To investigate whether the pleth variability index, a noninvasive and continuous tool, can predict fluid responsiveness in mechanically ventilated patients with circulatory insufficiency.
Surgical intensive care unit of a university hospital.
Forty mechanically ventilated patients with circulatory insufficiency in whom volume expansion was planned by attending physician. Exclusion criteria included spontaneous respiratory activity, cardiac arrhythmia, known intracardiac shunt, severe hypoxemia (Pao2/Fio2 <100 mm Hg), contraindication for passive leg raising, left ventricular ejection fraction of <50%, and hemodynamic instability during the procedure.
Fluid challenge with 500 mL of 130/0.4 hydroxyethyl-starch if respiratory variations in arterial pulse pressure were ≥13% or with passive leg raising if variations in arterial pulse pressure were <13%.
Pleth variability index, variations in arterial pulse pressure, and cardiac output estimated by echocardiography were recorded before and after fluid challenge. Fluid responsiveness was defined as an increase in cardiac output of ≥15%. Twenty-one patients were responders and 19 were nonresponders. Mean ± sd pleth variability index (28% ± 13% vs. 11% ± 4%) and arterial pulse pressure variation (22% ± 11% vs. 5% ± 2%) values at baseline were significantly higher in responders than in nonresponders. The pleth variability index threshold value of 17% allowed discrimination between responders and nonresponders with a sensitivity of 95% (95% confidence interval, 74% to 100%) and a specificity of 91% (95% confidence interval, 70% to 99%). The pleth variability index at baseline correlated (r = .72, p < .0001) with the percentage change in cardiac output induced by fluid challenge, suggesting that a higher pleth variability index at baseline will correlate with a higher percentage change in cardiac output after volume expansion.
The pleth variability index can predict fluid responsiveness noninvasively in intensive care unit patients under mechanical ventilation.
From Centre Hospitalier et Universitaire de Poitiers (TL, HN, DF, FP, LL, DB, BD, CD, OM), Institut National de la Santé Et de la Recherche Médicale ERI 23 (FP, LL, BD, CD, OM), and Université de Poitiers (BD, CD OM), Unité de Formation et de Recherche de Médecine-Pharmacie, Poitiers, France.
Supported, in part, by Masimo (Irvine, CA), supplier of the Radical-7 monitor and the sensor used for PVI measurement. The manufacturer had no input into the design or conduct of this study or in the decision to submit the manuscript for publication.
The authors have not disclosed any potential conflicts of interest.
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