Pulse pressure variation to predict fluid responsiveness in spontaneously breathing patients: Tidal vs forced inspiratory breathing

We evaluated whether pulse pressure variation can predict fluid responsiveness in spontaneously breathing patients. Fifty-nine elective thoracic surgical patients were studied before induction of general anaesthesia. After volume expansion with hydroxyethyl starch 6 ml.kg^-1, patients were defined as responders by a ≥ 15% increase in the cardiac index. Haemodynamic variables were measured before and after volume expansion and pulse pressure variations were calculated during tidal breathing and during forced inspiratory breathing. Median (IQR [range]) pulse pressure variation during forced inspiratory breathing was significantly higher in responders (n = 29) than in non-responders (n = 30) before volume expansion (18.2 (IQR 14.7-18.2 [9.3-31.3])% vs 10.1 (IQR 8.3-12.6 [4.8-21.1])%, respectively, p < 0.001). The receiver-operating characteristic curve revealed that pulse pressure variation during forced inspiratory breathing could predict fluid responsiveness (area under the curve 0.910, p < 0.0001). Pulse pressure variation measured during forced inspiratory breathing can be used to guide fluid management in spontaneously breathing patients.