Assessment of extravascular lung water and cardiac function in trimix SCUBA diving.
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.
Marinovic
Jasna
J
Department of Physiology, University of Split School of Medicine, Split, Croatia.
Ljubkovic
Marko
M
Obad
Ante
A
Breskovic
Toni
T
Salamunic
Ilza
I
Denoble
Petar J
PJ
Dujic
Zeljko
Z
D000328:Adult; D001794:Blood Pressure; D003665:Decompression Sickness / Q000097:blood / Q000000981:diagnostic imaging; D004242:Diving / Q000009:adverse effects* / Q000502:physiology; D004452:Echocardiography; D015633:Extravascular Lung Water / Q000000981:diagnostic imaging* / Q000502:physiology; D006371:Helium / Q000009:adverse effects* / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D009584:Nitrogen / Q000009:adverse effects* / Q000502:physiology; D010100:Oxygen / Q000009:adverse effects* / Q000502:physiology; D010446:Peptide Fragments / Q000097:blood; D011651:Pulmonary Artery; D013318:Stroke Volume / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000209:etiology*
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D006371:Helium; C045257:trimix; D009584:Nitrogen; D010100:Oxygen