In:
Journal of Applied Physiology, American Physiological Society, Vol. 93, No. 5 ( 2002-11-01), p. 1841-1851
Abstract:
Using positron emission tomography (PET) and intravenously injected 13 N 2 , we assessed the topographical distribution of pulmonary perfusion (Q˙) and ventilation (V˙) in six healthy, spontaneously breathing subjects in the supine and prone position. In this technique, the intrapulmonary distribution of 13 N 2 , measured during a short apnea, is proportional to regional Q˙. After resumption of breathing, regional specific alveolar V˙(sV˙a, ventilation per unit of alveolar gas volume) can be calculated from the tracer washout rate. The PET scanner imaged 15 contiguous, 6-mm-thick, slices of lung. Vertical gradients ofQ˙ and sV˙a were computed by linear regression, and spatial heterogeneity was assessed from the squared coefficient of variation (CV 2 ). Both CV[Formula: see text] and CV[Formula: see text] were corrected for the estimated contribution of random imaging noise. We found that 1) both Q˙ and V˙ had vertical gradients favoring dependent lung regions, 2) vertical gradients were similar in the supine and prone position and explained, on average, 24% ofQ˙ heterogeneity and 8% of V˙ heterogeneity, 3) CV[Formula: see text] was similar in the supine and prone position, and 4) CV[Formula: see text] was lower in the prone position. We conclude that, in recumbent, spontaneously breathing humans, 1) vertical gradients favoring dependent lung regions explain a significant fraction of heterogeneity, especially ofQ˙, and 2) although Q˙ does not seem to be systematically more homogeneous in the prone position, differences in individual behaviors may make the prone position advantageous, in terms of V˙-to-Q˙ matching, in selected subjects.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/japplphysiol.00223.2002
Language:
English
Publisher:
American Physiological Society
Publication Date:
2002
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
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