Making the case for pain management in your practice—why and how (Proceedings)

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Making the case for pain management in your practice—why and how (Proceedings)

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Aug 01, 2011

In the last 10 years, the veterinary profession has undergone what can only be described as a sea change in perspectives about animal pain and pain control. A 1993 evaluation of a veterinary teaching hospital surgical caseload revealed only 40% of patients that had undergone highly invasive, painful procedures (including orthopedic repair, thoracotomy, and intervertebral disc decompression) received any sort of pain control, and then only based on clinical signs. Looking at more routine elective procedures, a 1996 evaluation revealed that in primary care, no more than 17% of patients undergoing ovariohysterectomy received any sort of pain control, and of those, the vast majority received just one or two injections. Veterinarians at all levels continue to cite a variety of reasons for their reluctance to use or prescribe peri-operative analgesics.

In many ways the issue of pain management in animals closely parallels that in human pediatrics, whereby the patient is non-verbal and the clinician must rely on personal/staff observations and the reports of the patient's advocate (in some ways this parallel extends to human geriatrics, whereby the patients may be once again non-verbal and a caregiver is the patient's advocate). Thus it is that physicians have also long struggled with the critique of under-managing pain in children the cognitively impaired, and the elderly.

A landmark study in human neonatology illustrates the issue. Up until the early 1990's a standard anesthetic/analgesic protocol in neonates undergoing thoracotomy for repair of congenital cardiac defects included the use of halothane followed by intravenous morphine and diazepam post-operatively administered periodically on an as-needed basis. In a prospective trial, such procedures elicited a mortality rate of 27%. When the peri-operative protocol was modified to include sufentanil (a potent, rapid-acting, highly soluble pure mu agonist) by constant rate infusion, the mortality rate reduced to 0%.

Through this stark example we see the clinical effects of under- (or un-) managed pain. It elicits a cascade of debilitating neuro-hormonal effects that result in hypertension, catabolism, immunosuppression, and in what can be a terminal event, bacterial translocation and sepsis. This is called the "stress response." With under- (or un-) managed pain, patients at best recover more slowly from their condition, and at worst, may develop severe, even life-threatening complications.

However, the effect is not limited to pain of an acute nature. In addition to discomfort and physical disability, the capacity of chronic pain to impair cognition is becoming increasingly recognized in humans. A global summary of statistically significant findings in 42 studies of patients with chronic musculoskeletal pain revealed that deficits of memory, attention, psychomotor speed, and mental flexibility all can be attributed as a consequence of chronic pain, independent of other causes. In animals, for all of these reasons, under-attended, under-managed pain can become a criterion for euthanasia.

The case for aggressive pain management in veterinary medicine exists in two spheres. One is ethical, in which case we may say that our patients deserve the freedom from discomfort. However it is a curiosity that for all of veterinary medicine's well-known capacity for compassion, it is only recently that we include pain management as an integral part of patient care, and indeed veterinarians across the spectrum of age, training, work environment, geography, and species-interest still do not always agree on what our ethical responsibilities exactly are with regards to the relief of pain (and, one might add to complicate the discussion, fear, stress, and distress). This we must leave to the philosophers and sociologists, though the more pain management is integrated into the care of animals, the more it will become a cultural shift to the norm.

The other case for aggressive pain management exists in the sphere of clinical effect and scientific evidence. Pain itself is normal, and when physiologic it is protective. But undermanaged pain, as it becomes extended in time and intensity, becomes maladaptive and debilitating. And the younger the patient, the more long-term consequences of undermanaged pain because of the enhanced plasticity of the spinal cord: hypersensitivity to thermal stimuli can be documented years after the initial sets of painful experiences in both animals and humans. Thus for clinicians in a veterinary practice, their staff, and their clients, the first step to developing an aggressive, integrative pain management system is to internalize how dangerous and damaging undermanaged pain is to their patients. In fact, until so convinced, stocking drugs on a shelf and writing down protocols stands little chance of successful hospital-wide implementation.

The next obstacle that must be overcome is that of patient adaptation and human bias. In the study of neonates cited above, why did doctors and nurses in the NICU give morphine to some babies and not others, and at certain times and not others? Because their biases had them expecting certain behaviors to tell them their patients were in pain (crying, for example; but most premature infants do not have that capacity). Veterinarians and staff – and pet owners! - suffer the same prejudice. Animals' adaptive behaviors, and our own preconceived notions about what animals "should" be doing if they were in pain, have led us down a path of self-deception. The consequence is a tendency to under-appreciate and under-manage pain in animals. A recent study reveals that in cats, behavioral alterations persist for several days at home after ovariohysterectomy or castration. In order to fully embrace a comprehensive, integrative pain management system for a practice, all stake holders must consciously dismiss the arrogant thought that we can know with confidence the level of pain our patients are experiencing. With doctors and staff this can be done with one or a series of staff meetings, and a consensus can be developed. With clients, it is one pet owner at a time, to wit: "He has trouble getting up in the morning, and can't go up the stairs at all anymore, but he's not in pain."

Another common obstacle is the reluctance to use new medications or modalities, for lack of familiarity, or for fear of adverse effects. The following sessions will attempt to alleviate some of these concerns, and with regards to the potential for adverse effects, one must always measure that type of risk against the well-established risk of undermanaged pain. There are numerous resources available to the practitioner looking to leverage ever-more aggressive pain management on behalf of their patients; some are listed below. Health care providers in both human and veterinary medicine have also expressed a distaste of having to stock and manage controlled drugs; fortunately AAHA publishes an excellent guide on managing controlled drugs.