New method of cardiac output measurement using ultrasound velocity dilution in rats. Veal, Nary, Frédéric Moal, Jinhua Wang, Eric Vuillemin, Frédéric Oberti, Emmanuel Roy, Mehdi Kaassis, Renaud Trouvé, Jean-Louis Saumet, and Paul Calès. 1Laboratoire HIFIH and 2Laboratoire de Physiologie, UPRESS EA-2170, Université d'Angers, 49033 Angers, France
APStracts 8:0258A, 2001.
The aim of this study was to validate a new technique for the measurement of cardiac output (CO) based on ultrasound and dilution (COUD) in anesthetized rats. A transonic transit time ultrasound (TTU) probe was placed around the rat carotid artery, and ultrasound velocity dilution curves were generated on intravenous injections of saline. CO by COUD were calculated from the dilution curves for normal and portal hypertensive rats in which CO was known to be increased. COUD was compared with the radiolabeled microsphere method and with direct aortic TTU flowmetry for baseline CO and drug-induced CO variations. CO in direct aortic TTU flowmetry was the ascending aorta blood flow measured directly by TTU probe (normal use of TTU flowmetry). The reproducibility of COUD within the same animal was also determined under baseline conditions. COUD detected the known CO increase in portal hypertensive rats compared with normal rats. CO values by COUD were correlated with those provided by microsphere technique or direct aortic TTU flowmetry (ra = 0.76, P < 10«minus»4 and r = 0.79, P < 0.05, respectively). Baseline CO values and terlipressin- induced CO variations were detected by COUD and the other techniques. Intra- and interobserver agreements for COUD were excellent (ric = 0.99 and 0.98, respectively). COUD was reproducible at least 10 times in 20 min. COUD is an accurate and reproducible method providing low-cost, repetitive CO measurements without open-chest surgery. It can be used in rats as an alternative to the microsphere method and to direct aortic flowmetry. 

Received 11 August 2000; accepted in final form 19 April 2001
APS Manuscript Number A0816-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 18 June 2001