Plethysmography Variation Index (PVI) Utility In Guiding Goal-Directed Fluid Therapy During Major Abdominal Surgery

When considering intra-operative MAP maintenance, preload is a significant driving factor of stroke volume and therefore cardiac output. In major abdominal surgeries, large fluid shifts are common and accurate fluid resuscitation is extremely important to maintain hemodynamic stability and promote optimal patient outcomes. Invasive methods of measuring fluid status range from esophageal doppler derived flow time (FTc) and arterial line-derived metrics such as stroke volume variation (SVV) and pulse pressure variation (PPV). However, invasive means are not always warranted for every surgical procedure or patient and there is a higher potential risk for complication. Plethysmography Variation Index (PVI) has been introduced as a non-invasive alternative to gauge preload status, predict fluid responsiveness, and guide goal-directed fluid therapy. The success of PVI during major abdominal surgery is mixed. Significant predictive ability to determine fluid responsiveness exists and compares well to invasive techniques. However, the ability to track dynamic stroke volume (SV) changes correlates poorly with fluid bolus administration and PVI tracings. Overall, the total volume of fluid administered and post-operative patient outcomes all compare favorably with PPV, SVV, and FTc. Ultimately, the use of PVI during major abdominal surgery can be useful if fluid management is considered and approached in at least two distinct parts: first, recognition of hypovolemia and fluid responsiveness, to which PVI can accurately provide data; second, continued tracking of hemodynamic changes post bolus and the warranting of subsequent boluses, to which PVI is not well suited to direct