No abstract

SummaryWe sought to determine whether the forced air convection warmers (nine Bair Huggers, Augustine Medical, and one Warm Touch, Mallinkrodt Medical) used in our operating theatres could be a source of microbial pathogens. Agar plates were placed directly in the air stream of the warmers. Four of these grew potentially pathogenic organisms. When the warmers were set to blow through perforated blankets, no growth occurred. Three of the warmers were swabbed and sites of colonisation were found in their hoses. After fixing a microbial filter to the end of the hose, organisms were no longer detectable. We conclude that these warming devices are a potential source of nosocomial infection. They should only be used in conjunction with perforated blankets, should have their microbial filters changed regularly and their hoses sterilised. The inclusion of a microbial filter into the nozzle of the hose could be incorporated into the design of the warmer.

Lignocaine was administered to patients undergoing cardiopulmonary bypass at 28-29 degrees C in bolus doses of 1.5, 2.5 and 3.5 mg kg-1. Plasma concentrations greater than 1.5 micrograms ml-1 were found briefly and inconsistently in patients receiving the usually recommended dose (1.5 mg kg-1), but reliably for 14 min in those receiving 2.5 mg kg-1. The 3.5 mg kg-1 dose produced statistically and clinically significant decreases in mean arterial pressure. Examination of calculated kinetic parameters showed a two-fold decrease in T1/2 alpha, two-fold increases in T1/2 beta and Vss and unaltered ClP and VP when compared with those of unanaesthetized, normothermic patients. The alteration in pharmacokinetics may be attributed largely to decreased binding to albumin following haemodilution.

A self-tuning, closed-loop computerized system was used to maintain atracurium-induced neuromuscular blockade in patients undergoing routine lower abdominal gynaecological surgery. The controller is based on a unique algorithm which utilizes a bi-exponential model wherein two of the variables are estimated on-line. This enables the system to optimize the sizes of subsequent bolus doses according to patient sensitivity. In this study an initial bolus of 0.3 mg kg-1 was given in a trade-off aimed at achieving earlier intubating conditions rather than taking control of relaxation ab initio and obtaining the pre-programmed setpoint of 15% single twitch response (STR) without overshoot. This was successful in all of the 11 patients studied, the mean time from injecting the bolus to intubation being 2.47 (SD 0.95) min and the drug maintenance requirement being 0.34 (0.07) mg kg-1 h-1. This provided a mean value of 10.26% STR with minimal oscillation about the setpoint (average standard deviation = 4.31 (2.53)) for up to 147 min.

SHORT REPORTSReversible male subfertility due to hyperthyroidism Hyperthyroidism in women may cause oligomenorrhoea, amenorrhoea, and failure of ovulation. In men gonadal dysfunction is less apparent, though loss of libido, reduced potency,' and gynaecomastia2 may occur. We describe a man who presented with subfertility due to thyrotoxicosis and in whom normal fertility was restored with antithyroid drug treatment. Case reportA 26-year-old man with a one-year history of attempted conception was referred to a male subfertility clinic. Two previous semen analyses had disclosed oligospermia with sperm counts of 11 x 109/1 on both occasions (figure). He had had classical symptoms of thyrotoxicosis for five years and 18 months earlier had been investigated for palpitations.Examination showed a diffuse goitre, tremor, and tachycardia; vitiligo was present on the arms, trunk, and penis. There was no gynaecomastia and the testes were normal. Hyperthyroidism was confirmed biochemically: serum thyroxine concentration was 267 mmol/l (20-7 4g/100 ml) (normal range 70-160 mmol/l; 5-4-12-4 ,ug/10O ml) and free thyroxine index >500 (normal range 70-180). Basal serum luteinising hormone, follicle-stimulating hormone, and prolactin concentrations were normal. Serum testosterone