Midazolam in conservative dentistry. A cross-over trial

In a double-blind trial, 50 patients were randomly allocated to receive up to 0.29 mg/kg diazepam (Valium 5 mg/ml) or 0.14 mg/kg of midazolam (midazolam hydrochloride 5 mg/ml) intravenously at a first session of conservative dentistry, the alternative being administered at the second session. Good operating conditions were reported under each sedative and no important physiological differences were observed. Most patients failed to return to 'street fitness' 30 minutes after either session of treatment. Previous reports of reduced incidence of venous thrombophlebitis with midazolam were not convincingly confirmed in this trial, but data quality was poor. For about half the patients, the amnesic effect was stronger following midazolam.

Midazolam--does it cause resedation?

The objective of this double blind study was to compare the sedation following the intravenous injections of midazolam in three dose levels (0.07, 0.10 and 0.15 mg/kg), and to assess the time taken after each dose to return to street fitness. Recovery was monitored by measurement of reaction time. The mean results for each dose were compared against placebo and each other using the Student's t-test. All doses gave a significant (p less than 0.05) lengthening of reaction time compared to placebo. The two highest doses gave similar results when compared to 0.07 mg/kg, but not when compared to each other. Reaction times always returned to control values within 3 hours of injection. The Deletion of Ps test was also employed. A significant correlation was found between the results of reaction time testing and the Deletion of Ps test.

Evaluation of a new range of air drawover vaporizers. The 'PAC' series--laboratory and 'field' studies

The 'Ether Pac' and 'Fluo Pac' temperature compensated vaporizers have been evaluated in the laboratory and the 'field'. Rigorous testing has demonstrated that these vaporizers are robust and reliable. Shaking, tilting and overturning do not significantly affect their performance. Both vaporizers deliver lower concentrations of the vapour than the setting on the vaporizers at low tidal volumes (100 ml). The 'Ether Pac' vaporizer output declines progressively with ambient temperatures below 23 degrees C and a similar result occurs with the 'Fluo Pac' at temperatures below 20 degrees C. Clinical trials in Nepal, Kenya, Burma and the UK have demonstrated that, when halothane is used, oxygen enrichment is necessary during spontaneous and controlled ventilation. When ether is used with controlled ventilation oxygen enrichment is probably not necessary even with ambient pressures as low as 619 mmHg.

Total intravenous anaesthesia with etomidate-fentanyl. Use in general and gynaecological surgery

A total intravenous anaesthetic technique using etomidate, fentanyl and neuromuscular blocking drugs with artificial ventilation of the lungs has been used in 90 patients undergoing elective general and gynaecological surgery. A two-step schedule was used, based on a pharmacokinetic model for rapidly eliminated, intravenously administered drugs. Etomidate 100 micrograms/kg/minute with fentanyl 1 microgram/kg/minute were given for 10 minutes, followed by a maintenance dose at a rate of one-tenth this amount. Concurrent evaluation of the technique led to variations in the adjuvant drugs used (atropine, droperidol and neuromuscular blocking agent). The basic dose schedule provided adequate surgical anaesthesia for 76% of patients (although dose adjustments were used in the remainder), with recovery times of 10 minutes or less in 57% of patients. No further opiate analgesia was needed in 40% of patients postoperatively. Those patients given atropine intravenously prior to induction had a significantly lower incidence of nausea and vomiting postoperatively.

Immunological and non-immunological mechanisms involved in adverse reactions to drugs

This communication reviews the mechanisms involved in anaphylactic and anaphylactoid reactions to intravenous drugs used in anaesthesia. Although the mechanisms involved are pertinent to other drugs and substances used in clinical practice, the use of the intravenous route makes this a particularly worrying problem in anaesthetic practice. Despite the similarity of the clinical manifestations to those expected from immediate immunological hypersensitivity (anaphylaxis), relatively few reactions involve antibodies. Instead, a variety of mechanisms occur where activation of the blood inflammatory response systems, particularly complement, may be either primary or secondary to activation of the coagulation or fibrinolytic cascades of the blood clotting mechanisms. Immediate anaphylactoid reactions, manifest in the release of vasoactive substances such as histamine, may therefore pose very minor problems compared with coagulation problems arising in the peri- and post-operative period. It is important to discover the mechanism of all adverse reactions not only if these are to be avoided in the reactants in the future but also because of the necessity for devising suitable prophylactic and therapeutic measures for general use. The practical problems of such investigations are explored with particular reference to the laboratory investigation of subclinical reactions in terms of plasma histamine release and changes in blood leucocyte distribution.

Continuous thoracic epidural fentanyl. A comparison of epidural fentanyl with intramuscular papaveretum for postoperative pain

A prospective open trial was conducted to compare the analgesic and side-effects of continuously infused fentanyl into the thoracic epidural space with those of intramuscular papaveretum given 4 hourly as required. It was demonstrated that during the first 24 hours after upper abdominal surgery thoracic epidural fentanyl produced better analgesia with less sedation than intramuscular papaveretum. However, the epidural group suffered more nausea. Likewise, postoperative respiratory function tests were statistically significantly better in those patients who received epidural fentanyl. Despite a significantly greater volume of nasogastric aspirate during the period of study, the epidural fentanyl group also had a significantly greater urine output than did the patients receiving papaveretum. Hypotension and respiratory depression were not problems, but pruritus occurred in two patients given fentanyl. It is concluded that epidural fentanyl delivered by continuous infusion offers significant advantages over a conventional intramuscular narcotic regime.

Supernumerary senior house offices in anaesthesia: a review of a regional training scheme, 1962-1972

The Sheffield Regional Hospital Board, which became the Trent Regional Health Authority in 1974, initiated a scheme for training of Senior House Officers in anaesthesia in 1962; between 1962 and 1972, 73 graduates passed through the scheme of whom 29 (40%)* held consultant posts at the time of the review (mid 1979), another 8 (11%)* were senior registrars and on the way to consultant status. None of the 16 overseas graduates had achieved consultant status although one was a senior registrar. Twenty-six (35-6%)* of the 73 doctors (15(20-5%)* United Kingdom or Republic of Ireland graduates and 11 (15-1%)* from overseas) are thought to have left the practice of anaesthesia although some of these were not traced and may indeed be practising, and some of the females have indicated an intention to return to the specialty when their children are older.

Comparative studies of a new commercial kit for the estimation of vitamin B12 in serum

A commercial kit method (Technia Diagnostics) for the estimation of serum vitamin B12 claiming certain practical advantages was examined. Analytical and clinical performance were compared with a non-commercial radioisotope B12 method, previously compared to other commercial radioisotope B12 methods. The kit's analytical performance in our hands was satisfactory, although the within-batch precision and recovery of added cyanocobalamin were disappointing. Clinical performance was comparable with the non-commercial B12 method. Establishment of suitable reference ranges as a prerequisite to diagnostic use is apparent.

I.v. flunitrazepam and i.v. diazepam in conservative dentistry. A cross-over trial

In a randomized cross-over trial in 82 outpatients aged 15-45 yr undergoing conservative dentistry, a solution of flunitrazepam 0.25 mg ml-1 i.v. (average dose 0.014 mg kg-1) was compared with a solution of diazepam 5 mg ml-1 i.v. (0.29 mg kg-1). Cardiovascular changes, operating conditions and side-effects were similar. Forty minutes after the start of injection, about 85% of all patients could not remember the local anaesthetic injection. Thirty minutes after the end of treatment, only 25% of all patients had recovered. One week later, most patients receiving each drug had only vague memories of their treatment; they had felt more relaxed immediately after the i.v. injection than before. Drowsiness was equally common after flunitrazepam and diazepam. Ataxia was more prolonged with flunitrazepam but arm pain and venous thrombophlebitis were less frequent.

An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12

Five commercial kits for the determination of folate and six kits for the determination of vitamin B12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B12. The results show the importance of the determination of the reference range for an individual laboratory for each method. The precision of the kits varied appreciably, as did their performance using specimens from patients with different haematological disorders. In particular, certain kits failed to detect all patients with pernicious anaemia. The relative accuracy of the kits was assessed. Various factors which should be taken into account in the final selection of a satisfactory kit are discussed.