title: Delayed time response of the continuous cardiac output pulmonary artery catheter.
abstract: Previous studies of the accuracy of pulmonary artery catheters (PAC) which provide continuous cardiac output (CCO) monitoring have investigated the performance during steady-state conditions. We compared the response time to hemodynamic change using a CCO PAC and an ultrasonic flow probe (UFP). In five sheep, a CCO PAC was inserted, and an UFP for measurement of CCO was placed around the pulmonary artery via a left thoracotomy. Six interventions which rapidly alter cardiac output were studied: crystalloid bolus, balloon inflation in the inferior vena cava (IVC), IVC balloon deflation, dobutamine infusion, hemorrhage, and reinfusion of blood. Cardiac output measured before and after each intervention was used to calculate the total change caused by the intervention, and the time intervals from intervention to 20%, 50%, and 80% of that change were noted. For all interventions, the time response of CCO was significantly slower than UFP. The largest differences were seen with the rapid infusion of lactated Ringer's solution for which the time interval for 20% change was 7.3 +/- 2.3 min (mean +/- SD) for CCO versus 0.5 +/- 0.3 min for UFP. The time interval for 80% change was 14.5 +/- 4.1 min for CCO versus 1.8 +/- 0.9 min with UFP. The current study demonstrates clinically important time delays in the response of the CCO catheter. This delay must be considered when rapid alterations of the hemodynamic state may occur.
authors.affiliation: Department of Anesthesia, Stanford University School of Medicine, California 94305-5117, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Siegel
authors.forename: M M
authors.initials: MM
authors.lastname: Hennessy
authors.forename: R G
authors.initials: RG
authors.lastname: Pearl
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001804:Blood Transfusion, Autologous; D002302:Cardiac Output / Q000187:drug effects; D002404:Catheterization / Q000295:instrumentation; D002405:Catheterization, Central Venous / Q000295:instrumentation; D002407:Catheterization, Swan-Ganz / Q000295:instrumentation* / Q000706:statistics & numerical data; D000077324:Crystalloid Solutions; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D006470:Hemorrhage / Q000503:physiopathology; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000706:statistics & numerical data; D010952:Plasma Substitutes / Q000008:administration & dosage / Q000494:pharmacology; D011651:Pulmonary Artery / Q000502:physiology; D000077325:Ringer's Lactate; D012756:Sheep; D013908:Thoracotomy; D013997:Time Factors; D018608:Ultrasonography, Doppler / Q000295:instrumentation; D014682:Vena Cava, Inferior
chemical_list: D000318:Adrenergic beta-Agonists; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D000077325:Ringer's Lactate; D004280:Dobutamine