Fluid resuscitation is essential to treat hypovolemia and restore organ perfusion. Respiratory variation in arterial pulse pressure is a reliable predictor of fluid responsiveness in mechanically ventilated patients with circulatory failure. Respiratory variation in arterial pulse pressure is a reliable predictor of fluid responsiveness in mechanically ventilated patients. Respiratory variations in Pulse Oximetry Plethysmographic waveform peaks also correlate with pulse pressure variability in similar settings.