Evaluation of Perfusion Index Change Post Passive Leg Raising for Fluid Responsiveness in Critically Ill

Peripheral Perfusion Index (PI) has been investigated for its use in hemodynamic monitoring. The PI is derived from the photoelectric plethysmographic signal of the pulse oximeter. The changes in the PI reflect changes in peripheral vasomotor tone. In critically ill patients, the same value was found to represent a very sensitive cutoff point for determining abnormal peripheral perfusion, as defined by a prolonged Capillary Refill Time (CRT). However, age, gender, and ambient temperature have all been shown to affect the measure of CRT in normal volunteers, and the presence of a CRT \> 2 or 3 seconds was not predictive of blood loss in phlebotomized volunteers. In addition, the CRT has been shown to have poor intra-observer agreement when a cutoff a two seconds was used in adult emergency room patients.13 Therefore, PI can be used for monitoring peripheral perfusion in critically ill patients.14PI shows the perfusion status of the tissue in the applied area for an instant and a certain time interval. The PI value ranges from 0.02% (very weak) to 20% (strong). As non-invasive CO monitors (ICON ®) is not available in many centers in our country due to its high cost, we try to validate other simple non-invasive method to be used to assess FR in critically ill patients. The purpose of this study is to investigate the efficacy of pulse-oximeter derived PI measurement in assessment of fluid responsiveness in critically ill patients in comparison with CO response.