Cardiovascular changes after induction of anaesthesia

We read the observation by Nishikawa et al. that anaesthesia with either sevoflurane or a propofol and fentanyl combination produces a fall in heart rate, a fall in blood pressure and a reduction in left ventricular performance [1]. In this study the baseline observations appear to have been carried out on air and the observations during anaesthesia were carried out whilst breathing pure oxygen. This raises the possibility that some of the observed physiological changes may have been induced by the change in Fio2. We recently reported in this journal that volunteers who breathe oxygen 100% have cardiovascular changes. The significant changes were a reduction in cardiac index and heart rate and an increased systemic vascular resistance. The observations by Nishikawa and colleagues may be due to a combination of the anaesthetic agents and oxygen and their conclusions should be interpreted with caution.