Abstract: Objective · To observe the changes of perfusion index (PI), bispectral index (BIS), heart rate (HR), systolic blood pressure (SBP) and
respiratory rate (RR) under pulling stimuli in children undergoing open inguinal hernia repairs with spontaneous ventilation, so as to evaluate the clinical
value of PI in monitoring the stress response. Methods · Thirty children undergoing selective open inguinal hernia repairs with American Society of
Anesthesiologists (ASA) physical status I or II were recruited. Anesthesia was induced with fentanyl and propofol, and was maintained with sevoflurane
after the insertion of laryngeal mask. The PI, BIS, HR, SBP and RR were observed at the following time points: before induction of anesthesia (T0),
before pulling hernia sac (T1), at the time point of pulling hernia sac (T2), 1 min after pulling hernia sac (T3) and 5 min after pulling hernia sac (T4).
Results · Compared with the baseline level at T0, the PI value at T1, T3 and T4 increased significantly (P=0.000, P=0.033 and P=0.000, respectively).
The BIS, HR and SBP values at T1-T4 were significantly lower than baseline levels at T0 (all P=0.000). The PI values at T2 and T3 reduced significantly
compared with T1. The HR value at T2 was significantly higher than that of T1 (P=0.033). Compared with the SBP values at T1, the SBP values at T3 and T4
were significantly higher (P=0.000 and P=0.011, respectively). And the RR values at T2 and T3 were higher than that at T1 (both P=0.000). The proportion
of children with positive stress response based on PI was significantly higher than that based on other variables (all P=0.000). Conclusion · Perfusion
index can reflect the noxious stimuli of the pulling hernia sac effectively and immediately.

Key words: perfusion index, bispectral index, noxious stimuli, general anesthesia