Some surgeries, such as tonsillectomies, are particularly painful postoperatively because they are not very accessible to a complementary technique of loco-regional anesthesia and require the use of opioids in the postoperative period.

The use of opioids, in combination with usual analgesics, is common after this surgery. However, some risks are associated with the use of morphine in children, including more frequent respiratory distress, nausea and vomiting, and can cause hemorrhagic complications and lengthen the duration of hospitalization. Decreasing the consumption of morphine drugs is therefore a real challenge.

Although there is no randomized controlled study on the use of standard analgesics with or without morphine to date, a number of studies suggest that the use of morphine should not be systematic after a surgery.

The need for opioids after tonsillectomy as well as the level of pain vary between patients. Some teams use morphine at the end of general anesthesia to prevent pain on waking and others use it only if needed, once the child is awake.

Pain assessment scales are used in the Post-interventional Monitoring Room (PIMR) to adapt these analgesic therapies according to the intensity of pain. One of the validated and frequently used scales in pediatric PIMR is FLACC (Face Legs Activity Cry Consolability). Monitoring tools are also available to evaluate the quality of intraoperative analgesia in unconscious children :

• the analysis of the pupillary variation in response to a painful stimulus by videopupillometry,
• and the ANI (Analgesia Nociception Index) which consists of estimating the sympathetic-parasympathetic balance by a complex analysis of cardiac rhythm variability.

These two types of monitoring could predict which children will require post-operative morphine treatment.

To date, no study has demonstrated the relationship between videopupillometry and postoperative morphine consumption. The average ANI has already been evaluated in children as correlated with FLACC but both monitoring devices have never been compared for a predictive purpose.

The investigators hypothesize that the use of the PPI® (Pain Pupillary Index) scale of Algiscan® and the average ANI measured by the PhysioDoloris® monitor in children still sedated at the end of the intervention could have a prognostic value on post-operative morphine prescription.

Inclusion Criteria:

• Any child for whom tonsillectomy is programmed ≥ 2 years and up to 7 years inclusive
• Consent written and signed by at least one holder of exercise of parental authority

Exclusion Criteria:

• Eye disease
• Cardiac pathology
• Neurological pathology
• Chronic opioid treatment
• Any treatment interfering with the autonomic nervous system
• Any contraindication to NSAIDs