ABSTRACT: The decision for a veterinary surgeon to recommend total ear canal ablation [TECA] is not something that is taken lightly. An understanding of why the procedure is being performed and the peri-operative nursing care required, enables the veterinary nurse to be well placed to support both the owner and the patient. Nursing these patients can be very rewarding for the veterinary nurse and this article aims to discuss how best to manage them sympathetically.

For many animals, chronic ear disease is both debilitating and painful. A long history of ear infection that is unresponsive to medical management results in pain, malodour and regular (often uncomfortable) ear cleaning – not to mention the costs to the owner!

In cases where the pathogens growing in the ear are resistant to treatment, mineralisation, caused by chronic irritation, arises. When external cleaning and topical antibiotics no longer have an impact on an ear canal that is scarred and narrowed owing to this chronic irritation, surgical treatment will be necessary.

Total ear canal ablation (TECA) is an extremely effective treatment for severe chronic ear disease and results in a massively improved quality of life. Although there are reported complications associated with the procedure (Table 1), in experienced hands, the success rate should be high and it is a procedure to which few owners regret agreeing.

The surgery involves the removal of all the diseased tissue in the entire vertical and horizontal canal of the ear, so that the middle ear can be accessed through the tympanic membrane opening and drained, prior to closure of healthy tissue. TECA surgery, therefore, is often performed in the referral setting.

TECA surgery is also indicated in patients who experience the following problems:

•   chronic rupture of the tympanic membrane

•   infection of the middle ear – irreversible inflammatory ear canal disease in dogs

•   severe ear canal trauma (less common)

•   neoplasia of the ear canal.

A normal bulla is hollow and air-filled, but in these patients the chronic ear infection results in the bulla being full of infected material. A curette is used to remove all the epithelial lining and debris from the middle ear, and a bulla osteotomy (BO) may also be performed to enlarge the opening so that the curette can actually fit into the space.

If this is done correctly, it should prevent the recurrent formation of fistulae and infection.1 Figure 1 provides a diagram of the ear for reference.

Figure 1: A model of an inflamed ear with fluid in the middle ear llmage courtesy of Schering-Plough)

Diagnosis and pre-operative assessment

TECA surgery is not undertaken lightly and the use of computerised tomography (CT scan) (Figure 2), radiography or magnetic resonance imaging (MRI) may be used prior to a final decision to determine if the changes seen may be reversible. Surgical intervention may be avoided in some patients if their skin disease can be properly controlled and associated ear disease can be treated.

Figure 2: CT image of a patient with bilateral otitis externa and unilateral otitis media. Both ear canals are narrowed and filled with soft tissue material, representing a combination of wall swelling and discharge in the lumen of the canals. The darker regions (black arrows) represent residual small pockets of air. Additionally, the right tympanic bulla (white arrow) is partially filled with fluid (Image courtesy of Anderson Moores Veterinary Specialists)

The facial nerve runs close to the base of the ear canal and controls facial expression and the blink reflex (see postoperative considerations below). In chronic cases, the veterinary surgeon will assess cranial nerve function prior to surgery to see whether the nerve is already damaged.

If patients have a pre-existing head tilt and/or nystagmus caused by middle ear disease, these may be worse immediately after surgery. 

 

Nurse’s role

The TECA patient can provide many challenges for the veterinary nurse, including patient preparation, medication and monitoring and nursing for postoperative trauma.

Pre-operative considerations

Biochemical and haematological estimation may be performed as part of the pre-anaesthetic assessment.

Analgesia

An aggressive pre-emptive analgesia protocol is vitally important in these cases. Ear disease is very painful and can be magnified in these patients, as they are already experiencing ‘wind up’. This is when a patient experiences a repeated painful stimulus, and it will result in central nervous sensitisation, which increases their sensitivity to pain, aural examination and manipulation and can lead to chronic pain postoperatively.

Multi-modal analgesia is used in order to minimise the side effects of the agents used, whilst maximising pain relief. While ear surgery is painful, good analgesic techniques should ensure that these patients are comfortable in the postoperative period. A fentanyl transdermal patch can be placed the day before surgery, as it has a delayed onset of analgesic effect – 24 hours in dogs and 12 hours in cats – and will provide background analgesia for up to three days.

It is recommended that these patients receive an opioid in their pre-medication. Pure mu (or OP3) agonists – such as methadone or morphine – are advisable, as their pain-relieving properties are superior to partial opioid agonists, such as buprenorphine. Morphine can cause vomiting, which is more likely in patients who are not already experiencing pain, and for this reason the surgeon may prefer to use methadone.

Non-steroidal anti-inflammatory drugs (NSAIDs) given as part of the pre medication protocol will also be beneficial in controlling postoperative pain, but cannot be given if the patient has had recent steroid therapy, because of the increased risk of gut ulceration.

Antibiotics

Owing to the challenges in skin preparation (as discussed below) this procedure is classified as ‘dirty’ and a broad-spectrum intravenous antibiotic, such as a cephalosporin or potentiated amoxicillin, may be given 20 to 30 minutes before surgery – and every two hours during surgery – so that adequate plasma levels are maintained in the tissues.

Ideally the choice of antibiotic should be based on pre-operative bacterial culture.

Surgical preparation

Once the patient is anaesthetised, surgical preparation is the next challenge for the veterinary nurse. It can be a difficult area to clip, as the skin is prone to dermatitis, so a gentle approach and the use of sharp, well-maintained, size 40 clipper blades is essential. Clip against the grain of the coat, and don’t forget to lubricate eyes to prevent irritation from prep solutions.

Wear gloves when performing any skin preparation. Chlorhexidine scrub should be used to remove any organic matter and it is important to create lather when scrubbing. Swabs are used in preference to cotton wool because they do not leave filaments stuck to the clipped hair.

After the initial scrub, continue working in an outward-moving circular motion. The site may then be sprayed with a spirit-based antiseptic. A combination of the mechanical action of scrubbing, the effectiveness of the scrub used and ensuring the correct contact time is achieved ensures proper disinfection of the surgical site.

The ear canal should be flushed clean gently with dilute antiseptic solutions before the final exterior skin prep described above, to remove as much infected material as possible and help minimise bacterial contamination of normal tissue (Figure 3). Any excess solution should be swabbed out as much as possible.

Figure 3: Properative preparation of the operation site. Note the hyperplastic tissue at the entrance to the ear canal, indicating irreversible ear disease

Nerve blocks

Once the initial skin preparation has been performed, local anaesthetic (bupivacaine or ropivacaine) nerve blocks can be performed as these will have a significant impact on pain management (Figures 4 & 5).

Figure 4: A nerve block of the great auricular nerve. The needle is inserted ventrally to the wing of the atlas and caudal to the vertical ear canal, directly parallel to the vertical ear canal llmage courtesy of Davina Anderson) 

Figure 5: A nerve block of the auriculotemporal nerve. The needle is inserted rostral to the vertical ear canal whilst directing it towards the base of the V formed by the caudal aspect of the zygomatic arch and the vertical canal llmage courtesy of Davina Anderson)

Bupivacaine will take 20-30 minutes to start working and this should be considered so that analgesia is achieved prior to the first incision.

Intra-operative considerations

The patient is positioned in lateral recumbency and a sandbag is placed under the neck to help stabilise the surgical site. Specific surgical techniques are outside the scope of this article, but as a veterinary nurse assisting with these procedures – as a scrubbed assistant or anaesthetist – you should be aware of the potential surgical complications (Table 1).

Intra-operative analgesia

The use of multi-modal analgesia should not be overlooked in these patients, and additional methods may also be used to control pain:

•   splash block of bupivacaine during surgery (if local nerve blocks have not been placed or have proved to be ineffective)

•   placement of wound catheters postoperatively to enable further administration of local anaesthetic

•   use of a constant rate infusion (CR1) of fentanyl or ketamine intra-operatively and postoperative fentanyl patches as discussed earlier. Ketamine may be useful to treat pre-operative ‘wind up’, as it acts centrally.

A patient that has been given good analgesia will require less volatile agent during the procedure, and this will, therefore, reduce the negative effects on the cardiovascular and respiratory systems. Postoperative analgesia can also be reduced when pre-emptive analgesia protocols are successful.

Postoperative considerations

The use of in-dwelling drains is recommended in some texts, but in the UK few surgeons use drains. Some texts also mention the use of postoperative bandages; but using these may increase the risk of respiratory obstruction from postoperative swelling – which can be considerable in the first 24 hours – and patients may not tolerate them well.

Elizabethan collars are placed to prevent patient interference and these must be kept clean.

The wound should be monitored for postoperative ‘ooze’, especially if intra operative haemorrhage was a concern. Gentle cleaning with sterile saline should be tolerated in a patient with good analgesic control.

Pure mu agonists (OP3) such as methadone should be continued for at least 24 hours post-surgery before switching to buprenorphine and, if not contraindicated, NSAIDs should also be given.

Antibiotics and any treatment for primary causes of otitis or dermatitis should be continued. Patients that are receiving corticosteroids for the control of skin disease should not be given NSAIDs, or may be weaned off treatment for the period around surgery.

Complications

Complications are seen in 29 to 68 per cent of animals that undergo TECA with BO (Table l).1

Summary

Caring for patients undergoing TECA surgery can be very rewarding for the veterinary nurse, as it allows us to use our skills and knowledge in many areas. If we can manage the patient sympathetically and maintain analgesia and comfort in the post-operative period they should have an uneventful recovery. Regular pain assessment can be enhanced by using a pain-scoring system, such as those provided by Colorado State University or the Glasgow Composite Pain Scale. 

Author

Claire Roberts RVN DipAVN[Surg]

Claire qualified as a VN in 2000 and has worked in first opinion, charity and referral practices.

She gained a Diploma in Advanced Surgical Nursing in 2006 and has a keen interest in surgical nursing and anaesthesia. Claire is an assistant examiner for the RCVS and works part time at Anderson Moores Veterinary Specialists in Winchester, whilst caring for her daughter and running her own CPD business, Synergy CPD. which offers in-house training for veterinary nurses.

To cite this article use either

DOI: 10.1111/j.2045-0648.2012.00246.x or Veterinary Nursing Journal Vol 27 pp 450-453

Reference

1. TOBIAS. K. M. and MORRIS. D. [2005] The ear. In: BSAVA Manual of Canine and Feline Head. Neck and Thoracic Surgery. BSAVA. Cheltenham

Further reading

HARARI. J. [2004] Ear canal resection, ablation and bulla osteotomy. In: Small Animal Surgery Secrets 2nd Edition. Hanley and Belfus Inc.

Acknowledgements

With thanks to Davina Anderson MA VetMB PhD DipECVS DSASI[ST] MRCVS and Petra Agthe CertVDI DipECVDI MRCVS for their help and input

 

Veterinary Nursing Journal • VOL 27 • December 2017 •