In Reply: Drs Fagenholz and Harris suggest that in addition to right-to-left shunting through a PFO, subclinical pulmonary edema may have contributed to the observed exaggerated hypoxemia in HAPE-susceptible participants in our study; they propose the comet-tail technique of chest ultrasonography as a means to test this hypothesis in future studies. Subclinical pulmonary edema in climbers remains controversial and relies on the assumption that an increased closing volume at high altitude indicates increased pulmonary extravascular fluid1 rather than a nonspecific alteration related to exercise or subclinical bronchoconstriction. More important, pulmonary extravascular fluid accumulation may be present in the vast majority of healthy recreational climbers at our study site.1 It therefore appears unlikely that differences in arterial oxygenation between HAPE-susceptible and HAPE-resistant participants in our study were related to extravascular fluid accumulation, since this phenomenon, if existent, would be expected to occur with similar frequency in both groups. The suggestion to use ultrasound lung comets for the diagnosis and quantification of subclinical extravascular fluid accumulation at high altitude is interesting. However, this method, while potentially promising and easy to perform under field conditions, needs rigorous clinical validation before it can be proposed for this purpose.
Allemann Y, Seiler C, Scherrer U, Sartori C. High-Altitude Pulmonary Edema and Patent Foramen Ovale—Reply. JAMA. 2007;297(13):1432-1433. doi:10.1001/jama.297.13.1432-c