The need for a procedure-specific approach
Enhanced recovery after surgery (ERAS) has been on the agenda of our medical colleagues since the 1980s when Kehlet et al. first determined that the more pronounced the stress response is in the perioperative period, the longer the recovery from surgery. Recent guidelines typically list 15-20 peri-operative factors to be considered for enhanced recovery programs and this article highlights those relevant to veterinary practice.
Your learning outcomes for this pain update are;
Understand what ERAS is
Learn how some published studies can be used to practice ERAS in your clinic
The stress response is a homeostatic mechanism comprised of hormonal and metabolic changes, which occur in response to anaesthesia and surgery (and anaesthesia without surgery). It is described as an ebb and flow whereby catabolism occurs to provide substrates for the subsequent recovery, however this evolutionary survival mechanism is most likely deleterious in a modern surgical context (Desborough et al. 2000).
As an example from human medicine, an optimal ERAS program for major abdominal surgery (and specific to this surgery) includes minimally invasive surgery (ideally a laparoscopic approach), avoidance of mechanical bowel preparation, avoidance of overloading with fluids before administration of epidural analgesia (or preferably avoidance of epidural analgesia), goal directed fluid therapy, aggressive postoperative nausea, vomiting, and pain prophylaxis, limitation of intraoperative and postoperative opioids by using non-opioid analgesics and avoidance of unnecessary drains and catheters (Joshi & Kehlet 2016). Such elements have been shown to reduce postoperative complications such as ileus, nausea, and vomiting and encouraging early feeding. Early mobilization is essential.
The questions posed by Kehlet (2017) that we should consider with our patients are;
- Why is the patient in the hospital today?
- What are the reasons for developing a complication?
Encouraging early discharge is a key area of ERAS. Failure to mobilise following surgery in people is a huge risk factor for thrombotic events and whilst we don’t tend to see this in our canine and feline patients there are risks such as hospital-acquired infections to avoid. Of course we would all rather see our patients returned to the care of their owners as soon as possible.
One of our aims for reducing initiation of the stress response has to be a smooth anaesthetic, where depth of anaesthesia and use of analgesics prevents nociception whilst at the same time avoiding excessive depth. It is known in humans that even short periods of deep anaesthesia correlate with a greater incidence of post-operative delirium which is linked to a decline in cognitive function. The alpha-2-agonists fit the bill perfectly here, providing dose dependent sedation and analgesia, working synergistically with opioids (Grimm et al 2000). Preliminary studies in dogs indicate a reduction in measured stress hormones with medetomidine premedication compared to acepromazine (Vaisanen 2002) and clinical experience shows a smoother anaesthetic with either medetomidine or dexmedetomidine premedication.
The opioid crisis in the USA is currently driving a change to opioid-free regimens in human post-operative pain management, with increasing evidence that other analgesics are more effective in the immediate post-operative period. Opioids certainly have their place in our daily surgical and anaesthetic practice but also come with adverse effects. With multimodal techniques, notably preventive local anaesthesia, we can improve patient comfort and reduce our post-operative opioid use. Bini et al. (2018) compared the administration of methadone 0.3mg kg either every four hours or according to pain score (prn) in dogs undergoing TPLO surgery in which a locoregional technique was used. Dogs in the prn group showed improved food intake, less vomiting, and less vocalisation compared to the ‘by the clock’ approach to administration.
Further evidence in support of the huge role of locoregional techniques comes from a study in which dogs undergoing stifle surgery received either a femoral & sciatic nerve block, spinal anaesthesia or a fentanyl infusion. Outcome measures included plasma glucose and cortisol measurements to document the stress response and pain scores to guide interventional analgesic requirement (methadone 0.1 mg kg). Analgesia with a peripheral nerve block or spinal anaesthesia prevented the glycaemic and cortisol responses to surgery, promoted better recovery quality, and decreased postoperative pain scores compared with fentanyl (Romano et al. 2015).
What must be considered with these two previous examples is that analgesia must be specific to the procedure. With this knowledge anaesthetists are beginning to determine optimal analgesic options for common veterinary procedures. It is recognised that nerve blocks for cats undergoing dental extractions result in reduced anaesthetic requirements and improved comfort post operatively (Aguiar et al. 2014). Further work also recommends long term analgesia for cats with severe dental disease following extractions (Watanabe et al 2018), with the aim of enhancing recovery.
Clearly, pain scoring plays a pivotal role here in determining patient comfort. Studies in people show than post-operative assessment must include a procedure-specific functional outcome in addition to patient-reported pain scores. The example for the dog undergoing stifle surgery would be the ability to undergoing physiotherapy in the 24 hours following surgery with minimal pain. This also highlights the need to move the pet from the kennel to perform the pain scoring.
In the final paper we consider here, the authors examined the effect on both appetite and analgesia with two different anaesthetic protocols for feline castration (Armstrong et al 2018) Both groups showed equivalence in pain scores post-surgery with return to eating sooner after anaesthesia in the alfaxalone group.
With optimal perioperative management we can enhance recovery from the stress of anaesthesia & surgery. Focusing on suitable outcome measures for each surgery is necessary to determine the success of our interventions.
Your option for reflection
Consider how you can incorporate ERAS into your daily practice.
References
Aguiar, J., Chebroux, A., Martinez Taboada, F., & Leece, E. A. (2014). Analgesic effects of maxillary and inferior alveolar nerve blocks in cats undergoing dental extractions. Journal of Feline Medicine and Surgery.
Armstrong T, Wagner MC, Cheema J, Pang DS. Assessing analgesia equivalence and appetite following alfaxalone- or ketamine-based injectable anesthesia for feline castration as an example of enhanced recovery after surgery. J Feline Med Surg. 2018 Feb;20(2):73-82. doi: 10.1177/1098612X17693517.
Bini G, Vettorato E, De Gennaro C et al (2018) A retrospective comparison of two analgesic strategies after uncomplicated tibia plateau levelling osteotomy in dogs. Vet Anaesth Analg. 45(4) 557-565.
Desborough JP (2000) The stress response to trauma and surgery. Br J Anaesth 85, 109–117.
Joshi, G. P., & Kehlet, H. (2016). CON: Perioperative Goal-Directed Fluid Therapy Is an Essential Element of an Enhanced Recovery Protocol? Anesthesia & Analgesia, 122(5), 1261–1263.
Kehlet H (1989) Surgical stress: the role of pain and analgesia. Br J Anaesth 63, 189–195.
Kehlet, H., & Joshi, G. P. (2017). Enhanced Recovery After Surgery. Anesthesia & Analgesia, 125(6), 2154–2155.
Romano, M., Portela, D. A., Breghi, G., & Otero, P. E. (2015). Stress-related biomarkers in dogs administered regional anaesthesia or fentanyl for analgesia during stifle surgery. Veterinary Anaesthesia and Analgesia, 43(1), 44–54.
Väisänen, M., Raekallio, M., Kuusela, E., Huttunen, P., Leppäluoto, J., Kirves, P., & Vainio, O. (2002). Evaluation of the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication. American Journal of Veterinary Research, 63(7), 969–975.
Watanabe, R., Doodnaught, G., Proulx, C., Monteiro, B., Beauchamp, G., Dumais, Y., & Steagall, P. (2018) Pain scores, analgesic requirements and food intake in cats with oral disease undergoing dental treatment. Proceedings of the World Congress of Veterinary Anaesthesia. p138
This post was co-written by Matt & Carl.
Matt sees referrals in the pain clinic at Anderson Moores Veterinary Specialists. You can also receive telemedicine advice from us here if you have a pain case where you need a helping hand.
Matt & Carl established Zero Pain Philosophy to provide educational resources & telemedicine to veterinary professionals enabling optimal management of pain.
Matt Gurney is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and works at Anderson Moores Veterinary Specialists. Matt is Past President of the European College of Veterinary Anaesthesia & Analgesia.
Carl Bradbrook is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and is Past President of the Association of Veterinary Anaesthetists. Carl works at Anderson Moores Veterinary Specialists.
The intended audience for this pain update is veterinary professionals. This pain update is based on clinical experience and independent opinion.