Anaesthetic management of aortic coarctation in pregnancy.

We report two cases of aortic coarctation in pregnancy. The first was a 20-year-old nulliparous woman who underwent an aortic coarctation repair when she was 23 weeks old and subsequently developed an aneurysm at the site of initial repair. The second was a 20-year-old nulliparous woman with a severe uncorrected congenital aortic coarctation and upper body hypertension, who became pregnant whilst awaiting transcatheter dilatation of the coarctation. Antenatal care involved a multidisciplinary approach with obstetric, anaesthetic and cardiology input. Both parturients were delivered by elective caesarean section. A cautious, incremental regional anaesthetic technique was used, with no associated maternal or neonatal morbidity. Perioperative management focused on minimising haemodynamic disturbances. The management is discussed, together with the potential maternal and fetal complications of aortic coarctation in pregnancy.

Propofol target-controlled infusions for sedation--a safe technique for the non-anaesthetist?

OBJECTIVE: As an alternative to general anaesthesia for dentistry.attention has been focused on other, apparently safer, methods of pain and anxiety control. We have undertaken a study to evaluate the safety and efficacy of intravenous sedation using propofol target-controlled infusions. DESIGN: We describe a retrospective observational analysis of propofol conscious sedation as an adjunct to local anaesthesia for patients undergoing simple or surgical exodontia. All the patients were assessed,selected and treated according to standardized hospital sedation protocols. Experienced anaesthetists used a standard regimen, with ECG, pulse oximetry and non-invasive blood pressure monitoring. A standard sedation record was completed for each patient. The initial target plasma propofol concentration was set at 1.5 microg ml(-1), adjusted thereafter to achieve the desired level of sedation. Any adverse events were recorded. SETTING: Birmingham Dental Hospital. SUBJECTS: Three hundred consecutive sedation episodes in adult dental phobic patients requiring exodontia under local anaesthesia. RESULTS: Sedation and treatment were satisfactorily completed in 297 patients. The mean target propofol concentration required was 2.1 microg ml(-1), (SD = 0.47 microg ml(-1), range 1 - 4 microg ml(-1)). General anaesthesia occurred in two cases (target concentration (TC) 2 microg ml(-1)), over sedation in 11 cases(TC 1 - 3 microg ml(-1)), and transient hypoxaemia in 7 cases (TC 1.8 - 2.5 microg ml(-1)). CONCLUSION: Intravenous sedation with target-controlled propofol infusions is effective. However, significant adverse effects may occur at target concentrations below 2.1 microg ml(-1). Only anaesthetists working in an appropriate environment should practise this technique.

Cardiac arrhythmias in children during outpatient general anaesthesia for dentistry: a prospective randomised trial.

BACKGROUND: Deaths in children associated with outpatient general dental anaesthesia may be attributable to sudden cardiovascular collapse precipitated by ventricular arrhythmias. A causal link between halothane anaesthesia, ventricular arrhythmias, and deaths has been suggested. We did a prospective, randomised trial to investigate the frequency and character of arrhythmias during anaesthesia with halothane and the alternative anaesthetic agent, sevoflurane. METHODS: 150 children, aged 3-15 years, who needed dental extraction under general anaesthesia were randomly assigned sevoflurane or halothane supplementation of 66% nitrous oxide in oxygen with spontaneous ventilation. The halothane group (n=50) received halothane introduced in 0.75% increments, every two to three breaths, to a maximum of 3.0%, with maintenance at 1.5%. The incremental sevoflurane group (n=50) received sevoflurane introduced in 2% increments increased to a maximum of 8%, with maintenance at 4%. The 8% sevoflurane group (n=50) received sevoflurane introduced at 8%, with maintenance at 4%. FINDINGS: 24 (48%) children receiving halothane had arrhythmias compared with four (8%) receiving incremental sevoflurane (difference 40% [95% Ci for differences 24-56] p<0.0001), and eight (16%) receiving 8% sevoflurane (difference 32% [15-50] p=0.0013). Halothane-associated arrhythmias occurred during dental extraction or emergence and were mainly ventricular. Six (12%) children in the halothane group had ventricular tachycardia. The methods of sevoflurane administration did not differ significantly for the frequency of arrhythmias (p=0.357). Sevoflurane-associated arrhythmias were mainly single supraventricular ectopic beats. INTERPRETATION: There was a strong association between halothane and ventricular arrhythmias, especially ventricular tachycardia. The use of sevoflurane in preference to halothane could contribute to a decline in morbidity and mortality associated with dental anaesthesia.

A comparison of eltanolone and propofol anaesthesia for minor gynaecological surgery.

We have used eltanolone and propofol to induce anaesthesia and by intermittent injection to supplement nitrous oxide during maintenance in 67 patients undergoing minor gynaecological surgery. This study was a controlled randomized phase III with two parallel groups and a blinded assessment of post-operative recovery. Complications during induction and maintenance were few. Urticaria occurred in two patients given eltanolone and in none of those given propofol. Time to orientation and time to eye opening were significantly shorter in the propofol group (P < 0.001). Systolic and diastolic blood pressure decreased in both groups but the decrease was significantly greater in the propofol group (P < 0.005 systolic blood pressure; P < 0.001 diastolic blood pressure). Heart rate decreased significantly in the propofol group (P < 0.002). We conclude that eltanolone anaesthesia is associated with a greater haemodynamic stability than propofol anaesthesia but that early recovery occurs more slowly.

Comparison of induction and recovery between sevoflurane and halothane supplementation of anaesthesia in children undergoing outpatient dental extractions.

We have compared sevoflurane and halothane in a double-blind controlled study for supplementation of nitrous oxide and oxygen anaesthesia in 80 children undergoing dental extraction as outpatients. Induction of anaesthesia was more rapid in those who received sevoflurane compared with those who received halothane (89 s compared with 127 s for loss of eyelash reflex). In both groups, mean duration of administration of anaesthesia was less than 4 min. Those who received sevoflurane were slower to awaken (167 s compared with 102 s), although discharge times from hospital were similar. The incidence of complications during induction and maintenance was low in both groups and return to normal appetite and activity occurred in the majority of children on the same day. More children who received halothane suffered nausea after leaving hospital. We conclude that sevoflurane is a suitable alternative to halothane, with more rapid induction of anaesthesia, but in these short procedures, awakening time was slower than after halothane.

Nausea and vomiting after gynaecological laparoscopy: comparison of premedication with oral ondansetron, metoclopramide and placebo.

We have compared the incidence of postoperative nausea and vomiting up to 48 h after day-case gynaecological laparoscopy after oral premedication with ondansetron 4 mg, metoclopramide 10 mg or a placebo allocated randomly and assessed blindly. Emetic symptoms (nausea or vomiting) occurred in 26% of patients who received ondansetron, 42% of those who received metoclopramide and 50% of those given placebo.

Medical emergencies in dental practice: an update on drugs and the management of acute airway obstruction.

In response to interest from readers the authors provide an update of their 1986 papers on coping with medical emergencies in dental practice. In particular they review drug regimes and the technique of cricothyroidostomy.

The validity of informed consent in a clinical study.

Patients, aged 36 to 78 years, who had participated in two studies that included the ventilatory effects of postoperative analgesia, returned a questionnaire canvassing their views of the procedure for obtaining consent and the conduct of the study. Fourteen of 18 patients from one study, and all 18 from the second, returned their questionnaires. Thirty of the 32 patients were satisfied with the pre-operative explanation. Eleven patients felt obliged to take part, not because of coercion, but from a sense of duty to others. The breathing tests caused discomfort to eight patients but only one of them found this more than expected from the pre-operative explanation. Only two patients, both in the second study, said that they would not volunteer again for a similar study. There was no suggestion that the age of the patient or the fact that they were undergoing major surgery had any influence on their attitudes or comprehension. It may be prudent to use this type of questionnaire to evaluate the response of patients to some research projects.

Effect of rebreathing on psychomotor skills when wearing integral crash helmets.

Nine volunteer subjects underwent psychomotor testing when wearing an integral crash helmet in a variety of conditions which lead to rebreathing. There was a wide individual variation in the extent of rebreathing. In the worst conditions the minimum inspired carbon dioxide tension (PICO2) increased to 2.6 kPa. The psychomotor test was a tracking test based on a microcomputer. There was a significant deterioration in the ability to perform the test when the helmet was worn with the visor down and restricted airflow into the helmet (P = less than 0.05). In those tests when the minimum PICO2 exceeded 0.5 kPa the decrease in performance was more highly statistically significant (p = less than 0.005). Rebreathing wearing integral crash helmets results in a variable impairment in the subjects' ability to perform a tracking test. We recommend that the maximum level of CO2 retention inside integral crash helmets should not exceed 0.5 kPa minimum PICO2.

Ventilatory effects of pre- and postoperative diamorphine. A comparison of extradural with intramuscular administration.

Twenty-two patients were studied before and after major abdominal vascular surgery to determine the effect on ventilation of 5 mg diamorphine given either extradurally or intramuscularly. Diamorphine depressed ventilation maximally at 30 minutes when given by either route. Before operation resting ventilation was reduced by 33% after extradural and 17% after intramuscular diamorphine; PaCO2 increased by an average of 0.5 kPa (either route); ventilation at 7.3 kPa PaCO2 was reduced 40% after extradural and 33% after intramuscular diamorphine. After operation the effect of diamorphine on ventilation was qualitatively similar but resting baseline ventilation was increased from 9.4 to 10.9 litres/minute. The highest individual PaCO2 values were found during the pre-operative study: 6.5 kPa after extradural diamorphine, 6.4 kPa after intramuscular diamorphine. Pain relief was unsatisfactory after intramuscular diamorphine. Four out of six patients requested further analgesia by 3 hours after administration. No patient who received extradural diamorphine required further analgesia for at least 6 hours.

Rebreathing in a subject wearing an integral crash helmet.

The respired air of a volunteer was analysed while he was wearing a variety of integral crash helmets. Observations were made with and without a protective balaclava, bib or scarf, or both. Rebreathing occurred and the peak inspired oxygen tension fell as low as 16.0 kPa (120 mm Hg) with a minimum inspired carbon dioxide of 2.1 KPa (16.0 mm Hg). Accessories worn or attached to the helmet which restrict airflow into the helmet should not be used. Attention should be paid to the "air conditioning" of helmets when worn with flameproof balaclavas and bibs.

Pain relief in labour using epidural pethidine with adrenaline.

The degree of pain was assessed by use of a visual analogue scale in 20 patients in established labour before and after the epidural injection of pethidine 50 mg with adrenaline 1:200,000. Forty-two doses were administered and of these 83% gave good pain relief and only 5% had no effect at all. The duration of action was longest following the first dose decreasing with subsequent doses. No evidence of sympathetic or motor blockade was found and side-effects were minimal. In the postpartum period 17 of the mothers expressed full satisfaction with the technique.

Do they do as they are instructed? A review of out-patient anaesthesia.

Sixty patients who underwent out-patient anaesthesia were assessed by interview the day following surgery to determine the extent to which they remembered and complied with instructions given preoperatively concerning their post-anaesthetic activities such as, drinking, driving, cooking and operating machinery. The first group of thirty patients received verbal instructions only, except for a written instruction not to drive after anaesthesia. The following group of thirty patients received clear, concise printed instructions in addition to their pre-operative verbal instructions. There was a significant improvement between the two groups of patients in the ability to remember their instructions from a range of 77--99% failure rate to 4--12.5% depending on the sphere of activity. However, a certain proportion of patients deliberately ignored the instructions in both groups. It would appear from this study that verbal pre-operative instructions were easily forgotten unless re-inforced with written directives. Patients from ethnic minorities may need printed instructions in their native language and the services of an interpreter.

Pulmonary oedema after radiological investigation of peripheral occlusive vascular disease. Adverse reaction to contrast media.

5 patients developed pulmonary oedema after retrograde femoral arteriography under general anesthesia. Because of the haemodynamic changes associated with radiographic contrast media, a good preoperative cardiological assessment is essential. The volume and nature of the contrast media injected and any other fluid administered should be carefully monitored. There is no apparent safe maximum dose of radiographic contrast media, but this work suggests that for 'Conray 420' (sodium iothalamate 70% w/v) a total dose should be less than 200 ml in a fit patient. The dose should be substantially smaller in patients with a history of evidence of myocardial infarction, myocardial insufficiency, myocardial ischaemia, or hypertension.