Effect of pre-medication on arterial oxygen saturation in patients undergoing coronary artery bypass sugery

ABSTRACT

We studied 50 patients scheduled for coronary artery bypass surgery at Armed Forces Institute of Cardiology/ National Institute of Heart Diseases, Rawalpindi, following premedication with lorazepam, morphine and promethazine using pulse oximetry readings. Arterial oxygen saturation [SPO2] values were obtained a night before operation and compared with those values obtained after premedication administration. Twenty two of the 50 patients developed significant hypoxemia which was readily corrected by administration of supplementry oxygen in the operating theatre. It is concluded that significant oxygen de-saturation occurs after opioid plus sedative premedication in coronary artery bypass surgery patients. As a result of our findings we urge caution in the use of opioid plus sedative premedication and recommend that oximetry monitoring and oxygen supplement be considered after premedication of these patients