Intravenous or Intra-abdominal Local Anesthetics for Postoperative Pain Management. (PoPuLAR)

• Morphine consumption [ Time Frame: 0 - 24 h postoperatively ] [ Designated as safety issue: No ]
  Total rescue morphine consumption during 0 - 24 h would be the primary endpoint
  
  

• Postoperative pain [ Time Frame: 4 h postoperatively ] [ Designated as safety issue: No ]
  Postoperative pain measured on the numeric rating scale (0 - 10) would be measured at 4 h
  
  
• Plasma concentration of lidocaine [ Time Frame: 24 h ] [ Designated as safety issue: Yes ]
  The plasma concentration of LA lidocaine would be analysed at 24 h in order to assess whether the LA absorption from the abdomen is similar to that administered intravenously.
  
  
• Length of Hospital stay [ Time Frame: 1-5 days ] [ Designated as safety issue: No ]
  The time to discharge home would be assessed using standardized criteria for home discharge.
  
  

Abdominal hysterectomy with or without salipingo-oophorectomy is associated with moderate-severe postoperative pain. Poor pain control in the postoperative period can lead to increased postoperative morbidities and poor quality of life. Furthermore, an emerging clinical literature suggests that acute pain may rapidly evolve into chronic pain if poorly treated. A meta-analysis of the literature found that > 30% patients had chronic pain one year after abdominal hysterectomy (5). Therefore, efficient postoperative pain management is imperative for the patient and is one of the new pain management standards recommended recently.

Local anesthetics (LA) have been infiltrated subcutaneously, infused intra-abdominally, as well as injected into the peritoneal cavity as a single dose at the end of the operation following abdominal hysterectomy with variable effects. When injected as a single dose, analgesia is limited to approximately 2-4 hours due to the short duration of action of local anesthetics. In one recent study, the authors used a catheter inserted intra-abdominally and local anesthetic or placebo infusion into the abdominal cavity for 24 h postoperatively and found a reduction in postoperative analgesic requirements by 40% during 4-24 h. In another study, the investigators found that LA injected intermittently intra-abdominally resulted in better pain relief compared to intra-abdominal infusions.