Pain is an expected part of surgical recovery but effective pain management remains challenging. The high variability in postoperative pain experience and analgesic treatment response between patients is part of the challenge. Few studies have yet combined preoperative assessment of responses to experimental pain with measurements of cognitive and emotional processes in the prediction of postoperative pain.

We hypothesize, that preoperative evoked brain potentials (using standard electroencephalographic brain imaging), endogenous pain inhibition capacity (conditioned pain modulation), responses to pressure/thermal pain stimulation, and/or situational pain-related catastrophic thinking are useful clinical predictors of postoperative pain and analgesic consumption.

Preselected preoperative predictor variables/individual patient characteristics include the following:

• Evoked brain potentials (using standard electroencephalographic brain imaging)
• Capacity of descending pain inhibition induced by a cold pressor test (2C in 120 sec)
• Pressure pain detection and tolerance thresholds in muscle (m.quadriceps)
• Pressure pain tolerance thresholds in bone (sternum and tibia)
• Heat pain tolerance threshold in skin (forearm)
• Responses to the Situational and Dispositional Pain Catastrophizing Scale
• Response to the State-Trait and Anxiety Inventory
• Response to the Beck's Depression Inventory

Inclusion Criteria:

• Elective minimally invasive surgical correction of funnel chest (pectus excavatum
• age ≥15 years.

Exclusion Criteria:

• Previous thoracic surgical interventions
• Presence of diseases affecting the central and/or peripheral nervous system
• Presence of chronic pain conditions
• Inability to speak and/or understand Danish
• Inability to understand and participate in the experimental pain session
• Presence of psychiatric disorders
• History of frostbite in the non-dominant upper limb
• Presence of sores or cuts on non-dominant upper limb
• Presence of cardiovascular disease
• History of fainting and/or seizures
• Presence of fractures of the non-dominant upper limb
• Presence of Reynaud's phenomenon.

Secondary exclusions included:

• Insensitivity to experimental cold pressor pain
• Lack of epidural catheter placement
• Re-operation

Patients with funnel chest (pectus excavatum) undergoing corrective chest wall surgery at Aarhus University Hospital