Dectection of pneumothoraces in patients with multiple blunt trauma: use and limits of eFAST

Background: Trauma patients are commonly evaluated in the trauma room by extended focused assessment with sonography for trauma (eFAST). Little is known about the location or size of these missed PTXs in trauma patients with multiple blunt trauma and clinical predictors for successful detection are unclear.

Methods: This cross-sectional study includes all patients with multiple blunt trauma and PTX who were admitted to the emergency department of a level 1 trauma centre in Bern, Switzerland between June 1, 2012 and September 30, 2014 (n = 109). Demographic data, imaging modalities, medical data on admission and preclinical suspicion of pneumothorax were compared in patient groups with and without PTXs detected in eFAST, compared with CT, using the Mann-Whitney U or Pearson's chi-square tests. Univariate binary logistic regression models were used to identify predictors for detection of PTXs.

Results: The group of missed PTXs contained significantly fewer ventral PTXs (30 (47.6%) vs. 4 (9.3%), p < 0.001), but more apical and basal PTXs (7 (11.1%) vs. 15 (34.9%), p = 0.003;11 (17.5%) vs. 18 (41.9%), p = 0.008, respectively). The PTXs missed in the eFAST examination were smaller on both sides (left side: 30.7 ± 17.4 vs. 12.1 ± 13.9 mm; right side: 30.2 ± 10.1 vs. 6.9 ± 10.2 mm, both p < 0.001). In univariate analysis, we found that the preclinical suspicion of PTX was associated with the detection of PTXs in eFAST in all PTXs (p < 0.001, OR 7.002 (2.801; 17.507)) as well as in the subgroup analysis of patients who needed thoracic drainage (p = 0.004, OR 10.487 (2.117; 51.944)).

Conclusion: Our study demonstrates that missed PTXs are smaller and in more atypical locations than those detected in eFAST. Missed PTXs less often need treatment with thoracic drainage. Preclinical suspicion of PTX is strongly associated with the detection of PTX in eFAST and deserves special attention.