Previous work has shown that NOL (Medasense, Ramat Gan, Israel) accurately quantifies nociception during general anesthesia. Presumably, titrating opioids to NOL will therefore provide individual guidance so that patients will be given about the right amount. Patient given the right amount will presumably awaken quickly when anesthesia is done, and have good initial pain control in the post anesthesia care unit (PACU). To the extent that NOL titration facilitates optimal opioid dosing, patients are likely to have better PACU experiences - which would be an important outcome that clinicians and regulators are likely to take seriously.

Inclusion Criteria:

1. Adults having major non-cardiac surgery expected to last ≥2 hours;
2. American Society of Anesthesiologists physical status 1-3;
3. Age 21-85 years old;
4. Planned endotracheal intubation

Exclusion Criteria:

1. Planned neuraxial or regional block;
2. Local anesthetic infiltration at surgical field;
3. Clinician preference for an opioid other than, or in addition to, fentanyl;
4. Non-sinus heart rhythm;
5. Neurologic condition that, in the opinion of the investigators, may preclude accurate assessment of postoperative pain and nausea;
6. Lack of English language fluency;
7. Routine user of psychoactive drugs other than opioids;
8. Contraindication to sevoflurane, fentanyl, morphine, or ondansetron.
9. Intracranial surgery
10. BMI > 40

Anesthesia clinicians cannot be blinded since they will need to titrate opioid administration to NOL. However, all postoperative care and evaluations will be fully blinded to randomization, thus preventing measurement bias