Faculty Bibliography

Background: Drug overdose is the leading cause of injury-related fatality in the US, and respiratory failure remains a major source of morbidity and mortality. However, neither the incidence nor risk factors for respiratory failure in overdose patients are currently known. Objectives: To identify the incidence and risk factors for respiratory failure following acute drug overdose. Methods: Secondary data analysis was performed from a prospective cohort of adult ED patients with acute drug overdose at two urban tertiary-care hospitals over a 5-year period. Excluded were patients with alternate diagnoses, anaphylaxis, chronic drug toxicity, and missing outcome data. ED clinical data included demographics, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD defined as asthma, chronic bronchitis, or emphysema), drug information/screens, blood gas analysis, indications for endotracheal intubation (ETI), details of ETI (location, drugs, complications), and inhospital mortality. The study outcome was respiratory failure defined as the requirement for mechanical ventilation. Assuming 4% incidence of respiratory failure, we calculated the need to analyze 2500 patients to show 150% increased risk from common predictors with an 80% power. Univariate analysis (chi-square, t-test), 95% confidence intervals (CI), and multivariable logistic regression were performed with SPSS software. Results: We analyzed 2,497 patients (mean age 45, 54% male) of whom 87 (3.5%) had respiratory failure requiring ETI. Prehospital ETI was slightly associated with increased mortality (OR 2.0, p=0.28) compared with ED and inpatient ETI. Complications of ETI included desaturation (3.4%) and bradycardia (1%). Risk factors for respiratory failure included older age (p=0.06), and history of COPD (p<0.001); sex, type of drug exposures, and CHF had no association. After controlling for confounders, COPD was associated with a significantly increased risk of respiratory failure (adjusted OR 6.6, CI 3.5-12.3). Pati!