[Changes in systolic pressure and posture in the surgery of the lumbar spine]

Anesthetized patients for lumbar disk surgery can be placed in prone or knee chest position which may adversely affect circulation. Augmentation of the delta-down component of the systolic blood pressure variation in ventilated patient is a sensitive indicator of intra operative hypovolemia. According to results, cardiac filling pressure is more affected in the knee chest position than in prone position. Preload state variation between the two positions, evaluated with albumin fluid challenge, seems to be more important than 500 ml.