Sick Euthyroid Syndrome During Coronary Artery Bypass Graft Surgery With and Without Cardiopulmonary Bypass Impact on Global Oxygen Consumption and Critical Care Unit Morbidity
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- Category: Vol. 78, December 2010
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Sick Euthyroid Syndrome During Coronary Artery Bypass Graft Surgery With and Without Cardiopulmonary Bypass Impact on Global Oxygen Consumption and Critical Care Unit Morbidity,MOHSEN S. ABD EL-AZEEM, AHMAD A. OSMAN, MOHAMAD ABD ELHAMEED and OSAMA A. RASHWAN
Abstract
Background: Sick Euthyroid syndrome (SES) is a wide spectrum of hypothalamus-pituitary-thyroid axis dysfunction ranging from mild form with isolated low T3 level to more complex syndrome associated with low T3 and thyroxin T4 level [1]. Sick Euthyroid syndrome had multivariate aetiological causes such as systemic sepsis, starvation, acute coronary syndrome, major cardiac and non cardiac surgery and any severe illness. The use of cardiopulmonary bypass (CPB) in coronary artery bypass surgery (CABG) is a well known established technique employed worldwide. However, CPB has significant effect on various organs including thyroid gland. Thyroid dysfunction has clinical significance due to their impact on post operative recovery and hospital outcome. On the other hand off pump CABG is also well established technique carried its values based on assumption that avoidance of CPB and its complication on different organs including thyroid gland.
Aim of the Study: Was to assess thyroid function alteration in low-risk patients undergoing coronary surgery with and without CPB and their effect on global oxygen consumption (VO2) and its impact on patient morbidity and mortality.
Methods: Forty-two low risk patients undergoing elective primary CABG. Patients were randomized into either on-pump (ONCAB, n = 21) or off-pump (OPCAB, n = 21) groups. Thyroid-stimulating hormone (TSH), free thyroxine (FT4), reverse T3 (rT3) and free triiodothyronine (FT3) levels were measured at timed intervals using Radioimmuno assay. Global oxygen consumption (VO2) was also measured using a con-tinuous cardiac output through a Swan-Ganz catheter. The post operative morbidity and mortality was assessed in both groups.
Results: In both groups, TSH and FT4 remained within normal range throughout the study. There was a similar and progressive decline in FT3 levels with no significant difference between the groups over time. There was a significant inverse relationship between FT3 levels and global oxygen consump-tion. Also there was significant correlation between low FT3 and post operative atrial fibrillation.
Conclusions: It became clear that SES is a consistent finding post cardiac surgical intervention either being on or off CPB in the selected low risk patients subjected to CABG. There is a possibility that this thyroid dysfunction could be exaggerated in more sicker patients and reflected on post operative recovery period and patient morbidity as low FT3 in our study been an important, independent predictor of postoperative AF in both studied groups and being significantly low in patients who experienced atrial fibrillation.