SIMULTANEOUS RECORDING OF BLOOD-VOLUME SHIFTS IN DIFFERENT VASCULAR BEDS IN MAN BY A VERSATILE SCINTIGRAPHIC METHOD

A device was developed to record the blood volume changes occurring in the lung and calf during postural changes, physical exercise, and the Valsalva maneuver 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-men tioned external stimuli. Thus a sustained decrease in lung blood volum e was noted on assumption of the erect posture as well as during the f orced expiration of the Valsalva maneuver. In addition a rapid increas e and a sharp decrease in lung blood volume took place at the very ons et and at the very end of walking, respectively. The calf blood volume declined immediately at the onset of walking, increased slightly in t he ensuing two minutes, and returned to baseline quickly at the termin ation of walking. The authors' method enables real-time equilibrium bl ood pool scintigraphy to be recorded continuously and simultaneously f rom 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 systemic circulatory responses to selective physiologic and therapeutic interventions in health and d isease.