Photoplethysmography Response to Laryngeal Mask Airway Insertion during Propofol-Remifentanil Anethesia.

The present study was aimed to evaluate the abilities of photoplethysmography (PPG)-derived parameters, including sample entropy of PPG (SampEn), amplitude of PPG (PPGA), pulse beat interval (PBI) and diastolic interval (DI) extracted by nonlinear or linear methods, to monitor the balance between nociception and antinociception. 26 ASA I or II patients were randomized into one of the three groups to receive a remifentanil effect-compartment target controlled infusion (Ceremi) of 1, 3 and 5 ng/ml and an effect-compartment target controlled propofol infusion (Ceprop) to keep the state entropy (SE) at 50 (40~60). Laryngeal mask airway (LMA) insertion was applied as a noxious stimulus. The percentage of change in SampEn (△SampEn, AUC=0.896), PBI (△PBI, AUC=0.896) and DI (ΔDI, AUC=0.972), but not in PPGA (△PPGA, AUC=0.667), were statistically excellent in discriminating low Ceremi (1 ng/ml) from higher Ceremi (3 and 5 ng/ml). Additionally, the prediction probabilities (Pk) values of △SampEn, ΔPBI and ΔDI were high as well with 0.795, 0.754 and 0.813 for discriminating Ceremi. These results demonstrated that nonlinear and linear parameters of SampEn, PBI and DI had strong dependency on Ceremi in response to LMA insertion and could provide nociceptive information during propofol-remifentanil anesthesia. This indicated that PPG-derived parameters were potential to develop the clinical assessment of nociception-antinociception balance under general anesthesia.