Nonthyroidal Illness Syndrome and Prolonged Mechanical Ventilation in Patients Admitted to the ICU*
Methods: We evaluated all patients admitted over a 6-year period to our ICU who underwent invasive MV and had measurement of serum free triiodothyronine (fT3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) performed in the first 4 days after ICU admission and, subsequently, at least every 8 days during the time they received MV. The primary outcome measure was prolonged MV (PMV), which was defined as dependence on MV for > 13 days.
Results: Two hundred sixty-four patients were included. Fifty-six patients (normal-hormone group) had normal thyroid function test results, whereas 208 patients (low-fT3 group) had, at least in one hormone dosage, low levels of fT3 with normal (n 145)/low (n 63) levels of fT4 and normal (n 189)/low (n 19) levels of TSH. Patients in the low-fT3 group showed significantly higher mortality and simplified acute physiology score II, and significantly longer duration of MV and ICU length of stay compared with the normal-hormone group. Two of the variables studied were associated with PMV, as follows: the NTIS (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.18 to 4.29; p 0.01); and the presence of pneumonia (OR, 1.17; 95% CI, 1.06 to 3.01; p 0.03).
Conclusion: The NTIS represents a risk factor for PMV in mechanically ventilated, critically ill patients. (CHEST 2009; 135:1448 1454)
Abbreviations: APACHE acute physiology and chronic health evaluation; ARF acute respiratory failure; fT3 free triiodothyronine; fT4 free thyroxine; LOS length of stay; MV mechanical ventilation; NTIS nonthyroidal illness syndrome; PMV prolonged mechanical ventilation; SAPS simplified acute physiology score; TSH thyroid-stimulating hormone; T3 triiodothyronine; T4 thyroxine