Calibration of a respiratory system Multicompartimental model through the physiologic cardiorespiratory response to the acute exposure to high altitude

• Grant number: 18/07242-3
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2019
• End date: January 31, 2022
• Field of knowledge: Engineering - Biomedical Engineering - Bioengineering
• Principal Investigator: Fabio Turri
• Grantee: Fabio Turri
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Associated researchers: Celso Ricardo Fernandes de Carvalho ; Joaquim Edson Vieira ; Jurandir Itizo Yanagihara ; Mauro Roberto Tucci

Abstract

Flying at higher altitudes imposes a greater risk in an eventual decompression accident. An alveolar model that depends exclusively of the cabin altitude has been used to predict the severity of the accident. A disadvantage of this approach is that it is based on near steady state experimental data, although decompression accidents are a transient event. To solve this deficiency, a computational model that can simulate the transient changes in the body tissues is proposed. The body is represented by compartments which are modeled by O2 and CO2 differential equations derived through a mass conservation analysis. The model uses controls for cardiac output and ventilation. The mass transfer in the lungs includes diffusion and chemical reaction processes. The comparison of the model prediction preliminary data with experimental data shows good correlation with some discrepancies. One important aspect is that experimental data in the literature is controversial per se. Additionally, the most important trials were conducted in the forties and fifties of last century. These aspects suggest the necessity to collect new experimental data for the model calibration. To fulfill this necessity, the current work proposes the measurement of respiratory physiologic parameters corresponding to the alveolar PO2, alveolar PCO2, pulmonary ventilation, and arterial and cerebral regional oximetry. Additionally, cardiac output will be measured in a non invasive way. Healthy volunteers will be submitted to acute exposure to high altitudes as 8000, 12000, 16000 and 20000 feet. The exposure at the target altitude will last 10 minutes. During the ascent phase the volunteers will breath air with FiO2=100%. At the target altitude, the inhalatory gas will be changed to air with FiO2=21%. At this phase, the respiratory gases will be measured continuously by side-streaming. The experiments will be held at the Centro de Engenharia de Conforto Aeroespacial da Escola Politécnica da USP where an airplane cabin inside a vacuum chamber allows the generation of high altitudes hypobaric pressures. (AU)