title: A new equation to estimate temperature-corrected PaCO2 from PET CO2 during exercise in normoxia and hypoxia.
abstract: End-tidal PCO2 (PET CO2 ) has been used to estimate arterial pressure CO2 (Pa CO2 ). However, the influence of blood temperature on the Pa CO2 has not been taken into account. Moreover, there is no equation validated to predict Pa CO2 during exercise in severe acute hypoxia. To develop a new equation to predict temperature-corrected Pa CO2 values during exercise in normoxia and severe acute hypoxia, 11 volunteers (21.2 ± 2.1 years) performed incremental exercise to exhaustion in normoxia (Nox, PI O2 : 143 mmHg) and hypoxia (Hyp, PI O2 : 73 mmHg), while arterial blood gases and temperature (ABT) were simultaneously measured together with end-tidal PCO2 (PET CO2 ). The Jones et al. equation tended to underestimate the temperature corrected (tc) Pa CO2 during exercise in hypoxia, with greater deviation the lower the Pa CO2 tc (r = 0.39, P < 0.05). The new equation has been developed using a random-effects regression analysis model, which allows predicting Pa CO2 tc both in normoxia and hypoxia: Pa CO2 tc = 8.607 + 0.716 × PET CO2 [R(2)  = 0.91; intercept SE = 1.022 (P < 0.001) and slope SE = 0.027 (P < 0.001)]. This equation may prove useful in noninvasive studies of brain hemodynamics, where an accurate estimation of Pa CO2 is needed to calculate the end-tidal-to-arterial PCO2 difference, which can be used as an index of pulmonary gas exchange efficiency.
authors: Department of Mathematics, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.
authors: J J
authors: JJ
authors: González Henríquez
authors: Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.
authors: J
authors: J
authors: Losa-Reyna
authors: Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.
authors: R
authors: R
authors: Torres-Peralta
authors: Department of Clinical Sciences Lund, Cardiology, Lund University, Lund, Sweden.|The Haemodynamic Laboratory, The Section for Heart Failure and Valvular Disease, The Clinic for Heart and Lung Disease, Skåne University Hospital, Lund, Sweden.
authors: G
authors: G
authors: Rådegran
authors: Faculty of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece.
authors: M
authors: M
authors: Koskolou
authors: Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.
authors: J A L
authors: JA
authors: Calbet
mesh_terms: D001158:Arteries; D001784:Blood Gas Analysis; D001831:Body Temperature / Q000502:physiology*; D019296:Capnography; D002245:Carbon Dioxide / Q000032:analysis / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D008297:Male; D055641:Mathematical Concepts; D008954:Models, Biological; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange; D013990:Tidal Volume; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: PCO2; altitude; gas exchange; hypoxia