Case Report #40: Managing Pain in Adult Burns by Dr Harriet Scott and Dr Joe Hussey

A classification based on pain triggers is useful when considering methods to address types of pain using multi-modal analgesia³

• Background pain
  • Non-pharmacological management: dressings, positioning, measures to ensure psychological reassurance and safety
  • Pharmacological management: regular paracetamol, NSAIDs in carefully-selected patients, opioid infusions titrated to targeted effect
• Breakthrough pain – evoked or spontaneous: bolus of rapidly-acting agents, increase in the rate of opioid infusions, anticipatory doses of longer-acting drugs
• Procedural pain – opioid boluses delivered by different routes (intravenous/per oral/intranasal/sublingual), inhaled agents including nitrous oxide/methoxyflurane, ketamine

A classification based on mechanisms can also help guide pharmacological management

• Nociceptive pain – paracetamol, NSAIDs (caution in critically unwell patients), opioids, NMDA receptor antagonists, alpha-2 receptor agonists, peripheral nerve catheters e.g. for autograft donor sites
• Neuropathic pain – gabapentinoids, tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors

24 hours later, the patient is taken to the operating theatre for excision of his burns. He is kept under general anaesthetic with continuation of Propofol and Alfentanil infusions with addition of inhaled Sevoflurane. Skin grafts (autografts) are harvested from unburnt areas of his thighs and calf. The autografts are applied to some of the debrided areas, although there is not enough for full-coverage and allografts (cadaveric skin) are used in addition.

The anterolateral portion of the thigh is often used as a donor site for autografts.

What regional anaesthetic techniques would be useful?

The lateral femoral cutaneous nerve of the thigh can be blocked under ultrasound guidance aiming for local anaesthetic spread around the LFCN between the tensor fasciae latae and sartorius muscles.⁴

Over the next 8 weeks, the patient remains in the BICU while he is weaned from cardiovascular, renal and respiratory support. On alternate days, he has a shower and change of dressings, for which he is transferred to a shower trolley whilst sedated, his wounds are undressed, cleaned, scrubbed and redressed.

How would you manage sedation and analgesia for a sedated shower and dressing change?

These are repeated painful episodes for the patients.

They have the added challenge for the anaesthetist of managing the moving and handling of a patient who may be ventilated, often on multiple infusions, managing the lines and maintaining monitoring which may be problematic during washing. It is vital calorie intake is maintained to ensure healing, this is often achieved with continuous enteral feeding via a gastric tube.³ We often elect to place a tracheostomy in patients with larger burns requiring frequent dressing changes or operations. This facilitates minimal feed pausing and safe deep sedation/general anaesthesia procedures.

There are several analgosedative options that could be used, individualised to the patient and circumstances, which the aim to maintain analgesia and sedation at a level that is safe and the patient is comfortable. Considering that the patient will undergo multiple showers and dressing changes throughout their recovery, it is important that this does not become an experience they fear.

In our unit, we have protocols for deeply sedated procedures at the beginning of the patient’s illness when procedures are most painful, moving to lighter sedation with analgesics as their wounds recover.

Sedation and analgesia can be managed by increasing the infusions the patient is currently receiving in the BICU, such as propofol and alfentanil or propofol and remifentanil.

We tend to use target-controlled infusions for the showers and dressing changes. Frequently, patients with larger burns who have received large amounts of opioid, become tolerant to opioids for dressing changes. There may also be concerns over the development of acute opioid related hyperalgesia. In these cases, alternative modalities should be considered.

We have developed a protocol of a mixture of ketamine and propofol (colloquially named ‘ketofol’), infused using a propofol TCI model, titrated to the patient’s response. This drug admixture is physically compatible and chemically stable for up to 3 hours after mixture. The superior quality of maintaining sedation with propofol with analgesia from ketamine in a self-ventilating patient is efficacious and well tolerated.

Assessing and recording the effect of the sedation/analgesia gives a guide towards management for subsequent procedures.

As a patient’s wounds heal and become less painful to manage, they can progress to having a combination of oral ketamine, midazolam, opioids (as PO, IV or PCA routes) and entonox for dressing changes.

The patient has three further operations to complete the debridement and grafting of his wounds, which slowly start to heal. He recovers from periods of sepsis secondary to ventilator associated pneumonia and wound infection. He has a tracheostomy to assist his respiratory wean. He still has a high requirement for opioid analgesia on top of regular paracetamol, gabapentin, oral ketamine and clonidine.

How would you manage his multimodal analgesia?

Would you use NSAIDs in the burns population?

The patient’s pain should be addressed using a biopsychosocial model.

Multimodal analgesia is key to cover the pain pathologies and receptors implicated - regular paracetamol, antineuropathic agents such as amitriptyline, duloxetine, gabapentin, pregabalin, NMDA antagonists such as ketamine either IV and PO, alpha-2 receptor agonists and opioids. Opioid doses are often high and the risk of opioid-induced hyperalgesia should be remembered.

NSAIDs are used with caution in patients with smaller burns and avoided in patients with larger burns, the elderly, those with renal impairment and cardiovascular risk profiles.

Methadone can be useful in patients who have difficult to manage pain due to its multiple modes of action as a mu agonist, NMDA antagonist, 5HT and NA reuptake inhibitor and Na⁺ channel blocker.

Interrelated with multimodal analgesia comes careful management of polypharmacy. This becomes especially relevant in the elderly population and those with renal impairment, common in patients with burns.

Managing psychological distress of potentially life-changing and life-threatening injuries and anxiety around repeated procedures is essential. We have early psychological support which continues throughout their patient journey. PTSD and depression often accompany burns injuries.

Attainment of sleep is important, using non-pharmacological and pharmacological methods if needed.

Patients’ communication needs must be assisted with the use of translators and communication aids if required.

Patients’ spiritual needs and family support must be addressed.

Physiotherapy is started early in the patient’s journey and is ongoing. One of the primary aims for pain management in burn patients is to allow them to participate actively in physical and psychological rehabilitation.

The patient’s wounds continue to heal and he makes good gains with his rehabilitation.

His main complaint is of overwhelming, intrusive itch, as is common with recovery from burns.

How could you manage his itch?

Itch is often a very invasive symptom during recovery from burns and appears to have both pruritogenic and neuropathic elements. The primary pathophysiological “drivers” for itch change depending upon the phases of wound healing.⁵

In the earlier “inflammatory” phase of wound healing, itch tends to respond better to antihistamine therapy and dressing changes.

During the “proliferative” phase of wound healing, in addition to topical therapies (emollients / cooling), anti-neuropathics (particularly gabapentin) have been shown to be efficacious.

Chronic itch developed during the late “remodelling” phase of healing can be crippling and has been associated with the presence of PTSD often requiring psychological support. Unfortunately, pharmacological management in these circumstances is often limited, though topical lidocaine, topical/intra-lesional steroid, botox and laser therapy have been used and shown to be helpful in selected patients in small case series.

Over the next few weeks, the team start discharge planning.

What would you need to consider about his analgesia?

Discharge planning is often complex. Physical, psychological and social factors need to be considered by the multidisciplinary team in liaison with community services. It is important that a clear plan for pain / itch pharmacotherapy is in place prior to discharge. It is our practice to wean patient off schedule 2/3 drugs prior to discharge if possible. When this cannot be achieved, it is vital to communicate a clear plan for this to the patient and their secondary care providers.

In our institution, clinical oversight for this is managed via specialist outpatient appointments that run concurrently with surgical burns outpatient appointments. Very occasionally, discharged patients have difficult to manage pain which is ongoing; this is best managed by a specialist pain service with experience in managing burns.

Patients who survive a severe burn injury often suffer disfigurement, loss of identity and changes with work and family dynamics and it is important that these patients are followed up by a multidisciplinary team, often for many years. Patients with severe burns may also have decreased life expectancy compared to the non-burnt population, indicating that there are considerable health needs that are not being met.⁶