Plethvariability index to predict hemodynamic variability (PVI) during cesarean delivery - A new approach using novel algorithm
Abstract Number: 184
Abstract Type: Original Research
Plethvariability index (PVI, Massimo Corp. CA) and Pleth Index (PI) are novel algorithms derived from pulse oximetry waveforms. They are being validated for noninvasive assessment of circulatory status during anesthesia and critical care in non pregnant subjects. The trending of these non invasive variables has not been evaluated in obstetrics. The purpose of this study is twofold. (1) Define the trending of these variables during cesarean delivery. (2)Determine if the differences between preoperative PI and PVI variables between the left lateral decubitus position (LUD) and the standing position predict hemodynamic instability during intrathecal anesthesia for cesarean delivery.
Healthy parturients with a singleton pregnancy scheduled for elective cesarean section were selected and a reusable Masimo RainbowTM SET Radical 7TM pulse, (Irvine, CA) oximetry probe was placed on the index finger. Preoperative fluid administration, vital signs, pleth variability and perfusion indices were taken while in left uterine displacement, lateral decubitus and standing positions. Spinal anesthesia (hyperbaric bupivacaine 13 mg) was administered in the usual fashion. Intraoperatively, values for above variables were taken at five minute intervals by a separate investigator. Vasopressors were used to maintain blood pressure within 20% of baseline.
There is significant decrease in PI (P<0.05), and an increase in PVI and heart rate (P<0.05) on acquiring standing position from supine with LUD position. Vasopressor and fluid therapy normalized the PI. There is a significant increase in PI as compared to baseline following baby delivery most likely due to autotransfusion (P<0.05). Finally, there is correlation between the increased variations in PVI between supine LUD position and standing positions with the increased requirements of ephedrine during cesarean delivery (P<0.05).
Conclusion: Noninvasive novel pulse oximetry PVI algorithm seems to predict increased requirement of vasopressors during cesarean delivery. Furthermore, PI may be a useful alternative to follow during cesarean delivery in evaluating the need of vasopressor therapy.
1. Anesthesia and Analgesia 2008;4:1190
2. Brit J Anaesth 2008;101:200