Reappraisal of DLCO adjustment to interpret the adaptive response of the air-blood barrier to hypoxia.
DLCO measured in hypoxia must be corrected due to the higher affinity (increase in coefficient θ) of CO with Hb. We propose an adjustment accounting for individual changes in the equation relating DLCO to subcomponents Dm (membrane diffusive capacity) and Vc (lung capillary volume): 1/DLCO=1/Dm+1/θVc. We adjusted the individual DLCO measured in hypoxia (HA, 3269m) by interpolating the 1/DLCO to the sea level (SL) 1/θ value. Nineteen healthy subjects were studied at SL and HA. Based on the proposed adjustment, DLCO increased in HA in 53% of subjects, reflecting the increase in Dm that largely overruled the decrease in Vc. We hypothesize that a decrease in Vc (buffering microvascular filtration) and the increase in Dm (possibly resulting from a decrease in thickness of the air-blood barrier) represent the anti-edemagenic adaptation of the lung to hypoxia exposure. The efficiency of this adaptation varied among subjects as DLCO did not change in 31% of subjects and decreased in 16%.
Dipartimento di Medicina e Chirurgia, Università degli Studi di Milano-Bicocca, Via Cadore, 48 20900 Monza, Italy. Electronic address: egidio.beretta@unimib.it.
Egidio
E
Beretta
Dipartimento di Medicina e Chirurgia, Università degli Studi di Milano-Bicocca, Via Cadore, 48 20900 Monza, Italy.
Francesca
F
Lanfranconi
Dipartimento di Medicina e Chirurgia, Università degli Studi di Milano-Bicocca, Via Cadore, 48 20900 Monza, Italy.
Gabriele Simone
GS
Grasso
Dipartimento di Medicina e Chirurgia, Università degli Studi di Milano-Bicocca, Via Cadore, 48 20900 Monza, Italy.
Manuela
M
Bartesaghi
Dipartimento di Scienze Mediche e Biologiche, Università degli Studi di Udine, Piazzale M. Kolbe 4, 33100 Udine, Italy.
Hailu Kinfu
HK
Alemayehu
Dipartimento di Medicina e Chirurgia, Università degli Studi di Milano-Bicocca, Via Cadore, 48 20900 Monza, Italy.
Giuseppe
G
Miserocchi
D000328:Adult; D001784:Blood Gas Analysis; D001810:Blood Volume / Q000502:physiology; D015824:Blood-Air Barrier / Q000503:physiopathology*; D002248:Carbon Monoxide / Q000378:metabolism; D005260:Female; D064368:Healthy Volunteers; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D012129:Respiratory Function Tests; D013223:Statistics as Topic
D006454:Hemoglobins; D002248:Carbon Monoxide
High altitude; Lung capillary volume; Lung diffusive capacity; Lung interstitial edema