The Annals of Thoracic Surgery, Vol 58, 93-96, Copyright © 1994 by The Society of Thoracic Surgeons
Effect of pulsatile flow during cardiopulmonary bypass on thyroid hormone metabolism
S Buket, A Alayunt, M Ozbaran, A Hamulu, B Discigil, B Cetindag, H Ozkilic, Z Balkan, O Bilkay and I Durmaz
Department of Cardiovascular Surgery, Ege University Medical Faculty, Izmir, Turkey.
Changes in thyroid hormone levels during and after cardiopulmonary bypass
(CPB) are well documented. However, little is known about the effects of
pulsatile flow during CPB on thyroid hormone metabolism. To examine the
effect of flow pattern, a prospective study was carried out using 30
patients undergoing coronary artery bypass grafting. Fifteen patients had
pulsatile flow during CPB and 15, nonpulsatile flow. Serum samples were
obtained preoperatively, during bypass, and at 2 and 24 hours
postoperatively. Thyroid-stimulating hormone, thyroxine (T4),
triiodothyronine (T3), free T4, and free T3 levels were measured by
radioimmunoassay. All measured hormone levels except free T4 and
thyroid-stimulating hormone decreased after the initiation of CPB. There
were no differences in preoperative values between the two groups. However,
levels of T3 and free T3 during and after CPB showed a significant
difference between the two groups, with a smaller decrease in patients in
whom pulsatile flow was used during bypass (p < 0.05). Thyroxine, and
thyroid-stimulating hormone free T4 values showed no difference between the
two groups at any sampling time. These data provide support for the use of
pulsatile flow during CPB to establish a more physiologic state and
maintain better thyroid hormone metabolism.
