THE PRESSURE CHANGES INDUCED IN THE VASCULAR SYSTEM AS THE RESULT OF COMPRESSION OF A LIMB, AND THEIR EFFECT ON THE INDIRECT MEASUREMENT OF LATERAL PRESSURES

Abstract

Exps. on a schema and on dogs, with and without aortic re-gurgitation, are descr. Pressures were recorded with optical manometers on both the central and peripheral sides of the compressed segment. The compression of a segment by an air column alters the actual pressures within the vessels; the volume elasticity coefficient of the system as a whole is decreased during compression, lowering systolic and raising diastolic pressure; the vascular system is divided by the compression at certain stages into 2 separate parts in which the pressure changes proceed, independently; as full compression is attained, reflection of the wave and stoppage of flow raises the central systolic pressure by converting a lateral into an end pressure. The diastolic pressure in the peripheral section may be considerably lowered in normal, and raised in dogs with aortic regurgitation. The first recordable peripheral pulse occurs at compression pressures slightly above the true lateral systolic pressure; the lateral criterion at pressures slightly below it. Diastolic pressure appears to be accurately indicated by the occurrence of a much brisker upstroke of the oscillometer or a peripheral neg. wave or of both. These diastolic criteria are not affected by the changes in diastolic pressure below the cuff, though this is not true of the flattening of the oscillometric curve.