Estimation of Oxygen Delivery in Newborns With a Univentricular Circulation

Barnea, Ofer; Santamore, William P.; Rossi, Anthony F.; Salloum, Ellis; Chien, Sufan; Austin, Erle H.

doi:10.1161/01.cir.98.14.1407

Cited by 121 publications

(86 citation statements)

References 16 publications

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“…1,2,6,7 Bedside estimation of Q p:Q s from SaO 2 alone has been advocated on the basis of 2 untested assumptions: constant systemic ⌬A-V O 2 and normal SpvO 2 (Ն95%). This study demonstrates that SaO 2 is a poor predictor of Q p:Q s after Norwood palliation; SaO 2 alone predicted only 8% of the variability in Q p:Q s. Inaccuracy in Q p:Q s estimation was caused by variability in both SmvO 2 and SpvO 2 , thus challenging the dual assumptions used by clinicians for rapid bedside assessment of Q p:Q s. Although others have demonstrated variability in SmvO 2 after Norwood palliation, 3,8 this is the first study to demonstrate that PV desaturation is also common.…”

Section: Discussionmentioning

confidence: 99%

“…Our observations ( Figure 4B) provide clinical evidence to substantiate the computer modeling predictions of Barnea and colleagues. 6,7 If PV blood is assumed to be fully saturated (Ն95%), the error in Q p:Q s estimation can be substantial if true SpvO 2 falls below 95%. Q p:Q s is underestimated by 20% to 25% when SpvO 2 is 90%, and the underestimation error is as large as 30% to 70% if SpvO 2 falls below 90%.…”

Section: Discussionmentioning

confidence: 99%

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Unrecognized Pulmonary Venous Desaturation Early After Norwood Palliation Confounds Q̇p:Q̇s Assessment and Compromises Oxygen Delivery

et al. 2001

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Background —Hemodynamic stability after Norwood palliation often requires manipulation of pulmonary vascular resistance to alter the pulmonary-to-systemic blood flow ratio (Q̇p:Q̇s). Q̇p:Q̇s is often estimated from arterial saturation (Sa o 2 ), a practice based on 2 untested assumptions: constant systemic arteriovenous O 2 difference and normal pulmonary venous saturation. Methods and Results —In 12 patients early (≤3 days) after Norwood palliation, simultaneous arterial, superior vena caval (Ssvc o 2 ), and pulmonary venous (Spv o 2 ) oximetry was used to test whether Sa o 2 accurately predicts Q̇p:Q̇s. Stepwise multiple regression assessed the contributions of Sa o 2 , Ssvc o 2 , and Spv o 2 to Q̇p:Q̇s determination. Sa o 2 correlated weakly with Q̇p:Q̇s ( R 2 =0.08, P <0.05). Inclusion of Ssvc o 2 and Spv o 2 improved Q̇p:Q̇s prediction accuracy. Pulmonary venous desaturation (Spv o 2 <95%) was observed frequently (30%), especially at Fi o 2 ≤0.21, but normalized with higher Fi o 2 or PEEP in all patients. In 6 patients, Fi o 2 was increased incrementally from 0.17 to 0.50 to determine whether this was an effective means to manipulate Q̇p:Q̇s. Q̇p:Q̇s failed to change predictably with increased Fi o 2 . In 5 of 6 patients, however, higher Spv o 2 and Sa o 2 enhanced systemic oxygen delivery, as demonstrated by improvement in oxygen extraction. Conclusions —Sa o 2 correlated poorly with Q̇p:Q̇s because of variability in Ssvc o 2 and Spv o 2 . A novel observation was that pulmonary venous desaturation occurred frequently early after Norwood palliation but normalized with higher Fi o 2 or PEEP. Because unrecognized pulmonary venous desaturation confounds Q̇p:Q̇s assessment and compromises Sa o 2 and oxygen delivery, judicious use of inspired oxygen and PEEP may be beneficial in selected patients early after Norwood palliation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Unrecognized Pulmonary Venous Desaturation Early After Norwood Palliation Confounds Q̇p:Q̇s Assessment and Compromises Oxygen Delivery

et al. 2001

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“…Theoretical studies 5,6 have considered the effects of different Qp/Qs ratios with the aim of forming an analytical basis for the clinical manipulations. However, the standard mathematical model has persistently yielded target Qp/Qs ratios of Ͻ1.…”

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confidence: 99%

Oxygenation in Patients With a Functionally Univentricular Circulation and Complete Mixing of Blood

et al. 1999

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Background-Perioperative management of patients with complete mixing of pulmonary and systemic blood centers on approximately equating pulmonary (Qp) and systemic (Qs) blood flow (Qp/QsϷ1). This empirically derived target is opposed by theoretical studies advocating a target Qp/Qs well below 1. We studied the cause of this persistent discrepancy. Methods and Results-Classic theoretical studies have concentrated on maximizing 1 of many potential combination parameters of arterial oxygen content (CaO 2 ) and systemic blood flow: total oxygen delivery (DO 2 )ϭCaO 2 ϫQs. We defined "useful" oxygen delivery as the amount of oxygen above a notional saturation threshold (Sat Thresh ):

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“…[1][2][3][4][5][6][7][8][9][10] However, outside of research investigations, cardiac output is measured infrequently.…”

Section: Discussionmentioning

confidence: 99%

“…[1][2][3][4] Low cardiac output syndrome adversely affects the outcomes of critically ill children on the intensive care unit. [5][6][7][8][9][10] Cardiac output may be calculated by using the Fick equation if VȮ 2 , hemoglobin level, and the arterial-venous oxygen difference are known.…”

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confidence: 99%

Measurement of Oxygen Consumption in Critically Ill Children: Breath-by-Breath Method vs Mass Spectrometry

Guo

Cui

Bobhate

et al. 2016

American Journal of Critical Care

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Background Measurement of oxygen consumption (VȮ 2 ) is difficult in children but is essential to calculate cardiac index and systemic vascular resistance. Objective To compare measurements of VȮ 2 using respiratory mass spec trometry and the breath-by-breath method. Methods VȮ 2 was measured simultaneously and continuously for 10 minutes by using respiratory mass spectrometry and the breath-by-breath method in children receiving mechanical ventilation via cuffed endotracheal tubes. Results Sixteen children (7 boys ) were studied. The correlation between measurements of VȮ 2 by the 2 methods was good (R = 0.924). Mean VȮ 2 measured by mass spectrometry was 63 (95% CI, 47-78) mL/min vs 65 (95% CI, 47-83) mL/min measured by the breath-by-breath method. The mean VȮ 2 difference between the 2 methods was 3 (95% CI, -9 to 5) mL/min and statistically insignificant. Bland-Altman analysis showed that the 95% limits of agreement were between -28 and + 23. Cardiac index did not differ significantly when calculated using VȮ 2 measured with one method or the other (mean difference, 0.1; 95% CI, -0.2 to 0.3). Conclusions Measurements of VȮ 2 did not differ between mass spectrometry and the breath-by-breath method. Use of the breath-by-breath method may facilitate calculation of cardiac index and systemic vascular resistance in critically ill children.

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Estimation of Oxygen Delivery in Newborns With a Univentricular Circulation

Cited by 121 publications

References 16 publications

Unrecognized Pulmonary Venous Desaturation Early After Norwood Palliation Confounds Q̇p:Q̇s Assessment and Compromises Oxygen Delivery

Unrecognized Pulmonary Venous Desaturation Early After Norwood Palliation Confounds Q̇p:Q̇s Assessment and Compromises Oxygen Delivery

Oxygenation in Patients With a Functionally Univentricular Circulation and Complete Mixing of Blood

Measurement of Oxygen Consumption in Critically Ill Children: Breath-by-Breath Method vs Mass Spectrometry

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