New Study Evaluates the Use of Masimo PVi® As an Indicator of Fluid Responsiveness to Guide Goal-Directed Fluid Therapy in Elderly Patients Undergoing Gastrointestinal Surgery
Researchers Found That Fluid Therapy Guided by Noninvasive, Continuous PVi Reduced Cardiopulmonary Complications and Fluid Administered
Masimo (NASDAQ: MASI) today announced the findings of a prospective, randomized study published in Perioperative Medicine in which Dr. Yu Wang and colleagues at institutions in Shenzhen, Shaoguan, and Guangzhou, China evaluated the use of noninvasive, continuous Masimo PVi®, as part of goal-directed fluid therapy (GDFT), to guide intraoperative fluid administration during gastrointestinal (GI) surgery on elderly patients by comparing it to conventional fluid therapy. The researchers found that patients in the PVi group had a significantly lower rate of cardiopulmonary complications (8.4% vs 19.2%) and had a significantly lower total volume of fluid administered (median 2075 ml vs. 2500 ml).1
Noting the particular value of optimizing fluid management during GI procedures, especially in elderly patients, because of the high rate of postoperative complications and frequent fluid deficits (because of preoperative fasting, bowel preparation, and intraoperative fluid loss), the researchers sought to determine whether GDFT using Masimo PVi might improve outcomes in this challenging scenario. PVi, or pleth variability index, is a measure of the variations in perfusion index over the respiratory cycle, and has the advantage, compared to arterial line-based methods of gauging fluid responsiveness (e.g. stroke volume variation [SVV] and pulse pressure variation [PPV]), of being obtained via noninvasive Masimo rainbow SET® pulse oximetry and Pulse CO-Oximetry. PVi is indicated as a noninvasive, dynamic indicator of fluid responsiveness in select populations of mechanically ventilated adult patients. As the researchers note, PVi has been shown to perform similarly to invasive methods of fluid assessment, such as PPV and SVV, in a variety of surgeries.2
The researchers enrolled patients aged ≥ 65 years scheduled for elective GI surgery at two university hospitals between November 2017 and December 2020. Patients were randomly assigned to the GDFT group (n = 107) or the conventional fluid therapy (CFT) group (n = 104). In the GDFT group, fluid therapy was guided by PVi obtained from the photoplethysmographic waveform measured by fingertip rainbow® Pulse CO-Oximetry sensors. The outcomes evaluated and compared between the two groups were: composite complications at 30 days after surgery; cardiopulmonary complications at 30 days (pneumonia, atelectatis, pulmonary edema, arrhythmia, and acute myocardial infarction); time to first flatus; postoperative nausea and vomiting; infections including anastomotic leak rates; and postoperative length of hospital stay.
The researchers found that the rate of cardiopulmonary complications, as well as the total volume of fluid administered intraoperatively, were statistically significantly lower in the GDFT (PVi) group, as highlighted in the table below. Although there was a trend toward shorter length of stay and lower anastomotic leakage rates in the PVi group, these and other outcomes were not statistically significantly different.
*A p-value < 0.05 was considered statistically significant.
The researchers concluded, “Among elderly patients undergoing GI surgery, intraoperative GDFT based on the simple and noninvasive PVi did not reduce the occurrence of composite postoperative complications but was associated with a lower cardiopulmonary complication rate than usual fluid management.”
Joe Kiani, Founder and CEO of Masimo, said, “We introduced PVi in 2007. It was the first and is still the only way of measuring fluid responsiveness noninvasively via pulse oximetry, with our pulse oximeters, at a fraction of the cost of invasive methods and without risk of invasive procedures to the patient. Since then, PVi has made a tremendous contribution to patient care, and its utility as a fluid responsiveness indicator has been shown in more than 100 independent, published studies.2 This latest study adds to the outcomes evidence that PVi can be used to help clinicians manage the fluid levels of their patients without invasive catheters.”
In the U.S., PVi is FDA 510(k) cleared as a noninvasive dynamic indicator of fluid responsiveness in select populations of mechanically ventilated adult patients. Accuracy of PVi in predicting fluid responsiveness is variable and influenced by numerous patient, procedure and device related factors. PVi measures the variation in the plethysmography amplitude but does not provide measurements of stroke volume or cardiac output. Fluid management decisions should be based on a complete assessment of the patient’s condition and should not be based solely on PVi.
