J. W. Dundee

The effects of thiopentone and propofol on upper airway integrity

One hundred and fifty‐eight unpremedicated patients scheduled for elective surgery were allocated randomly to receive an unsupplemented induction dose of thiopentone or propofol. Visualisation of the vocal cords by standard laryngoscopy was possible more often after propofol (p < 0.01). Pharyngeal and laryngeal reactivity was similarity depressed more frequently.

Traditional Chinese acupuncture: a potentially useful antiemetic?

Two consecutive studies were undertaken to evaluate the effectiveness of acupuncture as an antiemetic used in addition to premedication with opioids in patients undergoing minor gynaecological operations. In the first study 25 of the 50 patients underwent acupuncture immediately after premedication with 100 mg meptazinol, the rest receiving the drug alone, and in the second 75 patients were allocated randomly to one of three groups: a group receiving 10 mg nalbuphine and acupuncture, a group receiving premedication and dummy acupuncture, and a group receiving premedication alone. Manual needling for five minutes at the P6 acupuncture point (Neiguan) resulted in a significant reduction in perioperative nausea and vomiting in the 50 patients who underwent acupuncture compared with the 75 patients who received no acupuncture. These findings cannot be explained, but it is recommended that the use of acupuncture as an antiemetic should be explored further.

Acupuncture prophylaxis of cancer chemotherapy-induced sickness.

The symptoms of 86 patients referred to a district terminal care support team were rated throughout care using a standardized schedule. Pain was the most common main symptom at referral, occurring in 35 (41%) of the patients. The assessment scores for pain showed significant improvements after one week of care (P<0.01) and there was a further improvement into the week of death. However, towards death, 18 (21%) patients developed dyspnoea as their main symptom, and this became the most severe symptom at death. The symptom assessment scores for patients with dyspnoea showed no change over time, suggesting that existing methods to control dyspnoea are ineffective and that new interventions are needed.

The antiemetic action of propofol

Eighty patients who underwent minor gynaecological surgery were anaesthetised with either incremental propofol or incremental methohexitone after an opioid premedication. The group anaesthetised with propofol had significantly fewer emetic sequelae and the results suggest that propofol has a definite antiemetic action.

Comparison of induction characteristics of four intravenous anaesthetic agents

The induction characteristics of thiopentone, etomidate and methohexitone have been compared to those of propofol (2,6 di‐isopropyl phenol) in unpremedicated patients. Propofo1 2.5 mg/kg caused significantly more hypotension, excitatory side effects and pain on injection at the dorsum of hand than thiopentone 5 mg/kg. However, with regard to the latter two sequelae. etomidate 0.3 mg/kg and methohexitone 1.5 mg/kg caused similar or more frequent upset. Propofol 2.0 mg/kg was equipotent with thiopentone 4.0 mg/kg in terms of successful induction of anaesthesia. Hypotension may contraindicate the use of propofol in the hypovolaemic or unfit patient.

Sensitivity to propofol in the elderly

Two studies were carried out on 609 fit, unpremedicated patients to assess the influence of patient age on the response to the rapidly‐acting hindered phenol, propofol, which is being evaluated for induction of anaesthesia. In the first study, 1.25 mg/kg was injected over 20 seconds followed by 10‐mg increments every 15 seconds until loss of verbal contact. This showed a great individual variation in response to the drug. A reduction in the ‘induction’ dose was found in elderly patients, which became marked around 60 years. In the second (340), doses ranging from 1.5–3.0 mg/kg in patients under 60 years and 1.25–2.25 mg/kg in those over 60 years were injected as a bolus over 20 seconds. Doses of 2.25–2.5 mg/kg were required to induce anaesthesia in patients under 60 years, whilst 1.5–1.75 mg/kg was adequate in those over 60 years. Side effects were more marked with the rapid injection and doses in excess of 1.75 mg/kg caused significant hypotension and apnoea in the elderly. These studies reveal marked sensitivity to propofol in the elderly with respect to both induction dose and acute toxicity.

Anterograde amnesic effects of pethidine, hyoscine and diazepam in adults

1 The intravenous administration of 5 and 10 mg of diazepam caused anterograde amnesia in 50 and 90% of adults, the peak effect occurring in 2–3 min and action persisting for 20–30 minutes. 2 Hyoscine (0·4 and 0·6 mg) caused amnesia in 35 and 50% of patients with peak effect not occurring until 50–80 min after injection and action persisting for at least 120 minutes. 3 With neither drug was there any relationship between the incidence of amnesia and the degree of drowsiness. 4 Amnesia was not observed after saline or after 50 mg pethidine. 5 On questioning 6 h after a short operation many patients had no memory of an object which they clearly recognized and described 1 h after surgery.

Cimetidine and ranitidine increase midazolam bioavailability.

Cimetidine has been shown to inhibit the oxidative metabolism of a variety of low‐ and high‐extraction drugs. Despite the findings of initial investigators, there is evidence that ranitidine may exert similar effects. Eight healthy volunteer subjects took part in a within‐subject crossover study. They received midazolam, 15 mg, by mouth after pretreatment with cimetidine, ranitidine, or nothing and midazolam, 10 mg, intravenously on separate occasions. Mean absolute bioavailability of midazolam was increased by more than 30% after cimetidine (P < 0.01) and 26% after ranitidine (P < 0.05). The data, which agree with a concurrent clinical study indicating greater hypnotic action of midazolam after ranitidine, indicate that this is not a result of enhanced midazolam absorption and that reduced hepatic clearance is the most likely explanation.

Glycopyrrolate: pharmacology and clinical use

This is a review of glycopyrrolate whose function in clinical practice is compared with that of atropine.

Evaluation of midazolam as an intravenous induction agent

Midazolam, a new water‐soluble benzodiazepine, was investigated as an intravenous anaesthetic agent in 260 adult patients in doses ranging from 0.15 to 0.5 mg/kg using a variety of premedications. Its onset of action was generally slow, taking up to 3 minutes to exert its maximum effect. A wide variability in response was found in that some unpremedicated patients were satisfactorily anaesthetised with 0.15 mg/kg while others were only moderately sedated following doses of 0.5 mg/kg. Less variability was found in the elderly who also required smaller doses. Narcotic premedication potentiated the sedative effect of midazolam. Few respiratory or cardiovascular effects were noted apart from hiccough following the larger doses. The incidence of venous sequelae was much lower than that found following diazepam.