Ultrasound Guided Distal Peripheral Nerve Blocks and Postoperative Pain.

Effectiveness of Distal Peripheral Nerve Blocks on Postoperative Pain Management After Ambulatory Thumb Resection Arthroplasty.

The aim of this clinical trial is to determinate if distal ultrasound guided peripheral nerve blocks on target nerves (radial and median nerve blocks at the elbow), using low volume and low concentration of long acting local anesthetic provide better postoperative pain control compare with systemic analgesia alone after thumb resection arthroplasty (TRA) due to a prolonged selective sensitive block on the tissue trauma.

We designed a prospective randomized controlled trial, with nursing blinded evaluation. We enrolled 52 patients scheduled for elective ambulatory TRA. 2 patients were excluded after randomization. Patients were randomized into two groups: A. Group A= no distal peripheral nerve blocks (no dPNBs group; n = 24 ): We performed usual anesthetic technique for surgery: an AXILLARY BRAQUIAL PLEXUS BLOCK using SHORT ACTING local anesthetic (mepivacaine 1%). Patients allocated in this group didn't received any additional intervention in the postoperative period. B. Group B (dPNBs group; n = 26): We performed the same anesthetic technique for surgery (AXILLARY BLOCK with 1% of mepivacaine) with an additional intervention. Patients allocated in this group received postoperatively dPNBs on target nerves. Based on surgical approached and technique we evaluated that radial and median nerves were responsible for the innervation of the surgical area, and therefore responsible for the postoperative pain. We performed dPNBs ON RADIAL AND MEDIAN NERVES (TARGET NERVES) WITH LONG ACTING AND LOW CONCENTRATION LOCAL ANESTHETIC (0,125% levobupivacaine 5ml/nerve). All blocks were performed under ultrasound guidance. Analgesic regime prescribed at discharge was the same in both groups: dexketoprofen with tramadol for rescue analgesia. The primary outcome was to evaluate the proportion of patients experienced moderate to severe pain during first and second day postoperatively, mesured using a numerical visual scale (NVS) of 0 to 10 (0= no pain and 10= worst pain imaginable). We defined mild pain (NVS 0-3), moderate pain (NVS 7-10) and severe pain (NVS 7-10). We considered dPNBs effective when patients experienced mild pain (NVS 0-3) for at least 6 hours after dPNBs puncture. Secondary outcomes included: Maximum pain intensity during first and second day postoperatively. Duration of dPNBs, defined as the interval between dPNBs performance and the occurrence of first pain. Time to discharge, defined as the interval since patient arrived at postoperative care unit (PACU) until discharge home. Presence of distal hand motor block after dPNBs puncture. Needed for rescue analgesia and total consumption of tramadol during first and second day postoperatively Incidence of postoperative nausea and vomiting during 1st and 2nd day postoperatively Needed for rescue antiemetic therapy, total consumption of ondansetron and effectiveness of treatment during 1st and 2nd day postoperatively. Patients were contacted by phone first and second day postoperatively from a blinded PACU nursing staff (all outcome data were collected by PACU nursing staff blinded to group allocation).

Patients in this group received ultrasound guided dPNBs on radial and median nerves (target nerves of TRA) in the postoperative period, before discharge. The procedural objective of dPNBs was to place local anesthetic around the target nerves to achieve a long lasting, sensitive and selective block in the surgical area. dPNBs were performed with 5 ml/nerve of levobupivacaine 0,125%. Ultrasound guidance allowed us to verify the correct distribution of LA around the target nerves target and optimize needle position if it was necessary, always avoiding the intraneural injection.

In dPNBs group, we performed ultrasound guided dPNBs on radial and median nerves using low concentration and low volume of long acting local anesthetic (0.125% levobupivacaine, 5 ml per nerve). Using low concentrations of levobupivacaine on target nerves could achieve a prolonged sensitive block in the surgical area without motor block of the hand.

Proportion of Patients Who Experienced Moderate to Severe Pain During First and Second Postoperative Day

Pain scores assessed using pain numerical visual scale (NVS) of 0-10 (o= no pain and 10= worst pain imaginable). We defined mild pain (NVS 0-3); moderate pain (NVS 4-6) and severe pain (NVS 7-10).The analysis of this variable at the end of the study will confirm or not the effectiveness of dPNBs for management of postoperative pain after TRA.

Maximum Pain Intensity, Rescue Analgesia, Nausea and Vomiting Incidence, Use of Ondansetron for NVPO, Efectiveness of Ondansetron

Number of participants with Maximum pain intensity NVS > 3; Rescue analgesia; Nausea and Vomiting incidence; use of ondansetron for NVPO; Ondansetron being effective (number of participants for whom ondansetron was effective to stop NVPO).

Inclusion Criteria: Age more than 18 years. Ambulatory TRA. Free acceptance to participate in the study, with informed consent signed by patient, guardian or family member. Exclusion Criteria: Age less than 18 years Pregnancy. Inability to provide informed consent. Allergy to amide local anesthetics/NSAIDs Preexisting chronic pain treated with opioids. Neuropathy involving the extremity undergoing surgery or neurological-cognitive deficits that may interfere in the assessement. Contraindications to dPNBs

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