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How to detect a positive response to a fluid bolus when cardiac output is not measured?
Zakaria Ait-Hamou1,2,3, Jean-Louis Teboul4,5,6, Nadia Anguel4,5,6
1Faculté de Médecine, Université Paris-Saclay, Le Kremlin-Bicêtre, France. zakaria.aithamou@yahoo.com.
Insights
Changes in pulse pressure (PP) roughly indicate a positive fluid response in patients with circulatory failure, while heart rate (HR) changes do not. Combined indices also failed to improve detection accuracy for fluid responsiveness.
Area of Science:
- Critical care medicine
- Hemodynamic monitoring
- Fluid resuscitation
Background:
- Volume expansion aims to increase cardiac output (CO), but CO is not always directly measured.
- Assessing fluid responsiveness is crucial in managing circulatory failure.
Purpose of the Study:
- To evaluate the ability of changes in arterial pressure, pulse pressure variation (PPV), and heart rate (HR) or their combinations to predict a positive CO response to fluid administration.
Main Methods:
- Retrospective analysis of 491 patients with circulatory failure.
- Measurements included CO, HR, arterial pressures (SAP, DAP, MAP, PP), PPV, shock index, and PP/HR ratio before and after 500-mL normal saline infusion.
Main Results:
- Fluid-induced changes in HR did not correlate with CO changes (AUROC ≈ 0.5).
- Changes in SAP, MAP, PP, PPV, shock index, and PP/HR ratio showed weak correlations with CO changes (r < 0.4).
- Increases in PP provided the best, albeit rough, detection of fluid response (AUROC = 0.719), with a threshold of ≥10% increase.
Conclusions:
- Changes in pulse pressure (PP) offer a rough estimation of fluid responsiveness.
- Heart rate (HR) changes are unreliable for detecting fluid responsiveness.
- Combined indices, including shock index and PP/HR ratio, did not enhance diagnostic accuracy compared to PP changes alone.
Background:
Volume expansion is aimed at increasing cardiac output (CO), but this variable is not always directly measured. We assessed the ability of changes in arterial pressure, pulse pressure variation (PPV) and heart rate (HR) or of a combination of them to detect a positive response of cardiac output (CO) to fluid administration.
Methods:
We retrospectively included 491 patients with circulatory failure. Before and after a 500-mL normal saline infusion, we measured CO (PiCCO device), HR, systolic (SAP), diastolic (DAP), mean (MAP) and pulse (PP) arterial pressure, PPV, shock index (HR/SAP) and the PP/HR ratio.
Results:
The fluid-induced changes in HR were not correlated with the fluid-induced changes in CO. The area under the receiver operating characteristic curve (AUROC) for changes in HR as detectors of a positive fluid response (CO increase ≥ 15%) was not different from 0.5. The fluid-induced changes in SAP, MAP, PP, PPV, shock index (HR/SAP) and the PP/HR ratio were correlated with the fluid-induced changes in CO, but with r < 0.4. The best detection was provided by increases in PP, but it was rough (AUROC = 0.719 ± 0.023, best threshold: increase ≥ 10%, sensitivity = 72 [66-77]%, specificity = 64 [57-70]%). Neither the decrease in shock index nor the changes in other indices combining changes in HR, shock index, PPV and PP provided a better detection of a positive fluid response than changes in PP.
Conclusion:
A positive response to fluid was roughly detected by changes in PP and not detected by changes in HR. Changes in combined indices including the shock index and the PP/HR ratio did not provide a better diagnostic accuracy.
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