PLASMA VASOPRESSIN LEVELS AND URINARY FLOW DURING CARDIOPULMONARY BYPASS IN PATIENTS WITH VALVULAR HEART-DISEASE - EFFECT OF PULSATILE FLOW

  • 1 January 1979
    • journal article
    • research article
    • Vol. 78  (5) , 779-783
Abstract
The effect of pulsatile flow on plasma vasopressin levels during cardiopulmonary bypass (CPB) was studied in 20 patients undergoing open valve replacement. Routine bypass was used in 10 patients and the AVCO pulsatile bypass pump was utilized in the other 10. In Group I (nonpulsatile) during CPB, the vasopressin level was markedly elevated (3.1 .+-. 2 to 80 .+-. 22 pg/ml) as was urine flow (0.6 .+-. 0.2 to 5.9 .+-. 2 ml/min) and urine Na+ concentration (69 .+-. 19 to 116 .+-. 7 meq/l). In Group II (pulsatile) during CPB, the vasopressin level (3.8 .+-. 3 to 54 .+-. 14 pg/ml), urine flow (0.6 .+-. 0.1 to 16.2 .+-. 4.8 ml/min), and urine Na+ concentrations (61 .+-. 13 to 97 .+-. 10 meq/l) were also elevated. The rise in vasopressin and urine Na+ was less in the pulsatile group (P < 0.05) whereas the urine flow was higher (P < 0.05). To maintain comparable blood pressure, the pulsatile flow group required significantly higher flows (4.5 .+-. 0.2 compared to 3.8 .+-. 0.2; P < 0.05). CPB apparently produces a marked vasopressin stress response which is beyond the physiological range for an antidiuretic effect on the kidney. At these levels vasopressin can exert a vasopressor effect to maintain resistance and affect renal blood flow, as well as producing Na+ diuresis. The addition of pulsatile flow creates a more physiological situation attenuating the vasopressin response and producing a decrease in systemic resistance and a less pronounced Na+ diuresis.

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