Continuous Local Anesthetic and Steroid Infusion in Abdominal Surgery

The aim of the study is the identification, comparing continuous infusion of local anesthetics and steroids intralesionally with the current gold standard therapy (PCA), of the effective dose of local anesthetics and steroids within 7 days following abdominal surgery in order to halve the consumption of opioids and give the best pain control with a lower incidence of side effects and persistent chronic pain (at 1 and 3 months) We also plan to measure the peripheral inflammation and oxidative stress by analyzing the pro-inflammatory cytokines and anti-inflammatory properties. Another objective is to investigate the combined effect of polymorphisms of genes related to pain sensitivity, and the correlation with the development of the inflammatory response and the incidence of chronic post-surgical pain (CPSP), which will be considered to validate the genotype-phenotype correlations. The intralesional catheter will be placed within the operating field by the surgeon at the end of the procedure. * first postoperative 24 hours: ropivacaine 0.2%-methylprednisolone 1 mg/kg/die infusion (10ml/h) in the wound. Rescue dose with morphine via intravenous PCA (0.5 mg/ml, bolus 1 mg, lock-out 5 min, max 20 mg in 4 hours) * from 24 hs to 48 hs: ropivacaine 0.2%-methylprednisolone 1 mg/kg/die infusion (10ml/h) or saline 0.9% 10 ml/h in the wound. Rescue dose with morphine via intravenous PCA (0.5 mg/ml, bolus 1 mg, lock-out 5 min, max 20 mg in 4 hours) . from 48 hs to 7th day: ropivacaine 0.2% or saline 0.9% via patient controlled intralesional analgesia (PCIA) (2 mg/ml, bolus 20 mg, lock-out 60 min, max 80 mg in 4 hours). Rescue dose Tramadol 100 mg. The first assessment will be by the anesthetist pre-operatively, to verify the patient eligibility. All patients will be evaluated at the end of surgery (T0) and after 3-6-12-24-36-48 hours after surgery. Further evaluations are scheduled every 24 hours until the seventh postoperative day. At each assessment will be recorded: Nume