Static Immersion and negative static lung load (SLL) induced right ventricle systolic function adaptation. A novel risk factor for Immersion Pulmonary Edema (IPE).

Abstract

Immersion pulmonary edema (IPE) is a form of hemodynamic edema, likely involves individual susceptibility. Can assessing right ventricular systolic adaptation during immersion be a marker for IPE susceptibility? Twenty-eight experimented divers participated: fifteen study subject with history of IPE ('IPE' group) (40.2 ± 8.2 years old, two females) and thirteen controls subjects ('no-IPE' group) (mean age, 43.1 ± 8.5 years old, two females) underwent three transthoracic echocardiogram under three different conditions: 'dry' (subjects supine on an examination table without immersion), 'surface immersion' (participants floating prone on the water's surface, breathing through a snorkel), and 'immersion & negative static lung load (SLL)' (divers submerged 20 cm below the water's surface in a prone position, using a specific snorkel connected to the surface). Echocardiographic measurements included Tricuspid Annular Plane Systolic Excursion (TAPSE), tissue S' wave, and right ventricle global strain (RVGLS). For all divers, immersion increased right ventricular preload. In the 'no-IPE' group, the increase in right ventricular preload induced by immersion is accompanied by an improvement in the contractility of the right ventricle, as evidenced by increases in TAPSE (17.08 ± 1.15 vs. 20.89 ± 1.32), S' wave (14.58 ± 2.91 vs. 16.26 ± 2.77), and RVGLS (25.37 ± 2.79 vs. 27.09 ± 2.89). Negative SLL amplified these right ventricular adaptations. In contrast, among 'IPE' divers, the increase in right ventricular preload does not coincide with an improvement in right ventricular contractility, indicating altered adaptive responses. In the IPE group, the TAPSE values changed from 17.19 ± 1.28 to 21.69 ± 1.67 and then to 23.55 ± 0.78, respectively, in the 'dry', 'surface immersion', and 'immersion & negative static lung load (SLL)' conditions. The S'wave values changed from 13.42 ± 2.94 to 13.26 ± 2.96 and then to 12.49 ± 0.77, and the RVGLS values changed from -24.09 ± 2.91 to -23.99 ± 3.38 and then to -21.96 ± 0.55. Changes in right ventricular systolic function induced by immersion (especially with the addition of negative SLL) vary among divers based on their history of IPE. Analyzing ventricular contractility during immersion, particularly RVGLS, could help identify individual susceptibility in divers. These findings provide insights for the development of preventive strategies.