Opening Pandora’s box: the potential benefit of the expanded FAST exam is partially confounded by the unknowns regarding the significance of the occult pneumothorax

Abstract

Abstract Introduction Point of care (POC) ultrasound brings another powerful dimension to the physical examination of the critically ill. A contemporary challenge for all care providers, however, is how to best incorporate ultrasound into contemporary algorithms of care. When POC ultrasound corroborates pre-examination clinical suspicion, incorporation of the findings into decision-making is easier. When POC ultrasound generates new or unexpected findings, decision-making may be more difficult, especially with conditions that were previously not appreciated with older diagnostic technologies. Pneumothoraces (PTXs), previously seen only on computed tomography and not on supine chest radiographs known as occult pneumothoraces (OPTXs), which are now increasingly appreciated on POC ultrasound, are such an example. Methods The relevant literature concerning POC ultrasound and PTXs was reviewed after an electronic search using PubMed supplemented by ongoing research by the Canadian Trauma Trials Collaborative of the Trauma Association of Canada. Results OPTXs are frequently encountered in the critically injured who often require mechanical ventilation with positive pressure breathing (PPB). Standard recommendations for post-traumatic PTXs and the setting of PPB mandate chest drainage, recognizing a significant rate of complications related to this procedure itself. Whether these standard recommendations generated in response to obvious overt PTXs apply to these more subtle OPTXs is currently unknown, and evidence-based recommendations regarding appropriate therapy are impossible due to the lack of clinical studies. Conclusions OPTXs are a condition that illustrates how incorporation of POC ultrasound findings brings further responsibilities to critically appraise the significance of these findings in terms of patient outcomes and overall care. Adequately powered and adequately followed-up clinical trials addressing the treatment are required.