Pressure recording analytical method (PRAM) for measurement of cardiac output during various haemodynamic states

Abstract

Background. Cardiac output (CO) can be measured using the pressure recording analytical method (PRAM), which is a new, less invasive technique allowing beat-by-beat stroke volume monitoring from the pressure signals recorded in femoral or radial arteries. Methods. We investigated PRAM by comparing its cardiac output (PRAM-CO) with paired measurements obtained by electromagnetic flowmetry (EM-CO) and by standard thermodilution (ThD-CO) during various haemodynamic states in a swine model. Nine pigs were monitored with a pulmonary artery catheter and a femoral artery catheter at baseline, in a hyperdynamic state produced by administration of dobutamine and in a hypodynamic state induced by progressive exsanguination. Bland-Altman analysis was used. Results. One hundred and eight paired cardiac output values over a range of EM-CO of 1.8-10.4 litre min-1 resulted. We found close agreement between the techniques. Mean bias between EM-CO and PRAM-CO was -0.03 litre min-1 (precision 0.58 litre min-1). The 95% limits of agreement were -0.61 to +0.55 litre min-1. Similar results between ThD-CO and PRAM-CO were found. Conclusions. In a porcine model we have demonstrated accuracy of PRAM during various haemodynamic states. PRAM is a reliable tool to detect changes in cardiac output in pigs and has ability as a basic research tool. © The Board of Management and Trustees of the British Journal of Anaesthesia 2005. All rights reserved.