Direct Fick cardiac output: Are assumed values of oxygen consumption acceptable?

Kendrick, Adrian; West, James W.; Papouchado, M; Rozkovec, A.

doi:10.1093/oxfordjournals.eurheartj.a062505

Cited by 57 publications

(35 citation statements)

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“…Similarly, many of the patients used to derive the Bergstra formula 8 were infants and children with congenital heart disease, possibly confounding the application of these methods in adult patients. Previous studies have demonstrated errors in VȮ 2 estimation using these and other formulae in pediatric [19][20][21][22] and adult [23][24][25] populations. However, these analyses have limitations, including small sample size with homogeneity of patient population, lack of sub-group analysis in determining other variables that may influence errors in estimation, and use fewer analytic methods to explain the errors observed.…”

Section: Discussionmentioning

confidence: 94%

Inaccuracy of Estimated Resting Oxygen Uptake in the Clinical Setting

Narang

Thibodeau²,

Levine

et al. 2014

Circulation

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Hence, we assessed the accuracy of estimated resting VȮ 2 compared with measured VȮ 2 obtained by the gold-standard analysis of timed collections of exhaled air by the method of Douglas in a large population of consecutive adult patients who underwent right-heart cardiac catheterization for clinical indications at our hospital. Clinical Perspective on p 210Background-The Fick principle (cardiac output = oxygen uptake (VȮ 2 )/systemic arterio-venous oxygen difference) is used to determine cardiac output in numerous clinical situations. However, estimated rather than measured VȮ 2 is commonly used because of complexities of the measurement, though the accuracy of estimation remains uncertain in contemporary clinical practice. Methods and Results-From 1996 to 2005, resting VȮ 2 was measured via the Douglas bag technique in adult patients undergoing right heart catheterization. Resting VȮ 2 was estimated by each of 3 published formulae. Agreement between measured and estimated VȮ 2 was assessed overall, and across strata of body mass index, sex, and age. The study included 535 patients, with mean age 55 yrs, mean body mass index 28.4 kg/m 2 ; 53% women; 64% non-white. Mean (±standard deviation) measured VȮ 2 was 241 ± 57 ml/min. Measured VȮ 2 differed significantly from values derived from all 3 formulae, with median (interquartile range) absolute differences of 28.4 (13.1, 50.2) ml/min, 37.7 (19.4, 63.3) ml/min, and 31.7 (14.4, 54.5) ml/min, for the formulae of Dehmer, LaFarge, and Bergstra, respectively (P<0.0001 for each). The measured and estimated values differed by >25% in 17% to 25% of patients depending on the formula used. Median absolute differences were greater in severely obese patients (body mass index > 40 kg/m 2 ), but were not affected by sex or age. Conclusions-Estimates

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Section: Discussionmentioning

confidence: 94%

Inaccuracy of Estimated Resting Oxygen Uptake in the Clinical Setting

Narang

Thibodeau²,

Levine

et al. 2014

Circulation

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“…The indirect Fick method also has limitations that may affect measurement accuracy, most notably the need to estimate V9O 2 , which when estimated erroneously will lead to an error of the same magnitude in the estimation of CO. Other factors that may affect the Fick method include errors in the measurement of oxygen saturations and haemoglobin levels and the variable influence of bronchial and thebesian venous drainage on the mixed venous saturation [26,28,29]. The indirect Fick method, however, is likely to be highly accurate and reliable in assessing percentage changes in CO in response to an acute intervention, since the only value that often changes in response to the intervention is the mixed venous saturation, and thus the other factors that go into the estimation will cancel out when calculating percentage changes in CO. HOEPER et al [26] compared CO measured by TD and by Fick in a cohort of patients with PAH and found that both methods correlated well, and that the presence of TR did not appear to influence the CO as determined by either method.…”

Section: Discussionmentioning

confidence: 99%

Noninvasive cardiac output measurements in patients with pulmonary hypertension

2012

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Pulmonary hypertension (PH) is characterised by a progressive decline in cardiac output (CO) and right heart failure. NICOM1 (noninvasive cardiac output monitor) is a bioreactance-based technology that has been broadly validated, but its specific application in right heart failure and PH is unknown.Cardiac catheterisation was performed in 50 consecutive patients with PH. CO measurements were performed using three different methods (thermodilution, Fick and NICOM) at baseline and after vasodilator challenge. We compared the precision (coefficient of variation) and accuracy of NICOM compared to thermodilution and Fick.The mean CO (L?min -1 ) at baseline as measured by the three methods was 4.73¡1.15 (NICOM), 5.69¡1.74 (thermodilution) and 4.84¡1.39 (Fick). CO measured by NICOM was more precise than by thermodilution (3.5¡0.3% versus 9.6¡6.1%, p,0.001). Bland-Altman analyses comparing NICOM to thermodilution and Fick revealed bias and 95% limits of agreement that were comparable to those comparing Fick to thermodilution. All three CO methods detected an increase in CO in response to vasodilator challenge.CO measured via NICOM is precise and reliably measures CO at rest and changes in CO with vasodilator challenge in patients with PH. NICOM may allow for the noninvasive haemodynamic assessment of patients with PH and their response to therapy. @ERSpublications Cardiac output measurements allow for haemodynamic assessment of patients with PH and their response to therapy

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“…First, the Fick principal is often applied to determine cardiac output by the use of an estimate of O 2 uptake. This introduces important error, and O 2 uptake should be measured directly at the time of catheterization 17,18 ; dilution methods are appropriate only in the absence of intracardiac shunting. Second, catheterization data represent a snapshot of supine resting hemodynamics at a single moment in time.…”

Section: Diagnosis: Cardiac Catheterizationmentioning

confidence: 99%

Clinical Evaluation and Management of Pulmonary Hypertension in the Adult With Congenital Heart Disease

Opotowsky

2015

Circulation

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200P ulmonary hypertension (PH) refers to elevated pulmonary artery (PA) pressure (PAP), defined as mean PAP≥25 mm Hg. PH is not synonymous with pulmonary arterial hypertension (PAH), which specifies resistive PH characterized by elevated pulmonary vascular resistance (PVR) and normal pulmonary venous pressure. Approximately 5% to 10% of adults with congenital heart disease (CHD) have PH, and this subset of CHD patients is at higher risk of hospitalization and death. [1][2][3] Understanding the epidemiology of PH associated with CHD (PH-CHD) is not straightforward, however, because definitions of PH-CHD and diagnostic techniques vary. Appropriate diagnosis and the management of PH-CHD rest on identifying the cause of elevated PAP: high pulmonary venous pressure, high pulmonary vascular resistance, high pulmonary flow, or some combination of these factors, which are referred to throughout this review as passive, resistive, hyperkinetic, and polygenic PH, respectively (Table 1).Prognosis in PH-CHD depends on the underlying cause, pulmonary vascular pathophysiology, and the interaction between the right heart and pulmonary circulation. Adult CHD is heterogeneous, with myriad permutations of underlying defects, previous interventions, and associated comorbidities. Although comprehensive understanding of clinical context is a prerequisite, identifying the optimal therapy for a patient with PH-CHD depends more heavily on an understanding of pathophysiology than it does on the underlying diagnosis. Therefore, the goal of this review is to frame an understanding of PH-CHD in terms of fundamental cardiopulmonary hemodynamic pathophysiology and to emphasize the clinical assessment and management of situations commonly encountered by adult cardiologists caring for patients with PH-CHD. Classifications of PH and PH-CHDClassification schemes in PH represent clinical perspectives of underlying pathophysiology and tend to parallel fundamental hemodynamic relationships of the pulmonary circulation. PVR

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Direct Fick cardiac output: Are assumed values of oxygen consumption acceptable?

Cited by 57 publications

References 0 publications

Inaccuracy of Estimated Resting Oxygen Uptake in the Clinical Setting

Inaccuracy of Estimated Resting Oxygen Uptake in the Clinical Setting

Noninvasive cardiac output measurements in patients with pulmonary hypertension

Clinical Evaluation and Management of Pulmonary Hypertension in the Adult With Congenital Heart Disease

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