Is mediastinal shift on chest X-ray of pneumothorax always an emergency?

Abstract

Objective: To determine the incidence of mediastinal shift on chest X-ray due to pneumothorax.

Methods: A retrospective chart review was undertaken of all patients with pneumothorax presenting to the ED over the period 1 January 1995 to 31 December 1999. The primary outcome was mediastinal shift on initial CXR. The incidence of clinical tension pneumothorax was noted.

Results: There were 176 presentations with pneumothorax in the study period. Two cases of clinical tension pneumothorax were identified and treated prior to CXR. Thirty patients with mediastinal shift on initial CXR, none of which clinically merited emergency needle decompression, were all managed with intercostal catheter (ICC) insertion. Overall, 141 of 176 (80.1%) had an ICC inserted as part of their management. Mean pulse rate (91.8 SD 29.5 vs 86.7 SD 23.6, P = 0.02) and respiratory rate (21.9 SD 14.4 vs 15.1 SD 11.5, P = 0.03) were greater in patients with mediastinal shift on CXR.

Conclusion: True clinical tension pneumothorax is an uncommon condition. Radiological evidence of mediastinal shift is more common. No patient in this latter group deteriorated while awaiting X-ray.