Patent ID: 6926838
Filing Date: 2005-08-09
Classification: A61B,A61M

Abstract:
1. A process for determining blood flow in an arterio-venous shunt in a cardiovascular circuit, comprising, (a) changing a selected blood parameter in blood flowing in a circulating system outside the cardiovascular circuit to produce a distinguishable blood characteristic in blood which is delivered to an arterio-venous shunt connected in the cardiovascular circuit and carrying a shunt blood flow; (b) delivering blood having the distinguishable blood characteristic from the circulating system into an upstream location in the arterio-venous shunt so that the delivered blood mixes with the shunt blood flow; (c) removing a portion of the mixed blood from the arterio-venous shunt at a location in the shunt which is downstream from the upstream location and delivering the removed portion of mixed blood to the circulating system; (d) measuring the amount of distinguishable blood characteristic in the removed portion of mixed blood; and (e) calculating the rate of flow of the shunt blood flow in the arterio-venous shunt from the measured amount of distinguishable blood characteristic, wherein the rate of flow of the shunt blood flow in the arterio-venous shunt is calculated using at least one of the following indicator dilution equations or an indicator dilution equation that can be derived from at least one of the following equations: where Q is a rate of blood flow; V is an amount of indicator; S is an amount of change in a parameter observed in response to the introduction of an indicator; Q V S Q V S S