Predictor of fluid responsiveness in the ‘grey zone’: augmented pulse pressure variation through a temporary increase in tidal volume

• Published in: British journal of anaesthesia : BJA Vol. 119; no. 1; pp. 50 - 56
• Main Authors: Min, J.J., Gil, N.-S., Lee, J.-H., Ryu, D.K., Kim, C.S., Lee, S.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-07-2017; Oxford University Press
• Subjects: Adult; Aged; Aged, 80 and over; Blood Pressure; cardiac output; cardiovascular system; effects; Female; Fluid Therapy; heart; Heart Rate; Humans; intraoperative; Male; Middle Aged; monitoring; Positive-Pressure Respiration; Tidal Volume; Young Adult; cardiac output; intraoperative; cardiovascular system; effects; fluid therapy; monitoring; heart
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/aex074

Pulse pressure variation (PPV) is widely used as a predictor of fluid responsiveness. However, a previous study has suggested a ‘grey zone’ between 9 and 13% in which PPV would be inconclusive to predict fluid responsiveness. Considering PPV is based on cardiopulmonary interactions, we evaluated whether an augmented PPV using a temporary increase in tidal volume (VT) from 8 to 12 ml kg−1 has the predictability for fluid responsiveness in patients within the grey zone.
Adult patients requiring general anaesthesia were enrolled. During the period when PPV was within the range of 9–13%, haemodynamic variables such as stroke volume index (SVI) and PPV with an 8 ml kg−1 tidal volume ventilation (PPV8) were obtained before and after volume expansion (6 ml kg−1) under mechanical ventilation. Augmented PPV induced by 2-min ventilation with a VT of 12 ml kg−1 (PPV12) was also recorded immediately before volume loading. The patients whose SVI increased ≥10% after volume expansion were considered responders.
In 38 enrolled patients, 20 were responders. Receiver operating characteristic curve analysis showed PPV12 had an excellent predictability for fluid responsiveness {area under the curve [AUC]=0.935 [95% confidence interval (CI) 0.805–0.989]; sensitivity 95%; specificity 72%; P<0.0001}. The optimal threshold for PPV12 was >17%. However, PPV8 failed to show significant predictability [AUC=0.668 (95% CI 0.497–0.812); sensitivity 65%; specificity 61%; P=0.06].
In mechanically ventilated patients, our augmented PPV successfully predicted fluid responsiveness in the previously suggested grey zone.
ClinicalTrials.gov, NCT02653469.