Anaesthesia and the QT intervalEffects of isoflurane and halothane in unpremedicated children

The effects of isoflurane and halothane on the QT interval were investigated during induction of anaesthesia. Fifty-one unpremedicated, ASA grade 1 children were studied. Anaesthesia was induced with either isoflurane ( n  = 25) or halothane ( n  = 26) and was maintained to the end of the study with end-tidal concentrations of between 2.5% and 3%. Recordings of the electrocardiograph, heart rate and systolic arterial pressure were obtained at the following times: before induction of anaesthesia; 1 min and 3 min after stable end-tidal concentrations of anaesthetic agent had been reached; 1 min and 3 min following vecuronium administration; at the time of tracheal intubation and 1 min and 3 min later. Isoflurane significantly prolonged the QT interval (p < 0.001), in contrast to halothane which shortened it (p < 0.01). Heart rate remained largely unchanged during isoflurane anaesthesia but it decreased in the presence of halothane (p < 0.001). In both groups, systolic arterial pressure decreased significantly after induction of anaesthesia (p < 0.001) and remained so to the end of the study. In the isoflurane group, 12 children developed ECG repolarisation abnormalities and in one child an arrhythmia was noticed. In the halothane group, one child developed repolarisation changes while arrhythmias were observed in 10 children. There were no adverse sequelae. It is concluded that halothane may be a better anaesthetic agent than isoflurane for use in children with a prolonged QT interval.     

The influence of halothane, isoflurane and sevoflurane on rocuronium infusion in children

BACKGROUND: Rocuronium is a non-depolarizing neuromuscular blocking agent with intermediate duration of action and without significant cumulative properties, suitable for continuous infusion. This study was designed to determine the infusion requirements in children under nitrous oxide and fentanyl, halothane, isoflurane or sevoflurane anaesthesia. METHODS: Forty children, 3-11 years old, ASA physical status group I or II were studied. They were randomly allocated to receive fentanyl-nitrous oxide, 1 MAC halothane-nitrous oxide, 1 MAC isoflurane-nitrous oxide or 1 MAC sevoflurane-nitrous oxide anaesthesia. Rocuronium, 0.6 mg(-1) was used to facilitate endotracheal intubation. Electromyographic response of adductor pollicis to train-of-four (TOF) stimulation, 2 Hz for 2 s, applied to the ulnar nerve at 10-s intervals was recorded using Relaxograph (Datex, Helsinki, Finland). Once the first twitch response (T1) returned to 5%, muscle relaxation was maintained by continuous infusion of rocuronium, adjusted automatically in a closed-loop system to maintain a stable 90-99% T1 depression. The block was considered stable if it changed by no more than 2% over a 10-min observation period. RESULTS: Halothane, isoflurane and sevoflurane groups had ower infusion requirements than the fentanyl-nitrous oxide group (P<0.00075). Rocuronium requirement (mean +/- SD) at one hour from the commencement of anaesthesia was 16.7+/-2.3, 13.6+/-3.7, 13.1+/-5.1 and 8.4+/-1.6 microg x kg(-1) x min(-1) for children receiving fentanyl-nitrous oxide, halothane, isoflurane and sevoflurane anaesthesia, respectively. CONCLUSIONS: The rocuronium infusion rate required to maintain stable 90-99% T1 depression was reduced by approximately 20% with halothane and isoflurane anaesthesia, and by 50% with evoflurane anaesthesia when compared to fentanyl-nitrous oxide anaesthesia. Significant patient-to-patient variability of infusion rate makes monitoring of neuromuscular transmission necessary.     

Safety and efficacy of the laryngeal mask airway A prospective survey of 1400 children

A survey of laryngeal mask airway usage in 1400 infants and children by ten trainee anaesthetists was undertaken to provide information about insertion and complication rates using the standard insertion technique and a limited range of standardised anaesthetic techniques. Placement was successful in 90% (1258/1400) at the first attempt, 8% (112/1400) at the second attempt and 2% (29/1400) required an alternative technique of insertion. One patient vomited during insertion and the procedure was abandoned, hut aspiration did not occur. The overall problem rate was 11.5% and there were significantly more problems during induction of anaesthesia (p < 0.02). Oxygen saturation decreased below 90% briefly on 23 occasions (1.7%). The incidence of problems was unrelated to the mode of ventilation, or whether isoflurane or total intravenous anaesthesia with propofol was used for maintenance. Most problems came with use of the size 1 laryngeal mask (p < 0.001). The subspecialty with the highest problem rate was ear, nose and throat surgery (p < 0.001). There was a significant decrease in problems with increasing experience (p < 0.001). There was no major morbidity associated with use of the device. We conclude that the laryngeal mask provides a safe and effective form of airway management for infants and children in the hands of supervised anaesthesia trainees both for spontaneous and controlled ventilation using either isoflurane or total intravenous anaesthesia.     

Comparison of plasma α glutathione S-transferase concentrations during and after low-flow sevoflurane or isoflurane anaesthesia

BACKGROUND: We evaluated the effect of low-flow sevoflurane anaesthesia, in which compound A is generated, and isoflurane anaesthesia, in which compound A is not generated (n=13 in each group), on hepatocellular integrity using alpha glutathione S-transferase (GST). Alpha GST is a more sensitive and specific marker of hepatocellular damage than is aminotransferase activity and correlates better with hepatic histology. METHODS: Sevoflurane or isoflurane were delivered without nitrous oxide with a fresh gas flow of 1 l/min. Concentrations of compound A in the circuit were measured hourly, and plasma alpha GST concentrations were measured perioperatively. RESULTS: Mean duration of anaesthesia was 338+/-92 min in the sevoflurane group and 320+/-63 min in the isoflurane group. Mean compound A concentration in the sevoflurane group was 28.6+/-9.0 ppm. There was no significant difference in alpha GST concentrations between the sevoflurane and isoflurane groups during or after anaesthesia. CONCLUSION: These results indicate that low-flow sevoflurane and isoflurane anaesthesia have the same effect on hepatic function, as assessed by plasma alpha GST concentrations.     

Comparison of recovery after intermediate duration of anaesthesia with sevoflurane and isoflurane

BACKGROUND: The purpose of this study was to compare recovery from anaesthesia after sevoflurane and isoflurane were administered to children for more than 90 min. METHODS: After parental informed consent and ethical committee approval, children aged between 2 months and 6 years, ASA I or II, were randomly allocated to sevoflurane (n=20) or isoflurane (n=20) groups. Halogenated agents were discontinued following skin closure and patients were ventilated mechanically with 100% oxygen until minimum alveolar concentration (MAC) values awake were obtained (endtidal concentrations 0.6 MAC for sevoflurane and 0.4 MAC for isoflurane). Effective perioperative analgesia was provided by a caudal block. RESULTS: The mean (+/- SD) duration of anaesthesia was 132 +/- 38 min and 139 +/- 49 min for sevoflurane and isoflurane, respectively. Early recovery occurred sooner in the isoflurane group (time to extubation was 16 +/- 7 min and 11 +/- 5 min, P<0.01; Aldrete's score at 0 min was 5.5 +/- 1.5 and 7.4 +/- 1.8, P<0.001, respectively). But the time to be fit for discharge from recovery room was similar at 136 +/- 18 min and 140 +/- 20 min, respectively. CONCLUSIONS: After intermediate duration of anaesthesia administered to children for up to 90 min, isoflurane and sevoflurane allow recovery after approximatively the same lapse of time.     

Isoflurane in paediatric anaesthesia

The characteristics of induction with and recovery from isoflurane anaesthesia were studied in 248 children. The mean time to loss of consciousness was 1.5 min (SD 0.5). Tracheal intubation, without interruption of spontaneous ventilation, was accomplished in a mean time of 4.2 min (SD 54 seconds). Movement and excitement, of 20-30 seconds duration, occurred in 23.9% children and 22 patients coughed during induction; 15 (12.6%) during the first 124 inductions; 7 (5.6%) subsequently. The mean half-times of reduction of alveolar isoflurane concentrations in 28 children whose lungs were ventilated with isoflurane and in 13 children who breathed isoflurane spontaneously during anaesthesia were: 45 sec after exposure for one hour, 70 sec after exposure of 2-3 hours and 110 seconds following exposures of 4-8 hours. The mean recovery times of the three groups were 6.5, 9.5 and 11.5 min respectively. In two further groups of nine children the mean half times of elimination of halothane and isoflurane were 220 seconds and 54 seconds respectively; recovery from isoflurane was markedly faster. Isoflurane is well accepted by children; induction is more rapid than with halothane, and the marked flexibility in the control of its effects are due to its relative insolubility. It has wide application in paediatric anaesthesia.     

Hepatocellular integrity during and after isoflurane and halothane anaesthesia in surgical patients

Subclinical disturbance in hepatocellular integrity, indicated by glutathione transferase Alpha (GSTA), has been associated with halothane, sevoflurane and propofol, but not with isoflurane anaesthesia. We anaesthetized 82 patients with isoflurane or halothane at 1 MAC for superficial surgery. GSTA concentration were measured with a sensitive time-resolved immunofluorometric assay in serum samples. GSTA concentrations increased from a baseline value of geometric mean 1.8 micrograms litre-1 (95% confidence intervals 1.4-2.2 micrograms litre-1) to a peak of 4.3 (3.3-5.7) micrograms litre-1 in the isoflurane group and from 2.1 (1.6-2.9) micrograms litre-1 to 6.2 (4.1- 9.5) micrograms litre-1 in the halothane group. The change in GSTA was significant within groups but the difference between groups was not significant. Two patients exhibited an unexpectedly large increase in GSTA (peaks 370 and 620 micrograms litre-1) and a mild increase in alanine aminotransferase after halothane anaesthesia. We conclude that hepatocellular integrity was mildly disturbed after isoflurane and halothane anaesthesia but there was no difference between anaesthetics. Halothane anaesthesia may be associated with more advanced hepatocellular disturbance in some cases.      

Comparison of sufentanil/propofol versus isoflurane/nitrous oxide anaesthesia on mesenteric artery blood flow

Duplex sonography was used to determine the changes in mesenteric arterial blood flow occurring in patients undergoing aortic surgery, anaesthetised either by total intravenous anaesthesia with propofol and sufentanil (group A) or inhalational anaesthesia with isoflurane and nitrous oxide (group B). Sixteen patients were studied. Measurements were performed immediately before and 15 min after induction of anaesthesia, before surgery. There was a 38% decrease (p = 0.015) in the superior mesenteric artery end diastolic velocity in group A and a 23% decrease (p = 0.033) in the superior mesenteric artery peak systolic velocity in group B. There were no changes in any of the other sonography parameters in either group. We conclude that neither total intravenous anaesthesia with propofol and sufentanil nor inhalational anaesthesia with isoflurane and nitrous oxide have any clinically significant influence on mesenteric blood flow in the absence of surgical stimulation.     

Longterm functional recovery following day-case laparoscopic sterilisation: inhalational versus TIVA maintenance

In this study we have evaluated the influence of anaesthetic technique on functional recovery and symptom distress following gynaecological surgery. Previous studies in this area focus on in hospital recovery parameters and no anaesthetic technique comparison study has followed patients postoperatively, daily for a week. We studied 99 females undergoing laparoscopic sterilisation; they were randomly allocated to receive either total intravenous anaesthesia with propofol or isoflurane inhalational anaesthesia.The results showed no significant differences between the two groups in respect to functional recovery, nausea, vomiting or pain over the 7 day study period.In both groups, functional recovery was relatively slow; with some patients taking 7 days to achieve normal function and energy levels. We found that 90% of patients required help at home on Day 1.     

The respiratory effects of isoflurane, enflurane and halothane in spontaneously breathing children

The respiratory effects of halothane, isoflurane and enflurane were assessed during nitrous oxide anaesthesia (N2O 50%) in three groups of unstimulated, spontaneously breathing children who weighed 10-20 kg and were aged 1-6 years. Respiratory variables were measured or calculated from capnographic and pneumotachographic recordings at three multiples of minimal alveolar concentration (MAC). The slope of the carbon dioxide response was measured. Similar increases in end tidal carbon dioxide were found for the three agents at each MAC multiple, and similar decreases in tidal volume and in the slope of the ventilatory response to carbon dioxide. A dose-related tachypnoea occurred with halothane and a significant decrease in the duration of inspiration and the duration of each breath at the deepest level of anaesthesia. A significant increase in both these times occurred with enflurane, and a decrease in respiratory rate. No change in respiratory rate occurred with isoflurane at increasing alveolar concentrations whereas at each level of anaesthesia inspiratory time was significantly reduced.     

Dreams, images and emotions associated with propofol anaesthesia

One hundred and twelve patients scheduled for day case varicose vein surgery were randomly allocated to one of three groups: total intravenous anaesthesia with propofol, propofol induction followed by inhalational anaesthesia with nitrous oxide and isoflurane or thiopentone induction followed by inhalational anaesthesia with nitrous oxide and isoflurane. Assessments were made in the recovery room of the incidence of dreaming, the content of the dreams and the emotional status of the patients. The groups differed significantly in reporting that they had been dreaming: patients who underwent total intravenous anaesthesia reported the most dreaming and patients who received thiopentone the least. However, despite the large number of case reports of sexual imagery following propofol anaesthesia and despite the two groups who had received propofol experiencing significantly greater happiness upon recovery than the thiopentone group, there were no appreciable differences in the sexual content of the dreams. Each group had only a small number of dreams even remotely related to sex.     

A review of recovery from sevoflurane anaesthesia: comparisons with isoflurane and propofol including meta-analysis

BACKGROUND: Sevoflurane has a lower blood:gas partition coefficient than isoflurane and thus should be associated with a more rapid recovery from anaesthesia. METHODS: A review and meta-analysis were employed to examine the recovery profiles of adult patients following anaesthesia, comparing sevoflurane to isoflurane and sevoflurane to propofol. RESULTS: There were significant differences in times to several recovery events that favoured sevoflurane to isoflurane anaesthesia, including time to emergence, response to commands, extubation, and orientation. Likewise, there were significant differences in times to the same recovery events following anaesthesia with sevoflurane versus propofol. There were no differences in time to recovery room discharge when comparing sevoflurane to isoflurane or propofol. CONCLUSION: The observed differences between sevoflurane and isoflurane or propofol anaesthesia support the postulate that the use of sevoflurane is associated with a more rapid recovery from anaesthesia than either isoflurane or propofol.     

Induction characteristics of propofol in children: comparison with thiopentone

The induction characteristics of propofol were studied and compared with thiopentone in children aged 3-14 years who received either no premedication or pethidine-atropine or trimeprazine. Anaesthesia was maintained with nitrous oxide in oxygen, and isoflurane. The induction doses of propofol and thiopentone were 2.9 mg/kg and 6.5-7.1 mg/kg respectively; premedication had no significant effect on the induction doses of either agent. Spontaneous movement and hypertonus occurred in about 20% of children with both agents. The use of propofol was associated with a high incidence of pain on injection (injections were mostly in veins on the dorsum of the hand), but this was reduced by mixing lignocaine with propofol. Cardiovascular effects were not clinically significant with either agent. Apnoea occurred in 35% of patients given propofol and in 50% of those given thiopentone. Children anaesthetised with propofol awoke significantly earlier after cessation of all anaesthesia. It is concluded that the use of propofol is safe in children and may have advantages where early recovery from anaesthesia is desirable, but offers no advantage over thiopentone for routine induction of anaesthesia.     

Ventilatory changes during nitrous oxide isoflurane anaesthesia in children

The changes in ventilatory variables under nitrous oxide isoflurane anaesthesia were studied in 10 children (mean age 46 +/- 13.4 months, mean weight 16.2 +/- 2.1 kg). Measurements of flow and volume were performed by pneumotachography. PE'CO2 was measured by capnography. The following variables (VE, VT, TI/TTOT, VI, PE'CO2) were measured or calculated under three increasing inspired isoflurane concentrations (0.75%, 1.5%, 2.25%). At each level of anaesthesia, ventilatory changes during exposure to an inspired CO2 fraction of 2% were studied. The increase in the inspired concentration of isoflurane was associated with a decrease in alveolar ventilation. PE'CO2 increased significantly with increasing depth of anaesthesia. The respiratory rate was slightly increased under light nitrous oxide isoflurane anaesthesia, but no further changes were observed with increasing depth of anaesthesia, although the children were breathing a mixture of nitrous oxide and oxygen. The ventilatory response to a raised inspired CO2 is markedly decreased under light nitrous oxide isoflurane anaesthesia, and decreases significantly with increasing depth of anaesthesia. In response to a raised CO2, VE, VT and VI increase, but respiratory rate decreases or remains constant and TI/TTOT is unchanged.     

Anaesthesia for laparoscopy

This is a report about five anaesthetic techniques for laparoscopy. Propofol and etomidate were used for total intravenous anaesthesia. Propofol, etomidate and thiopentone were used as induction agents prior to inhalational anaesthesia with isoflurane and nitrous oxide. Fentanyl was used for analgesia. Induction with propofol and thiopentone was rapid. Etomidate induction was characterised by myoclonus. Maintenance was smooth with inhalational anaesthesia. Of the groups that received total intravenous anaesthesia, propofol provided stable anaesthesia but required extra bolus doses. Recovery was the most rapid following total intravenous anaesthesia with propofol. Postoperative side effects were much lower after propofol. No difference was observed between the groups with regard to changes in arterial blood pressure and heart rate.     

Comparison of the effects of desflurane and isoflurane anaesthesia on hepatocellular function assessed by alpha glutathione S-transferase

The purpose of this study was to investigate the influence of isoflurane and desflurane on hepatocellular function. Twenty male patients undergoing elective surgery were randomly assigned to receive either isoflurane or desflurane anaesthesia. Alpha glutathione S-transferase concentrations and aminotransferase activities were measured at induction of anaesthesia (t0), 15 min (t1), 90 min after induction (t2), end of surgery (t3) and 2 h thereafter (t4). A significant increase in alpha glutathione S-transferase concentration was observed only in the isoflurane group. Alpha glutathione S-transferase levels increased significantly from 2.3 microg.l-1 at t0 to 6.1 (1.9) microg.l-1 at t2 and to 7.8 (2.1) microg.l-1 at t3. A significant difference in alpha glutathione S-transferase concentration between the two groups was found at t2 and t3. The significant increases in alpha glutathione S-transferase concentrations in patients receiving isoflurane suggest a transient disturbance of hepatocellular function.     

Anaesthesia, recovery and postoperative nausea and vomiting after breast surgery. A comparison between desflurane, sevoflurane and isoflurane anaesthesia

BACKGROUND: Whereas induction and recovery will occur more rapidly with the new low soluble anaesthetics than with isoflurane, the quality of anaesthesia and recovery with special emphasis on postoperative nausea and vomiting (PONV) is not well known. METHODS: In an open (peroperatively), double-blinded (postoperatively), randomised controlled study, we assessed anaesthesia characteristics, recovery and 24 h PONV after breast surgery comparing isoflurane, desflurane and sevoflurane. RESULTS: There were no significant quality differences between the three agents during anaesthesia and recovery except for the incidence of PONV in the postanaesthesia care unit (PACU). The PONV rate (24 h in PACU and ward) was higher in the desflurane group (67%) than in the isoflurane group (22%), (P<0.01). The corresponding PONV rate for sevoflurane was 36%. CONCLUSION: The quality of anaesthesia, time to opening of eyes and influence on respiration was similar with all three anaesthetics. As the emergence from anaesthesia did not differ significantly between the three agents, the choice of agent could be based on PONV rate and price. Desflurane had a significantly higher 24 h PONV rate than isoflurane. Early PACU PONV rate was significantly (P<0.05) lower for the more soluble isoflurane (4%) than for the low soluble gases, desflurane and sevoflurane together (28%). The result of this study does not give a rationale for a transition to the new low soluble agents in breast cancer surgery.     

Emergence and recovery in children after desflurane and isoflurane anaesthesia: effect of anaesthetic duration

Background. We hypothesized that increasing duration of inhalationanaesthesia is associated with slower emergence and recoveryin children, and that this effect would be less marked withdesflurane in comparison with isoflurane. Methods. Fifty-four infants and children assigned in groupsaccording to age and expected length of operation were prospectivelyrandomized to receive either isoflurane (I) or desflurane (D)for anaesthesia. After standard induction, the anaesthesia wasmaintained using an age-related 1.0 minimum alveolar concentration(MAC) equivalent for either agent in air and oxygen. Local analgesiawas used as appropriate. End-tidal volatile agent concentrationwas recorded until extubation. Clinical evaluation of recoverywas made by observers, blinded to group allocation. Results. For patients <4 yr of age, the median (95% CI) timesin minutes to first movement [5.27 (D), 9.22 (I)], eye opening[9.42(D), 13.3(I)] and extubation [7.18 (D), 12.5 (I)] weresignificantly shorter (P<0.05) for desflurane. In the group>4 yr of age, the median (95% CI) times in minutes to firstmovement [4.42 (D), 11.6 (I)], eye opening [8.55(D), 18.0(I)]and extubation [7.08 (D), 16.7 (I)] were significantly shorter(P<0.001) for desflurane. Times to leave recovery were notsignificantly different for the group <4 yr of age, but weresignificantly shorter for desflurane in the group >4 yr ofage (P<0.01). The isoflurane, but not desflurane, had a time-dependenteffect on arousal. There were no significant differences inincidence of airway irritation or emergence delirium betweenthe two agents. Conclusions. The rate of recovery in children after exposureto desflurane was faster than those patients receiving isoflurane;recovery from desflurane, but not isoflurane, was relativelyunaffected by the duration of anaesthesia.     

Mivacurium infusion requirement and spontaneous recovery of neuromuscular transmission in children anaesthetized with nitrous oxide and fentanyl,halothane, isoflurane or sevoflurane

BACKGROUND: Forty children, aged 3-11 years, ASA I or II, were allocated at random to receive N2O/O2-fentanyl or 1 MAC halothane, isoflurane or sevoflurane-N2O/O2 anaesthesia. Mivacurium was used for muscle relaxation. METHODS: Electromyographic response of the adductor pollicis to train-of-four (TOF) stimulation, 2 Hz for 2 s, applied to the ulnar nerve at 10-s intervals was recorded using the Relaxograph (Datex, Helsinki, Finland). An intubating dose of mivacurium, 0.2 mg.kg-1 was given, and when T1 returned to 5%, muscle relaxation was maintained by continuous infusion of mivacurium, adjusted manually to maintain a stable 90-99% block. RESULTS: Halothane, isoflurane and sevoflurane groups had lower infusion requirements for mivacurium than the N2O-fentanyl group (P=0.000083). Mivacurium requirement was 18.8 +/- 6.8, 10.8 +/- 4.2, 6.9 +/- 3.9 and 9.6 +/- 5.6 microg.kg-1.min-1 for children receiving N2O/O2-fentanyl, halothane, isoflurane and sevoflurane anaesthesia, respectively. CONCLUSIONS: Spontaneous recovery from T1=10% to TOF ratio=0.7 was insignificantly prolonged from 6.3 to 12.5 min in the fentanyl group to 7-16.5 min in children anaesthetized with inhalational anaesthetics.     

Liver function after sevoflurane or isoflurane anaesthesia in neurosurgical patients

Purpose

Although both sevoflurane and isoflurane are thought to be less hepatotoxic than halothane or enflurane, recent case reports have described liver injury after sevoflurane or isoflurane anaesthesia. There are no studies comparing liver function after sevoflurane or isoflurane anaesthesia. The purpose of this study was to compare serum liver enzyme concentrations in patients receiving either sevoflurane or isoflurane anaesthesia prospectively.

Methods

Ninety patients scheduled for elective neurosurgery were studied. Serum concentrations of aspartame aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBil), alkaline phosphatase (ALP), γ- glutamyl transpeptidase (GTP), and lactate dehydrogenase (LDH) were measured before and, 1, 2, 3, 7, and 14 days after either sevoflurane (45 patients) or isoflurane (45 patients) anaesthesia.

Results

AST ALT and GTP increased peaking seven days after anaesthesia, especially in the isoflurane group. The numbers of patients with abnormal values in AST and ALT were not different in the isoflurane from that in the sevoflurane group. The increase in TBil peaked one day after anaesthesia in both groups.

Conclusion

Even in a small number of patients, isoflurane induced an elevation of serum levels of liver enzymes more frequently than did sevoflurane three to 14 days after anaesthesia.