Change in cardiac output during Trendelenburg maneuver is a reliable predictor of fluid responsiveness in patients with acute respiratory distress syndrome in the prone position under protective ventilation

Abstract

Background: Predicting fluid responsiveness may help to avoid unnecessary fluid administration during acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the diagnostic performance of the following methods to predict fluid responsiveness in ARDS patients under protective ventilation in the prone position: cardiac index variation during a Trendelenburg maneuver, cardiac index variation during an end-expiratory occlusion test, and both pulse pressure variation and change in pulse pressure variation from baseline during a tidal volume challenge by increasing tidal volume (VT) to 8 ml.kg^-1.

Methods: This study is a prospective single-center study, performed in a medical intensive care unit, on ARDS patients with acute circulatory failure in the prone position. Patients were studied at baseline, during a 1-min shift to the Trendelenburg position, during a 15-s end-expiratory occlusion, during a 1-min increase in VT to 8 ml.kg^-1, and after fluid administration. Fluid responsiveness was deemed present if cardiac index assessed by transpulmonary thermodilution increased by at least 15% after fluid administration.

Results: There were 33 patients included, among whom 14 (42%) exhibited cardiac arrhythmia at baseline and 15 (45%) were deemed fluid-responsive. The area under the receiver operating characteristic (ROC) curve of the pulse contour-derived cardiac index change during the Trendelenburg maneuver and the end-expiratory occlusion test were 0.90 (95% CI, 0.80-1.00) and 0.65 (95% CI, 0.46-0.84), respectively. An increase in cardiac index ≥ 8% during the Trendelenburg maneuver enabled diagnosis of fluid responsiveness with sensitivity of 87% (95% CI, 67-100), and specificity of 89% (95% CI, 72-100). The area under the ROC curve of pulse pressure variation and change in pulse pressure variation during the tidal volume challenge were 0.52 (95% CI, 0.24-0.80) and 0.59 (95% CI, 0.31-0.88), respectively.

Conclusions: Change in cardiac index during a Trendelenburg maneuver is a reliable test to predict fluid responsiveness in ARDS patients in the prone position, while neither change in cardiac index during end-expiratory occlusion, nor pulse pressure variation during a VT challenge reached acceptable predictive performance to predict fluid responsiveness in this setting.

Trial registration: ClinicalTrials.gov, NCT01965574 . Registered on 16 October 2013. The trial was registered 6 days after inclusion of the first patient.

Keywords: Acute circulatory failure; Acute respiratory distress syndrome; Cardiac output; Fluid responsiveness; Prone position; Protective ventilation.

Fig. 1

Trendelenburg maneuver. a Starting position of the Trendelenburg maneuver with bed angulation +13°. b Trendelenburg position with a −13° downward bed angulation. c Pressure transducers taped on the thorax at the phlebostatic reference point

Fig. 2

Individual values from five diagnostic tests to detect fluid responsiveness in fluid responders and non-responders. Closed circles are individual values. Red dotted lines display optimal thresholds for each diagnostic test computed by receiver operating characteristic (ROC) curve analysis. a. ΔCCI_TREND, change in continuous cardiac index during the Trendelenburg maneuver; b. PPV_BASELINE-1, pulse pressure variation during ventilation with 6 ml.kg^-1 predicted body weight tidal volume; c. PPV_VT8, pulse pressure variation during ventilation with 8 ml.kg^-1 predicted body weight tidal volume; d. ΔPPV_6-8, change in pulse pressure variation between ventilation with 6 and 8 ml.kg^-1 predicted body weight tidal volume; e. ΔCCI_EEO, change in continuous cardiac index during end-expiratory occlusion

Fig. 3

Relationship between change in continuous cardiac index during the Trendelenburg maneuver (ΔCCI_TREND) and change in transpulmonary thermodilution-cardiac index by volume expansion (ΔCI_VE). The black line is the regression line. The shaded area is the 95% confidence interval of the regression line. There are 33 data points presented although some data points are overlapping

Fig. 4

Receiver operating characteristics curves from five diagnostics tests to detect fluid responsiveness. ΔCCI_TREND, change in continuous cardiac index during the Trendelenburg maneuver; ΔCCI_EEO, change in continuous cardiac index during end-expiratory occlusion; PPV_BASELINE-1, pulse pressure variation during ventilation with 6 ml.kg^-1 predicted body weight tidal volume; PPV_VT8, pulse pressure variation during ventilation with 8 ml.kg^-1 predicted body weight tidal volume; ΔPPV_6-8, change in pulse pressure variation between ventilation with 6 and 8 ml.kg^-1 predicted body weight tidal volume

Fig. 5

Sensitivity and specificity of each diagnostic test according to the value of the diagnostic cutoff. Blue and red data points are sensitivity and specificity, respectively, computed at each value of the diagnostic cutoff. Blue and red curves are fitted curves to sensitivity and specificity computed values. The 95% confidence intervals for optimal value of cutoff are depicted as a shaded zone (gray zone defining inconclusive response). ΔCCI_TREND, change in continuous cardiac index during the Trendelenburg maneuver; ΔCCI_EEO, change in continuous cardiac index during end-expiratory occlusion; PPV_BASELINE-1, pulse pressure variation during ventilation with 6 ml.kg^-1 predicted body weight tidal volume; PPV_VT8, pulse pressure variation during ventilation with 8 ml.kg^-1 predicted body weight tidal volume; ΔPPV_6-8, change in pulse pressure variation between ventilation with 6 and 8 ml.kg^-1 predicted body weight tidal volume