Factors that influence the induction dose of propofol.

Factors that influence the induction of anaesthesia with propofol were investigated in a prospective study of 1000 patients. Pre-operative albumin and urea concentrations correlated with the minimum induction dose of propofol, but less strong correlations were found with haemoglobin, globulin and total protein concentrations. Age was an important influence on the induction dose of propofol (r = -0.34) which was also closely related to ASA grade. Induction of anaesthesia with propofol is dependent on a number of variables, and this study suggests that pre-operative albumin and urea concentrations are important.

The Engström Elsa anaesthetic machine. An electronic system for anaesthesia.

Six Engström Elsa anaesthetic machines have been in regular use for 18-24 months. The machine incorporates a number of new concepts for anaesthetic delivery and monitoring. At flows below 1000 ml/minute, each machine delivered 20% more than the indicated value; at higher flows, the indicated value was within 10% of the flow delivered. Minute volume, tidal volumes and oxygen concentrations were within the manufacturer's specifications. However, vaporizer and vapour monitor performance was outside the (SD) 5% accuracy claimed by the manufacturers. It was noted that the bistable valve requires user familiarity for the change from controlled to spontaneous ventilation to be accomplished with ease. It was also possible to misconnect the breathing system and so isolate the excess pressure escape valve and high-pressure alarm. Nevertheless, once familiarisation was achieved, the machines have proved easy to operate and are particularly satisfactory when used with low fresh gas flows.

Pre-operative anxiety and serum potassium.

Small decreases in serum potassium in a study of 200 pre-operative patients were demonstrated in those who had an increase in anxiety, as measured on a linear analogue anxiety scale, in the 24 hours before anaesthesia. The possible aetiology and implications of this change are discussed. The combination of temazepam and a pre-operative visit by the anaesthetist effectively reduced pre-anaesthetic anxiety in 60% of patients.

Venous sequelae following i.v. administration of diclofenac.

Diclofenac sodium (Voltarol) was administered i.v. to 149 consecutive patients who were thought likely to benefit from its anti-inflammatory action. Patients were allocated randomly to one of two groups: group A received the undiluted i.m. preparation (25 mg ml-1) and group B the i.m. preparation diluted in normal saline (5 mg ml-1). Diclofenac 1 mg kg-1 administered over a 10-min period via a 23-gauge needle into a vein at either the antecubital fossa or the dorsum of the hand. No local or systemic problems were encountered in either group, at the time of injection. A high incidence of painless local venous thrombosis occurred in both hand and arm veins, 72 h after administration in group A (85% and 58%, respectively). The incidence of thrombosis was reduced markedly after administration of the diluted drug: 38% hand veins; 8% antecubital fossa veins.

Diclofenac sodium for post-tonsillectomy pain in children.

Diclofenac sodium was assessed as an analgesic for postoperative pain following paediatric tonsillectomy in a randomised double blind trial. In a comparison made with both a pethidine and a control group diclofenac was shown to be an effective analgesic. No significant difference in analgesic efficacy was demonstrated between the two drugs, although patients who received diclofenac tended to be less drowsy postoperatively than those who received pethidine. There were no significant differences between the two drugs in respect of time to awaken from anaesthesia or incidence of postoperative vomiting.