Non-invasive respiratory volume monitoring in patients with traumatic thoracic injuries

Abstract

Background Respiratory decompensation is common after traumatic thoracic injuries such as multiple rib fractures and pulmonary contusions. A continuous, non-invasive, impedance-based respiratory volume monitor generates right and left tidal volume measurements, reflecting air exchange in the lungs and derives an instantaneous respiratory rate. The feasibility of using unilateral respiratory volume monitor–based tidal impedance measurements to monitor respiratory status in trauma patients is evaluated. Methods Three intensive care unit patients with three or more rib fractures following blunt trauma had continuous respiratory volume monitor measurements with a novel non-invasive impedance-based device (ExSpiron, Respiratory Motion Inc., Waltham, MA) and corresponding clinical data to permit analysis. Tidal impedance measurements were collected from both the injured and non-injured sides and converted into bilateral respiratory volume monitor measurements using advanced algorithms. Results In Patient 1, following evacuation of a pneumothorax, the respiratory volume monitor showed a significant increase in tidal measurements coupled with a compensatory decrease in tidal measurements on the uninjured side and a decrease in respiratory rate. In Patient 2, tidal measurements were only slightly decreased on both the injured side and uninjured side; respiratory rate remained unchanged. This patient remained stable and required no intervention. Patient 3 demonstrated a sustained decrease in tidal measurements on the injured side that corresponded with radiograph findings and clinical deterioration leading to the need for endotracheal intubation. Conclusions The results from these cases demonstrate that respiratory volume monitor can generate unilateral respiratory tidal measurements and respiratory rate in patients with traumatic thoracic injuries. Continuous respiratory volume monitor in patients with thoracic trauma has strong potential for application in the military, aeromedical, and other austere environments where respiratory monitoring is problematic. Future studies to investigate the utility of this technology are warranted.