Hypothyroidism is known to cause respiratory failure. We have noted the occurrence of clinically undiagnosed hypothyroidism in patients admitted with failure to wean to this regional weaning center . The objective of this study was to determine the incidence of hypothyroidism in patients on prolonged mechanical ventilation (PMV) with failure to wean and assess it’s relation with successful weaning.
Medical records of 146 patients admitted to this institution between 1999-2001 were reviewed. One hundred fifteen patients were noted to have had thyroid studies. Further parameters abstracted from these patients included: age, sex, TSH levels, number of patients with clinically diagnosed hypothyroidism. Number of patients successfully weaned from ventilator support was noted. Univariate analysis was performed to determine relation between serum TSH levels and successful weaning. p < 0.05 was considered statistically significant.
Of 115 patients studied, 49 were males and 56 females, with a mean age of 65.3 ± 15.4 years. None of these patients had a known history of thyroid disorders. None were on any antithyroid medication or thyroid supplements. Of these 115 patients, 84 ( 73%)were successfully liberated from mecahnical ventilation while 31 (27%) failed weaning. TSH levels ranged from 0.19 to 121mU/L. Mean TSH level was 4.6± 13.5 mU/L in the liberated patients and 3.5± 4.7 mU/L in the failed patients (p >0.05). A clinical diagnosis of hypothyroidism was made in 4/115 (3%) of these patients on admission to the weaning center. Fourteen out of 115 patients (12%) were found to have elevated serum TSH levels. T3/T4 levels confirmed hypothyroidism in 5 (4%) of these patients. Patients diagnosed with hypothyroidism were treated with thyroid replacement therapy and 4 were successfully weaned from the ventilator.
Hypothyroidism is an uncommon cause of failure to wean, with an incidence of 4 % in patients on PMV.CLINICAL IMPLICATION: Hypothyroidism, though uncommon, is a treatable cause and should be considered in all patients who fail to wean.
D. Datta, None.