Isoflurane for anaesthesia in the dental chair. A comparison of the incidence of cardiac dysrhythmias during anaesthesia with halothane and isoflurane

A randomised single-blind trial was performed to compare the effects on cardiac rhythm of isoflurane and halothane in 100 dental outpatients having extractions under general anaesthesia in the dental chair without tracheal intubation. The incidence of supraventricular dysrhythmias did not differ significantly. No patient in the isoflurane group developed a ventricular dysrhythmia, whilst nine of those who received halothane did so (p = 0.0013). The quality of anaesthesia was acceptable in the isoflurane group, but induction time was longer (p less than 0.05) and the maximum heart rate was faster (p less than 0.01). There was no difference in the maximum end tidal carbon dioxide concentrations measured in a further 20 cases.     

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.     

A comparison between isoflurane and alfentanil supplemented anaesthesia for short procedures

Sixty unpremedicated patients undergoing short urological and gynaecological procedures were randomly allocated to three groups to receive either methohexitone, alfentanil, nitrous oxide and oxygen, methohexitone, isoflurane and oxygen or methohexitone, isoflurane, nitrous oxide and oxygen. The group receiving methohexitone, isoflurane and oxygen was abandoned after 11 patients had been studied, due to poor conditions during induction of anaesthesia. Therefore, data from only 51 patients are presented. Early recovery was assessed by time to opening eyes, giving correct name and date of birth; later, recovery was assessed by using the postbox test and deletion of 'p's. During anaesthesia and surgery, there was a high incidence of coughing and laryngospasm in the isoflurane groups. The patients in the alfentanil group opened their eyes and gave their names and dates of birth significantly faster postoperatively (p less than 0.01) than those in the isoflurane groups. However, there were no significant differences between the three groups regarding the later tests of recovery. The late recovery after isoflurane was equal to that obtained using an intravenous technique with alfentanil, although the peroperative complication rate was higher.     

Butorphanol compared with fentanyl in general anaesthesia for ambulatory laparoscopy

Butorphanol was compared with fentanyl as the narcotic component of general anaesthesia for ambulatory laparoscopic surgery. This double-blind, randomized study enrolled 60 healthy women who received equianalgesic doses of fentanyl 1 microgram.kg-1 (F, n = 30) or butorphanol 20 micrograms.kg-1 (B, n = 30) prior to induction of anaesthesia. Tracheal anaesthesia was maintained with nitrous oxide/oxygen, isoflurane, and succinylcholine by infusion. Intraoperatively, patients who received B demonstrated lower pulse rate before and after intubation (P less than 0.05, P less than 0.01) and lower diastolic blood pressure after intubation (P less than 0.01). Anesthesiologists judged the maintenance phase as satisfactory more often with B (P less than 0.05). Postoperatively, there were no differences in analgesic need. No major side-effects occurred in either group. Among minor side-effects, patients who received B reported postoperative sedation more often, 77% vs 37% (P less than 0.01), which occurred during the first 45 min of recovery (P less than 0.05). Discharge times were not different. On the first postoperative day, more subjects who received B were satisfied with their anaesthesia experience (P less than 0.05). Butorphanol 20 micrograms.kg-1 is an acceptable alternative analgesic in general anaesthesia for ambulatory laparoscopy.     

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.     

Quality of recovery after general anesthesia with isoflurane or halothane

The quality of recovery and the time required for it were compared in two groups of 20 patients after general anaesthesia with isoflurane or halothane for elective head and neck surgery. The groups were comparable with regard to age, sex ratio, ASA physical status, type of surgery and duration of anaesthesia. After premedication with diazepam and atropine, a standard induction technique was used (thiopentone, succinylcholine), avoiding opiates and sedatives. Maintenance was assured with a mixture of 30% oxygen, 70% nitrous oxide and isoflurane or halothane. The time between the end of administration of anaesthetic drugs and eye opening was 7.15 +/- 2.9 min in the isoflurane group, and 11.0 +/- 4.7 min in the halothane group (p less than 0.01). The differences between the times for the return of spatial and temporal orientation and of mental arithmetic were not significant, though they were clinically clearly perceptible. The patients were less sleepy, livelier and less agitated in the isoflurane group in the first hour of recovery. Recovery was more rapid after general anaesthesia with isoflurane, and of better clinical quality.     

Buprenorphine as premedication and as analgesic during and after light isoflurane-N2O-O2 anaesthesia. A comparison with oxycodone plus fentanyl

Sixty patients undergoing gynaecological laparotomies under isoflurane anaesthesia received 0.4 mg of buprenorphine sublingually or 0.12 mg/kg of oxycodone intramuscularly in random order for preanaesthetic medication. Patients premedicated with buprenorphine were given buprenorphine before, during and after anaesthesia and patients premedicated with oxycodone received fentanyl before and during anaesthesia and oxycodone after anaesthesia. Buprenorphine premedication produced less drowsiness and sedation and alleviated patients' apprehension significantly (P less than 0.05) less than oxycodone. Systolic and diastolic blood pressure and heart rate were significantly (P less than 0.05 to P less than 0.01) higher after intubation in the buprenorphine group when compared with the oxycodone plus fentanyl group. After anaesthesia, spontaneous respiration started rapidly; the return of consciousness and immediate recovery occurred at the same rate in both groups. In the recovery room moderate to severe pain was more common (P less than 0.05) in the oxycodone plus fentanyl group than in the buprenorphine group. The respiratory rate in the recovery room was lower among patients given buprenorphine, and two patients given buprenorphine developed severe respiratory depression. In the ward (2 to 24 h after operation) sublingual buprenorphine provided pain relief as good as intramuscularly administered oxycodone. No differences were noted in the incidence or severity of emetic symptoms between the groups. It is concluded that buprenorphine can provide good postoperative pain relief for gynaecological laparotomies performed under light isoflurane anaesthesia, but patients need to be monitored carefully after operation because of the possibility of respiratory depression.     

Comparison of continuous spinal and continuous epidural anaesthesia for lower limb surgery in elderly patients A retrospective study

This retrospective study compared continuous spinal anaesthesia with continuous epidural anaesthesia for lower limb orthopaedic surgery in the elderly. The anaesthetic records of 457 patients who received continuous spinal anaesthesia and 274 who received continuous epidural anaesthesia over a 5-year period were analysed. The patients who had continuous spinal anaesthesia were at a higher anaesthetic risk (ASA 3-4, 76% as compared with 37%, p less than 0.001), but the incidence of failures was significantly lower (1.7%, as compared with 9%, p less than 0.001) and fewer patients showed a decrease in mean arterial pressure of more than 30% (44%, as compared with 65%, p less than 0.001) and (or) received vasopressors (65%, as compared with 77%, p less than 0.01). Our data show continuous spinal anaesthesia to be more reliable and to provide better cardiovascular stability.     

Total intravenous anaesthesia with propofol or inhalational anaesthesia with isoflurane for major abdominal surgery: Recovery characteristics and postoperative oxygenation—an international multicentre study

Two hundred and ten adult patients undergoing open cholecystectomy, vagotomy or gastrectomy were included in a randomised multicentre study to compare postoperative nausea and vomiting, oxygen saturations for the first three postoperative nights, time to return of gastrointestinal function, mobilisation, and discharge from the hospital following induction and maintenance of anaesthesia with propofol and alfentanil or with thiopentone, nitrous oxide, isoflurane and alfentanil. Recovery from anaesthesia was significantly faster in the propofol group (mean (SD) times to eye opening and giving correct date of birth of 14.0 (SD 13.8) and 25.5 (SD 29.5) minutes, and 18.5 (SD 14.8) and 35.5 (SD 37.2) minutes in the propofol and isoflurane groups respectively). There was significantly less nausea in the propofol group (15.4%) than in the isoflurane group (33.7%) in the first two postoperative hours (p < 0.003) but not thereafter. There were no significant differences between the groups in any other recovery characteristics. The incidence of hypoxaemia (arterial oxygen saturation less than 93%) was close to 70% in both groups for the first three postoperative nights, indicating the need for oxygen therapy after major abdominal surgery.     

Isoflurane as an alternative to halothane for Caesarean section

Two series of 25 patients who underwent elective Caesarean section with general anaesthesia were given either 0.75% isoflurane or 0.5% halothane as supplements to 50% nitrous oxide in oxygen used for maintenance. The potent inhalational agent was given for the entire operative period and no case of intra-operative dreaming or awareness was reported. The infusion dose of suxamethonium was significantly less with isoflurane, 50 micrograms/kg/minute (SD 17), as compared to halothane, 64 micrograms/kg/minute (SD 24) (p less than 0.02). Recovery from anaesthesia was more rapid with isoflurane. The surgeon's assessment of uterine relaxation and bleeding using a visual analogue score indicated that this was significantly less with isoflurane. Infant well-being as judged by Apgar score and cord blood gas analysis, showed little difference between the two inhalational agents.     

Induction reflex actions with intravenous nalbuphine as an adjunct to isoflurane

Ninety unpremedicated patients undergoing mask anaesthesia were assigned to one of three groups according to the volatile anaesthetic and the acute intravenous premedication administered. Group I received saline placebo as premedication and halothane by inhalation. Group II received saline placebo and isoflurane by inhalation. Group III received nalbuphine 0.1 mg.kg-1 IV as premedication and isoflurance by inhalation. Mean time to loss of consciousness (71 sec) did not differ among groups. The dosage of thiopentone required to induce loss of consciousness was decreased by 15 per cent (from 3.9 to 3.3 mg.kg-1) by nalbuphine premedication (P less than 0.05), and time to induction of surgical anaesthesia using isoflurane was decreased by 15 per cent (P less than 0.05). The incidence of reflex actions (coughing, laryngospasm, breath holding, hiccoughs and movement) during induction was no different in the saline-premedicated halothane or isoflurane groups. Acute intravenous nalbuphine premedication decreased significantly the incidence of reflex actions during induction of isoflurane anaesthesia from 77 per cent to 37 per cent (P less than 0.02). Desaturation episodes (SaO2 less than 90 per cent) were more frequent with isoflurane inductions compared with halothane (55 per cent vs 17 per cent, P less than 0.01). Apnoeic episodes accounted for the majority of desaturations associated with nalbuphine premedication, while excitatory reflexes (coughing and laryngospasm) accounted for more desaturations with isoflurane alone.     

Clinical and economic choices in anaesthesia for day surgery: a prospective randomised controlled trial

We compared the cost-effectiveness of general anaesthetic agents in adult and paediatric day surgery populations. We randomly assigned 1063 adult and 322 paediatric elective patients to one of four (adult) or two (paediatric) anaesthesia groups. Total costs were calculated from individual patient resource use to 7 days post discharge. Incremental cost-effectiveness ratios were expressed as cost per episode of postoperative nausea and vomiting (PONV) avoided. In adults, variable secondary care costs were higher for propofol induction and propofol maintenance (propofol/propofol; p < 0.01) than other groups and lower in propofol induction and isoflurane maintenance (propofol/isoflurane; p < 0.01). In both studies, predischarge PONV was higher if sevoflurane/sevoflurane (p < 0.01) was used compared with use of propofol for induction. In both studies, there was no difference in postdischarge outcomes at Day 7. Sevoflurane/sevoflurane was more costly with higher PONV rates in both studies. In adults, the cost per extra episode of PONV avoided was pound 296 (propofol/propofol vs. propofol/ sevoflurane) and pound 333 (propofol/sevoflurane vs. propofol/isoflurane).     

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.     

Pressure support ventilation with the ProSeal laryngeal mask airway. A comparison of sevoflurane, isoflurane and propofol

BACKGROUND AND OBJECTIVE: There are no data about the influence of anaesthetics on cardiovascular variables during pressure support ventilation of the lungs through the laryngeal mask airway. We compared propofol, sevoflurane and isoflurane for maintenance of anaesthesia with the ProSeal laryngeal mask airway during pressure support ventilation. METHODS: Sixty healthy adults undergoing peripheral musculo-skeletal surgery were randomized for maintenance with sevoflurane end-tidal 2%, isoflurane end-tidal 1.1% or propofol 6 mg kg(-1) h(-1) in oxygen 33% and air. Pressure support ventilation comprised positive end-expiratory pressure set at 5 cmH2O, and pressure support set 5 cmH2O above positive end-expiratory pressure. Pressure support was initiated when inspiration produced a 2 cmH2O reduction in airway pressure. A blinded observer recorded cardiorespiratory variables (heart rate, mean blood pressure, oxygen saturation, airway occlusion pressure, respiratory rate, expired tidal volume, expired minute volume and end-tidal CO2), adverse events and emergence times. RESULTS: Respiratory rate and minute volume were 10-21% lower, and end-tidal CO2 6-11% higher with the propofol group compared with the sevoflurane or isoflurane groups, but otherwise cardiorespiratory variables were similar among groups. No adverse events occurred in any group. Emergence times were longer with the propofol group compared with the sevoflurane or isoflurane groups (10 vs. 7 vs. 7 min). CONCLUSION: Lung ventilation is less effective and emergence times are longer with propofol than sevoflurane or isoflurane for maintenance of anaesthesia during pressure support ventilation with the ProSeal laryngeal mask airway. However, these differences are small and of doubtful clinical importance.     

Reduced isoflurane consumption with bispectral index monitoring

BACKGROUND: Bispectral index (BIS) monitoring has been found to decrease the requirements for propofol, sevoflurane and desflurane and to improve recovery. We wanted to assess the effect of BIS monitoring on intraoperative isoflurane utilisation, and the early recovery profile. METHODS: Eighty patients undergoing various surgical procedures were studied. In the first phase of the study, patients were anaesthetised without the use of BIS, the anaesthetists being blinded to the BIS readings, and isoflurane being administered according to standard clinical practice (control group). In a second phase, isoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60-70 during 15 min prior to the end of surgery (BIS group). Isoflurane consumption was measured. Recovery times and the time to achieve a modified Aldrete score of 9 were recorded. RESULTS: Despite similar mean BIS levels during maintenance of anaesthesia, the cumulative time spent with BIS values between 40 and 60 during maintenance of anaesthesia was significantly longer in the BIS group as compared with the control group (P<0.001). The isoflurane usage in the BIS group was 12-25% lower than in the control group (P<0.05). The time to awakening and extubation were comparable in the two groups. Although the patients were less sedated (P<0.01) during the three postoperative hours in the BIS (vs. control) group, no significant differences were observed in the time to obtain an Aldrete score of 9. CONCLUSION: The addition of BIS to standard monitoring decreases isoflurane consumption. However, we found only a small advantage in using BIS with respect to recovery from isoflurane anaesthesia.     

Effect of halothane,enflurane and isoflurane on the end-systolic pressure-length relationship

Myocardial contractility was measured using the end-systolic pressure-length (ESPL) relationship in dogs subjected to increasing concentrations of halothane (0.5-2 per cent), enflurane (0.77-2.6 per cent) or isoflurane (0.70-2.13 per cent), combined with an infusion 7 micrograms X kg-1 X min-1 of fentanyl, after induction of anaesthesia with 15 mg X kg-1 thiopentone. The relationship between the concentrations of the different drugs and contractility (ESPL) can best be described by ESPL = a + b/(MAC fraction) where "a" is a constant and "b" is the slope of the curve relating ESPL to MAC. At 1.0 MAC values, the ESPL for halothane (69.04 +/- 25.83 mmHg X mm-1) did not differ from that of isoflurane (63.19 +/- 17.36 mmHg X mm-1). However, the myocardial contractility during 1.0 MAC halothane and isoflurane anaesthesia was better preserved than that of enflurane (38.66 +/- 9.73 mmHg X mm-1: p less than 0.01, p less than 0.05 respectively).     

The cardiorespiratory effects of ICI 35 868 in patients with valvular heart disease

The haemodynamic effects at induction of anaesthesia with ICI 35 868 (1.5 mg/kg) are reported in ten patients with severe aortic or mitral valve disease. The average decrease of mean arterial pressure was 19.1% (p less than 0.01), heart rate decreased by 10% (p less than 0.01). Cardiac index and stroke volume index were both little changed but there were significant reductions in rate pressure product and left ventricular stroke work index (p less than 0.01).     

Endocrine reaction pattern in abdominal surgical patients as affected by isoflurane anesthesia

The effects of isoflurane anaesthesia on the per- and postoperative change in blood concentrations of aldosterone, cortisol, dehydroepiandrosterone, insulin, prolactin, thyroxine, t3-uptake, epinephrine, norepinephrine, dopamine, glucose, FFS, lactate, and pyruvate were investigated in connection with major abdominal surgery. Contrary to prolactin levels (8.42 +/- 1.71 ng/ml----46.25 +/- 6.78 ng/ml; p less than 0.001) the plasma concentrations of the adrenal steroids aldosterone, cortisol, and dehydroepiandrosterone sank initially after induction of anaesthesia with thiopentone. However, after skin incision the levels of aldosterone (49.9 +/- 11.6 pg/ml----202.1 +/- 57.6 pg/ml; p less than 0.01), cortisol (16.7 +/- 2.57 ng/dl----25.2 +/- 3.72 ng/dl; p less than 0.01) and DHEA (2.70 +/- 0.99 ng/ml----5.02 +/- 1.03 ng/ml; p less than 0.05) rose significantly. Generally, plasma insulin was not markedly influenced by isoflurane anaesthesia and surgery. No significant alterations in plasma catecholamine concentrations were observed.     

A comparison of total intravenous with balanced anaesthesia for middle ear surgery: effects on postoperative nausea and vomiting,pain, and conditions of surgery

We compared postoperative nausea and vomiting (PONV), pain and conditions for surgery in patients scheduled for middle ear surgery. In a double-blind study, 100 patients were randomly allocated to receive either balanced anaesthesia (group A) using fentanyl, propofol and isoflurane, or total intravenous anaesthesia (group B) using propofol and remifentanil infusions. Pain scores, nausea/vomiting scores, conditions for surgery and analgesic requirements were recorded for 18 h post operatively. In the recovery ward, patients in group B suffered significantly less PONV (p = 0.026) with a reduced requirement for anti-emetic medication (p = 0.023); however, this difference was not maintained on the ward. The overall incidence of PONV was 34% and 17% in groups A and B, respectively. Initial pain scores were higher in group B in the recovery ward (p = 0.003) and patients required more morphine administration (p = 0.002); however, pain scores were similar on the ward. Conditions for surgery were found to be better in group B.     

Comparison of effects of fentanyl and alfentanil on intra-ocular pressure

The effects of fentanyl and alfentanil on intra-ocular pressure during anaesthesia were investigated in 50 consecutive patients in a double-blind controlled trial. Both drugs produced a significant reduction in intraocular pressure (p less than 0.01). Alfentanil produced significantly greater reduction (48.5 percent) than fentanyl (28.6 percent) (p less than 0.01). A small but statistically significant reduction in arterial pressure (15 percent approximately) and heart rate (18 percent approximately), were observed with both agents, but no significant differences between them were noted. It is suggested that alfentanil may be a suitable alternative to fentanyl in ophthalmic anaesthesia.