Evaluation of the Pupil Dilation Reflex in Response to Noxious Stimulation in Anaesthetized Children. A Proof of Concept Trial (Pain@OR-kids)

Evaluation of the Pupil Dilation Reflex in Response to Noxious Stimulation in Anaesthetized Children. A Proof of Concept Trial

Evaluation of the Pupil Dilation Reflex (PDR) Using a Pupillary Pain Index (PPI) Stimulation Protocol in Response to Noxious Stimulation in Anaesthetized Children. A Proof of Concept Trial

After conduction a pilot study, pupillary dilation reflex (PDR) is measured in response to nociceptive stimulation perioperatively in infants, children and adolescents.

An infrared camera of the video pupillometer measures the pupillary dilation reflex (PDR) in response to incremental nociceptive stimuli. The PDR is a robust reflex, even in patients under general anesthesia, and may provide a potential evaluation of the autonomous nociceptive circuit. American Society of Anesthesiologists (ASA) classification I or II patients from the age of 28 days till 18 years undergoing elective surgery under general anesthesia are recruited. Enrolled patients perioperative undergo PDR measurement at 2 different standardized times (before and after opioid administration) generated by an inbuilt pupillary pain index (PPI) protocol. PPI, as a surrogate for nociception includes noxious stimulations from 10 up to 60 milli ampere (mA) until pupil dilation is larger than 13% from baseline diameter. Therefore, no inappropriate high stimulation is executed.

Two measurements of PDR perioperatively before and after opioid administration in toddlers (28 days until 23 months)

Two measurements of PDR perioperatively before and after opioid administration in children (2 until 11 years)

Two measurements of PDR perioperatively before and after opioid administration in adolescents (12 until 18 years)

PDR measurement at two standardized times perioperatively: Anesthetized subject by sevoflurane sedation until a minimum alveolar concentration (MAC) of at least 1,5 is reached Administration of fentanyl 2µg/kg, in the absence of adjustments in sedation depth

Device specific PPI score defined in accordance to stimulation intensity necessary for pupil dilation more than 13%

Hypertension as a common used parameter for perioperative nociceptive assessment defined as an increase in systolic blood pressure by >10% of the initial systolic blood pressure

Inclusion Criteria: Scheduled abdominal, urological or otorhinolaryngology surgery under general anaesthesia ASA I-II Exclusion Criteria: History of eye deformity, invasive ophthalmologic surgery Known cranial nerve(s) deficit Infection of the eye Predicted difficult airway management (Paediatric Difficult Airway Guidelines - Difficult Airway Society) Chronic opioid use (>3 months) Ongoing treatment with beta-blockers, dopamine antagonists, topical atropine Preoperatively administrated benzodiazepins or antiemetics