Risk factors for the misdiagnosis of pneumothorax in the intensive care unit

Objective: To identify risk factors predisposing to the misdiagnosis of pneumothorax in the ICU. Design: A prospective case series investigation. Setting: A medical ICU service of a military referral hospital. Patients: All adult medical ICU patients were evaluated during a 12-month period. Of 464 admissions, 28 (6%) were found to have acquired a pneumothorax during their medical ICU stay. Interventions: Nineteen (67.9%) patients with pneumothorax were diagnosed correctly on initial presentation of their pneumothorax. The remaining nine (32.1%) patients' pneumothoraces were misdiagnosed at initial presentation. Measurements and Main Results: Tension pneumothorax occurred more frequently in patients with an initially misdiagnosed pneumothorax (33.3%) than in patients with pneumothoraces that were correctly diagnosed during their medical ICU stay (5.3%) (p < .06). Thirteen variables chosen prospectively were examined using a chi-square statistic. The following four variables occurred statistically more often in nine patients with an initially misdiagnosed pneumothorax: a) mechanical ventilation required at the time of the development of pneumothorax (p < .05); b) an atypical radiographic location of the pneumothorax (p < .05); c) altered mental status exhibited at the time of pneumothorax presentation (p < .05); and d) development of pneumothorax after peak physician staffing hours (p < .02). Conclusions: Certain medical ICU patients appear to be at higher risk for the initial misdiagnosis of pneumothorax. Familiarity with factors predisposing to this problem should allow for a higher index of suspicion for the diagnosis of pneumothorax in critically ill patients and possibly improve the early detection of pneumothorax.