Table 1 Inclusion and exclusion criteria
Inclusion criteria | Exclusion criteria |
|---|---|
• Healthy male (ASA I–II) | • Participant does not understand Danish |
• 18 ≤ age ≤ 65 years | • Participant is not cooperative |
• Patients submitted to elective, unilateral, primary, open groin herniarepair 6–8 weeks prior to study start | • Participant had previous surgery in the inguinal region |
• Open surgical procedure by the Lichtenstein method | • Pain at rest > 3 (NRS, 0–10) |
• Signed informed consent | • Activity-related pain in the surgical field > 5 (NRS, 0–10) |
• 18 kg/m2 < BMI < 30 kg/m2 | • Nerve lesions in the assessment sites (for instance, after trauma, disc herniation, etc.) |
• Urine sample without traces of opioids (morphine, methadone, buprenorphine, codeine, tramadol, ketobemidone, oxycodone, hydromorphone, dextromethorphan) | • Skin or nerve lesions or tattoos in the assessment areas |
|  | • Regular use of analgesic drugs (≥ twice a week) |
|  | • Allergy against morphine or other opioids (including naloxone) |
|  | • Alcohol or drug abuse |
|  | • Use of psychotropic drugs (except SSRI) |
|  | • Neurological or psychiatric disease |
|  | • Chronic pain condition |
|  | • Use of prescription drugs 1 week before the experimental days |
|  | • Use of over-the-counter drugs 48 hours before the experimental days |