Acute pain assessment and treatment (Proceedings)

Benefits of pain management in the acute situation

     1. It is the type of care we would want for ourselves. Why wouldn't we want to give it to our own patients?

     2. Avoidance of wind-up pain and central sensitization

          a. Hyperalgesia

          b. Allodynia

     3. Earlier return to function

     4. Affects morbidity and mortality

     5. Low cost/high return

Strategies

     1. It is better to anticipate pain than to chase after it.

     2. Frequent evaluations so that over-treatment is avoided

Assessment of acute pain

     1. Don't confuse acute pain with chronic pain. Must be assessed in different ways

     2. When using a pain scale, be aware of the limitations of that scale

     3. Most scales are developed with acute surgical pain in mind. To use them for non-surgical diseases probably is not appropriate

     4. You need to know your patient

          a. Especially important when there are shift changes in evaluators. Hiding cat with back to cage door could be pain, or maybe it was doing that when it came in

Use of pain scale

     1. Intervals of use should be determined by anticipated pain, i.e. OHE v. Lumpectomy v. Fracture repair, the health and age of the animal and the expected duration and onset of the analgesic drug

          a. Hourly is appropriate for the first 4 hours post-surgery

          b. Start immediately upon recovery from anesthesia

          c. Don't wake up sleeping animals to assess pain

          d. Continuous distant observations with periodic interactive observations are best

     2. Characteristics of the "perfect" pain scale

          a. Objectivity

          b. Repeatability

          c. Validity

          d. Dogs scale for dogs, cat scale for cats

          e. Allowances given for differences in demeanor

Types of pain scales

     1. Numeric Analog scale

          a. Subjective

          b. Great in humans

          c. Poor correlation of pain in veterinary medicine

     2. Physiologic Assessment

          a. Good tool intra-operatively

          b. No correlation between pain and anxiety in an awake animal

     3. Numeric Rating Scale

          a. Can put a rating on whatever

                    i. Physiologic parameters

                    ii. Appearance and demeanor

                    iii. Interactive behaviors

          b. Human scales don't translate to veterinary medicine

          c. Potentially useful

     4. University of Melbourne Pain Scale

          a. Combination of behavior and physiologic responses

          b. Knowledge of demeanor prior to surgery is a must

          c. May not be sensitive enough to detect small changes

          d. In my clinical setting, I just found it unreliable and repeatable.

     5. Glasgow Short-Form Composite Scale

          a. Based on behavioral signs believed to represent pain in the dog

          b. Developed by the veterinary school at University of Glasgow

          c. Advantages

                    i. Limited bias by observer

                    ii. Observers look for absence or presence of behavior: Simple

                    iii. Specific terminology: No confusion

                    iv. No physiologic data involved

          d. Disadvantages

                    i. Little validation (but that is true for most pain scales)

                    ii. Dogs only

                    iii. Does not account for demeanor or temperament of patient

                    iv. Does not account for residual effects of anesthesia

     6. Colorado State University Veterinary Medical Center Acute Pain Scales

          a. I consider it the best pain scale intended to incorporate the most practical features of other pain scales

          b. Drawings of animals at various levels of pain

          c. Includes evaluation of body tension

          d. Not really open to interpretation – good repeatability.

          e. Separate dog and cat scales

          f. Has a provision for non-assessment of sleeping animal

Conclusion

The practitioner has to choose a method of acute pain assessment that is comfortable for the practice situation. Make sure that it is reliable and repeatable by first training and then practicing on the same post-surgical cases. Compare results with other evaluators.

It is also important to familiarize yourself with expressions and postures of pain in both the dog and the cat. There have been many publications in recent years with pictures, such as the ones shown in lecture, of animals in pain.