CENTRAL-TO-PERIPHERAL ARTERIAL-PRESSURE GRADIENT DURING CARDIOPULMONARY BYPASS - RELATION TO PREOPERATIVE AND INTRAOPERATIVE DATA AND EFFECTS OF VASOACTIVE AGENTS

A significant central-to-peripheral arterial pressure gradient may exi st during and after cardiopulmonary bypass (CPB). The etiology and mec hanisms of this phenomenon remain controversial. we studied the pressu re gradient between aorta, brachial artery and radial artery in 68 pat ients, scheduled for elective coronary artery bypass surgery. We evalu ated whether choice of cardioprotection during CPB (use of cold cardio plegic solution or use of intermittent crossclamping under protection with lidoflazine), and choice of pulsatile or nonpulsatile flow during the course of CPB, affected the magnitude and duration of the systoli c pressure gradient. We also studied whether central-to-peripheral pre ssure gradient was influenced by administration on CPB of different va soactive drugs with different mode of action: sodium nitroprusside (di rect action on the vessels), droperidol (alpha-adrenergic blocking act ion), ketanserin (5-hydroxytryptamine antagonist) and phenylephrine (s elective alpha(1)-agonist). It appeared that central-to-peripheral gra dient occurred early during CPB and remained constant throughout the c ourse of CPB. The gradient disappeared within 60 min after weaning fro m CPB. We found the main pressure gradient to occur between the brachi al and the radial artery. There was no relation between magnitude of t he gradient and sex, weight, length or age of the patient. There was a lso no relation between magnitude of the pressure gradient and type of cardioprotection, choice of pulsatile vs nonpulsatile flow on CPB and duration of CPB. We also found no relation between pressure gradients and changes in temperature; haematocrit and systemic vascular resista nce. The pressure gradient was not affected by any of the vasoactive d rugs.