Figures
- FIGURE 1
Patient flow. GOLD: Global Initiative for Chronic Obstructive Lung Disease.
- FIGURE 2
Pressure–flow relationship displayed as tricuspid regurgitation pressure gradient (TRPG) in relation to the cardiac index from baseline to end-exercise, reflecting the pressure/flow relationship for (a) highlanders and lowlanders and (b) all groups: lowlanders, no high-altitude pulmonary hypertension (HAPH; resting mean pulmonary artery pressure mPAP<20 mmHg), borderline HAPH (resting mPAP 20–30 mmHg) and HAPH (resting mPAP>30 mmHg).
- FIGURE 3
Vital signs of the lowlanders and highlanders during exercise (baseline, 3 min, 6 min, 9 min and individual end exercise). TAPSE: tricuspid annular plane systolic excursion; TRPG: tricuspid regurgitation pressure gradient.
Tables
- TABLE 1
Baseline characteristics
Lowlanders n=22 Highlanders n=52 p-value Male/female n 14/8 26/26 Age years 42.3±8.0 47.9±10.7 0.033 Height cm 168.5±10.4 162.2±9.4 0.014 Weight kg 75.9±10.4 70.2±13.4 0.078 BMI kg·m−2 26.9±4.1 26.7±4.6 0.845 Body surface area m2 1.89±0.16 1.75±0.19 0.017 Heart rate beats·min−1 68±7 75±11 0.010 Blood pressure systolic mmHg 121±15 127±23 0.274 Blood pressure diastolic mmHg 82±10 85±12 0.348 New York Heart Association functional class I/II/III 18/3/1 30/18/4 0.379 Workload achieved Watts 48±11 45±14 0.344 SpO2 % 96±1 91±5 <0.001 Haemoglobin concentration g·dL−1 14.4±1.7 16.0±2.3 0.008 Haematocrit % 39.1±5.0 46.8±7.6 <0.001 PaO2 mmHg 79.3±10.9 56.2±6.2 <0.001 PaCO2 mmHg 38.9±2.9 32.5±2.8 <0.001 Oxygen content mL O2·dL−1 18.3±2.4 18.9±2.8 0.447 Pack-years 1.9±5.2 3.7±6.2 0.227 Data are presented as mean±sd, unless otherwise stated. BMI: Body mass index; SpO2: oxygen saturation by pulse oximetry; PaO2: partial pressure of arterial oxygen; PaCO2: partial pressure of arterial carbon dioxide.
- TABLE 2
Between-group differences of the pressure–flow slope
Lowlanders Highlanders Between group differences p-value Subjects n 22 52 ΔTRPG/ΔCI WU 3.0±2.4 9.4±11.4 6.4 (1.4 to 11.3) 0.012 ΔmPAP/ΔCO WU 1.0±0.8 3.3±3.8 2.3 (0.6 to 3.9) 0.007 Data are presented as mean±sd or mean difference (95% CI), unless otherwise stated. TRPG: tricuspid regurgitation pressure gradient; CI: cardiac index; mPAP: mean pulmonary artery pressure; CO: cardiac output.
- TABLE 3
Assessment during stepwise exercise
Lowlanders Highlanders Between group difference p-value Subjects 22 52 SpO2 % Baseline 96±2 91±3 −5 (−6 to −4) <0.001 End-exercise 95±1 89±3 −6 (−8 to −5) <0.001 End-exercise−baseline −0.4±1.1 −1.4±2.9 −1.0 (−2.2 to 0.3) 0.133 Heart rate beats·min−1 Baseline 77±13 82±12 5 (−2 to 11) 0.137 End-exercise 101±15 110±14 9 (2 to 16) 0.012 End-exercise−baseline 24±15 28±13 −4 (−2 to 11) 0.185 TRPG mmHg Baseline 13.9±4.2 22.8±5.5 8.9 (6.3 to 11.5) <0.001 End-exercise 20.0±7.4 36.4±12.2 16.4 (10.8 to 21.9) <0.001 End-exercise−baseline 6.1±4.8 13.6±10.5 7.5 (2.8 to 12.2) 0.002 Cardiac index L·min·m−2 Baseline 1.98±0.47 2.36±0.58 −0.38 (−0.66 to −0.09) 0.011 End-exercise 4.00±1.17 4.14±0.78 −0.14 (−0.62 to 0.34) 0.566 End-exercise−baseline 2.02±0.89 1.78±0.61 0.24 (−0.13 to 0.61) 0.206 SVI L·min·m−2 Baseline 26.0±5.4 29.2±6.8 −3.3 (−6.6 to 0.1) 0.055 End-exercise 38.6±6.6 37.8±6.3 0.8 (−2.5 to 4.1) 0.634 End-exercise−baseline 12.6±3.7 9.3±7.5 3.4 (0.0 to 6.8) 0.052 TAPSE cm Baseline 2.1±0.3 1.9±0.4 −0.1 (−0.3 to 0.1) 0.153 End-exercise 2.7±0.4 2.5±0.5 −0.2 (−0.4 to 0.1) 0.163 End-exercise−baseline 0.6±0.4 0.6±0.4 0.0 (−0.2 to 0.2) 0.739 FAC % Baseline 42.7±5.5 41.7±8.1 1.0 (−6.3 to 4.2) 0.691 End-exercise 50.0±7.0 44.0±7.7 −6.0 (−11.3 to −0.8) 0.024 End-exercise−baseline 7.8±7.5 3.9±12.0 −3.9 (−12.7 to 5.0) 0.380 RVEDA cm2 Baseline 13.4±2.2 18.1±3.7 4.7 (2.4 to 7.1) <0.001 End-exercise 17.6±2.7 19.5±3.4 1.8 (−0.4 to 4.1) 0.112 End-exercise−baseline 3.5±1.8 1.8±4.3 −1.7 (−4.7 to 1.4) 0.275 RVESA cm2 Baseline 7.7±18 10.6±2.9 2.9 (1.0 to 4.8) 0.003 End-exercise 8.9±2.5 10.9±2.2 2.0 (0.4 to 3.6) 0.014 End-exercise−baseline 0.6±1.3 0.2±3.1 −0.4 (−2.6 to 1.8) 0.707 TAPSE/TRPG mm·mmHg−1 Baseline 1.6±0.5 0.9±0.1 −0.7 (−0.9 to −0.4) <0.001 End-exercise 1.6±0.8 0.8±0.3 −0.8 (−1.0 to −0.5) <0.001 End-exercise−baseline −0.1±0.4 −0.1±0.3 −0.01 (−0.20 to 0.18) 0.901 TAPSE/sPAP mm·mmHg−1 Baseline 1.1±0.3 0.7±0.2 −0.39 (−0.52 to −0.26) <0.001 End-exercise 1.2±0.5 0.7±0.3 −0.50 (−0.67 to −0.34) <0.001 End-exercise−baseline −0.01±0.26 −0.06±0.23 −0.04 (−0.17 to 0.09) 0.515 BPs mmHg Baseline 104±19 112±15 7 (−1 to 15) 0.094 End-exercise 123±20 133±23 9 (−2 to 20) 0.095 End-exercise−baseline 19±12 21±17 2 (−6 to 10) 0.579 BPd mmHg Baseline 70±11 77±10 7 (1 to 12) 0.015 End-exercise 68±14 78±13 10 (3 to 17) 0.004 End-exercise−baseline −2±8 2±12 4 (−2 to 9) 0.191 Data are presented as n, mean±sd or mean difference (95% CI), unless otherwise stated.
Baseline: baseline upright on cycle ergometer; end-exercise: values at end exercise; SpO2: oxygen saturation by pulse oximetry; TRPG: tricuspid regurgitation pressure gradient; SVI: stroke volume index; TAPSE: tricuspid annular plane systolic excursion; FAC: fractional area change; RVEDA: right ventricle end-diastolic area; RVESA: right ventricle end-systolic area; sPAP: systolic pulmonary artery pressure; BPs: blood pressure systolic; BPd: blood pressure diastolic.
Supplementary Material
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Supplementary material 00937-2020.SUPPLEMENT
