Abstract: A blood flowmeter responsive only to the pulsatile component of blood flow is combined with apparatus for converting normal blood flow in a limb to fully pulsated flow to provide accurate zero baseline and total flow information. Preferably, the arterial flow in a limb is fully pulsatized by inflating a pressure cuff, which surrounds the limb on the distal side of a flow sensor location, to a pressure at or slightly above the local diastolic pressure. Arterial flow in the limb is thereby occluded during the diastolic and post-diastolic period of each heart cycle, preventing any flow that otherwise typically occurs during this period. The resulting pulsatile flow during the higher pressure systolic period will increase to compensate for any lost residual forward flow during the post-diastolic period; so that the total net forward flow with the cuff pressurized is approximately the same as the total net forward flow without the cuff pressurized. The altered flow is totally pulsatile, however.

Abstract: Normal steady venous return flow in a limb is rendered intermittent by means to occlude the venous system in the limb for a first period of time while permitting pulsatile arterial inflow to the limb. Means to release the venous system for a second period of time allows a rapid exponentially decreasing outflow of the blood that was pooled in the venous system during the first period. The exponentially decreasing outflow may be detected by a flowmeter responsive only to pulsatile flow. The flowmeter may also detect unwanted heart-synchronized signals. The latter may be cancelled from the venous blood flow signal by detecting and storing heart-synchronized signals during at least a part of the first period (of zero venous flow) and subtracting the stored signals from signals detected during the second period.

Abstract: A measuring technique for eliminating the ballistic artifacts created by the mechanical body recoil upon the motion of the heart and the surge of blood within each heart cycle. The limb is restrained by mechanical devices which channel the kinetic energy into a motion which is in a plane favorable to the measurement. A magnetic field is created in the area where blood flow is to be recorded. The ballistic artifact creates a perturbative component in the desired blood flow waveform recording. This perturbation is eliminated by placing an electrically conductive loop around the limb near the location of the blood flow measuring electrodes and amplifying the signal produced by the loop to produce a ballistic signal. This loop signal is then added, subtractively, to the combination of blood flow plus perturbation signal from the electrodes to substantially cancel out the undesired ballistic component.

Abstract: A pair of magnets is adapted to be rotated into several positions around the periphery of a limb for the purpose of producing the magnetic field used in blood flow measurements. Electrodes are arranged in pairs located diametrically opposite each other on the limb. The blood flow measurements are obtained by sequentially monitoring each pair in the array of electrodes located on the skin of the limb so as to obtain blood flow measurements at a plurality of circumferential locations on the limb. Each measurement is stored in a memory, with the heartbeat providing the timing reference. The averaged contributions of each of the several arteries in the limb are picked up by the electrodes to provide a valid total measurement of the overall blood flow in the limb.