Posture primarily affects lung tissue distribution with minor effect on blood flow and ventilation.
We used quantitative single photon emission computed tomography to estimate the proportion of the observed redistribution of blood flow and ventilation that is due to lung tissue shift with a change in posture. Seven healthy volunteers were studied awake, breathing spontaneously. Regional blood flow and ventilation were marked using radiotracers that remain fixed in the lung after administration. The radiotracers were administered in prone or supine at separate occasions, at both occasions followed by imaging in both postures. Images showed greater blood flow and ventilation to regions dependent at the time of imaging, regardless of posture at radiotracer administration. The results suggest that a shift in lung parenchyma has a major influence on the imaged distributions. We conclude that a change from the supine to the prone posture primarily causes a change in the vertical distribution of lung tissue. The effect on the vertical distribution of blood flow and ventilation within the lung parenchyma is much less.
Petersson
Johan
J
Department of Anesthesiology and Intensive Care Medicine, Karolinska University Hospital Solna, 171 76 Stockholm, Sweden. johan.petersson@karolinska.se
Rohdin
Malin
M
Sánchez-Crespo
Alejandro
A
Nyrén
Sven
S
Jacobsson
Hans
H
Larsson
Stig A
SA
Lindahl
Sten G E
SG
Linnarsson
Dag
D
Neradilek
Blazej
B
Polissar
Nayak L
NL
Glenny
Robb W
RW
Mure
Margareta
M
D000328:Adult; D003627:Data Interpretation, Statistical; D005260:Female; D006112:Gravitation; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008168:Lung / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D008176:Lung Volume Measurements; D008297:Male; D011187:Posture / Q000502:physiology*; D016684:Prone Position / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology*; D016683:Supine Position / Q000502:physiology; D015899:Tomography, Emission-Computed, Single-Photon