Masimo, the inventor of Pulse CO-Oximetry and Measure-Through Motion and Low Perfusion pulse oximetry, has said that its pleth variability index (PVI) can be used to help clinicians assess risk for mean arterial pressure (MAP) decreases and subsequent hypotension during anesthesia administration.

Masimo said that, according to a new clinical study published in the May 2010 issue of Acta Anaesthesiologica Scandinavica, PVI may be ‘useful to identify patients at high risk for developing severe hypotension during anesthesia induction’, allowing ‘anesthesiologists to adopt preventive measures to ensure greater patient safety.’

The ability to properly identify patients at-risk for hypotension could help anesthesiologists to plan preventive strategies to reduce patient risk and ensure safer inductions. Anesthesia-induced hypotension is linked to both patient volume status and vascular tone, and previous studies have shown PVI’s association with the physiologic changes.

In the study, researchers from the Osaka City University Medical School in Japan measured PVI (via the Masimo Radical-7 Pulse CO-Oximeter), heart rate (HR), and blood pressure [systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP] in 76 healthy adult surgical patients at 30-second intervals before and during anesthesia induction (bolus administration of 1.8 mg/kg propofol and 0.6 mg/kg rocuronium).

The analysis demonstrated that HR, SBP, DBP, and MAP were significantly decreased after anesthesia administration by 8.5%, 33%, 23%, and 26%, respectively. Pre-anesthesia PVI, which ranged from 7 to 28 with a mean value of 16 +/- 5.5, correlated significantly (r -0.73) with the decrease in MAP.

Researchers also found that a pre-anesthesia PVI value >15 successfully predicted a decrease in MAP of >25 mmHg with 79% sensitivity, 71% specificity, 73% positive predictive value, and 77% negative predictive value. According to researchers, PVI represents an ‘easy to perform, noninvasive, and inexpensive method for predicting patients who may develop severe hypotension.’

Masimo said that the PVI may show changes that reflect physiologic factors such as vascular tone, circulating blood volume, and intrathoracic pressure excursions. PVI is available as part of Masimo Rainbow SET Pulse CO-Oximetry, a noninvasive monitoring platform capable of measuring multiple blood constituents that previously required invasive procedures.