Date post: | 18-Jan-2016 |
Category: |
Documents |
Upload: | justin-woods |
View: | 216 times |
Download: | 0 times |
Burn Analgesia
James Huffman, R-2 Emergency Medicine
March 19, 2007
Willie Sutton
Depression era bank robber
When asked why he robbed banks – simply replied: “Because that’s where the money is”
Outline
1. Pathophysiology
2. Treatment Surgical
Pharmacological
Behavioural
3. Special Circumstances (if time) Pediatric patients
Ventilated patients
Introduction
37% response rate
Only 55% of responding Ontario emergency physicians included analgesia in their treatment plan!
Introduction
Studies on the characteristics of burn pain show the one constant factor is the unpredictable and variable intensity of the pain
Burn pain is multifactorial:
Nocioception – nerve pain
Hyperalgesia – secondary to inflammatory markers
Neuropathy – nerve damage and regeneration
Components of burn pain:
Injury / background
Procedures
Introduction
Several studies have shown physicians do a poor job assessing and treating pain (both general and burns)
Reasons for inadequate analgesia: Fear of opiod side-effects
Fear of opiod addiction
Lack of pain evaluation
Differences in physician practices
Pathology of burn injury pain
Full thickness burns completely destroy the network of nerve endings Leads to an initially completely anesthetic wound to sharp
stimulus
Yet, dull or pressure type pain in these areas
Neuropathic component (insect walking on skin with spikes on its feet)
Neural reorganization takes approx 5-6 months
Burn size may correlate with pain on VAS
Psychological factors (anxiety and depression)
Grafting vs. Granulation
Measuring burn pain
Why? Improved control of pain
Assessment of pain management / protocols
Improved communication with patients
No gold standard
Ideal tool
VAS / numeric scales
McGill Pain Questionnaire
Other Considerations
Anxiety
Itching Both poorly researched and utilized but preliminary studies
and anecdotal reports tend to emphasize the importance of these factors in burn analgesia
Treatment of Burn Pain
1. Surgical
2. Pharmacological
3. Behavioural
Treatment - Surgical
Much pain is produced by the open wound – once closed, this is relieved
Resection and grafting both significantly reduce pain
For 2nd ° burns, OpSite® or Tegaderm® applications can provide nearly immediate relief
Treatment – Pharmacological
Tenets of pain medication:
1. A pt’s reports of pain are accurate and should be acted upon
2. Analgesics are most effective when given regularly, NOT PRN
3. Analgesics should rarely be given IM
Adjust dosing for pt condition and concurrent illness
Treatment – Pharmacological
Review articles have typically found three distinct stages:
1. Emergency / resuscitative phase (0-72h)
2. Acute phase – until wounds closed (72h – 3/52)
3. Rehab phase – until scar maturity (months to years)
Emergency Phase IV is preferred route of admin
Opiods excellent for both background and procedural pain
(Ketamine, NO) and anxiolytics good adjuncts
Treatment - Pharmacologic
Acute Phase: Backgroud pain: PCA and non-pain contingent
administration of opioids (IV / PCA / PO)
Procedural pain: opiods, anxiolytics, Nitrous oxide
Neuropathic pain: Neuroleptics and TCAs
Rehabilitative Phase: Oral routes preferred for obvious reasons
Opiods, Acetaminophen, NSAIDs (*GI effects)
Continue treatment of neuropathic pain
Treatment - Pharmacologic
Lidocaine and relatives Nerve blocks shown to be effective in several studies
Opioid analgesics Mainstay in all three phases for both procedural and
background pain
Methadone may be an underutilized option (NMDA action)
α2 Adrenergic agonists
Clonidine, dexmedotomidine: sedative, anxiolytic, analgesic and sympatholytic properties
Requires intense, invasive monitoring – probably better suited for an ICU setting
Treatment - Pharmacologic
NSAIDs
Acetaminophen Dose is 10-15mg/kg
Anxiolytics:
Lorazepam: (T ½ = 13h)
Diazepam (36h)
Midazolam (2.5h)
Treatment - Pharmacological
Itch Medications:
85% of burn injury patients (Field et al.)
Poorly understood mechanism (histamine, kinins, proteases, prostaglandins, substance P, 5-HT)
Moisturizing body shampoos / lotions (non-steroid)
Anti-histamines
Topical TCAs
Gabapentin
Cyproheptadine (anti 5-HT) 0.1mg/kg q6h
Treatment - Behavioural Pain experience is strongly influenced by psychological factors
– esp. anxiety
Non-pharm Tx can play an impt role in addressing these factors
Treatment - Behavioural
Classical conditioning
Prevent negative associations and promote positive ones
Operant conditioning
Reinforcement of behaviours
Treatment – Behavioural
Cognitive Interventions Control
Distraction
Hypnosis At least a dozen case reports and one small controlled
study of burn patients
Summary Vigilance is key to good analgesia
Phases or burn pain:
Emergent/Resuscitative
Acute
Rehab
Components of burn pain:
Background pain
Procedural pain
Neuropathic pain
Multi-faceted approach to treating burn pain:
Surgical
Pharmacological
Behavioural
Questions?
Infants and Children
For many years, it was thought infants did not feel pain d/t incomplete myelination of sensory nerves
Research by Anand et al has shown via a number of metabolic and physiologic parameters that pain is experienced
Noxious stimuli is likely transmitted by C fibers, unlike in adults as a result of immature status of A fibers
Children may be more sensitive to the respiratory depressive effects of opiates
Ventilated Patients
Will need increased analgesia for the ETT