Measurement of surgical stress in anaesthetized children

The surgical stress index (SSI), derived from a combination of heart rate (HR) and photoplethysmographic amplitude (PPGA) time series, is a novel method for continuous monitoring of intraoperative stress and has been validated in adults. The applicability of SSI and its constituents to monitoring children has not been previously evaluated. In this controlled trial, 22 anaesthetized patients, aged 4–17 yr, undergoing strabismus surgery were randomized into two groups, Group LL and Group BSS. Patients in Group LL received topical conjunctival anaesthesia with a 1:1 mixture of lidocaine 2% and levobupivacaine 0.75%, and patients in Group BSS received balanced salt solution. Endotracheal intubation (n=22) increased median (range) SSI from 39.2 (22.6–55.6) to 53.6 (35.8–63.3) (P