Published in:
01-07-2007 | Original
Can dynamic indicators help the prediction of fluid responsiveness in spontaneously breathing critically ill patients?
Published in: Intensive Care Medicine | Issue 7/2007
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Objective
To investigate whether the respiratory changes in arterial pulse (ΔPP) and in systolic pressure (ΔSP) could predict fluid responsiveness in spontaneously breathing (SB) patients. Because changes in intrathoracic pressure during spontaneous breathing (SB) might be insufficient to modify loading conditions of the ventricles, performances of indicators were also assessed during a forced respiratory maneuver.
Design
Prospective interventional study.
Setting
A 34-bed university hospital medico-surgical ICU.
Patients and participants
Thirty-two SB patients with clinical signs of hemodynamic instability.
Intervention
A 500-ml volume expansion (VE).
Measurements and results
Cardiac index, assessed using transthoracic echocardiography, increased by at least 15% after VE in 19 patients (responders). At baseline, only dynamic indicators were higher in responders than in nonresponders (13 ± 5% vs. 7 ± 3%, p = 0.003 for ΔPP and 10 ± 4% vs. 6 ± 2%, p = 0.002 for ΔSP). Moreover, they significantly decreased after VE (11 ± 5% to 6 ± 4%, p < 0.001 for ΔPP and 8 ± 4% to 6 ± 3%, p < 0.001 for ΔSP). ΔPP and ΔSP areas under the ROC curve were high (0.81 ± 0.08 and 0.82 ± 0.08; p = 0.888, respectively). A ΔPP ≥ 12% predicted fluid responsiveness with high specificity (92%) but poor sensitivity (63%). The forced respiratory maneuver reproducing a dyspneic state decreased the predictive power.
Conclusions
Due to their lack of sensitivity and their dependence to respiratory status, ΔPP and ΔSP are clearly less reliable to predict fluid responsiveness during SB than in mechanically ventilated patients. However, when their baseline value is high without acute right ventricular dysfunction in a participating patient, a positive response to fluid is likely.