Perfusion technology in the hypothyroid patient.

Cardiopulmonary bypass may, by necessity, have to be performed in patients who are frankly hypothyroid. In treating five such patients, all of whom required coronary revascularization, it was noted that fluid balance during perfusion was considerably different than that in the normal population. In order to attempt to evaluate this difference, ten consecutive euthyroid patients having revascularization and the five hypothyroid patients were compared to correlate all fluid absorbed and excreted with the duration of bypass, the serum sodium, and subsequent weight gain. Fluid intake, urine output, and retained fluid were significantly elevated in the hypothyroid as compared to the euthyroid group, while serum sodium following operation was not significantly different. While there are considerable data indicating that hypothyroidism is associated with abnormal salt and water excretion, there is no information concerning the alterations which occur during cardiopulmonary bypass. The present study indicates that hypothyroidism is associated with significant diuresis (without administration of exogenous diuretic agents during cardiopulmonary bypass). The proposed explanation for this diuresis rests with the assumption that with cardiopulmonary bypass and appropriate fluid administration, the contracted blood volume in hypothyroid patients expands acutely and a diuresis results.