Chronic Pain Following Inguinal Hernia Repair:a Retrospective Study And Intravenous Low Dose Ketamine For The Prevention Of Chronic Postoperative Pain

Part one:Efficacy of low dose of ketamine for chronic postoperative pain in patients undergoing inguinal hernia repairObjective:To evaluate the efficacy of low dose ketamine for chronic postoperative pain in patients undergoing inguinal hernia repair.Methods:Patients scheduled for elective unilateral inguinal hernia repair combined general anesthesia, were randomly divided into 2 groups:Ketamine group (group K) and Control group (group C).At induction the K group received 0.5mg/kg ketamine while the control group received the same amount of normal saline. Pain was assessed at return to ward,24h,48h after surgery by Visual Analogue Scale(VAS). After discharge, we contact patients by telephone to assess pain of patients using numerical rating scale (NRS). Patients were investigated by State-Trait Anxiety Inventory (STAI) on the day before operation and the day after operation,The C-reactive protein(CRP),the vital signs before induction and incision and the side effects like nausea and vomitting and delirium were recorded.Results:Compared with group C,pain scores were significantly decreased(P< 0.05).There are no significant difference between the two groups of the change of STAI. The CRP and the side effects like nausea and vomitting and delirium did not differ significantly (P> 0.05).While at induction, group K had slightly fewer reduction of heart rate and blood pressure than group C.Conclusion:The efficacy of low dose ketamine for chronic postoperative pain was better in patients undergoing inguinal hernia repair and the safety was higher.Part two:The incidence and risk factors of chronic postoperative pain following inguinal hernia repair a retrospective studyObjective. This research is to investigate the predictive risk factors and protective factors for chronic postoperative pain (CPOP) following inguinal hernia repair. This research is to investigate the predictive risk factors and protective factors for CPOP following inguinal hernia repair.Methods. This prospective study included 236 patients scheduled for inguinal hernia repair at a single tertiary medical center (2014.10-2015.6). We collected the predictive clinical factors of CPOP. Binary logistic analysis was used to determine the association between CPOP and clinical factors and built a CPOP risk model.Result. The prevalence of pain was 14.4% at 3 months after surgery. The risk model included 4 risk factors:(1) bilateral inguinal hernia repair (OR,4.44; 95% CI,1.62 to 12.17; P=0.004), (2) preoperative pain (OR,2.57;95% CI,1.14 to 5.79; P=0.023), (3) preoperative anxiety (OR,1.05;95% CI,1.01 to 1.09; P=0.018) and (4) severe acute pain at 1 week (OR,1.40;95% CI,1.03 to 1.91; P=0.031) were the risk factors for CPOP while the use of low-dose ketamine (OR,0.42;95% CI,0.18 to 0.98; P=0. 044) was the protective factor for CPOP in patients undergoing inguinal hernia repair.Conclusion. Bilateral inguinal hernia repair, preoperative pain, preoperative anxiety and severe acute pain at 1 week were the independent risk factors for CPOP while the use of low-dose ketamine was the protective factor. These findings may assist with primary prevention by allowing clinicians to screen for individuals with the risk of CPOP.