Abstract
A device was developed to record the blood volume changes occurring in the lung and calf during postural changes, physical exercise, and the Valsalva ma neuver in man.
The changes in regional counting rates from the right middle lung and the calf mirrored the well-known changes in venous return that are expected to occur in response to the above-mentioned external stimuli. Thus a sustained decrease in lung blood volume was noted on assumption of the erect posture as well as during the forced expiration of the Valsalva maneuver. In addition a rapid increase and a sharp decrease in lung blood volume took place at the very onset and at the very end of walking, respectively. The calf blood volume de clined immediately at the onset of walking, increased slightly in the ensuing two minutes, and returned to baseline quickly at the termination of walking.
The authors' method enables real-time equilibrium blood pool scintigraphy to be recorded continuously and simultaneously from different districts over sustained periods of time irrespective of the posture and the physical activity performed by the patient. Their method might improve knowledge of the sys temic circulatory responses to selective physiologic and therapeutic interven tions in health and disease.
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