In patients under standardized steady-state general anesthesia, 6 tetanic stimulations of incremental intensities were applied to the patients. Pupillary dilation in response to these stimulations was recorded.

The aim of the study was to investigate a possible correlation between the intensity of a nociceptive stimulus and the magnitude of pupillary reflex dilation in patients anesthetized with propofol and remifentanil target-controlled infusion.

Anesthetic protocol: 10 minutes of steady-state general anesthesia (before extubation during a scheduled gynecological surgery) with remifentanil target concentration of 1 ng/ml, and propofol target concentration adjusted to maintain bispectral index between 45 and 55.

Study period: 6 tetanic stimulations of incremental intensities were applied to the patients: 10, 20, 30, 40, 50, 60 milliamps Pupillary dilation in response to these stimulations was recorded.

Then, propofol and remifentanil infusions were discontinued, and patients were extubated.

Inclusion Criteria:

• Scheduled gynecological surgery requiring general anesthesia and orotracheal intubation
• written informed consent

Exclusion Criteria:

• ophthalmic disease
• neurologic disease
• preoperative chronic pain or pain medication
• medication interfering with autonomous nervous system (beta blockers, alpha agonists, metoclopramide, droperidol, atropine, catecholamines)