Anaesthesia systems that minimize the use of volatile anaesthetics to reduce cost and pollution are of interest. Closed circuit anaesthesia is the ideal solution, but requires continuous adjustment of fresh gas flow and composition and thus is demanding in routine practice. We describe an alternative system, the Reflector system, which is open in regard to oxygen, nitrogen and N2O, and semiclosed in regard to volatile anaesthetics. The Reflector system is a circle system with a carbon dioxide absorber and an automatic vapour delivery device placed in the inspiratory limb of the circle. A zeolite filter, the Reflector, is placed between the ventilator and the circle. The Reflector functions as a molecular sieve, preventing the volatile anaesthetic from leaving the circle. Isoflurane consumption using the Reflector system in bench tests and an animal study was compared with that of an open system. In bench tests consumption was reduced by 79% and 82%, at a respiratory frequency of 10 and 20 min-1, respectively. The corresponding mean figures from the animal experiment were 65% and 77%.
The effects of xenon anaesthesia on myocardial function and cerebral blood jlow velocities were investigated with transoesophageal echocardiography and transcranial Doppler sonography. Seventeen A S A I patients undergoing open cholecystectomy ( n = 16) or abdominal hysterectomy ( n = I ) were studied. Anaesthesia with 65% xenon in oxygen was induced by ventilating the lungs through a circle system with minimal fresh gas jlow. The echocardiographically obtained mean ( S D ) fractional area change in a short axis view of the left ventricle at the level of the papillary muscles was 65 (lo)% ( n = 14) before xenon. There was no significant change after 5. I0 and I5 min of xenon anaesthesia. Cerebral blood jlow velocities were unchanged during thejrst 5 min of xenon anaesthesia, but were significantly increased in the left and right middle, and the right anterior, cerebral arteries after I5 and 30 min ( n = 16) ( p < 0.05). In conclusion, xenon anaesthesia had no adverse effect on myocardial function, but probably increased cerebral jloodjlow.
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