No abstract

Vortex pumping has become popular for mechanical assist applications, but has only recently received serious consideration for use as the arterial pump of choice for routine open-heart surgery. We report on a prospective randomized study designed to evaluate this pump in routine use. Sixteen patients undergoing routine coronary artery surgery were randomized into two groups in which the only difference in equipment and technique was the use of a Stockert roller pump in group S and a Biomedicus vortex pump in group B. The groups were compared with respect to haematology, perioperative fluid balance, transfusion requirements, complement activation, haemolysis and microbubble transmission. The groups were reasonably well matched, with slightly longer mean bypass and ischaemic times in group S (94.8 vs 105.5 minutes and 75.7 and 83.8 minutes respectively). Group B patients showed significant improvements over group S patients with respect to preservation of platelet numbers, decreased complement activation and reduced microbubble transmission. The afterload sensitivity of the vortex pump did not present the perfusionist with any practical problems although a different technique is required for initiating and terminating bypass. We conclude that vortex pumping would seem to offer better blood handling for routine use. More extensive testing is required to establish whether or not this would be reflected in clinically measurable improved patient outcome.

Forty-four patients undergoing coronary artery surgery were allocated randomly to receive an infusion of propofol or methohexitone as a hypnotic supplement to a fentanyl-based anaesthetic technique. A taped message was played to the patients, consisting of 10 words associated with prompt sentences and a suggestion for a specific postoperative behavioural response. Twenty patients (10 propofol and 10 methohexitone) (perioperative group) were exposed to the taped message during surgery and in the immediate postoperative period and the other 24 patients (postoperative group) were exposed to the tape only in the postoperative period, after return to the intensive care unit (ICU). No patient had explicit recall of any events during the period when the tape was played. The patients in the propofol group who heard the tape during surgery had significant implicit recall of the word associations compared with the equivalent 10 methohexitone patients (P = 0.004), when tested 48 h after surgery. The patients who were played the tape whilst receiving identical infusion regimens for sedation in the ICU did not demonstrate implicit recall of the word associations in either the propofol or the methohexitone groups. There was no evidence of a response to the specific behavioural suggestion during the postoperative interview. The results confirm that auditory perception can occur during clinically adequate anaesthesia, and that suppression of auditory awareness or learning is a function of both the pharmacological degree of sedation and the degree of surgical stimulation.