[Controlled hypotension? Watch the capnograph closely!].

Abstract

During the surgery of the middle ear, a profound general anaesthesia associated to the monitoring of arterial hypotension may obtain a fiel of operation free of any blood. The patient surveillance needs the modern techniques of monitoring. SaO2 is altered only for severe falls of mean arterial pressure. PetCO2 reflects three factors: the cellular metabolism that is stable under general anaesthesia, the ventilatory conditions which are controlled and haemodynamic conditions. The cellular metabolism and the ventilatory being stable, PetCO2 modifications reflect mean arterial pressure variations. We have observed minimal falls of PetCO2 (2-3 mmHg) accompanying falls of mean arterial pressure. Monitoring mean arterial pressure every 5 minutes neglects periods of time. On the contrary capnography allows a constant haemodynamic survey. The capnography seems to be a precious help during the technique of controlled arterial hypotension.