Comparison of bedside measurement of cardiac output with the thermodilution method and the Fick method in mechanically ventilated patients

Gonzalez Jésus, Delafosse Christian, Fartoukh Muriel, Capderou André, Straus Christian, Zelter Marc, Derenne Jean-Philippe, Similowski, Thomas Similowski

Description

Bedside cardiac output determination is a common preoccupation in the critically ill. All available methods have drawbacks. We wished to re-examine the agreement between cardiac output determined using the thermodilution method (Q T THERM ) and cardiac output determined using the metabolic (Fick) method (Q T FICK ) in patients with extremely severe states, all the more so in the context of changing practices in the management of patients. Indeed, the interchangeability of the methods is a clinically relevant question; for instance, in view of the debate about the risk–benefit balance of right heart catheterization. Patients and methods Eighteen mechanically ventilated passive patients with a right heart catheter in place were studied (six women, 12 men; age, 39–84 years; simplified acute physiology scoreII, 39–111). Q T THERM was obtained using a standard procedure. Q T FICK was measured from oxygen consumption, carbon dioxide production, and arterial and mixed venous oxygen contents. Forty-nine steady-state pairs of measurements were performed. The data were normalized for repeated measurements, and were tested for correlation and agreement. Results The Q T FICK value was 5.2 ± 2.0 l/min whereas that of Q T THERM was 5.8 ± 1.9 l/min ( R = 0.840, P < 0.0001; mean difference, -0.7 l/min; lower limit of agreement, -2.8 l/min; upper limit of agreement, 1.5 l/min). The agreement was excellent between the two techniques at Q T THERM values <5 l/min but became too loose for clinical interchangeability above this value. Tricuspid regurgitation did not influence the results. Discussion and conclusions No gold standard is established to measure cardiac output in critically ill patients. The thermodilution method has known limitations that can lead to inaccuracies. The metabolic method also has potential pitfalls in this context, particularly if there is increased oxygen consumption within the lungs. The concordance between the two methods for low cardiac output values suggests that they can both be relied upon for clinical decision making in this context. Conversely, a high cardiac output value is more difficult to rely on in absolute terms.

Sujets

• Cardiac output
• Mechanical ventilation

Informations

• Publié par: biomed
• Publié le: 01 janvier 2002
• Nombre de lectures: 13
• Langue: English

Extrait

Available onlinehttp://ccforum.com/content/7/2/171

Open Access Research Comparison of bedside measurement of cardiac output with the thermodilution method and the Fick method in mechanically ventilated patients 1 23 45 Jésus Gonzalez, Christian Delafosse, Muriel Fartoukh, André Capderou, Christian Straus, 6 78 Marc Zelter, JeanPhilippe Derenneand Thomas Similowski

1 Senior Resident, Laboratoire de Physiopathologie Respiratoire et Unité de Réanimation, Service de Pneumologie, Groupe Hospitalier PitiéSalpêtrière, Assistance PubliqueHôpitaux de Paris, Paris, France 2 Junior Consultant (Chef de Clinique), Réanimation Médicale, Groupement Hospitalier EaubonneMontmorency, Hôpital Simone Veil, Eaubonne, France 3 Junior Consultant (Chef de Clinique), Laboratoire de Physiopathologie Respiratoire et Unité de Réanimation, Service de Pneumologie, Groupe Hospitalier PitiéSalpêtrière, Assistance PubliqueHôpitaux de Paris, Paris, France 4 Assistant Professor of Physiology, Centre Chirurgical MarieLannelongue, Le PlessisRobinson, France 5 Assistant Professor of Physiology, Service Central d’Explorations Fonctionnelles Respiratoires, Groupe Hospitalier PitiéSalpêtrière, Assistance PubliqueHôpitaux de Paris, Paris, France 6 Professor of Physiology, Head of the Pulmonary Function Tests, UPRES EA 2397, Université Paris VI Pierre and Marie Curie, Paris, France 7 Professor of Respiratory Medicine, Head of Respiratory Medicine, Groupe Hospitalier PitiéSalpêtrière, Assistance PubliqueHôpitaux de Paris, Paris, France 8 Professor of Respiratory Medicine, UPRES EA 2397, Université Paris VI Pierre and Marie Curie, Paris, France

Correspondence: Thomas Similowski, [e-mail]hopparis.fr

Received: 3 July 2002

Revisions requested: 16 August 2002

Revisions received: 25 October 2002

Accepted: 8 November 2002

Published: 20 December 2002

Critical Care2003,7:171178 (DOI 10.1186/cc1848) This article is online at http://ccforum.com/content/7/2/171 © 2003 Gonzalezet al., licensee BioMed Central Ltd (Print ISSN 13648535; Online ISSN 1466609X). This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.

Abstract IntroductionBedside cardiac output determination is a common preoccupation in the critically ill. All available methods have drawbacks. We wished to reexamine the agreement between cardiac output determined using the thermodilution method (Q TTHERM ) and cardiac output determined using the metabolic (Fick) method (Q TFICK ) in patients with extremely severe states, all the more so in the context of changing practices in the management of patients. Indeed, the interchangeability of the methods is a clinically relevant question; for instance, in view of the debate about the risk–benefit balance of right heart catheterization. Patients and methodsEighteen mechanically ventilated passive patients with a right heart catheter in place were studied (six women, 12men; age, 39–84years; simplified acute physiology scoreII, 39–111). Q TTHERM was obtained using a standard procedure. Q TFICK was measured from oxygen consumption, carbon dioxide production, and arterial and mixed venous oxygen contents. Fortynine steadystate pairs of measurements were performed. The data were normalized for repeated measurements, and were tested for correlation and agreement. ResultsThe Q TFICK value was 5.2± 2.0 l/minwhereas that of Q TTHERM was 5.8± 1.9l/min (R= 0.840, P< 0.0001;l/min; lower limit of agreement, –2.8mean difference, –0.7l/min; upper limit of agreement, 1.5 l/min).The agreement was excellent between the two techniques at Q TTHERM 5 l/minbutvalues < became too loose for clinical interchangeability above this value. Tricuspid regurgitation did not influence the results.

– APACHE = Acute Physiology and Chronic Health Evaluation; CaO= arterial oxygen content; CvO= mixed venous oxygen content; Q TFICK = 2 2 cardiac output determined using the metabolic (Fick) method; Q TTHERM = cardiac output determined using the thermodilution method;R= respira tory quotient; SD =on; V′= oxygen consumption. standard deviatiO 2 171