Extravascular lung water and cardiac function assessed by echocardiography in healthy lowlanders during repeated very high-altitude exposure

Abstract

Background: High-altitude pulmonary edema is associated with elevated systolic pulmonary artery pressure (sPAP) and increased extravascular lung water (EVLW). We investigated sPAP and EVLW during repeated exposures to high altitude (HA). Methods: Healthy lowlanders underwent two identical 7-day HA-cycles, where subjects slept at 2900 m and spent 4-8 h daily at 5050 m, separated by a weeklong break at low altitude (LA). Echocardiography and EVLW by B-lines were measured at 520 m (baseline, LA 1 ), on day one, two and six at 5050 m (HA 1-3 ) and after descent (LA 2 ). Results: We included 21 subjects (median 25 years, body mass index 22 kg/m 2 , SpO 2 98%). SPAP rose from 21 mmHg at LA 1 to 38 mmHg at HA 1 , decreased to 30 mmHg at HA 3 (both p < 0.05 vs LA 1 ) and normalized at 20 mmHg at LA 2 (p = ns vs LA 1 ). B-lines increased from 0 at LA 1 to 6 at HA 2 and 7 at HA 3 (both p < 0.05 vs LA 1 ) and receded to 1 at LA 2 (p = ns vs LA 1 ). Overall, in cycle two, sPAP did not differ (mean difference (95% confidence interval) −0.2(−2.3 to 1.9) mmHg, p = 0.864) but B-lines were more prevalent (+2.3 (1.4-3.1), p < 0.001) compared to cycle 1. Right ventricular systolic function decreased significantly but minimally at 5050 m. Conclusions: Exposure to 5050 m induced a rapid increase in sPAP. B-lines rose during prolonged exposures to 5050 m, despite gradual decrease in sPAP, indicating excessive hydrostatic pressure might not be solely responsible for EVLW-development. Repeated HA-exposure had no acclimatization effect on EVLW. This may affect workers needing repetitive ascents to altitude and could indicate greater B-line development upon repeated exposure.

Right Ventricular Response to Acute Hypoxia Exposure: A Systematic Review

“…Twenty-five studies were conducted in high-altitude field conditions and included 1144 healthy adults exposed to altitudes of 3100 to 7042 m (Huez et al, 2009 ; de Vries et al, 2010 ; Pratali et al, 2010 ; Page et al, 2013 ; Boos et al, 2014 ; Stembridge et al, 2014 , 2019 ; Dedobbeleer et al, 2015 ; Hilty et al, 2016 , 2019 ; Maufrais et al, 2017 , 2019 ; Qiu et al, 2017 ; Berger et al, 2018 ; De Boeck et al, 2018 ; Sareban et al, 2020 ; Stewart et al, 2020 ; Tian et al, 2020 ; Yang et al, 2020a , b ; Ewalts et al, 2021 ; Gaur et al, 2021 ; He et al, 2021 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ). At high-altitude, echocardiographic examinations were conducted at various time points of the sojourn ranging from a few hours to 26 days.…”

“…In 3 of them, measurements were taken serially over a progressive altitude increment (Huez et al, 2009 ; Boos et al, 2014 ; Stewart et al, 2020 ). In 12 studies, both male and female subjects were included (Huez et al, 2009 ; de Vries et al, 2010 ; Pratali et al, 2010 ; Page et al, 2013 ; Boos et al, 2014 ; Dedobbeleer et al, 2015 ; Berger et al, 2018 ; De Boeck et al, 2018 ; Hilty et al, 2019 ; Stewart et al, 2020 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ), while in 13 studies participants consisted of male subjects only (Stembridge et al, 2014 , 2019 ; Hilty et al, 2016 ; Maufrais et al, 2017 , 2019 ; Qiu et al, 2017 ; Sareban et al, 2020 ; Tian et al, 2020 ; Yang et al, 2020a , b ; Ewalts et al, 2021 ; Gaur et al, 2021 ; He et al, 2021 ). Mode of ascent also differed significantly between the studies ranging from a rapid transportation to high-altitude by airplanes to a staged acclimatization with spending nights at intermediate altitudes.…”

“…In addition, RV free wall or global strain were assessed in 8 studies (Page et al, 2013 ; Stembridge et al, 2014 , 2019 ; Maufrais et al, 2017 ; Sareban et al, 2020 ; Yang et al, 2020a , b ; Ewalts et al, 2021 ). The most frequently reported RV systolic function parameter TAPSE was assessed in 18 studies (Huez et al, 2009 ; de Vries et al, 2010 ; Pratali et al, 2010 ; Page et al, 2013 ; Stembridge et al, 2014 ; Dedobbeleer et al, 2015 ; Hilty et al, 2016 , 2019 ; Maufrais et al, 2017 , 2019 ; Berger et al, 2018 ; De Boeck et al, 2018 ; Sareban et al, 2020 ; Stewart et al, 2020 ; Yang et al, 2020a ; Gaur et al, 2021 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ). In 6 of these studies (de Vries et al, 2010 ; Stembridge et al, 2014 ; Dedobbeleer et al, 2015 ; Maufrais et al, 2019 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ), TAPSE was evaluated once while in others it was measured at two (Huez et al, 2009 ; Pratali et al, 2010 ; Page et al, 2013 ; De Boeck et al, 2018 ; Hilty et al, 2019 ; Stewart et al, 2020 ), or 3 (Berger et al, 2018 ; Sareban et al, 2020 ) or 4 (Hilty et al, 2016 ; Maufrais et al, 2017 ; Sareban et al, 2020 ; Gaur et al, 2021 ) time-points over the course of high altitude acclimatization.…”

“…The most frequently reported RV systolic function parameter TAPSE was assessed in 18 studies (Huez et al, 2009 ; de Vries et al, 2010 ; Pratali et al, 2010 ; Page et al, 2013 ; Stembridge et al, 2014 ; Dedobbeleer et al, 2015 ; Hilty et al, 2016 , 2019 ; Maufrais et al, 2017 , 2019 ; Berger et al, 2018 ; De Boeck et al, 2018 ; Sareban et al, 2020 ; Stewart et al, 2020 ; Yang et al, 2020a ; Gaur et al, 2021 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ). In 6 of these studies (de Vries et al, 2010 ; Stembridge et al, 2014 ; Dedobbeleer et al, 2015 ; Maufrais et al, 2019 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ), TAPSE was evaluated once while in others it was measured at two (Huez et al, 2009 ; Pratali et al, 2010 ; Page et al, 2013 ; De Boeck et al, 2018 ; Hilty et al, 2019 ; Stewart et al, 2020 ), or 3 (Berger et al, 2018 ; Sareban et al, 2020 ) or 4 (Hilty et al, 2016 ; Maufrais et al, 2017 ; Sareban et al, 2020 ; Gaur et al, 2021 ) time-points over the course of high altitude acclimatization. Regardless of measured time-points in 8 studies out of 18, TAPSE values were maintained during high-altitude stay suggesting preserved RV systolic function (Huez et al, 2009 ; Pratali et al, 2010 ; Page et al, 2013 ; Hilty et al, 2016 ; Maufrais et al, 2017 , 2019 ; De Boeck et al, 2018 ; Lichtblau et al, 2021 ).…”

“…In 6 of these studies (de Vries et al, 2010 ; Stembridge et al, 2014 ; Dedobbeleer et al, 2015 ; Maufrais et al, 2019 ; Lichtblau et al, 2021 ; Yuan et al, 2021 ), TAPSE was evaluated once while in others it was measured at two (Huez et al, 2009 ; Pratali et al, 2010 ; Page et al, 2013 ; De Boeck et al, 2018 ; Hilty et al, 2019 ; Stewart et al, 2020 ), or 3 (Berger et al, 2018 ; Sareban et al, 2020 ) or 4 (Hilty et al, 2016 ; Maufrais et al, 2017 ; Sareban et al, 2020 ; Gaur et al, 2021 ) time-points over the course of high altitude acclimatization. Regardless of measured time-points in 8 studies out of 18, TAPSE values were maintained during high-altitude stay suggesting preserved RV systolic function (Huez et al, 2009 ; Pratali et al, 2010 ; Page et al, 2013 ; Hilty et al, 2016 ; Maufrais et al, 2017 , 2019 ; De Boeck et al, 2018 ; Lichtblau et al, 2021 ). Only one study reported increased TAPSE values upon high-altitude exposure (Berger et al, 2018 ).…”