Background: In perioperative period inhibition of N-Methyl-D-Aspartate receptor prevents opioid-induced hyperalgesia and reduce postoperative opioid requirement after abdominal surgery. Methadone is both a µ-opioid receptor agonist like Morphine and a N-Methyl-D-Aspartate antagonist. Study Aim. To evaluate the efficacy of intraoperative Ketamine and postoperative Methadone analgesia in preventing opioid-induced hyperalgesia after abdominal surgery.
not desired
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
113
Ketamine infusion scheme: 5mcg/Kg/min from induction od anaesthesia for 10 min, than 2,5mcg/Kg/min for 20 min and than 2 mcg/Kg/min to the end of surgery
Methadone administered by a PCA system (dose 2 mg, lock-out 12min.)
Fondazione IRCCS Istituto Nazionale dei Tumori
Milan, Italy
the Extent of Hyperalgesia Area Proximal to Surgical Wound
Hyperalgesia is determined by stimulating with a won Fray hair N°16 along three lines at a right angle to the top, middle, and bottom sides of the surgical incision. Each line starts from the edge of the abdomen to the surgical incision. Stimulation continue from the edge toward the surgical incision until the patients reported a worsening in sensation The distance from the incision to where sensation change was measured. The mean of the three assessments was used as a measure of the extent of the hyperalgesia area.
Time frame: 24 and 48 hours after surgery
Pain Intensity Measured by a Numeric Rating Scale (NRS)
A Numerical Rating Scale (NRS) from 0 to 10 is used as a measure of pain intensity. Zero indicates the absence of any pain and 10 the worse pain never felt.
Time frame: 24 and 48 hours after surgery
Opioid Consumption
Cumulative opioid consumption at 48 hours from surgery ( end of the study)
Time frame: 48 hours
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