The Minnesota system for cardiorespiratory assistance: test of a new system on dogs.

Abstract

<h2>Abstract</h2> Venoarterial extracorporeal partial bypass, with asynchronous and synchronous pulsatile perfusion with aortic arch coagulation, was studied in 17 sedated male dogs for up to 24 h, and they were followed up for i month. A specially developed preperfusion drug protocol is described, which allowed the use of homologous blood for both prime and fluid replacement. Five animals survived long-term asynchronous bypass, which was characterized by a reduction in mean aortic and peak left ventricular pressures, left ventricular work index, and tension-time index. Cardiac index was maintained throughout the bypass interval. Viscerocutaneous blood flow was increased and systemic arterial oxygenation was improved. Damage to formed elements of the blood or to coagulation factors was minimal. Synchronized pumping at flows 1200–2000 ml/min resulted in successful augmentation of diastolic pressure. Aortic root pressure curves indicated the presence of ‘ejection phenomenon' in early diastole and an elastic recoil pressure wave in late diastole. As a result of these studies, we are now developing a mobile cardiorespiratory assistance unit which combines synchronous pulsatile perfusion with membrane oxygenation and monitoring sensors.