Blunt traumatic occult pneumothorax: is observation safe?--results of a prospective, AAST multicenter study.

Background: An occult pneumothorax (OPTX) is found incidentally in 2% to 10% of all blunt trauma patients. Indications for intervention remain controversial. We sought to determine which factors predicted failed observation in blunt trauma patients.
Methods: A prospective, observational, multicenter study was undertaken to identify patients with OPTX. Successfully observed patients and patients who failed observation were compared. Multivariate logistic regression was used to identify predictors of failure of observation. OPTX size was calculated by measuring the largest air collection along a line perpendicular from the chest wall to the lung or mediastinum.
Results: Sixteen trauma centers identified 588 OPTXs in 569 blunt trauma patients. One hundred twenty-one patients (21%) underwent immediate tube thoracostomy and 448 (79%) were observed. Twenty-seven patients (6%) failed observation and required tube thoracostomy for OPTX progression, respiratory distress, or subsequent hemothorax. Fourteen percent (10 of 73) failed observation during positive pressure ventilation. Hospital and intensive care unit lengths of stay, and ventilator days were longer in the failed observation group. OPTX progression and respiratory distress were significant predictors of failed observation. Most patient deaths were from traumatic brain injury. Fifteen percentage of patients in the failed observation group developed complications. No patient who failed observation developed a tension PTX, or experienced adverse events by delaying tube thoracostomy.
Conclusion: Most blunt trauma patients with OPTX can be carefully monitored without tube thoracostomy; however, OPTX progression and respiratory distress are independently associated with observation failure.