Identifying infants at risk of marked thyroid suppression post-cardiopulmonary bypass
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The clinical benefit of tri-iodothyrinone (T3) replacement following congenital heart surgery with cardiopulmonary bypass (CPB) is not clear in unselected cohorts of children. Infants with more marked thyroid hormone suppression or prolonged post-CPB recovery may benefit from T3 replacement. This study aimed to identify infants at risk of more marked suppression by examining the relationship between organ support parameters during CPB and post-operative thyroid hormone levels.
Design and setting
Prospective observational study in a tertary referral centre for congenital heart surgery.
36 infants less than 12 months of age were recruited following CPB.
Measurements and results
Thyroid hormone levels were measured on admission to the intensive care unit and on post-operative days 1 and 2. Increasing CPB time was associated with decreasing admission free T3 and thyroid-stimulating hormone. Younger, smaller infants had lower admission levels of free T3 on univariant analysis. Infants who continued to require ventilation 48 h after admission to the ICU had a mean free T3 level on post-operative day 2 that was 0.9 pmol/l lower than in those who had been extubated.
Prospective studies of T3 replacement in selected young infants (less than 3 months) with long CPB time (greater than 120 min) during congenital heart surgery are warranted.
KeywordsTri-iodothyrinone Thyroid-stimulating hormone Paediatric Congenital heart disease Cardiopulmonary bypass Pediatric intensive care
The authors acknowledge the statistical advice given by Harry Bartlett, School of Mathematical Sciences, Queensland University of Technology. This statistics consultation service is part of an ARC-SPIRT Grant in collaboration with Queensland University of Technology, Prince Charles Hospital and Princess Alexander Hospital, Brisbane, Queensland, Australia.
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