J Thorac Cardiovasc Surg 2006;131:507
© 2006 The American Association for Thoracic Surgery
Reply to the Editor
U. Fakler, MD,
J. Hess, MD
German Heart Center, Department of Pediatric Cardiology and Congenital Heart Disease, Technische Universität München, Munich, Germany
We thank Benallal for his comments on our article and appreciate his remarks.
Our study was specifically designed to assess the importance of measured oxygen consumption (VO2) in the preoperative diagnostic hemodynamic evaluation during cardiac catheterization and to assess whether published formulas allow a reliable calculation of VO2. We did not intend to develop a new formula to assume VO2.
Our results emphasize that both the Krovetz-Goldbloom formula,
1
which had been used to this point in our institution, and the more commonly used formula published by LaFarge and Miettinen
2
are not feasible in all patients to assume VO2 and thereby calculate cardiac output by the Fick principle.
Li and colleagues
3
presented the important conclusion that other predictive equations published by Lundell and associates,
4
Wessel and colleagues,
5
and Lindahl
6
also do not accurately estimate VO2. All these formulas were developed to offer a suitable and reliable method to assume VO2 in order to simplify the calculation of hemodynamic parameters. However, these formulas cannot be used in all patients and settings.
As Benallal pointed out, these formulas include coefficients depending on characteristics of the population investigated in these studies. The difference between measured and assumed VO2 might be due to a population difference. In addition, it is also influenced essentially by other conditions such as the mode of general anesthesia and relaxation used in different institutions.
It is difficult to identify feasible coefficients to develop a formula fitting to all conditions of hemodynamic evaluation during cardiac catheterization.
Moreover, we are convinced that our population of 143 patients is too small to identify and validate suitable coefficients for a new formula. LaFarge and Miettinen derived their most commonly used formulas from a multivariate analysis of covariance applied to data on a series of 879 patients.
 |
References
|
|---|
- Krovetz LJ, Goldbloom S. Normal standards for cardiovascular data. I. Examination of the validity of cardiac index. Johns Hopkins Med J 1972;130:174-186.[Medline]
- LaFarge CG, Miettinen OS. The estimation of oxygen consumption. Cardiovasc Res 1970;4:23-30.[Abstract/Free Full Text]
- Li J, Bush A, Schulze-Neick I, Penny DJ, Redington AN, Shekerdemian LS. Measured versus estimated oxygen consumption in ventilated patients with congenital heart disease. the validity of predictive equations. Crit Care Med 2003;31:1235-1240.[Medline]
- Lundell BPW, Casas ML, Wallgren CG. Oxygen consumption in infants and children during heart catheterization. Pediatr Cardiol 1996;17:207-213.[Medline]
- Wessel HU, Rorem D, Muster AJ, Acevedo RE, Paul MH. Continuous determination of oxygen uptake in sedated infants and children during cardiac catheterization. Am J Cardiol 1969;24:376-385.[Medline]
- Lindahl SGE. Oxygen consumption and carbon dioxide elimination in infants and children during anaesthesia and surgery. Br J Anaesth 1989;62:70-76.[Abstract/Free Full Text]
Top
References