An increasing number of recreational self-contained underwater breathing 
apparatus (SCUBA) divers use trimix of oxygen, helium, and nitrogen for dives 
deeper than 60 m of sea water. Although it was seldom linked to the development 
of pulmonary edema, whether SCUBA diving affects the extravascular lung water 
(EVLW) accumulation is largely unexplored.
METHODS: Seven divers performed six dives on consecutive days using compressed 
gas mixture of oxygen, helium, and nitrogen (trimix), with diving depths ranging 
from 55 to 80 m. The echocardiographic parameters (bubble grade, lung comets, 
mean pulmonary arterial pressure (PAP), and left ventricular function) and the 
blood levels of the N-terminal part of pro-brain natriuretic peptide (NT-proBNP) 
were assessed before and after each dive.
RESULTS: Venous gas bubbling was detected after each dive with mean probability 
of decompression sickness ranging from 1.77% to 3.12%. After each dive, several 
ultrasonographically detected lung comets rose significantly, which was 
paralleled by increased pulmonary artery pressure (PAP) and decreased left 
ventricular contractility (reduced ejection fraction at higher end-systolic and 
end-diastolic volumes) as well as the elevated NT-proBNP. The number of 
ultrasound lung comets and mean PAP did not return to baseline values after each 
dive.
CONCLUSIONS: This is the first report that asymptomatic SCUBA dives are 
associated with accumulation of EVLW with concomitant increase in PAP, 
diminished left ventricular contractility, and increased release of NT-proBNP, 
suggesting a significant cardiopulmonary strain. EVLW and PAP did not return to 
baseline during repetitive dives, indicating possible cumulative effect with 
increasing the risk for pulmonary edema.