Despite various efforts there is still the need for adequate monitoring of pain and nociception during anesthesia. In a previous protocol the investigators measured pain responses during anesthesia based on single end-points, eg heart rate,blood pressure and pulse transit time. None of these parameters provided sufficient information regarding nociception. The investigators therefore want to further investigate this matter using a composite parameter, the Nociception Level or NoL. The NoL is a novel index that measures the magnitude of the autonomic response to painful stimuli. The NoL combines information from several physiological parameters, which represent different autonomic pathways. The multi-parameter approach empowered with state-of-the-art signal processing and machine learning techniques. In the current study the investigators will measure the NoL in ASA 1-3 patients undergoing elective surgery under general anesthesia. The investigators will measure NoL responses and the occurrence of patient movement upon the administration of a painful stimulus: Introduction of the laryngoscope, Insertion of the endotracheal tube, Insertion of the gastric tube, Insertion of the bladder catheter and Skin incision.

Inclusion Criteria:

• Age: 18-80 years;
• Sex: male or female;
• Surgery: Any surgery under general anesthesia;
• ASA status: 1, 2 or 3.

Exclusion Criteria:

• Age: < 18 or > 80 years;
• Unable to give written informed consent;
• Pregnancy/lactation;
• Extreme obesity: BMI > 35;
• Perceived difficult intubation.
• Patients requiring a rapid sequence induction
• Patients on beta-blockers