A Non-Invasive Gas Exchange Monitor To Assess Swimming-Induced Pulmonary Edema

Swimming-induced pulmonary edema (SIPE) occurs in physically demanding environments. SIPE has been identified among U.S. Naval Special Warfare (NSW) candidates, risking trainees' lives or, less severely, preventing them from completing training. Diagnosis is based on clinical examination and chest X-ray. The MediPines gas exchange monitor AGM-100 is a noninvasive diagnostic tool approved by the FDA and used in hospital settings. This study aimed to assess noninvasive physiological parameters and evaluate the use of the AGM-100 in NSW candidates with SIPE.

In this observational study, eighteen subjects were tested (nine with confirmed SIPE). Data on a noninvasive surrogate for oxygen deficit, based on end-tidal oxygen (EtO₂),carbon dioxide (EtCO₂), and SpO₂ were collected. Chest X-rays (CXR) were graded for interstitial and airspace edema.

Subjects with confirmed SIPE displayed an oxygen deficit (28.1 ± 12.9 mm Hg), while eight of nine subjects without SIPE did not (3.1 ± 8.79 mm Hg, p < 0.001). There were no differences in EtCO₂. SpO₂ was lower in individuals with confirmed SIPE (95.1 ± 2.23%) compared to controls/unconfirmed SIPE (98.1 ± 0.31%, p-value < 0.0001). The group with the oxygen deficit had a correspondingly worse edema grade on CXR.

These limited results showed a possible correlation between O₂ deficit and SIPE, while the AGM-100 performed reliably in this prehospital setting. Future higher-powered studies are needed to substantiate these findings and the AGM-100's utility, possibly extending to other environments, such as combat field hospitals, for rapid diagnosis and severity assessment of pulmonary edema.