A total heart/lung bypass simulator.

The often overlooked role of device design is the need to teach the optimal use of the device. A mathematical model was used in the development of the Sarns/3M SMO oxygenator, as presented at the 1985 ASAIO meeting. This model accepts inlet saturation, hemoglobin levels, and other variables, and returns output saturation, and has been verified in over 100 clinical cases. A patient oxygen consumption model including oxygen stores was developed, using clinical data based on size, temperature, and a term called "anesthesia level." This interesting factor accounts for differences between institutions. The two models were integrated with a heat exchanger model and a patient temperature model to allow accurate predictions of cooling and heating, and a hemoconcentrator model. The combination was programmed for IBM compatible computers to create a bypass simulator. A potential user can put a patient on bypass starting with any selected patient variables, track progress on a minute by minute basis, and adjust the circuit variables as dictated by his technique. The program runs in accelerated time, and accepts defaults to continue without changes as long as desired. Such a simulator is valuable for the initial introduction of the new device to experienced perfusionists, the training of potential new perfusionists, study of unusual or complex cases, the design of new devices, and even as a "track along" system during an actual clinical case.