Abstract
BACKGROUND: Tension pneumothorax (TP) traditionally is defined pleural pressure (P(pl)) exceeding atmospheric pressure, which reduces venous return and leads to hemodynamic collapse. However, P(pl) has yet to be measured directly in TP because of technical limitations, nor has it been studied in predicting outcomes for pneumothorax. RESEARCH QUESTION: Do increased pleural pressures increase the risk of TP and are they associated with pleurodesis or death? STUDY DESIGN AND METHODS: In this multicenter, prospective, observational study, participants with newly diagnosed pneumothorax (tension and nontension) were recruited. P(pl) throughout the respiratory cycle was measured at the time of chest thoracostomy, and patients were followed up for outcomes of pleurodesis and death during hospitalization. RESULTS: At 5 centers, 37 patients with a pneumothorax (9 tension, 28 nontension) were enrolled. Seventy-three percent of recruited patients had an iatrogenic pneumothorax. Both increased inspiratory P(pl) (OR, 1.40; 95% CI, 1.10-1.76) and expiratory P(pl) (OR, 1.22; 95% CI, 1.05-1.42) were associated with increased risk of tension. A subset of patients without tension were found to have supraatmospheric P(pl). Lower inspiratory P(pl) also was associated with an increased risk of pleurodesis (OR, 0.66; 95% CI, 0.45-0.96). INTERPRETATION: Our results show that measurement of P(pl) in TP is feasible. Elevated P(pl) alone may not dictate the development of TP. In this small study, with most participants demonstrating iatrogenic pneumothorax, an association between P(pl) and need for pleurodesis was found that may be a useful predictive tool to guide earlier definitive management. These findings should be explored further in other causes of pneumothorax as well. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT04630301; URL: www. CLINICALTRIALS: gov.