Exaggerated Hypoxic Pulmonary Vasoconstriction Without Susceptibility to High Altitude Pulmonary Edema

Abstract

Abstract

Dehnert, Christoph, Derliz Mereles, Sebastian Greiner, Dagmar Albers, Fabian Scheurlen, Stefanie Zügel, Thomas Böhm, Peter Vock, Marco Maggiorini, Ekkehard Grünig, and Peter Bärtsch. Exaggerated hypoxic pulmonary vasoconstriction without susceptibility to high altitude pulmonary edema. High Alt Med Biol 16:11–17, 2015.— Background: Abnormally high pulmonary artery pressure (PAP) in hypoxia due to exaggerated hypoxic pulmonary vasoconstriction (HPV) is a key factor for development of high-altitude pulmonary edema (HAPE). It was shown that about 10% of a healthy Caucasian population has an exaggerated HPV that is comparable to the response measured in HAPE-susceptible individuals. Therefore, we hypothesized that those with exaggerated HPV are HAPE-susceptible.

Methods and Results:

We screened 421 healthy Caucasians naïve to high altitude for HPV using Doppler echocardiography for assessment of systolic PAP in normobaric hypoxia (PASP_Hx; Po₂ corresponding to 4500 m). Subjects with exaggerated HPV and matched controls were exposed to 4559 m with an identical protocol that causes HAPE in 62% of HAPE-S. Screening revealed 39 subjects with exaggerated HPV, of whom 33 (PASP_Hx 51±6 mmHg) ascended within 24 hours to 4559 m. Four (13%) of them developed HAPE during the 48 h-stay. This incidence is significantly lower than the recurrence rate of 62% previously observed in HAPE-S in the same setting. None of the control subjects (PASP_Hx 33±5 mmHg) developed HAPE.

Conclusion:

An exaggerated HPV cannot be considered a surrogate maker for HAPE-susceptibility although excessively elevated PAP is a hallmark in HAPE, while a normal HPV appears to protect from HAPE in this study.