Rationale: Surgical trauma and post-surgical pain induce a physiological stress response that can be detrimental to the patient. Non-pharmacological interventions aimed at stress reduction are known to reduce pain scores and opioid consumption. The effect of these interventions on the surgical stress response are unknown.

Objective: To assess the effect of a bundle of non-pharmacological interventions implemented in the post-anesthesia care unit on the total serum cortisol levels after intermediate and major surgery.

Study design: This is a prospective before-after study. Study population: Patients scheduled for intermediate or major oncological surgery in a tertiary referral cancer center.

Intervention: The implementation of a bundle of four non-pharmacological interventions aimed at stress reduction in the post-anesthesia care unit. The bundle consists of: access to music, aromatherapy, natural images on the walls and ceiling and communication techniques aimed at reduction of stress and pain.

Main study parameters/endpoints: Serum cortisol levels on the first postoperative day.

This protocol is a substudy of a larger observational before-after study that studies the effects of the planned implementation of a bundle of non-pharmacological interventions in the post-anesthesia care unit on pain scores, opioid consumption and quality of recovery.

In this current protocol, a subset of 90 surgical patients of a tertiary referral cancer centre in the Netherlands will be included and will be asked to provide informed consent for additional blood samples to be drawn to study the effects of the stress-reducing bundle on biomarkers of the surgical stress response.

45 eligible patients will be approached in the before-arm of the study and 45 will be included for the after-arm. Inclusion criteria are: planned for intermediate to major oncological surgery with an expected duration of >120 minutes, without the use of neuraxial anesthetic techniques. Patients with a planned postoperative ICU-admission will be excluded. After providing informed consent, they will be asked to complete a Quality of Recovery (QoR-15) questionnaire prior to surgery. Additional blood will be drawn with their routine preoperative blood sample on the morning of surgery to determine levels of cortisol, interleukine-6 (IL-6), glucose, C-reactive protein (CRP) and Neutrophil-Lymphocyte Ratio(NLR). The same blood sample will be drawn on arrival in the PACU and on the morning of the first postoperative day. Patients will also be asked to complete the QoR-15 questionnaire again on the first postoperative day.

The primary outcome will be serum cortisol level on the first postoperative day (as a biomarker of the surgical stress response).

Inclusion Criteria:

• ASA 1-3
• scheduled for intermediate to major oncological surgery
• with a minimum duration of 120 mins

Exclusion Criteria:

• Neuraxial anesthetic technique
• planned for postoperative ICU admission
• day case surgery
• Indication for peri-operative steroids
• chronic use of steroids
• Bronchial hyperreactivity

Adults scheduled for intermediate to major oncological surgery in a tertiary referral cancer centre in the Netherlands