Clinical Review Post-Operative Respiratory Dysfunction

Abstract

] 9titi) and is most severe in the elderly. the obese and those with chronic airway obstruction. In addition. alterations in lung volume and pulmonary mechanical function follow abdominal operations (Lewis and Welch 19tH>. Okinaka 19H5). ARTERIAL HYPOXAEMIA Arterial hypoxaemia can be causnl by desaturated venous admixture when cardiac output becomes low in relation to the oxygen requirement of the tissues. It is. however. unlikely that this is an important factor in postoperative cases showing no evidence of circulatory instability. Although changes in cardiac output may accompany anaesthesia and operation (Prys-Roberts. Kelman and Greenbaum 19tH). the cardiac index returns in uncomplicated cases to normal by the first postoperative day (Billig and Jordan J 9(9). Also oxygen consumption may be increased in the immediate post operative period especially if shivering is a problem (Bay. Nunn and Prys-Roberts 1968), but, by the first postoperative day, the oxygen consumption has returned to normal levels in uncomplicated cases (Ellison et al. 1966). Another major cause of arterial hypoxaemia in certain instances is hypoventilation due to the effects of anaesthetic drugs and techniques. Once again the elderly. the obese and those with chronic airways obstruction are * l\1.B., l\l.S .• Scnior Specialist. Critical Care l\Iedicinc.