As altitude increases, the availability of oxygen in the air decreases, and just to compensate for this lack, the body increases cardiac and respiratory work and changes blood pressure. But that is not all: at altitude the body's ability to use oxygen is also limited. Thus, there is on one hand less oxygen available, and on the other a lower capacity to use it. All this generates significant alterations at the cardiovascular level, to the point of running possible risks of heart attack, stroke and acute pulmonary edema, particularly for individuals already suffering from cardiovascular disease.

The availability of modern cable cars allows an increasingly large number of individuals, including sedentary people, elderly subjects, and cardiorespiratory patients, to easily and rapidly reach high-altitude locations. Data on what happens on the cardiovascular system at high altitude are relatively scarce, and most experiments in the literature are limited by low sample sizes.

The primary purpose of this study is to assess the characteristics of a large population that acutely reached high altitude at Punta Helbronner (3,466 m above sea level), a location on Mont Blanc that is readily accessible by a 20-minute cableway ride from Courmayeur (Entreves station, 1,300 m, Skyway Monte Bianco). We aim to create a unique database and study correlations between altitude and cardiorespiratory parameters (heart rate, blood pressure, and Hb saturation) by collecting medical history data and biometric measurements in a very large population and to identify subjects most at risk of developing hypoxia at altitude. In a subset of subjects, differences in biometric variables after acute exposure at high altitude (in the transition between the downstream and the upstream measuring station) will be evaluated.

Two biometric multiparametric recording systems (Keito K9; Keito, Barcelona, Spain) were installed at Entreves station as well as at Punta Helbronner. Keito K9 is an automatic multiparametric recoding system for measuring peripheral oxygen saturation SpO2, heart rate HR (pulse oximeter), blood pressure (BP; wrist pressure cuff, automatic), height (laser height meter), weight (scale platform), and body mass index (BMI). Once initiated by the subject with the completion of a cardiology history questionnaire (self-reported), the automated Keito K9 system provides a sequence of vocal and animated directions to guide subjects through the measurements (the subject may elect to abstain from some of the measurements). Upon completion, the system prints a summary receipt for the subject, and the measurements are transmitted through a Wi-Fi network and collected in an Excel sheet.

It should be noted that all data collected will be anonymized or not traceable to the subject, through the use of a disposable identification card (for subjects who will perform both downstream and upstream measurement).

Inclusion Criteria:

• Age ≥ 18 years

Exclusion Criteria:

• Age < 18 years

All consecutive volunteer subjects accessing the Skyway Monte Bianco cableway and stopping to take measurements at the two biometric multiparametric recording systems Keito K9