Using ventilation-induced plethysmographic variations to optimize patient fluid status

Purpose of review Hypovolemia is one of the most frequent causes of arterial hypotension in the operating room. Pulse oximeter plethysmographic waveform, obtained using a noninvasive and widely available device, has recently shown its potential interest in predicting fluid responsiveness in mechanically ventilated patients under mechanical ventilation. This review highlights new applications of this routine monitoring. Recent findings Respiratory variations in the plethysmographic waveform amplitude have been correlated with respiratory variations in arterial pulse pressure and can predict fluid responsiveness in mechanically ventilated patients under general anesthesia. Until recently, pulse oximeter plethysmographic waveform had to be recorded and analyzed off line using software algorithms. Bringing this new index into the clinical field would require devices allowing for automated and continuous real time calculation. Such devices will have potential to guide fluid optimization in the operating room. Summary Automatic detection of respiratory variations in pulse oximetry plethysmographic waveform amplitude can predict fluid responsiveness in the operating room in patients under mechanical ventilation and has potential for fluid optimization in this setting.