Blood gases in routine anaesthesia

Abstract

IN PRovmlNC ANAESTHESIA for routine cases for surgery, practising anaesthetists assume that the patient is in satisfactory clinical condition during anaesthesia as long as the respiration appears adequate, the cardiovascular system is stable, and the general colour is good. This study was originally initiated to confirm the belief that these clinical impressions were correct. METHODPatients were chosen at random for general anaesthesia. There were no prior decisions as to the choice of anaesthetic agents, technique, or types of patients (age or physical condition). There were 17 thoracotomies out of the 75 cases studied. Arterial blood samples were taken from the brachial or radial artery prior to the induction of anaesthesia; subsequently samples were taken at 30-minute intervals either as single arterial punctures or from an indwelling needle in the radial artery. Blood samples were analysed for Pao_o, Paco2, pH, and HCO8 by the Astrup method (Radiometer and Instrumentation Laboratories). Minute volumes and tidal volumes were measured with a Wright respirometer. RESULTSPreoperative Pao..,

The introduction of blood gases into clinical practice

“…Preoperative arterial pO 2 showed such a wide variation in the patients studied that they concluded it should be an essential investigation in 'major or seriously ill patients so that a baseline is available for comparison during and after anaesthesia'. 13 While early endobronchial tubes had been available since 1931, 14 the introduction of the Bjork and Carlens' double lumen tube in 1950 15 led to a rapid increase in thoracic surgery. 16,17 Blood gases became an important tool, providing information to both surgeons and anaesthetists.…”

“…Preoperative arterial pO 2 showed such a wide variation in the patients studied that they concluded it should be an essential investigation in ‘major or seriously ill patients so that a baseline is available for comparison during and after anaesthesia’. 13 …”