Techniques for measuring arterial pressure in the postoperative cardiac surgery patient.

Blood pressure measurement and management of the cardiac surgical patient do not appear to be simple processes. The critical care nurse needs to understand thoroughly the many technical and physiologic variables pertaining to the equipment used (i.e., cuff size, stethoscope placement, automated device cycling patterns, and monitoring system accuracy and reliability); the patient (i.e., cardiac output, PVR, hypothermia, and placement site and length of the intra-arterial catheter); and the relationship of indirect to direct measurement. The choice of therapy, i.e., volume or drug therapy (vasodilator or vasopressor), should be based on a thorough understanding of the technical and physiologic factors influencing the readings and their relationship to indirect and direct measurement of the blood pressure. Once the nurse understands the correlation of the indirect and direct blood pressure readings, choosing the pressure reading that one "likes" will no longer be an issue.