caa a22 4500 467940398 CHVBK 20180406153010.0 cr unu---uuuuu 170328e20061101xx s 000 0 eng 10.1007/s00421-006-0288-4 doi (NATIONALLICENCE)springer-10.1007/s00421-006-0288-4 CO2 rebreathing model in COPD: blood-to-gas equilibration [Elektronische Daten] [Jack Loeppky, Milton Icenogle, Arvind Caprihan, Marcos Vidal Melo, Stephen Altobelli] Rebreathing in a closed system can be used to estimate mixed venous $$P_{{\rm CO}_{2}}\;(P\bar{v}_{{\text{CO}}_2})$$ and cardiac output, but these estimates are affected by $$\dot{V}_{\rm A}/\dot{Q}$$ heterogeneity. The purpose of this study was to validate a mathematical model of CO2 exchange during CO2 rebreathing in 29 patients with chronic obstructive pulmonary disease (COPD), with baseline arterial $$P_{{\rm CO}_{2}}\;(\hbox{Pa}_{{\rm CO}_{2}})$$ ranging from 28 to 60mmHg. Rebreathing increased end-tidal $$P_{{\rm CO}_{2}}\;(\hbox{PET}_{{\rm CO}_{2}})$$ by 20mmHg over 2.2min. This model employed baseline values for inspired (bag) $$P_{{\rm CO}_{2}},$$ estimated $$P\bar{v}_{{\text{CO}}_2},$$ distribution of ventilation and blood flow in one high $$\dot{V}_{\rm A}/\dot{Q}$$ and one low $$\dot{V}_{\rm A}/\dot{Q}$$ compartment, the ventilation increase and conservation of mass equations to simulate time courses of $$\hbox{PI}_{{\rm CO}_{2}},\hbox{PET}_{{\rm CO}_{2}},\; P\bar{v}_{{\text{CO}}_{2}}$$ and $$\hbox{Pa}_{{\rm CO}_{2}}.$$ Measured $$\hbox{PI}_{{\rm CO}_{2}}$$ and $$\hbox{PET}_{{\rm CO}_{2}}$$ during rebreathing differed by an average (SEM) of 1.4 (0.4) mmHg from simulated values. By end of rebreathing, predicted $$P\bar{v}_{{\text{CO}}_2}$$ was lower than measured and predicted $$\hbox{Pa}_{{\rm CO}_{2}},$$ indicating gas to blood CO2 flux. Estimates of the ventilatory response to CO2, quantified as the slope (S) of the ventilation increase versus $$\hbox{PET}_{{\rm CO}_{2}},$$ were inversely related to gas-to-blood $$P_{{\rm CO}_{2}}$$ disequilibria due to $$\dot{V}_{\rm A}/\dot{Q}$$ heterogeneity and buffer capacity (BC), but not airflow limitation. S may be corrected for these artifacts to restore S as a more valid noninvasive index of central CO2 responsiveness. We conclude that a rebreathing model incorporating baseline $$\dot{V}_{\rm A}/\dot{Q}$$ heterogeneity and BC can simulate gas and blood $$P_{{\rm CO}_{2}}$$ in patients with COPD, where $$\dot{V}_{\rm A}/\dot{Q}$$ variations are large and variable. Springer-Verlag, 2006 Body CO2 stores nationallicence Buffering capacity nationallicence Gas exchange nationallicence Ventilatory response to CO2 nationallicence Ventilation/perfusion heterogeneity nationallicence Loeppky Jack Cardiology Section, VA Medical Center, 1501 San Pedro Dr SE, 87108, Albuquerque, NM, USA aut Icenogle Milton Cardiology Section, VA Medical Center, 1501 San Pedro Dr SE, 87108, Albuquerque, NM, USA aut Caprihan Arvind New Mexico Resonance, 2301 Yale Blvd. SE, 87106, Albuquerque, NM, USA aut Vidal Melo Marcos Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St., 02114, Boston, MA, USA aut Altobelli Stephen New Mexico Resonance, 2301 Yale Blvd. SE, 87106, Albuquerque, NM, USA aut European Journal of Applied Physiology Springer-Verlag 98/5(2006-11-01), 450-460 1439-6319 98:5<450 2006 98 421 https://doi.org/10.1007/s00421-006-0288-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00421-006-0288-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Loeppky Jack Cardiology Section, VA Medical Center, 1501 San Pedro Dr SE, 87108, Albuquerque, NM, USA aut NATIONALLICENCE 700 1- Icenogle Milton Cardiology Section, VA Medical Center, 1501 San Pedro Dr SE, 87108, Albuquerque, NM, USA aut NATIONALLICENCE 700 1- Caprihan Arvind New Mexico Resonance, 2301 Yale Blvd. SE, 87106, Albuquerque, NM, USA aut NATIONALLICENCE 700 1- Vidal Melo Marcos Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St., 02114, Boston, MA, USA aut NATIONALLICENCE 700 1- Altobelli Stephen New Mexico Resonance, 2301 Yale Blvd. SE, 87106, Albuquerque, NM, USA aut NATIONALLICENCE 773 0- European Journal of Applied Physiology Springer-Verlag 98/5(2006-11-01), 450-460 1439-6319 98:5<450 2006 98 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer