Open AccessAge‐dependent effects of thoracic and capillary blood volume distribution on pulmonary artery pressure and lung diffusing capacity
Author(s) -
Coffman Kirsten E.,
Boeker Matthew G.,
Carlson Alex R.,
Johnson Bruce D.
Publication year - 2018
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13834
Subject(s) - supine position , dlco , medicine , sildenafil , cardiology , pulmonary artery , diffusing capacity , pulmonary diffusing capacity , anesthesia , lung , lung volumes , blood volume , vital capacity , lung function
Abstract Aging is associated with pulmonary vascular remodeling and reduced distensibility. We investigated the influence of aging on changes in cardiac output (Q), mean pulmonary artery pressure ( mPAP ), and lung diffusing capacity in response to alterations in thoracic blood volume. The role of pulmonary smooth muscle tone was also interrogated via pulmonary vasodilation. Nine younger (27 ± 4 years) and nine older (71 ± 4 years) healthy adults reached steady‐state in a Supine (0°), Upright (+20°), or Head‐down (−20°) position in order to alter thoracic blood volume. In each position, echocardiography was performed to calculate mPAP and Q, and lung diffusing capacity for carbon monoxide ( DLCO ) and nitric oxide ( DLNO ) was assessed. Next, 100 mg sildenafil was administered to reduce pulmonary smooth muscle tone, after which the protocol was repeated. mPAP ( P ≤ 0.029) and Q ( P ≤ 0.032) were lower in the Upright versus Supine and Head‐down positions, and mPAP was reduced following sildenafil administration ( P = 0.019), in older adults only. SV was lower in the Upright versus Supine and Head‐down positions in both younger ( P ≤ 0.008) and older ( P ≤ 0.003) adults. DLCO and DLNO were not greatly altered by position changes or sildenafil administration. However, the DLNO / DLCO ratio was lower in the Supine and/or Head‐down positions ( P ≤ 0.05), but higher following sildenafil administration ( P ≤ 0.007), in both younger and older adults. In conclusion, older adults experience greater cardiopulmonary alterations following thoracic blood volume changes, and pulmonary smooth muscle tone plays a role in resting mPAP in older adults only. Furthermore, mPAP is an important determinant of pulmonary capillary blood volume distribution ( DLNO / DLCO ), regardless of age.