Incidence of persistent postoperative pain after hepatectomies with 2 regimes of perioperative analgesia containing ketamine

Abstract

Studies designed to assess persistent postoperative pain (PPP) incidence after hepatectomies are lacking. Our aim was to assess PPP incidence 6 months after hepatectomies with intravenous (IV) or epidural (EPI) analgesia containing ketamine.Prospective observational comparative study between 2 cohorts of patients submitted to hepatectomy. Patients received 1 of 2 analgesic regimes containing ketamine: EPI group or IV group. Visual analog scale (VAS), Neuropathic Pain Symptom Inventory (NPSI), Pain Catastrophizing Scale (PCS), and quantitative sensorial testing (QST: to determine area of hyperalgesia/allodynia) were assessed preoperatively and postoperatively at 2 h, 24 h, 7 days, 1 month, and 6 months. VAS ≥ 1 at 1 and 6 months was considered indicative of PPP and VAS > 3 was considered as not controlled pain. Side effects and complications were registered.Forty-four patients were included: 23 in EPI group and 21 in IV group. Patients in IV group were older and had more comorbidities. No patient presented VAS > 3 at 1 or 6 months. VAS ≥ 1 at 1 and 6 months was 36.4% and 22.7%, respectively. No differences in VAS, NPSI, or PCS were found between groups. Allodynia/hyperalgesia area did not differ between groups and was infrequent and slight. Pain pressure threshold in the wound vertical component was significantly higher in EPI group after 7 days. IV group showed more cognitive side effects.Incidence of PPP at 6 months after open hepatectomies with EPI or IV analgesia containing ketamine was lower than previously reported for other abdominal surgeries.Ketamine influence on low PPP incidence and hyperalgesia cannot be discarded.

Incidence of contralateral neurosensitive changes and persistent postoperative pain 6 months after mastectomy

“…Incidence of PPP, defined as VAS > 3 at 6 months was 21.23%, similar to previous studies [ 21 , 22 ] ; 57.4% of patients reported VAS ≥ 1 at 6 months, a value that can be considered clinically irrelevant but has been used as threshold to define PPP in previous studies. [ 16 – 18 , 26 ] The most relevant finding of this study is the high incidence of MISD assessed by QST, which was present in almost 80% of patients. Furthermore, 15.6% of patients referred contralateral spontaneous pain (MIP).…”

“…This study applied a brief QST protocol which had been previously used by our group [ 16 , 18 ] as original QST testing is cumbersome, time–consuming and difficult to apply repeatedly in postoperative patients and therefore seldom published after surgery. Reference values for QST around surgical area are scarce.…”

“…Values of VAS > 3 were considered as non-controlled pain in the immediate postoperative period and as PPP at month 1 and 6. Based on the criteria used in previous studies, [ 16 , 18 , 26 ] VAS ≥ 1 values in the ipsilateral side after 1, 3, and 6 months in the above mentioned zones were recorded. Contralateral spontaneous pain (Mirror image pain), which has been reported as less intense [ 1 ] was defined as VAS ≥ 1 referred in the same zones but in the contralateral side of the surgery at any moment of the follow-up.…”

“…The process was repeated with the 4 tested VFM outlining an area of response on the skin for each VFM. As in previous studies from our group [ 16 , 17 ] this information was transferred to planimetry paper in order to calculate the size of the area. On the contralateral breast a line simulating the surgical incision was defined and measurements were done in the same manner.…”

“…A semi-objective exploration with quantitative sensory testing (QST) would allow detection of MISD. [ 5 ] Simplified QST protocols, such as the one previously used by our group [ 16 – 18 ] would permit repeated explorations in postoperative patients.…”