Vomiting, retching, headache and restlessness after halothane-, isoflurane- and enflurane-based anaesthesia. An analysis of pooled data following ear, nose, throat and eye surgery.

BACKGROUND: Isoflurane has exceeded halothane and enflurane in usage. A literature search, however, revealed no data comparing the effects on emesis, headache and restlessness of these three agents. METHODS: With hospital ethics committee approval and patient consent, a prospective, randomised, double-blind study of 556 patients undergoing ENT and eye surgery was undertaken to evaluate the effects of halothane, isoflurane and enflurane on vomiting, retching, headache and restlessness until 24 h after anaesthesia. Balanced general anaesthesia was administered comprising benzodiazepine premedication, induction with thiopentone-atracurium-morphine (ENT patients) or fentanyl (eye patients), controlled ventilation and maintenance with either halothane 0.4-0.6 vol% (n = 186), isoflurane 0.6-0.8 vol% (n = 184) or enflurane 0.8-1 vol% (n = 186) in nitrous oxide 67% and oxygen. RESULTS: The three study groups were comparable, and comprised comparable subgroups having ear, nose, throat, intraocular and non-intraocular surgery. During early recovery from anaesthesia, the respective requirements for halothane, isoflurane and enflurane for analgesia (7%, 9% and 10%), frequency of emesis (6%, 8% and 8%), antiemetic requirements (1%, 1% and 2%), restlessness-pain scores and time spent in the recovery ward (27 SD 10, 31 SD 12 and 26 SD 9 min) were similar. During the ensuing 24-h postoperative period, patients who had isoflurane experienced emesis less often than those who had halothane (36% vs 46%, P < 0.025) but did so with similar frequency to those who had enflurane (46% vs 41%). Antiemetic requirements were least in those given isoflurane (isoflurane 12%, halothane and enflurane 23% each, P < 0.005), but headache and analgesic requirements were similar. CONCLUSION: Isoflurane induces less postoperative emesis than halothane, but headache is similarly frequent after anaesthesia with any of these agents.

Electroconvulsive therapy and intraocular pressure.

Psychiatric patients receiving phenothiazine, tricyclic antidepressant and antiparkinsonian drugs for prolonged periods, occasionally develop mydriasis and angle closure glaucoma. Suxamethonium, usually given to modify the convulsion of electroconvulsive therapy (ECT) increases intraocular pressure (IOP) by about 7-8 mmHg, the increase being maximal and having returned to baseline 2 min and 6 mins after injection, respectively. We studied the effects on IOP of an electrically induced convulsion following induction of anesthesia using methohexitone 1 mg.kg(-1) and suxamethonium 0.5 mg.kg(-1) in 21 consecutive cooperative psychiatric patients, all receiving antipsychotropic drugs. IOP was recorded sequentially from before induction of anesthesia to after resumption of spontaneous respiration. Their mean IOP was 15.3 (SD 3.7) mmHg prior to induction of anesthesia, 13.5 (SD 3.5) mmHg after loss of eyelash reflex following injection of methohexitone, 16.1 (SD 2.4) mmHg after cessation of muscle fasciculations induced by suxamethonium, 19.2 (SD 5.6) mmHg after cessation of convulsion and 15.5 (SD 4.4) mmHg following resumption of regular spontaneous respiration. The successive stepwise changes in the mean IOP were all statistically significant (p < 0.001 each change compared with the preceding pressure; paired 't' tests). These data reveal that the reduction in IOP produced by methohexitone is reversed by the increase in IOP produced by suxamethonium. Collated with the time course of the effects of barbiturates and suxamethomium on IOP, the increase in IOP observed following the induced convulsion was not greater than that expected after suxamethonium alone, suggesting that the induced convulsion during ECT does not pose an ocular hazard to psychiatric patients receiving medications which have iatrogenic glaucomatous potential.

Attenuation of the haemodynamic responses to noxious stimuli in patients undergoing cataract surgery. A comparison of magnesium sulphate, esmolol, lignocaine, nitroglycerine and placebo given i.v. with induction of anaesthesia.

A study was conducted on 100 middle-aged to elderly patients (n = 52, healthy; n = 48, suffering from either diabetes, hypertension, ischaemic heart disease or a combination of these diseases) undergoing cataract extraction to assess the effects of laryngoscopy and tracheal intubation, anaesthesia and surgery, eye bandaging and tracheal extubation, saline (control), magnesium sulphate 40 mg kg-1, esmolol 4.0 mg kg-1, lignocaine 1.5 mg kg-1 and glyceryl trinitrate 7.5 micrograms kg-1 given i.v. at induction of anaesthesia on heart rate (HR), blood pressure (BP), rate-pressure product (RPP) and pressure-rate quotient (PRQ). Anaesthesia was standardized. Haemodynamic responses and requirements for atropine, ephedrine and labetalol to maintain HR and BP during surgery were similar in healthy and diseased patients, and in the test drug groups. Differences produced by the test drugs were evident until 5 min following intubation. Esmolol prevented rises in HR and RPP. Glyceryl trinitrate prevented a rise in BP, but was associated with tachycardia and a fall in PRQ to < 1.0. Magnesium sulphate and lignocaine did not prevent responses to laryngoscopy and tracheal intubation, and were associated with rises in RPP. Application of the eye dressing and tracheal extubation at the end of surgery each caused significant increases in HR, BP and RPP in all groups.

Comparison of total intravenous, balanced inhalational and combined intravenous-inhalational anaesthesia for tympanoplasty, septorhinoplasty and adenotonsillectomy.

Two hundred and thirty-five consecutive Saudi patients aged between two and fifty-three years undergoing elective tympanoplasty (n = 32), septorhinoplasty (n = 68) or adenotonsillectomy (n = 135) were studied. They were randomized to receive either a total intravenous anaesthetic (10 ears, 23 noses, 44 throats) consisting of propofol for induction of anaesthesia followed by a propofol infusion, a combined intravenous-inhalational anaesthetic (11 ears, 22 noses, 46 throats) consisting of the above with isoflurane in oxygen-enriched air, or a balanced inhalational anaesthetic (11 ears, 23 noses, 45 throats) consisting of thiopentone for induction of anaesthesia and oxygen in nitrous oxide with isoflurane for maintenance. During tympanoplasty, all three anaesthetic techniques produced stable heart rates and arterial pressures. During septorhinoplasty, blood pressure rose in patients who received total intravenous anaesthesia, while combined and balanced techniques produced haemodynamic stability. During adenotonsillectomy, total intravenous anaesthesia produced a rise in both heart rate and blood pressure, the combined technique produced a rise in heart rate alone while balanced anaesthesia produced haemodynamic stability. Postoperatively, vomiting, pain scores and analgesic requirements were similar following all three types of anaesthetic within each surgical site subgroup. Our findings support the choice of balanced inhalational anaesthesia for all three types of ENT surgery and, where cost and facilities permit, total intravenous anaesthesia for tympanoplasty and combined intravenous-inhalational anaesthesia for septorhinoplasty.

Spontaneous respiration versus controlled ventilation anaesthesia with halothane for intra-ocular surgery.

One hundred and thirty-seven patients were randomly allocated to receive halothane anaesthesia for intra-ocular surgery either by IPPV (n = 71) or breathing spontaneously (n = 66). Both techniques provided satisfactory operating conditions in 87% and 80% of procedures, respectively. Intra-ocular pressure was reduced in a similar majority of patients, rose in a similar percentage (spontaneous = 11%, controlled = 21%) and remained unchanged in a few. Surgeons' reports of good operative conditions correlated very well with intra-ocular pressure changes whether they rose or fell intra-operatively. The duration of anaesthesia and the time taken to achieve full recovery following the two techniques were similar. Post-operative vomiting, headache, sore throat and confusion occurred with similar frequency, and analgesic and antiemetic requirements were not influenced by the technique. Resumption of ambulation, oral intake and micturation occurred similarly. In both groups, patients with a low normal pre-operative intra-ocular pressure tended to show a rise in intra-ocular pressure during anaesthesia, and those with a high normal pre-operative intra-ocular pressure tended to show a fall.

Clinical comparison of spontaneous respiration versus controlled ventilation general anaesthesia using isoflurane for intraocular surgery: intraoperative, recovery and postoperative effects.

A prospective randomized study was undertaken on elderly patients undergoing intraocular, predominantly cataract, surgery to compare the intraoperative, recovery and postoperative features associated with general anaesthesia employing either the spontaneous (SV) or controlled ventilation (IPPV) techniques of respiration using isoflurane, nitrous oxide and a constant FiO2 of 0.33. SV patients received isoflurane 0.97% (mean). IPPV patients were intubated with atracurium alone, and received isoflurane 0.60% (mean). Heart rates were lower intraoperatively with IPPV, and blood pressures were lower with SV. Intraocular pressure measurement identified three subgroups of patients within each respiratory group: a large subgroup (70% of SV, 64% of IPPV patients) with a high-normal initial mean intraocular pressure which fell intraoperatively; a small subgroup (25% of SV, 24% of IPPV patients) with a low normal initial mean intraocular pressure which rose intraoperatively; and a small subgroup (5% of SV and 11% of IPPV patients) in whom the intraocular pressure remained unchanged. A satisfactory operative field was reported by surgeons in 87% of SV and in 86% of IPPV patients. SV patients had a lower mean end-operative SaO2 than IPPV patients (SV 95.0%; IPPV 96.7%), and were extubated sooner at the end of anaesthesia. In the recovery ward the times to awakening, vomiting incidences, analgesic usages and recovery times were similar, and patients were similarly restful. Postoperatively, the incidences of vomiting, headache, fever, sore throat and myalgia were similar, but SV patients required more analgesia for headache. We conclude that both technique properly performed are similarly satisfactory for cataract surgery in elderly patients.

Analgesics and ENT surgery. A clinical comparison of the intraoperative, recovery and postoperative effects of buprenorphine, diclofenac, fentanyl, morphine, nalbuphine, pethidine and placebo given intravenously with induction of anaesthesia.

1. Vomiting and restlessness following ENT and eye surgery are undesirable, and may be related to the emetic and analgesic effects of any analgesic given to augment anaesthesia during surgery. 2. To rationalise the choice of analgesic for routine ENT surgery we examined the intraoperative, recovery and postoperative effects following the administration of either buprenorphine (3.0 to 4.5 micrograms kg-1), diclofenac (1 mg kg-1), fentanyl (1.5 to 2.0 micrograms kg-1), morphine (0.1 to 0.15 mg kg-1), nalbuphine (0.1 to 0.15 mg kg-1), pethidine (1.0 to 1.5 mg kg-1) or saline (as control) given with the induction of anaesthesia in 374 patients. A standardised anaesthetic technique with controlled ventilation using 0.6-0.8% isoflurane in nitrous oxide and oxygen was employed. The study population constituted 7 similar groups of patients. 3. Intraoperatively, their effects on heart rate and blood pressure, airway pressure and intraocular pressure, were similar. This implies, most surprisingly, that neither their analgesic nor their histamine releasing effects were clinically evident during surgery. By prolonging the time to extubation at the end of anaesthesia, only buprenorphine, fentanyl, morphine and pethidine provided evidence of intraoperative respiratory depression. 4. Postoperatively, buprenorphine was associated with severe respiratory depression, prolonged somnolence, profound analgesia and the highest emesis rate. Diclofenac exhibited no sedative, analgesic, analgesic sparing, emetic or antipyretic effects. Fentanyl provided no sedative or analgesic effects, but was mildly emetic. Morphine provided poor sedation and analgesia, delayed the requirement for re-medication and was highly emetic. Nalbuphine and pethidine produced sedation with analgesia during recovery, a prolonged time to re-medication and a mild emetic effect. None provided evidence, from analysis of postoperative re-medication times and analgesic consumption, of any pre-emptive analgesic effect. 5. We conclude that nalbuphine (mean dose 0.13 mg kg-1) and pethidine (mean dose 1.35 mg kg-1), given individually as a single i.v. bolus during induction of anaesthesia, are the most efficacious analgesics for routine in-patient ENT surgery.

Effects of heart rate, blood pressure and bronchomotor tone of halothane, enflurane and isoflurane in young fit patients.

A prospective study was undertaken on 169 healthy young patients undergoing elective ear, nose and throat surgery to assess the intraoperative effects on heart rate, blood pressure and bronchomotor tone of MAC in nitrous oxide concentrations of halothane (0.4 to 0.6%), isoflurane (0.6 to 0.8%) and enflurane (0.8 to 1%). All the agents produced a progressive slowing of the heart rate during anesthesia. Halothane did so most profoundly, resulting in a maximum slowing of 40 beats-1 compared with a maximum slowing of about 20 beats min-1 with both isoflurane and enflurane. The three volatile agents also produced progressively similar degrees of hypotension during anesthesia. The hypotension produced by enflurane occurred earliest and was most profound; that produced by isoflurane occurred less early and was less severe, but occurred earlier and was more severe than that produced by halothane. Neither halothane, isoflurane nor enflurane appeared to have any effect on bronchomotor tone.