Work at high altitude: concepts of physiopathology, risk factors, health surveillance and criteria for the development of work capacity evaluation criteria.

Work at high altitude (elevation equal to or greater than 3000 m above sea level) results in a physiological adaptation of the human organism to changing environmental conditions. The main problem related to the altitude is represented by the reduction of partial pressure of oxygen (hypoxia) that occurs in proportion to the reduction of barometric pressure. Our study, starting with an analysis of the human body's physiological response to acute hypoxic conditions and acclimatization for reaching protracted stays, takes into consideration all risk factors related to the performance of work at high altitude. We identified risk factors related to physical environment of high altitude and represented by temperature, humidity, latitude, speed wind, atmospheric pressure and hypoxia, risk factors related to the worker and represented by age, sex, state of health and individual susceptibility, degree of training. With reference to the state of health we analyzed the major pathophysiological conditions that can create situations of susceptibility to high altitude. We then analyzed risk factors related to the characteristics of the job that are represented by the degree of physical effort and energy expenditure required, by the personal protective equipment (PPE) used and by the concomitant exposure to other occupational risk factors of physical and chemical nature. It was finally addressed the decision making process related to the formulation of the judgment of suitability for performance of work activities at high altitude. The health protocol proposed requires an accurate anamnestic investigation aimed at gathering information on pre-existing pathophysiological conditions that need, once identified, clinical and instrumental tests specific and targeted. These clinical protocols are analyzed and proposed for the main pathophysiologic conditions that pose a risk to health at high altitude. For workers, in which clinical investigation and medical history has not shown significant pathophysiological conditions, we propose a basic health protocol, including clinical and instrumental examinations, modulated in relation to age of workers. Among the specific instrumental tests necessary to process a judgment of suitability to work in complex cases, the ergospirometric test performed under conditions of hypoxia was considered. This test is important for the study of the main predictive parameters in assessing the ability to work at high altitude. The test involves measurement of three key parameters (heart rate, oxygen saturation, ventilation) that are then integrated in the construction of variables useful for the interpretation of the test: cardiac response and ventilatory response to hypoxia, desaturation at rest and during exercise, respiratory rate.