Incidence of Respiratory Pathogens in Naval Special Warfare Sea, Air, and Land Team Candidates With Swimming-Induced Pulmonary Edema

Abstract

Background: Swimming-induced pulmonary edema (SIPE) is a respiratory condition frequently seen among Naval Special Warfare (NSW) trainees. The incidence of positive respiratory panel (RP) findings in trainees with a diagnosis of SIPE currently is unknown.

Research question: Does a significant difference exist in the incidence of respiratory pathogens in nasopharyngeal samples of NSW candidates with SIPE and a control group?

Study design and methods: Retrospective analysis of clinical information from NSW Sea, Air, and Land (SEAL) team candidates with a diagnosis of SIPE over a 12-month period. Candidates who demonstrated the common signs and symptoms of SIPE underwent a nasopharyngeal swab and RP test for common respiratory pathogens. SIPE diagnoses were supported by two-view chest radiography. RP tests were obtained for a selected control group of first-phase trainees without SIPE.

Results: Forty-five of 1,048 SEAL team candidates received a diagnosis of SIPE (4.3%). Five had superimposed pneumonia. Thirty-six of 45 showed positive results for at least one microorganism on the RP (80%). In the study group, human rhinovirus/enterovirus (RV/EV) was the most frequently detected organism (37.8%), followed by coronavirus OC43 (17.8%), and parainfluenza virus type 3 (17.8%). Sixteen of 68 candidates from the control group showed positive RP (24%) findings. Patients with SIPE and positive RP results reported dyspnea (94%), pink frothy sputum (44%), and hemoptysis (36%) more frequently than the control participants with positive RP results. Those who reported respiratory infection symptoms in both the study and control groups showed higher incidences of positive RP results (P = .046).

Interpretation: We observed that 80% of trainees with a diagnosis of SIPE showed positive results on a point-of-care RP. This positivity rate was significantly higher than that of RP test results from the control cohort. These findings suggest an association between colonization with a respiratory pathogen and the development of SIPE in NSW candidates.

Keywords: chest radiograph; pulmonary edema; respiratory panel; upper respiratory infection.