The Ability of Pulse Oximetry-Derived Peripheral Perfusion Index as a New Predictor of Fluid Responsiveness in Critically Ill Patients

Background: Prediction of fluid responsiveness (FR) is of utmost significance in management of critically-ill patients. Echocardiography is a bedside, feasible tool in assessment of FR. Based on passive leg raising test (PLR), pulse oximetry-derived peripheral perfusion index (PPI) can be utilized in prediction of FR in critical-ill cases.
Aim: This study aimed to investigate the ability of pulse oximetry-derived PPI as a new predictor of FR in critically-ill patients.
Methods: This study included 95 critically-ill patients, after PLR test, 36 of our patients were found to be fluid responsive and 59 patients were fluid non-responsive. FR was defined by increase in ≥ 10% increase in left ventricular outflow tract (LVOT) velocity time integral (VTI) (LVOT-VTI) after PLR test. Bedsides, echocardiography and pulse co-oximetry were used to measure LVOT-VTI and PPI before and after both PLR and 200 mL fluid challenge with Ringer’s solution in responders. Sequential Organ Failure Assessment (SOFA) score was calculated.
Results: VTI and PPI increased after PLR test compared to baseline values. ΔPPI showed moderate ability to detect fluid responder [A cutoff value of 0.28 achieved a sensitivity (Sn) of 75.0% and specificity (Sp) of 72.9%, with a positive predictive value (PPV) of 63.4%, a negative predictive value (NPV) of 81.5%, and an accuracy of 73.7%. A significant relationship was recorded between ∆PPI and ∆VTI caused by the fluid challenge.
Conclusion: Using bedside transthoracic echocardiography, PPI maneuver was a feasible, sensitive and highly specific method for prediction of fluid-responsiveness in critically-ill patients.