Abstract
Cardiovascular physiological responses involving hypoxemia in low temperature environments at high altitude have yet to be adequately investigated. This study aims to demonstrate the health effects of hypoxemia and temperature changes in cardiovascular functions (CVFs) by comparing intra-individual differences as participants ascend from low (298 m, 21.9 °C) to high altitude (2729 m, 9.5 °C). CVFs were assessed by measuring the arterial pressure waveform according to cuff sphygmomanometer of an oscillometric blood pressure (BP) device. The mean ages of participants in winter and summer were 43.6 and 41.2 years, respectively. The intra-individual brachial systolic, diastolic BP, heart rate, and cardiac output of participants significantly increased, as participants climbed uphill from low to high altitude forest. Following the altitude increase from 298 m to 2729 m, with the atmosphere gradually reducing by 0.24 atm, the measured average SpO2 of participants showed a significant reduction from 98.1% to 81.2%. Using mixed effects model, it is evident that in winter, the differences in altitude affects CVFs by significantly increases the systolic BP, heart rate, left ventricular dP/dt max and cardiac output. This study provides evidence that cardiovascular workload increased significantly among acute high-altitude travelers as they ascend from low to high altitude, particularly in winter.
Highlights
Hypertensive adults taking medication accounted for 18.2% of the participants, and 6.3% were diagnosed with hypercholesterolemia
This study demonstrated hypoxemia and cold temperature significantly increased cardiovascular workloads in acute high-altitude travelers
The significant increase in cardiovascular loads was accompanied by a marked decrease in SpO2 and low temperature at high altitude
Summary
High cardiovascular stress associated with altitude-environment changes is an important emerging public health issue. High-altitude activity involves traveling from a low altitude flat land to a medium-high altitude area of 2500–3500 m became more and more popular in recent decades. Rapid ascension from low to high altitude often causes acute mountain sickness (AMS) [1,2]. The convenience of modern transportation allows for rapid ascent to high altitudes, and can compromise acclimatization and expose inexperienced travelers or climbers to the hazards of high altitude [3]. Mountains with an altitude of 8000 feet or higher above sea level are known to increase the risk of mountain
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