Post-operative analgesia options
Keeping your Patients Pain Free in the Post-op and Beyond
Tasha McNerney, CVT, CVPP, VTS (Anes.)
During recovery each surgical patient should have a dedicated nurse responsible for supervising them until they are stable enough to be transferred to another area (ex: home, kennel) Patients should be monitored for any changes in temperature, heart rate, respiration rate & effort. Pain is also an important vital sign to monitor in the post-operative period. Post-operatively, patients’ pain can be evaluated using a pain score system. Your clinic may choose to make their own numerical pain scoring system, or implement an already established system. See below for web links to pain scoring systems.
In the post-operative period, it is often hard for the technician to distinguish pain from dysphoria or “emergence delirium”. Analgesics should always be administered if the procedure was perceived as painful. Analgesics can be provided as intermittent injections or as a constant rate infusion (example: an MLK CRI for a post-splenectomy patient). Most patients require more than one analgesic to control the pain pathways. It is important that the post-operative analgesics also be multi-modal in nature. If hydration status is good and kidney values are adequate, adding an NSAID post-operatively can help relieve patient inflammation. It is safe to say that if opioid analgesics have been given post-operatively and at the appropriate doses, patient pain should be controlled. Some patients however will need the addition of sedatives or tranquilizers in addition to analgesics during the recovery period.
Pain should be treated as an individual experience and patients should receive analgesic drugs if they are exhibiting pain regardless of whether or not they have already received analgesic drugs. For many surgical and dental patients a low dose of an alpha-2 antagonist such as dexmedetomidine (1mcg/kg IV) can be a useful post-operative medication, as it not only provides sedation, but analgesia as well. It is important to note that dexmedetomidine has potent cardiovascular effects and should be used on stable patients ASA 1-2. An anxiolytic drug such as acepromazine (0.01mg/kg IM or IV) can also be useful for the dysphoric patient emerging from anesthesia (Cheyne, 2011). But acepromazine should not be administered without first assessing pain since the drug provides no analgesia but can cause sedation profound enough to prohibit the animal from exhibiting pain. Animals that become fractious in the recovery period should be sedated for the safety of the animal as well as the technicians and staff.
Husbandry and Non-Pharmacologic Therapy
Post-operative patient comfort comes from many avenues, with analgesics being the cornerstone. After surgery some other important factors to consider are: dry, comfortable bedding, a quiet recovery area, and supplemental heat or oxygen if needed. If an animal underwent a particularly painful surgery, such as a limb amputation, a urinary catheter should be placed to minimize the number of times that patient is moved post-operatively.
Application of heat or cold can also be useful in the acute setting. After surgery, cold packs can be applied to postoperative sites to decrease swelling (Cantwell, 2010) Cold packs should be wrapped in a cloth covering and should not come into direct contact with the skin. Cold packs should be placed at incision sites for no longer than 20 minute intervals.
Low level laser therapy should also be considered for post-operative pain management. Laser therapy may help in normalizing nerve signal transmission in the autonomic, somatic, and sensory neural pathways (Moore, 1992) Laser therapy may optimize cell utilization of oxygen, helping to heal wounds faster. The cold laser therapy is a noninvasive procedure that uses light to stimulate cells and increase blood circulation. At the correct laser wavelength, pain signals are reduced and nerve sensitivity decreases. The procedure also releases endorphins, or natural painkillers, but it is not recommended for animals that have cancer because the device can stimulate blood flow to cancer cells.
In addition, forms of physical rehabilitation such as massage therapy and aquatic therapy can be added to create a balanced multimodal analgesic plan for the post-operative patient. Aquatic therapy provides an ideal low impact exercise for dogs with chronic pain. The buoyancy of the water reduces the stress on painful joints. Water pressure itself can reduce swelling and edema, and water resistance is useful for muscle strengthening. (Millis et al, 2004) Hydrotherapy along with laser therapy and physical therapy exercises can be an important factor in increased healing after orthopedic surgery.
Case Study: Hind Limb Amputation Analgesic Protocol (canine)
-Gabapentin started two days prior
-Pure-mu opioid agonist + midazolam +/- dexmedeotomidine
-Ketamine/valium induction or
-Ketamine loading dose if alfaxalone used
-Lidocaine loading dose
-MLK CRI intra operatively ( if patient cannot be maintained at low levels of inhalant anesthetic)
-MLK continued into post-op period, tapered off after 2-6 hours
-Oral meds started: NSAID, Gabapentin, and oral opioid of choice (oxycodone Rx, Tramadol) or fentanyl patch
-Start laser therapy immediately post operatively (provided the amputation was not due to osteosarcoma) and continue for at least two weeks post operatively every two-three days.
Managing pain rapidly and effectively in the post-operative period is the best way to reduce the risk of chronic pain developing.
Cantwell, S. (2010) Pain Management III: Ancillary Therapies, In BSAVA Manual of Canine and Feline Anaesthesia and Analgesia, second edition. pgs 115-118 British Small Animal Veterinary Association
Cheyne, Michelle (2011), Recovery of the Anesthetic Patient in: Anesthesia for Veterinary Technicians. (Editor: Bryant, Susan) Ames, IA: Wiley- Blackwell.
Millis, DL, Levine, D, Taylor, RA, Adamson, CA. 2004. Canine Rehabilitation and Physical Therapy. St. Louis, WB Saunders.
Moore, 1992: Cost effective benefits of the use of laser therapy in the treatment of intractable post herpetic neuralgia. Conference Proceedings - Laser Application in Medicine and Surgery, Bologna Italy:61-63)