Nails, ears and other painful exams: Using analgesia and sedation to make it better for the patient (Proceedings)

Currently available sedative analgesic agents have opened up a wonderful world of opportunity to practice with intelligent compassion: to work smarter, not harder when managing patients that resent a variety of necessary procedures.

This session will focus on strategies that combine opioids, sedative/tranquilizers, and dissociative agents to provide predictable chemical restraint with properties that include rapid onset, reversibility, and minimal potential for clinically significant adverse effects.

Overview of presentation:

Veterinary medicine often has a tough side to it; brute-a-caine is the general term for gathering enough people to overcome any physical resistance by the patient to force their compliance. It seems expedient to just get the job done but the consequences of these events are often inadequately considered.

With heavy physical restraint, there is high-level stress for both the patient and the staff, there is every expectation that the patient will generate a substantial negative association with the practice, and there is predictable risk of physical harm, including death, to the patient as well as the risk of physical harm to the staff. As an extension of this overall negative association, when the patient has a negative association with the practice, the client is likely to avoid trips to the practice for routine care, impacting the business of veterinary medicine. What seems easiest in the short term has ongoing life-long consequences.

The first step in the effective utilization of procedural sedation is to recognize which patients require it. We try to build the most positive relationship that we possibly can from the earliest patient visits. Freeze dried liver treats are in the canine rooms and a variety of strained meat baby foods are in the feline exam room. Every attempt is made to distract the patient from the unpleasantries of their initial vaccinations.

When blood draws and other more challenging needs arise, we conduct those away from the DVM in a room apart from the outpatient area, making an attempt to diffuse negative associations. If the patient becomes agitated by a procedure we consider abandoning the event that day, postponing it until a future visit. We then set up a series of "Happy Visits" prior to the next stressful event making an attempt to build a more positive bond with both client and patient. This is a more successful sequence when managing canine compared to feline patients.

When all else fails, procedural sedation is woven into the patient's visits. Whenever possible, we avoid trying to gain control of a highly agitated patient preferring to reschedule a patient that has become highly reactive to another day (if their condition allows). To do otherwise risks escalating hostilities and escalating drug requirements.

For the toughest patients, procedural sedation is the only way we can gain enough control to perform even the most basic of all procedures: a physical examination. This reduces the safety of the event as these patients require more aggressive drug combinations while offering the clinician the least understanding of their health status.

Simply put, the timing of the medication administration has a crucial impact to the success of the process. A known difficult patient should be given their sedative IM medication combination as a soon as they walk through the door of the practice. If they are allowed to become increasingly agitated, their medication strategy is less likely to be effective delaying the patient procedure and forcing the need for additional drugs.

For cats, we prefer to have the patient transported to the practice in a simple 2-part plastic carrier that has an easily removed top. The patient is ushered into an exam room that has a calming pheromone diffuser in place. The top of the carrier is removed and the patient is quickly covered with a towel that has also been sprayed with a calming pheromone. The staff member gently but firmly presses the patient against the floor of the carrier while a second staff member lifts the towel off of the lower lumbar area allowing a quick IM injection in the lumbar epaxial musculature using a 25 g or 27 g needle.

The patients head is uncovered and the staff exits the room leaving instructions with the owner to open the door when the patient begins to act sleepy. Subdued lighting may help accelerate the medication's effects. The staff member returns in 10 minutes if the owner hasn't already come to the door. If the patient escapes into the room we use a clam-shell cat collection device to safely gather up the patient and easily allow for the IM injection while restrained in the mesh. We can usually gain control of even the toughest cats using this method. What varies is the choice of drugs for these patients; usually ketamine is required to securely gain control of these agitated tough cats.

For dogs, some can be distracted by a treat while a quick epaxial IM injection is delivered. Some will be sufficiently distracted by a muzzle to allow for their IM injection. Others may not harbor excessive resentment if their leash is slipped through cage bars to control their head while their trunk is quickly pushed up against the cage door allowing a caudal IM injection without significant staff risk.

There are, however, dogs that absolutely flip out, spraying urine, anal sac secretions, and stool when restrained in any way. There are also dogs that are so aggressive that even their owner cannot safely muzzle them. These two groups are a problem without ideal solution. Oral tiletamine/zolazepam based tranquilization delivered at home, prior to patient transport, may be the only effective tool for these difficult canine groups.

Whenever working with patients that require substantial chemical restraint prior to physical examination, the practice should have a frank talk with the owner about the opposing risks: the risk of skipping needed medical procedures, the risk of excessive physical restraint, and the risk of sedating a patient without full evaluation. A written liability waiver should be signed by the client prior to the administration of the procedural sedative.

Opioids provide the ideal base medication for procedural sedation. They can contribute analgesia as well as sedation although this varies amongst the opioid family members. Butorphanol and nalbuphine are kappa agonists (mu antagonists) that are well suited for procedural sedation when performing services associated with little or no pain. They are limited by the fact that, should the procedure turn out to be more painful, following a kappa agonist with a mu agonist may not have the expected additional analgesic benefit. On the plus side, kappa agonists are not expected to cause vomiting. The partial mu agonist buprenorphine has greater analgesic potential than the kappa agonists, is not expected to cause vomiting, but buprenorphine lacks consistent sedative qualities. While both kappa agonists and buprenorphine are generally free of unwanted effects they are difficult to reverse should any unwanted effects occur.

The pure mu agonists are attractive for their versatility. They posses high level analgesic potential, provide good sedative benefit, and they are fully reversible. Morphine and hydromorphone are commonly associated with vomiting, oxymorphone less commonly so, with methadone being the least likely to cause vomiting.

Benzodiazepines are an extremely safe group of medications. The two main agents in current use, midazolam and diazepam, are not attractive as sole agents but they are capable of enhancing the sedative effects of the opioids and other sedative/tranquilizer combinations. Of the two, only midazolam is suited to IM drug delivery as diazepam's propylene glycol vehicle makes IM injections painful and drug absorption unpredictable. The benzodiazepines may produce an amnestic effect that could help reduce escalating negative associations with the practice and staff. Benzodiazepines are not associated with nausea and they are fully reversible.

The alpha-2 agonists medetomidine and dexmedetomidine are the authors preferred sedative for healthy patients. The alpha-2 agonists are capable of providing additional analgesia, anxiolysis, profound sedation, generally do not cause vomiting, and they are fully reversible.

Acepromazine is an alpha antagonist capable of enhancing opioids sedation. Its biggest drawback are its relatively poor effect on feline patients and its lack of reversibility. Used at low dose, it can still be an attractive agent for short term procedural sedation for canine patients when used with pure mu agonist opioids. In this combination the opioids can be reversed to allow recovery of consciousness and an adequate ambulatory capability but at the expense of analgesic benefit.

Occasionally, a dissociative agent (ketamine, tiletamine) is required to secure control over the most difficult patients. More often than not, a dissociative is needed when the patient has had significant time to become highly agitated prior to sedative administration. Dissociatives are also needed when dealing with patients that are not tolerant of alpha-2 agonists (for example, those with cardiac disease) or those poorly responsive to acepromazine (feline patients as a group). When used in combination with an opioid and benzodiazepine, low doses of ketamine or tiletamine are usually adequate to gain adequate patient control.

Dosing of the individual agents is best viewed as a practitioner's judgment rather than establishing a fixed combination across broad patient groups. Emphasizing reversible agents provides greater total flexibility. Trending towards lower drug doses for older, larger, calmer patients and higher doses for younger, smaller, more excitable patients helps to maximize the likelihood of ideal patient effect. Intramuscular administration in the epaxial musculature also helps to insure the most predictable absorption and drug effect.

At the conclusion of the procedure, reversal agents are generally administered in this order: alpha-2 antagonist, opioids antagonist, and very rarely, benzodiazepine antagonist. In most cases, partial alpha-2 reversal is enough to safely discharge the patient while still in a calm, relaxed state.

Procedural sedation for nonpainful feline events: Butorphanol 0.2 mg/kg with 0.1 to 0.2 mg/kg midazolam as a base. Add 0.0005 to 0.010 mg/kg dexmedetomidine for healthy patients. Substitute 1 to 2 mg/kg ketamine for the alpha-2 agonist if the patient has significant systemic disease including heart disease. Consider all 4 agents for the toughest of healthy feline patients.

Procedural sedation for nonpainful canine events: Butorphanol 0.2 mg/kg with 0.05 to 0.2 mg/kg midazolam as a base. Add 0.0005 to 0.005 mg/kg dexmedetomidine for healthy patients. Substitute 1 to 2 mg/kg of tiletamine/zolazepam for the alpha-2 agonist if the patient has significant systemic disease including heart disease. Consider all 4 agents for the toughest of healthy canine patients.

Procedural sedation for painful feline events: Methadone 0.3 to 0.5 mg/kg or 0.1 mg/kg hydromorphone with 0.1 to 0.2 mg/kg midazolam as a base. Add 0.0005 to 0.010 mg/kg dexmedetomidine for healthy patients. Substitute 1 to 2 mg/kg ketamine for the alpha-2 agonist if the patient has significant systemic disease including heart disease. Consider all 4 agents for the toughest of healthy feline patients.

Procedural sedation for painful canine events: Hydromorphone 0.1 to 0.2 mg/kg or morphine 0.5 to 1.0 mg/kg with 0.05 to 0.2 mg/kg midazolam as a base. Add 0.0005 to 0.005 mg/kg dexmedetomidine for healthy patients. Substitute 1 to 2 mg/kg of tiletamine/zolazepam for the alpha-2 agonist if the patient has significant systemic disease including heart disease. Consider all 4 agents for the toughest of healthy canine patients.

Alpha-2 reversal using atipamezole is usually administered IM in the epaxial musculature. For feline patients, ¼ to ½ of the dexmedetomidine volume is usually adequate; for canine patients ¼ to ¾ of the dexmedetomidine volume is usually appropriate.

Opioid reversal is usually not necessary. If a pure mu agonist has persisting unwanted effects, including hyperthermia, administering buprenorphine IV is our preferred partial reversal technique. Butorphanol administered IV is an alternative consideration but its effects are of shorter duration and its analgesic capabilities are inferior to buprenorphine.

Flumazenil is an affordable benzodiazepine reversal option (should that very unlikely need arise). Reducing benzodiazepine dose for the more aged patient typically avoids sustained unwanted cognitive dysfunction.

In all cases of procedural sedation, the patient should have an IV catheter in place and they should be closely monitored by a dedicated staff member utilizing blood pressure, temperature and, when possible, pulse oximeter monitors. Supplemental oxygen via face mask is a recommended supportive measure particularly for the more heavily sedated patients. In addition, heavily sedated patients may allow endotracheal intubation; a supportive measure that is usually in the patient's best interest while they are unable to protect their own airway.

When the details of each sedative procedure are carefully recorded, you create a better opportunity to tailor the patient's dosing strategy from event to event.