Transesophageal lung ultrasonography: a novel technique for investigating hypoxemia

Abstract

Background: Acute deterioration in respiratory status commonly occurs in patients who cannot be transported for imaging studies, particularly during surgical procedures and in critical care settings. Transthoracic lung ultrasonography has been developed to allow rapid diagnosis of respiratory conditions at the bedside. Nevertheless, the thorax is not always accessible, especially in the perioperative setting. Transesophageal lung ultrasonography (TELU) can be used to circumvent this problem. Purpose: The aim of this narrative review is to provide a complete description of the TELU technique by summarizing the existing literature on the subject and describing our own experience that extrapolates from transthoracic lung ultrasonography. Principal findings: The use of TELU can provide point-of-care real-time information for quickly establishing the etiology of acute hypoxemia. The transesophageal probe is placed in close proximity to the posterior regions of the lungs where lung consolidation and pleural effusions are most often seen; however, most of the artefacts relied on by transthoracic ultrasound have yet to be validated with TELU. Moreover, the relative invasiveness of TELU compared with transthoracic ultrasonography may limit its use to specific situations when the probe is already in place, as during cardiac anesthesia or when the anterior thorax is inaccessible. The main advantage of TELU may lie in the ability to integrate both cardiac and pulmonary assessments in one single examination. Conclusion: Anesthesiologists and intensivists who already use transesophageal echocardiography on a regular basis should consider adding TELU to their clinical assessment of hypoxemia and related pulmonary pathologies. Nevertheless, the literature specifically supporting TELU is relatively limited, and further validation studies are needed.