Meningitis after obstetric spinal anaesthesia.

A case of meningitis after obstetric spinal anaesthesia is reported. The possible aetiological causes of postspinal meningitis are discussed and the difficulty in differentiation between aseptic and bacterial meningitis noted. Ways to reduce the risk of bacterial contamination of cerebrospinal fluid are mentioned. The patient in this case made a full recovery, but the use of spinal anaesthesia in these patients is open to question.

Effects of atracurium and vecuronium on the latency and the duration of the negative deflection of the evoked compound action potential of the adductor pollicis.

The effect of atracurium or vecuronium on the depolarization phase of the evoked compound action potential of the adductor pollicis has been investigated in 30 adult patients. Patients were studied using single supramaximal stimulation of the ulnar nerve at the wrist. The evoked compound action potential was measured over the adductor pollicis muscle. When blockade by atracurium exceeded 80%, a significant decrease in latency was recorded (P less than 0.05). There was no significant change in latency after vecuronium. During the onset of blockade, depression of the amplitude of the evoked compound action potential was associated with a prolongation of its duration (P less than 0.05). The mean maximum increase in the negative deflection time was found to be similar after atracurium and after vecuronium. However, this phase was prolonged to a greater extent for a given degree of amplitude depression during the onset of blockade by atracurium (P less than 0.05).

Changes in the power spectrum of the evoked compound action potential of the adductor pollicis with the onset of neuromuscular blockade.

The effects of neuromuscular blockade by atracurium and vecuronium on the power spectrum of the evoked compound action potential (ECAP) of the adductor pollicis were investigated in 30 adult patients undergoing elective surgery. The changes in amplitude and mean power frequency (MPF) of the ECAP were measured. Ten patients received an ED95 (0.23 mg kg-1) of atracurium and 10 received an ED95 (0.055 mg kg-1) of vecuronium. The remaining 10 patients did not receive any neuromuscular blocking drug, and were monitored for 6 min to exclude any time-related changes in the ECAP. Neuromuscular blockade produced a decrease in total power and a shift towards lower frequencies. This was reflected in a decrease in the MPF in those patients receiving atracurium or vecuronium. There was no significant difference (P less than 0.05) between the atracurium and vecuronium groups in the magnitude of the change in MPF. These findings suggest that the previously reported increase in the duration of the negative deflection of the ECAP is predominantly the result of a change in its frequency components.

Atracurium and vecuronium: effect of dose on the time of onset.

The time intervals measured from the administration of either atracurium or vecuronium to maximum or 95% neuromuscular blockade (Tmax) were compared in 70 patients using the evoked compound action potential of the adductor pollicis muscle. Equipotent doses, calculated from the relationship between dose and response for both drugs obtained in an earlier study, were compared. The doses of atracurium and vecuronium ranged from 0.135 to 0.5 mg kg-1 and from 0.02 to 0.1 mg kg-1, respectively. The dose range for both drugs included the ED50, ED95 and the dose required to produce 100% blockade (ED"100"). No significant changes in mean Tmax occurred for doses of atracurium in the range 0.135-0.2 mg kg-1 and in the range 0.24-0.5 mg kg-1. Similarly, no change in Tmax occurred at doses of vecuronium in the range 0.02-0.05 mg kg-1 and 0.06-0.1 mg kg-1. Tmax changed significantly in the dose ranges atracurium 0.2-0.24 mg kg-1 and vecuronium 0.05-0.06 mg kg-1. There was no significant difference in Tmax when equipotent doses of atracurium and vecuronium were compared.

Neuromuscular block: atracurium and vecuronium compared and combined.

The neuromuscular blocking action of atracurium and vecuronium acting separately and in combination have been compared using the evoked EMG of the adductor pollicis muscle. Dose response curves have been drawn for the drugs given separately and found to be nonparallel (P less than 0.05). Atracurium was calculated to be 5.25 and 4.1 times less potent than vecuronium, ED50 and ED95 respectively. The effect on neuromuscular transmission of a combined medication using equipotent doses of atracurium and vecuronium, determined from the dose response plots, was found to be greater than would be expected by addition of their separate actions. The combination of small doses resulted in significant neuromuscular blockade.

Interactions of morphine and methotrimeprazine in mouse and man with respect to analgesia, respiration and sedation.

Interactions between morphine and methotrimeprazine have been studied in mice and man with respect to analgesia or antinociceptive activity, respiratory effects and sedation. The volunteer study was a double-blind cross-over trial with 10 volunteers. In mice, methotrimeprazine only possessed antinociceptive activity in doses which caused marked sedation. However, small non-sedative doses of methotrimeprazine potentiated the analgesic action of morphine. The volunteer study did not confirm this finding in man. Methotrimeprazine 7.5 mg i.m. caused significant sedation, but did not alter the effects of morphine 5 mg on pain threshold or ventilatory response to carbon dioxide.

Once daily treatment of mild to moderate hypertension with xipamid: a controlled study.

A double-blind, placebo controlled, crossover trial of 20 and 40 mg of xipamid once daily in the treatment of mild to moderate hypertension is reported and some of the difficulties and pitfalls of multicentre trials of this type are described. 2 Both doses were significantly more effective in reducing the blood pressure than the placebo and neither was superior to the other. Both produced some potassium loss. Xipamid acted for at least 22 h and was effective in up to 83% of the patients. 3 Further trials are suggested to investigate the activity of a lower dose than 20 mg.