Sonographic detection of pneumothorax and hemothorax in microgravity.

INTRODUCTION: An intrathoracic injury may be disastrous to a crew-member aboard the International Space Station (ISS) if the diagnosis is missed or delayed. Symptomatic or clinically suspicious thoracic trauma is treated as a surgical emergency on Earth, usually with immediate stabilization and rapid transport to a facility that is able to deliver the appropriate medical care. A similar approach is planned for the ISS; however, an unnecessary evacuation would cause a significant mission impact and an exorbitant expense.

HYPOTHESIS: The use of ultrasound imaging for the detection of pneumothorax and hemothorax in microgravity is both possible and practical.

METHODS: Sonography was performed on anesthetized pigs in a ground-based laboratory (n = 4) and microgravity conditions (0 G) during parabolic flight (n = 4). Aliquots of air (50-500 ml) or saline (10-200 ml) were introduced into the pleural space to simulate pneumothorax and hemothorax, respectively.

RESULTS: The presence of "lung sliding" excluded pnemothorax. In microgravity, a loss of "lung sliding" was noted simultaneously in the anterior and posterior sonographic windows after 100 ml of air was introduced into the chest, indicating pneumothorax. The presence of the fluid layer in simulated hemothorax was noted in the anterior and posterior sonographic windows after 50 ml of fluid was injected into the pleural space. During the microgravity phase, the intrapleural fluid rapidly redistributed so that it could be detected using either anterior or posterior sonographic windows.

CONCLUSION: Modest to severe pneumothorax and hemothorax can be diagnosed using ultrasound in microgravity.