Noninvasive, continuous PVi performed well; pressure-based invasive techniques performed poorly


Masimo Root with PVi (Credit: Business Wire)

Masimo (NASDAQ: MASI) today announced the findings of a prospective study published in Pediatrics International in which Dr. Ya-Fei Liu and colleagues at Peking University First Hospital in Beijing evaluated the ability of noninvasive, continuous Masimo PVi, alongside other dynamic parameters, to predict fluid responsiveness in children 1-3 years old who were undergoing major neurosurgery. The researchers concluded, “Volume-based PVi and ∆Vpeak [respiratory variation in aortic blood flow peak velocity] showed acceptable reliabilities for fluid responsiveness prediction in young children undergoing major neurosurgery, while pressure-based SVV [stroke volume variation] using FloTrac/Vigileo, Eadyn [dynamic arterial elastance], and PPV [pulse pressure variation] [did] not.”

Noting that dynamic variables have been shown to predict fluid responsiveness more accurately than static variables, and the critical importance of optimizing fluid administration in pediatric surgical patients, the researchers sought to evaluate and compare the performance of a variety of dynamic variables in such a scenario. The parameters evaluated were noninvasive, continuous PVi (pleth variability index, obtained from the photoplethysmographic waveform measured by fingertip pulse oximetry sensors and, in this study, the Masimo Radical-7 Pulse CO-Oximeter), ∆Vpeak (obtained intermittently by Doppler echocardiography), SVV (measured by the Edwards Lifesciences FloTrac/Vigileo system), PPV (obtained from the peripheral arterial pressure waveform), and Eadyn (an index of arterial load).

The researchers enrolled 60 patients, aged 1-3, who were undergoing major neurosurgery with mechanical ventilation set at a fixed tidal volume of 8 ml/kg. Following induction of anesthesia, during a hemodynamically stable period, the patients were administered 10 ml/kg of Ringer’s lactate solution, over 10 minutes; all variables were measured before and within five minutes of fluid loading. Patients with an increase in cardiac index (CI) of 10% or more were identified as a fluid responder. (CI was defined as stroke volume index multiplied by heart rate.)

The researchers identified 26 of the 60 patients as fluid responders. They found that baseline PVi showed “fair diagnostic accuracy” for CI-fluid responsiveness, with an area under the receiver operating characteristic curve (AUROC) of 0.775, p < 0.001. A baseline PVi cutoff value of 15% predicted CI-fluid responsiveness with 77% sensitivity and 68% specificity. Baseline ∆Vpeak was an “excellent predictor” of a CI increase, with AUROC of 0.982, p < 0.001, and a cutoff value of 9.6%. However, ∆Vpeak, which is dependent on the timing of echocardiograms, can only be obtained intermittently; the authors also note, as a practical drawback, that the limited availability of echocardiographic professionals “decreases its wide use in routine clinical settings.” The researchers found the other methods were either “poor” or “were not” predictors.

The researchers concluded, “Volume-based PVI and ∆Vpeak showed acceptable reliabilities to predict fluid responsiveness, defined by a CI increase, after anesthesia induction in mechanically ventilated young children undergoing major neurosurgery. However, pressure-based FloTrac/Vigileo-derived SVV, Eadyn, PI, PPV, and SVIc were not or [were] poorly reliable predictors. PVi’s noninvasiveness, continuity and acceptable predictability for fluid responsiveness could make it a potential aid in evaluating hemodynamic status, facilitating fluid administration, and developing optimal fluid management protocols in young children undergoing neurosurgery.”

Joe Kiani, Founder and CEO of Masimo, said, “From its inception, Masimo has focused on developing technologies that improve outcomes for the very youngest and most fragile of patients. This latest study on PVi – the second we are reporting on just this week! – adds to the body of evidence that PVi can help clinicians predict fluid responsiveness.”

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.

Source: Company Press Release