Prognostic Significance of Thyroid Hormone For Prolonged Mechanical Ventilation In Critically Ill Patients With Cardiac Surgery

Background: This study aimed to examine the correlation between thyroid hormone and prolonged mechanical ventilation (MV) in the adult critically ill patients having undergone cardiac surgery. Methods: The present study refers to a retrospective, cohort study that was conducted at Cardiovascular Intensive Care Unit (CVICU) of Nanjing First Hospital from March 2019 to December 2020. Patients receiving cardiac surgery and admitted to the center of the authors in the study period were screen for a potential inclusion. Demographic information, thyroid hormone and other laboratory measurements and outcome variables were recorded for analyses. Prolonged MV was defined as the duration of MV after cardiac surgery longer than 5 days. Thyroid hormones were assessed for the prognostic significance for prolonged MV.Results: On the whole, 118 patients having undergone cardiac surgery were included and analyzed in this study. Patients fell to the control (n=64) and the prolonged MV group (n=54) by complying with the duration of MV after cardiac surgery. The median total triiodothyronine (TT3) and free triiodothyronine (FT3) were 1.03 nmol/L and 3.52 pmol/L in the prolonged MV group before cardiac surgery, significantly lower than 1.23 nmol/L (P=0.005) and 3.87 pmol/L, respectively in the control (P=0.038). multivariate logistic regression analysis indicated that TT3 before surgery (pre-op TT3) had a good prognostic significance for prolonged MV (OR: 0.049, P=0.012). Conclusions: This study concluded that decreased triiodothyronine (T3) could be common in the cardiac patients with prolonged MV, and it would be further reduced after patients undergoing cardiac surgery. Besides, decreased T3 before surgery could act as an effective predictor for prolonged MV after cardiac surgery.