Pain management, post operative care, anaesthesia and local analgesia in arthroscopy

Pain management, post operative care, anaesthesia and local analgesia in arthroscopy.Prof. Giancarlo Vesce V.M.D.Department of Clinical Veterinary Sciences – University of Napoli “Federico II” gvesce@unina.itArthroscopy is often performed on articulations affected by Degenerative Joint Disease (DJD), also known as Osteoarthritis. Such condition is progressive, chronic/acute, self-aggravating and very painful. DJD is characterized by alterations of the articular cartilage and subchondral bone, associated with osteophyte formation and changes in periarticular tissues.Joints have a very sensitive innervation provided by Nociceptors (Ad or C fibers) and by Mechanoreceptors (Ab fibers). Thus movement and weight bearing of diseased joints, leads to hyperalgesia, central sensitization and allodynia aggravating articular pain.Anaesthetic requirements for arthroscopy are similar to orthopedic surgery, including immobility, profound analgesia and postoperative analgesia. The arthroscopy patient is rarely a critical patient, but suffers from chronic pain and must endure a painful procedure and recovery.A careful preoperative patient evaluation and detailed anesthetic planning of the procedure, including pre-emptive analgesia, anesthetic monitoring and long-term analgesia, are mandatory. The risk of a long-lasted preoperative anti-inflammatory therapy (steroids or NSAIDs) must be evaluated before choosing the anesthetic protocol. Best results are achieved by a multimode anesthetic technique.Preoperative analgesia should include a NSAID to decrease recovery analgesic requirements and an opioid or Alpha-2 agonist, to decrease the intra-operative ones.General anesthesia is best induced by a short acting intravenous agent and maintained by inhalation anaesthesia. Patient preparation allows time for a local analgesic treatment, which further decreases local response to painful stimulation, intra-operative anesthetic requirement and post-operative pain.Postoperative treatment for arthroscopy must consider the preceding analgesic/anesthetic treatment and consists of scheduled doses of NSAID and either an alpha2 agonist or an opioid according to patient needs.Local anesthesia is a safe, valuable, simple and economical analgesic treatment, but can't be the only mean of anesthesia for arthroscopy. The outcome of local anaesthesia depends on the correct choice of the technique, of the agent and it's concentration. Furthermore the recommended dose must be respected and the patient status monitored. Local Anesthesia allows preventing and treating acute pain. Thus it can be “preventive” (nerve-, intra-articular-, regional-, central- block) if given before starting the procedure; “intra-operative” (intra-articular, intra-venous) if provided during the procedure; “post-operative” (regional, intra-articular) when is given at the end or after the procedure.Lidocaine HCl can be administered also as a systemic analgesic by the intravenous route, providing anesthetic, analgesic, anti arrhythmic and anti-inflammatory effects.Intra-articular anesthesia is the first choice for arthroscopy, due to the familiarity with articular access gained by such surgeons; it must be performed 15-20' before starting surgical trauma: one to ten ml of local anesthetic solution are injected by sterile arthrocentesis, after withdrawing an equal amount of sinovial fluid. Opioids or ketamine can be added to the solution, increasing analgesic effect and duration.Brachial plexus block provides anesthetic silence for elbow arthroscopy, but is less immediate and can fail more frequently than intra-articular block. After identifying the 1st rib and the “point of shoulder”, a 7,5 – 10 cm needle is fully inserted medially to the scapulo-umeral joint and parallel to the costo-chondral articulation. A retrograde injection of 3 to 15 ml of 0,5% Bupivacaine or Laevobupivacaine is performed. Jaluronidase can be added to the solution to increase the speed of absorption, which is critical for the ensuing of the anaesthetic action. This technique blocks the radial n., the median n., the ulnar n., the muscolocutaneous n. and the axillary n., producing complete loss of sensitive and motor function to the lower part of the limb.Central Blocks, known as Epidural Analgesia (EA) or Spinal Analgesia (SA) can be used for rear limb arthroscopy. These blocks consist of injecting a local anaesthetic solution (1 ml/4 kg) in the epidural or in the subarachnoid space at the L7-S1 junction. Such blocks produce a long lasting anesthesia (sensitive and motor paralysis) of large districts of lower trunk and rear legs, following the injection of reduced doses of anaesthetic agent. Multiple injections are made possible by inserting an epidural catheter. General anaesthesia must head these regional blocks, since the unexpected, unpleasant motor paralysis makes conscious animals react trashing around until the effect wears off. Furthermore the extension of the block can produce unwanted circulatory and respiratory effects. To create a central block it's better to dilute the original local anesthetic solution, bearing in mind that the volume injected affects proximal spreading of the paralysis, while the concentration affects it's duration. Adding adrenaline (1:100.000) prolongs the sensory and motor paralysis. The analgesic effect of central blocks can also be prolonged without prolonging motor paralysis, by adding to the solution opioids (morphine [20 mcg/kg up to 12–24 hrs], or fentanyl 2 mcg/kg [up to 6-12 hrs]) or alpha-2 agonists, or benzodiazepines, or ketamine.Long-term postoperative care of the arthroscopy patient includes early recovery of deambulation and main organic functions. For this to happen pain must be kept under control on a long term basis by administering NSAIDs and/or opioids, according to the severity of symptoms and to the patient metabolic status. A warm environment, a dietary plan, physical therapy and tender loving care are measures able to reduce pain and to allow a faster recovery of the arthroscopy patient.