Anaesthesia
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We 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. ⋯ 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.
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We studied the effects of hypothermia and cardiopulmonary bypass (CPB) on four depth of anaesthesia monitors; spectral edge frequency (SEF), median frequency (MF), bispectral index (BIS) and auditory evoked potential index (AEPIndex) in 12 patients during uneventful cardiac anaesthesia. Each variable was recorded simultaneously at 10 periods during anaesthesia. All four variables were not affected by the transition to CPB. ⋯ The variability decreased during rewarming. The values of AEPIndex throughout the anaesthesia never overlapped with those before induction of anaesthesia. The AEPIndex was the most stable and reliable as a depth of anaesthesia monitor among the four variables in cardiac bypass surgery.
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We have performed a retrospective analysis of the peri-operative course of 218 consecutive patients who underwent routine coronary artery bypass graft surgery in this institution. All patients received a standardised general anaesthetic using target-controlled infusions of alfentanil and propofol. One hundred patients also received thoracic epidural anaesthesia with bupivacaine and clonidine, started before surgery and continued for 5 days after surgery. ⋯ There was also a trend towards a reduced incidence of respiratory complications in the thoracic epidural anaesthesia group. The time to tracheal extubation was decreased in the epidural group, with the tracheas of 21% of the patients being extubated immediately after surgery compared with 2% in the general anaesthesia group (p < 0.001). There were no serious neurological problems resulting from the use of thoracic epidural analgesia.
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Synthetic colloids have been implicated as a cause of coagulopathy when administered in large quantities. The effect of profound haemodilution (50%) on coagulation profile was measured in vitro by thromboelastography. Blood samples were taken from 11 ASA grade 1 patients prior to induction of anaesthesia for elective surgery. ⋯ There was also a significant decrease in clot formation rate and maximum amplitude in the hydroxyethyl starch 6% group. Clot formation time, clot formation rate and maximum amplitude did not change in the modified fluid gelatin 4% group. Profound haemodilution with dextran 40 10% exerted extreme effects on the measured variables, very often resulting in a straight line on the thromboelastography profile.