Pulmonary hemodynamic response to exercise in highlanders versus lowlanders

The question addressed by the study To investigate the pulmonary hemodynamic response to exercise in Central Asian high- and lowlanders (HL&LL).

Patients and methods Cross-sectional study in Central Asian HL (living >2500 m) compared to LL (living <800 m), assessing cardiac function, including tricuspid regurgitation pressure gradient (TRPG), cardiac index and tricuspid annular plane systolic excursion (TAPSE) by echocardiography combined with heart rate (HR) and SpO₂ during submaximal stepwise cycle exercise (10 W increase/3 min) at their altitude of residence (at 760 m/3250 m, respectively).

Results 52 HL (26 females; age 47.9±10.7 years; BMI 26.7±4.6 kg·m⁻²; HR 75±11 bpm; SpO₂ 91±5%;) and 22 LL (8 females; age 42.3±8.0 years; BMI 26.9±4.1 kg·m⁻²; HR 68±7 bpm; SpO₂ 96±1%) were studied. HL had a lower resting SpO₂ compared to LL but change during exercise was similar between groups (HL versus LL. −1.4±2.9% versus −0.4±1.1%, p=0.133). HL had a significantly elevated TRPG and exercise induced increase was significantly higher (13.6±10.5 mmHg versus 6.1±4.8 mmHg, difference 7.5 [2.8 to 12.2]mmHg, p=0.002), whereas cardiac index increase was slightly lower in HL (2.02±0.89 L·min⁻¹ versus 1.78±0.61 L·min⁻¹, difference 0.24 [−0.13 to 0.61]L·min⁻¹, p=0.206) resulting in a significantly steeper pressure-flow ratio (ΔTRPG/Δcardiac index) in HL 9.4±11.4 WU and LL 3.0±2.4 WU (difference 6.4 [1.4 to 11.3]WU, p=0.012). Right ventricular-arterial coupling (TAPSE/TRPG) was significantly lower in HL but no significant difference in change with exercise in between groups was detected (−0.01 [−0.20 to 0.18] p=0.901).

The answer to the question In highlanders, chronic exposure to hypoxia leads to higher pulmonary artery pressure and a steeper pressure-flow relation during exercise.