Risk Factors for Respiratory Failure Requiring Mechanical Ventilation in Patients With Pulmonary Tuberculosis

Abstract

PURPOSE Previous studies have examined the characteristics and mortality outcome of patients with pulmonary tuberculosis admitted to the intensive care unit. However none have specifically looked at the risk factors for respiratory failure in these patients. This study aims to determine the factors at admission associated with the development of acute respiratory failure requiring mechanical ventilation in patients with newly diagnosed pulmonary tuberculosis. METHODS Retrospective study of all patients aged above 18 years old admitted from 1 April 2009 to 1 April 2011 to a teaching hospital in Singapore, with microbiologically proven pulmonary tuberculosis. Clinical data obtained included demographic characteristics, comorbid conditions, disease presentation, laboratory investigations and chest radiographic findings. Univariate and multivariate regression analysis were performed to identify risk factors for mechanical ventilation RESULTS 202 patients were studied and 17 of them required mechanical ventilation (8.4%). Previous pulmonary tuberculosis, positive HIV status, history of chronic pulmonary disease, ischemic heart disease, breathlessness, absence of cough, low hemoglobin, low albumin and raised procalcitonin at admission were risk factors for mechanical ventilation. Previous pulmonary tuberculosis (OR 72, 95% CI 1.42 - 3668) and low albumin (OR 1.92, 95% CI 1.18 - 3.13) were independent risk factors based on multivariate analysis. Subgroup analysis of patients requiring mechanical ventilation showed a mortality rate of 47% (8/17). Survivors had a lower mean age compared to non survivors (49.8A+/-16.7 vs 63.8A+/-13.0, p=0.077) and a statistically significantly higher platelet level (306A+/-56 vs 200A+/-132, p=0.044). Interestingly none of the non-survivors had history of previous tuberculosis. The other factors examined were not statistically significant but is likely related to the small subgroup sample size. CONCLUSIONS Patients with previous pulmonary tuberculosis and those with low albumin at presentation were more likely to develop acute respiratory failure needing mechanical ventilation. This was associated with a high mortality rate.