Pleth variability index predicts hypotension during anesthesia induction

The pleth variability index (PVI) is a new algorithm used for automatic estimation of respiratory variations in pulse oximeter waveform amplitude, which might predict fluid responsiveness. Because anesthesia-induced hypotension may be partly related to patient volume status, we speculated that pre-anesthesia PVI would be able to identify high-risk patients for significant blood pressure decrease during anesthesia induction.

We measured the PVI, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) in 76 adult healthy patients under light sedation with fentanyl to obtain pre-anesthesia control values. Anesthesia was induced with bolus administrations of 1.8 mg/kg propofol and 0.6 mg/kg rocuronium. During the 3-min period from the start of propofol administration, HR, SBP, DBP, and MAP were measured at 30-s intervals.

HR, SBP, DBP, and MAP were significantly decreased after propofol administration by 8.5%, 33%, 23%, and 26%, respectively, as compared with the pre-anesthesia control values. Linear regression analysis that compared pre-anesthesia PVI with the decrease in MAP yielded an r value of -0.73. Decreases in SBP and DBP were moderately correlated with pre-anesthesia PVI, while HR was not. By classifying PVI >15 as positive, a MAP decrease >25 mmHg could be predicted, with sensitivity, specificity, positive predictive, and negative predictive values of 0.79, 0.71, 0.73, and 0.77, respectively.

Pre-anesthesia PVI can predict a decrease in MAP during anesthesia induction with propofol. Its measurement may be useful to identify high-risk patients for developing severe hypotension during anesthesia induction.