The measurement of metabolic gas exchange and minute volume by mass spectrometry alone

doi:10.1016/0034-5687(79)90029-X

Respiration Physiology

Volume 36, Issue 2, February 1979, Pages 261-267

Respiration Physiolo...

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Abstract

Metabolic gas exchange and respired minute volume were measured on 37 occasions in 9 normal adults on exercise and at rest, using the concentration of an injected gas, argon, as a measure of flow. These measurements were compared with simultaneous Douglas bag collections in which volumes were determined with a dry gas meter. The two types of measurements agreed within ±5%. It was concluded that this technique, designed for the remote monitoring of unconscious patients was suitable for a wide variety of clinical and experimental situations.

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J.S. Clark et al.
Synchronous tracer injection for O₂ and CO₂ production measurement
J.E. Cotes
Lung Function
J.E. Cotes
Lung Function

There are more references available in the full text version of this article.

Cited by (135)

The inaccuracy of LaFarge equations estimating the oxygen consumption in children under 3 years age
2019, Revista Espanola de Anestesiologia y Reanimacion
La medición precisa del consumo de oxígeno (VO₂) es fundamental para una evaluación hemodinámica fiable, en especial en pacientes con cardiopatías congénitas intervenidos de cateterización cardiaca. Las ecuaciones predictivas de LaFarge pueden introducir estimaciones del VO₂ no fiables, particularmente en población pediátrica. A nivel clínico, se podría traducir en fallos de cálculo en importantes parámetros hemodinámicos, con posibles consecuencias a nivel diagnóstico y terapéutico.
Nuestro objetivo es validar las ecuaciones de LaFarge (las más usadas actualmente para la estimación del VO₂), comparándola con la medición directa en niños durante la cateterización cardiaca en la sala de hemodinámica. Un estudio prospectivo observacional unicéntrico fue desarrollado con 21 pacientes (de 0-3 años de edad) con diferentes cardiopatías congénitas y programados para cateterización cardiaca diagnóstica. Bajo ventilación mecánica y con anestesia general, se monitorizó directamente el VO₂ con un módulo metabólico en nuestra sala de hemodinámica. Por otra parte, se calculó el estimado con la ecuación de LaFarge. Para el análisis estadístico, se usaron el gráfico Bland-Altman, el coeficiente de Pearson y el porcentaje de error, entre otros. Las ecuaciones de LaFarge sobrestiman el valor de VO₂ en todos los pacientes del estudio. Es por ello que, en la población pediátrica menor de 3 años, la utilización de métodos de medición directa del VO₂ aporta más exactitud y aceptación, en lugar de su estimación con las ecuaciones de LaFarge.
Accurate oxygen consumption measurement (VO₂), is essential to obtain a reliable hemodynamic assessment, particularly in patients with congenital heart diseases undergoing cardiac catheterization. LaFarge equations can be unreliable in predicting VO₂, particularly in the pediatric population. In a clinical setting, these inaccurate estimates can lead to important hemodynamic parameter miscalculations, with possible therapeutic or diagnostic consequences.
Our aim is to validate LaFarge equations (the most widely used for estimating VO₂) and compare them with direct measurement in children during cardiac catheterization in the cath lab. We performed a prospective observational study in 21 patients (0-3 years of age) with different congenital cardiac diseases, scheduled for diagnostic cardiac catheterization. Under general anesthesia and mechanical ventilation, VO₂ was measured directly with a metabolic module in our cath lab, and also estimated using LaFarge equations. Statistical analysis included Bland-Altman plots, Pearson coefficient and percentage error, among others. LaFarge equations overestimated VO₂ values in all study patients. Therefore, in pediatric patients under 3 years of age, the use of direct VO₂ measurement methods are more accurate and acceptable than LaFarge equations.
Right Heart Catheterization for the Diagnosis of Pulmonary Hypertension: Controversies and Practical Issues
2018, Heart Failure Clinics
A comparison of cardiac output by thoracic impedance and direct fick in children with congenital heart disease undergoing diagnostic cardiac catheterization
2011, Journal of Cardiothoracic and Vascular Anesthesia
To evaluate the measurement of cardiac output (CO) using continuous electrical bioimpedance cardiography (Physioflow; Neumedx, Philadelphia, PA) (CO_PF) with a simultaneous direct Fick measurement (CO_FICK) in children with congenital heart disease.
A prospective cohort study comparing 2 methods of measurement of CO.
A quaternary university-affiliated pediatric hospital.
Children undergoing cardiac catheterization for clinical care.
The Physioflow measured continuous real time CO in 15-second epochs and simultaneous measurement of cardiac output by direct Fick (with mass spectrometry to assess VO₂) were acquired.
Sixty-five patients were recruited, and data from 56 (25 males) were adequate for analysis. The median age at study was 3.5 years (range, 0.4-16.6 years), and the median body surface area was 0.62 m² (range, 0.31-1.71). There were 25 of 56 (45%) with univentricular physiology. A total of 19,228 Physioflow data points were available for the analysis of which 14,569 (76%) were valid; 96% of the invalid measurements were identified as artifacts by the device. The average cardiac index of valid measurements was 3.09 ± 0.72 L/min/m². Compared with the Fick CO, the mean bias was −0.09 L/min, but the 95% limits of agreement were −3.20 to +3.01 L/min/m². Consequently, only 20 of 56 (36%) of measurements were within 20%, and 31 of 56 (55%) of measurements were within 30% of each other.
Compared with measurements made by direct Fick, CO measured using the Physioflow device was unreliable in anesthetized children with congenital heart disease.
Validity of the LaFarge equation for estimation of oxygen consumption in ventilated children with congenital heart disease younger than 3 years - A revisit
2010, American Heart Journal
Citation Excerpt :
This requires analysis of inspired and expired gases, together with the collection of all expired gas. This is a sensitive and accurate method for continuous gas analysis that allows simultaneous measurements of multiple gas fractions within a mixture.2,18-20 The agreement between estimated and measured Vo2 was analyzed using the method of Bland and Altman21 for comparison of 2 methods estimating the same quantity.
The LaFarge equation is the most commonly used equation to estimate oxygen consumption (Vo₂) in patients of all ages with congenital heart disease, although it was generated in patients older than 3 years. We sought to determine the validity of the LaFarge equation in estimating Vo₂ in children younger than 3 years undergoing cardiac catheterization with general anesthesia.
Vo₂ was measured directly using respiratory mass spectrometry in 75 sedated, paralyzed, and mechanically ventilated children in the pediatric cardiac catheterization laboratory. Age ranged from 0.13 to 24 years; 40 children being younger than 3 years. Estimated values for Vo₂ were calculated using the LaFarge equation for all patients. The agreement between measured and estimated Vo₂ was evaluated by the bias and limits of agreement in the 2 age groups. Regression analysis was used to analyze the influence of age on the agreement.
A failure of agreement between measured and estimated Vo₂ was noted in both groups of children. As compared to the older group of patients, the agreement was significantly poorer in children younger than 3 years, with a significantly greater overestimation introduced by the LaFarge equation (11% ± 21% vs 53% ± 52%, P < .0001).
The LaFarge equation introduces significant error in the estimation of Vo₂ in ventilated patients with congenital heart disease of all ages, particularly in children younger than 3 years.
Left ventricular strain and untwist in hypertrophic cardiomyopathy: Relation to exercise capacity
2010, American Heart Journal
Citation Excerpt :
This was performed using a Schiller (Baar, Switzerland) CS-200 Ergo-Spiro exercise machine that was calibrated before every study. Subjects underwent spirometry, and this was followed by symptom-limited erect treadmill exercise testing using a standard ramp protocol with simultaneous respiratory gas analysis.10,11 Samplings of expired gases were performed continuously, and data were expressed as 30-second means.
Nonobstructive hypertrophic cardiomyopathy (nHCM) is often associated with reduced exercise capacity despite hyperdynamic systolic function as measured by left ventricular ejection fraction. We sought to examine the importance of left ventricular strain, twist, and untwist as predictors of exercise capacity in nHCM patients.
Fifty-six nHCM patients (31 male and mean age of 52 years) and 43 age- and gender-matched controls were enrolled. We measured peak oxygen consumption (peak Vo₂) and acquired standard echocardiographic images in all participants. Two-dimensional speckle tracking was applied to measure rotation, twist, untwist rate, strain, and strain rate.
The nHCM patients exhibited marked exercise limitation compared with controls (peak Vo₂ 23.28 ± 6.31 vs 37.70 ± 7.99 mL/[kg min], P < .0001). Left ventricular ejection fraction in nHCM patients and controls was similar (62.76% ± 9.05% vs 62.48% ± 5.82%, P = .86). Longitudinal, radial, and circumferential strain and strain rate were all significantly reduced in nHCM patients compared with controls. There was a significant delay in 25% of untwist in nHCM compared with controls. Both systolic and diastolic apical rotation rates were lower in nHCM patients. Longitudinal systolic and diastolic strain rate correlated significantly with peak Vo₂ (r = −0.34, P = .01 and r = 0.36, P = .006, respectively). Twenty-five percent untwist correlated significantly with peak Vo₂ (r = 0.36, P = .006).
In nHCM patients, there are widespread abnormalities of both systolic and diastolic function. Reduced strain and delayed untwist contribute significantly to exercise limitation in nHCM patients.
Myocardial Contractile Inefficiency and Dyssynchrony in Heart Failure With Preserved Ejection Fraction and Narrow QRS Complex
2010, Journal of the American Society of Echocardiography
Using speckle-tracking imaging (STI), the aims of this study were to assess dyssynchrony and quantify the myocardial energy wasted by contractility in delayed segments by determining the longitudinal strain delay index (LSDi) in patients with heart failure with preserved ejection fraction (HFpEF).
Thirty-eight patients with HFpEF and 33 matched controls were recruited. All subjects underwent clinical examinations, 12-lead electrocardiography, pulmonary function tests, echocardiography, and metabolic exercise tests. LSDi was determined, the magnitude of which is a measure of the amount of wasted energy. Global and segmental systolic and diastolic dyssynchrony was assessed by STI.
LSDi was significantly higher in patients with HFpEF than controls (−14.36 ± 8.24% vs −10.73 ± 5.62%, P < .05). Patients with HFpEF exhibited left ventricular (LV) systolic and diastolic dyssynchrony, with the LV anterior wall displaying the most delayed motion.
Patients with HFpEF exhibited increased myocardial contractile inefficiency. They also exhibited LV systolic and diastolic dyssynchrony, with the LV anterior wall displaying the most delayed motion.

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The measurement of metabolic gas exchange and minute volume by mass spectrometry alone

Abstract

Synchronous tracer injection for O2 and CO2 production measurement

Lung Function

Lung Function

Synchronous tracer injection for O₂ and CO₂ production measurement