occur in the thiopentone group, whereas in the Althesin I and II groups its incidence ranged from 6 to 13%. In all patients ECG changes disappeared without any special treatment after the manipulation of the vocal cords. The results suggest that there is no decisive difference in the occurrence of ECG changes between the three methods of anaesthesia.     

Endocrine response to surgery in children after premedication with midazolam or papaveretum

The effect of two premedications on the sympatho-adrenal and endocrine stress-response to minor surgery under halothane anaesthesia was investigated in 16 children. One group (n = 9) was premedicated with midazolam, 0.1 mg kg-1, and atropine 0.2-0.4 mg i.m. The other group (n = 7) received papaveretum 0.4 mg kg-1 and hyoscine 0.008 mg kg-1 i.m. Plasma concentrations of catecholamines, ACTH and cortisol were measured during undisturbed anaesthesia, during surgery and 15 min post-operatively. There were no differences in catecholamine concentrations between the groups. Prior to surgery, plasma ACTH was significantly lower (P less than 0.05) in the papaveretum group. During surgery, plasma cortisol and plasma ACTH were significantly lower after papaveretum premedication. Post-operatively there were no differences. End-tidal CO2 concentrations were similar in the two groups. It was concluded that the endocrine stress-response immediately after induction of anaesthesia and during surgery was lower after papaveretum than after midazolam premedication.     

Comparison of the incidence of complications at induction and emergence in infants receiving oral atropine vs no premedication

We studied 120 patients less than 1 yr of age, allocated randomly to receive atropine 40 micrograms kg-1 orally 1 h before operation (group A) or no premedication (group B). All patients underwent a standardized anaesthetic, including inhalation induction with halothane followed by atracurium 0.5 mg kg-1, tracheal intubation and positive pressure ventilation. Monitoring during anaesthesia included heart rate, arterial oxygen saturation, temperature and airway conditions at induction and emergence. The incidence of a decrease in arterial oxygen saturation to 94% or less at induction and recovery was similar in both groups (30.5% at induction, 39% at extubation in group A; 31% at induction, 41% at extubation in group B). There were significantly more airway complications in group B both at induction and emergence (25% and 49%, respectively, compared with 9% and 25% in group A; P < 0.015). Mean heart rate at induction and in the peroperative period was significantly higher in the group receiving atropine (P < or = 0.001). There was an increased incidence of bradycardia (decrease in heart rate of > or = 20%) at induction in the non-premedicated group (23% in group B compared with 10% in group A), but this was not statistically significant. We conclude that the incidence of airway complications at induction and emergence was reduced by orally administered atropine premedication.      

Effect of i.v. Atropine on Cardiac Rhythm, Heart Rate, Blood Pressure and Airway Secretion during Isoflurane Anaesthesia

Atropine, 0.01 mg kg-^-1, was given i.v. to 30 patients before mask anaesthesia with isoflurane. Controls (n = 28) received a placebo. ECG was recorded on tape throughout anaesthesia and analysed later. There were no ventricular arrhythmias, but six patients in the atropine group and two patients in the placebo group had supraventricular arrhythmias of very short duration. Most cases occurred shortly after atropine, i.e. before anaesthesia. Heart rate increased significantly in both groups, more so after atropine (up to 60%), and remained elevated. In both groups blood pressure fell after the induction of anaesthesia but was close to control during surgery. Suction of airway secretions was necessary in three placebo patients, but excessive secretions were not met. The frequency of airway reflexes was similar in the two groups. It is concluded that due to the pronounced tachycardia the routine use of i.v. atropine can hardly be recommended before mask anaesthesia with isoflurane.     

Atropine before Enflurane Anaesthesia: Effects on Cardiac Rhythm, Pulse Rate, Blood Pressure and Airway Secretion

The occurrence of cardiac arrhythmias and changes in pulse rate and blood pressure during mask anaesthesia with enflurane was investigated in 92 patients with special reference to the influence of atropine (0.01 mg kg-1 5 min before anaesthesia) and thiopental. The average duration of anaesthesia was a little less than 1 h in all four groups. More than five ventricular extrasystoles occurred in one patient (38 min after atropine). Supraventricular (mainly nodal) arrhythmias were significantly (P less than 0.005) more common in the atropine groups (15/45) than in the non-atropine groups (4/47). Following atropine, heart rate increased by about 25 beats min-1, whereas only very slight increases were seen in the non-atropine groups. Blood pressure fell at the induction but was almost back to normal at the end of anaesthesia. Blood pressure was unaffected by atropine. Slightly lower values of blood pressure were suggested in the thiopental groups, whereas thiopental did not modify cardiac rhythm or pulse rate. Suction of the pharynx was necessary in only one patient. In conclusion, the present study does not support the routine administration of atropine before enflurane anaesthesia with or without thiopental induction.     

Oral clonidine blunts the heart rate response to intravenous atropine in humans.

Clonidine, recently introduced into anesthesia practice, may cause bradycardia. Whether this bradycardia is reversible with atropine is not known. Accordingly, we studied heart rate (HR) responses to intravenous atropine in 80 patients assigned randomly to either a control group, who received no medication (n = 20), or a clonidine group, who received oral clonidine of approximately 1.2 micrograms.kg-1 (n = 20), 2.5 micrograms.kg-1 (n = 20), or 5 micrograms.kg-1 (n = 20). All patients received incremental doses of atropine, 2.5, 2.5, and 5 micrograms.kg-1, at 2-min intervals (total dose 10 micrograms.kg-1). Positive chronotropic response to the cumulative atropine dose of 10 micrograms.kg-1 was attenuated significantly only in patients given clonidine 5 micrograms.kg-1 (7 +/- 1 beats per min, mean +/- standard error) when compared with those given smaller doses of clonidine (15 +/- 2, 16 +/- 2 beats per min) or no clonidine (19 +/- 2 beats per min) (P less than 0.05). To determine whether HR hyporesponsiveness to atropine induced by clonidine can be overcome by a larger dose of atropine, the authors studied 30 additional patients given clonidine 5 micrograms.kg-1 or no medication. In all patients not receiving clonidine (n = 15), HR increased by more than 20 beats per min when atropine of 15 micrograms.kg-1 was administered, whereas in only 5 patients (33%) receiving clonidine did the HR increase by 20 beats per min after atropine 15 micrograms.kg-1 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Thoracic epidural anaesthesia decreases the incidence of ventricular arrhythmias during acute myocardial ischaemia in the anaesthetized rat

The aim of the present investigation was to study the effect of high thoracic epidural anaesthesia (TEA) on the incidence of ventricular arrhythmias after ligation of the left coronary artery in chloralose-anaesthetized rats. Forty animals were randomly assigned to receive either 40-50 microliter of bupivacaine (5 mg/ml) or saline in implanted thoracic epidural catheters. TEA decreased mean arterial pressure (MAP) from 118 +/- 5 mmHg to 72 +/- 4 mmHg and heart rate (HR) from 450 +/- 9 to 387 +/- 8 beats/min, while epidural saline did not affect MAP and HR. In both groups coronary artery ligation induced a transient decrease in MAP within the first 5-10 min after ligation. In the control group HR increased, during the 30-min post-ligation period, from 453 +/- 9 to 474 +/- 10 beats/min (P less than 0.05) while no significant change was seen in the TEA group. In both groups the mortality rate was 10%. In the TEA group 30% and in the control group 0% had normal sinus rhythm during the recording period (P less than 0.001). The incidence of ventricular fibrillation and/or tachycardia was significantly lower (P less than 0.05) in the TEA group (20%) compared to the control group (53%). The incidence of ventricular extrasystoles did not differ between the two groups. We conclude that TEA-induced blockade of sympathetic afferents and efferents may offer protection against malignant ventricular arrhythmias in the early phase of acute myocardial infarction.     

Effects of halothane and sevoflurane on QT dispersion in paediatric patients

BACKGROUND: The QT dispersion (QTd) of the ECG is an indirect measure of heterogeneity of ventricular repolarization which may contribute to complex ventricular arrhythmias. We compared the effects of halothane and sevoflurane on QTd, and heart-rate corrected QT dispersion (QTcd). METHODS: Fifty ASA physical status I patients, aged 5-15 years, undergoing general anaesthesia were studied. A control ECG recording was printed before induction of anaesthesia. In the halothane group, anaesthesia was induced with halothane 4% in 2 : 1 ratio of air : O2 mixture and in the sevoflurane group with sevoflurane 8% in 2 : 1 ratio of air : O2 mixture. The ECG was recorded 1 and 3 min after induction of anaesthesia, 1 and 3 min after the administration of vecuronium 0.08 m.kg(-1) intravenous and 1 and 3 min after the tracheal intubation. All ECGs were analysed by two cardiologists blinded to the anaesthetic. RESULTS: Although QTd increased in both groups following intubation, this difference was not statistically significant when compared with control values. Following intubation five patients in the halothane group had ventricular arrhythmias of short duration, whereas no arrhythmias were recorded in the sevoflurane group (P = 0.052). Following intubation, QTd (45 +/- 15 ms vs 40 +/- 14 ms) and QTcd (60 +/- 17 ms vs 55 +/- 16 ms) values in the halothane group were significantly greater than the sevoflurane group (P < 0.05). CONCLUSION: Neither sevoflurane nor halothane caused a significant increase in QTd compared with control values before induction. Only QTd following intubation was significantly greater in the halothane group than the sevoflurane group.     

Atracurium with halothane and isoflurane in pediatric anesthesia

The study was carried out to assess the effects of atracurium neuromuscular blockade in children anaesthetized with N2O:O2: halothane vs N2O:O2: isoflurane. Thirty-two ASA I-II children, age 1-13 yr, undergoing elective surgery, were divided into two groups according to age and the mode of anaesthesia induction. Anaesthesia was induced in the younger children (group 1: 1-6 yr) with nitrous oxide and inspired halothane or isoflurane in oxygen via a face mask. Intravenous thiopental (6-7 mg/kg-1) was used to induce anaesthesia in older children (group 2: 7-13 yr). Each group of patients was randomly allocated to two groups each receiving halothane (group A: n = 8) or isoflurane (group I: n = 8). Halothane 0.8% end-tidal and isoflurane 1% end-tidal as anaesthesia maintenance. A bolus dose of atracurium 0.35 mg/kg-1 was administered. Premedication consisted of oral flunitrazepam (0.04 mg/kg-1) and bellafoline (0.02 mg/kg-1). Heart rate (by electrocardiography), arterial pressure (by auscultation) were monitored. Then end-expired carbon dioxide concentration was maintained at 30-40 mmHg. Neuromuscular transmission was evaluated by response to indirect stimulation (TOF) of the ulnar nerve at the wrist via surface electrodes. Conditions for endotracheal intubation were excellent in 25 of the children, good in 6 and poor in 1. The intubation was carried out within 112 s (group 1A), 130 s (group 1 I), 112 s (group 2A) and 135 s (group 2 I) following the administration of atracurium. The maximum twitch depression was recorded in the isoflurane groups.(ABSTRACT TRUNCATED AT 250 WORDS)