Reply to the Editor

Abstract

We appreciate the interest of Haas and Camphausen in our recently published trial of triiodothyronine (T3) in neonatal heart surgery.1Mackie A.S. Booth K.L. Newburger J.W. Gauvreau K. Huang S.A. Laussen P.C. et al.A randomized, double-blind, placebo-controlled pilot trial of triiodothyronine in neonatal heart surgery.J Thorac Cardiovasc Surg. 2005; 130: 810-816Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar The points they raised are addressed below. Our center, like many other centers performing infant heart surgery in the United States, routinely uses high-dose intravenous loop and thiazide diuretics rather than peritoneal dialysis to manage postoperative fluid overload. We agree that the results of our study cannot be generalized to patients who are treated with peritoneal dialysis. The inotrope score used in our study, adapted from Wernovsky and associates,2Wernovsky G. Wypij D. Jonas R.A. Mayer Jr, J.E. Hanley F.L. Hickey P.R. et al.Postoperative course and hemodynamic profile after the arterial switch operation in neonates and infants a comparison of low-flow cardiopulmonary bypass and circulatory arrest.Circulation. 1995; 92: 2226-2235Crossref PubMed Scopus (837) Google Scholar was determined by the use of dopamine, dobutamine, milrinone, epinephrine, and norepinephrine. The cumulative dose of dopamine in particular did not differ between treatment groups during the first 5 days after the operation. Vasodilator use was also similar between treatment groups: milrinone was used routinely in our patients, with no difference in cumulative milrinone dose between treatment arms at 5 days. A single patient (randomized to the T3 group) received nitroprusside; no patients received phenoxybenzamine. Amiodarone was not used in any subject. We planned our trial so that cardiac output was one of two primary outcome measures. The technique used (direct measurement of oxygen consumption by real-time gas exchange) provides an objective determination of cardiac output in children who are sedated, ventilated, and stable.3Chang A.C. Kulik T.J. Hickey P.R. Wessel D.L. Real-time gas-exchange measurement of oxygen consumption in neonates and infants after cardiac surgery.Crit Care Med. 1993; 21: 1369-1375Crossref PubMed Scopus (35) Google Scholar During the study period, infants were weaned from mechanical ventilation at increasingly shorter times after surgery, rendering this measurement infeasible at 48 hours after surgery in several subjects. However, the proportion of patients in each treatment group in whom this end point could not be measured (9/22 in the T3 group and 5/20 in the placebo group) was not statistically significant (P = .34). Triiodothyronine in neonatal heart surgery: Looking for an answerThe Journal of Thoracic and Cardiovascular SurgeryVol. 131Issue 2PreviewWe congratulate Mackie and colleagues1 on their randomized study on triiodothyrodine (T3) treatment in neonatal heart surgery. In their study group the authors correctly enrolled a homogenous group of infants at highest risk of postoperative low cardiac output syndrome and marked thyroid hormone suppression.2 As already shown by several other authors, the thyroid hormone levels are suppressed after cardiopulmonary bypass (CPB), decreasing to a nadir at around 48 hours after CPB and recovering over approximately 1 week. Full-Text PDF