A RAPID METHOD AND SIMPLE COMPUTER FOR CALCULATING CARDIAC OUTPUT BY DYE SOLUTION

• Main Authors: Graesch ,Patrick J, Finley,Theodore N
• Format: Report
• Language: English
• Subjects: ANALOG COMPUTERS; ARMY RESEARCH; BLOOD CIRCULATION; CARDIOGRAPHY; COMPUTERS; DETERMINATION; DYES; HEART; INTEGRATORS; LABORATORY EQUIPMENT; MATHEMATICAL ANALYSIS; MEDICAL RESEARCH; TEST METHODS

A method is described in which cardiac-output can be rapidly and accurately calculated. The method is one of finding the area under the dilution curve. Recirculation artifact is eliminated by sampling the slope and the instantaneous value of the curve before recirculation. The ratio of the instantaneous value (E) to the exponential downslope yields the time constant. The product of E and the time constant is the area under the exponential. These characteristics of exponential curves are proven rigorously. The area under a recorded dilution curve may be computed quickly by drawing a tangent to the curve and constructing a rectangle whose sides are E and the time constant. Using the sum of the ordinates along the path of the curve and thence along the top of the rectangle yields the area. The functional block diagram of a computer is presented. The computer performs the electronic analog of the graphical operations described above. It was constructed using three operational amplifiers and four mercury relays, costs less than $300, and operates on =12 volts. (Author)