2024.2 Day 2 VIVA 21

Pain Medicine

You are Scenarioville Hospital's on-call rural generalist. At 5 p.m., your emergency colleague calls you for assistance with analgesic management.

An 86-year-old man has fallen at home, and the chest X-ray shows four left-sided rib fractures. His respiratory rate is 22/min, but all other observations are within normal limits. There is no evidence of any other injuries.

Paramedics have given him a methoxyflurane inhaler (Penthrox) during transport to the hospital.

Describe your considerations with regard to his analgesic management.

Pain Assessment:

• Use elderly-appropriate tool (e.g., Abbey Pain Scale if cognitive impairment suspected)

• Record baseline function and mobility, pain history, and pre-hospital analgesic use

• Identify opioid-naïve vs. tolerant status to tailor dose safely

Multimodal Analgesia Plan:

• Non-opioid base:

  • Paracetamol 1g IV Q6H if eGFR adequate

  • Topical lidocaine over fracture area (especially for focal rib pain)

• Opioid strategy:

  • Start with low-dose oxycodone IR 2.5mg PO Q4H PRN

  • Avoid IV boluses unless closely monitored (Scenarioville lacks HDU)

• Adjuvants:

  • Gabapentin 100mg nocte if neuropathic features or sleep disturbance

Safety Measures:

• Frequent sedation and respiratory monitoring (RR, sedation scale, SpO₂)

• Fall precautions, particularly with nocturnal dosing

• Involve family in observations (delirium, confusion, intake/output)

Given he received Penthrox in the ambulance and now has worsening renal function, how would you assess and modify your plan?

• Penthrox (methoxyflurane) is nephrotoxic—particularly in prolonged exposure or dehydration.

• I would review cumulative dose, ensure good hydration, and check serum creatinine/eGFR.

• Discontinue Penthrox on arrival; avoid nephrotoxic adjuvants (NSAIDs, high-dose gabapentin).

• Reassess analgesic plan with renal dosing adjustment and ensure renal trends are monitored.

If you suspect undiagnosed cognitive impairment, how would that influence your pain and sedation strategy?

• Use scheduled non-opioid analgesics to reduce breakthrough requirements.

• Avoid benzodiazepines and centrally acting agents unless absolutely necessary.

• Regular orienting cues, frequent re-evaluation of pain using behaviour-based tools.

• Involve geriatrics (if available) and prioritise early mobilisation and supportive environment.

Pain control is still inadequate despite oxycodone and paracetamol. What else would you consider, and how do you weigh risks vs benefit?

• Add NSAID (e.g., ibuprofen 200mg TDS) only if renal function is stable and no GI bleed risk.

• Consider SC morphine 2.5–5mg Q4H with nursing monitoring plan and naloxone available.

• Evaluate nerve block feasibility: intercostal block or serratus anterior plane block (if staff skilled).

• Use of low-dose ketamine boluses (0.1–0.2mg/kg) IV for analgesic-sparing effect.

Aside from numeric pain scores, how would you judge whether your analgesia is effective?

• Functional improvement: improved inspiratory effort, less splinting.

• Objective markers: improved SpO₂, lower RR, better participation in physio.

• Subjective: ability to sleep, verbalised comfort, family reports less agitation.

• Track response to medications using regular pain team or nursing assessments.

Twelve hours later, his SpO₂ drops to 88% on room air with increased work of breathing. Outline your management.

Immediate Clinical Assessment:

• Assess ABC: look for accessory muscle use, auscultate chest, measure RR/HR

• Rule out complications: pneumonia, contusion, atelectasis, or pneumothorax

Investigations:

• Portable chest X-ray (with stat report)

• Consider POCUS for pneumothorax or consolidation

• ABG if tachypnoeic or drowsy → assess for CO₂ retention and acidosis

Supportive Measures:

• Apply supplemental oxygen via nasal prongs or face mask

• If available: HFNC to reduce WOB and splint airway

• Escalate analgesia—IV ketamine or regional block if trained staff available

CXR shows left lower lobe collapse. Can you explain the likely cause, and how would you manage this in a resource-limited setting?

• Likely due to pain-induced hypoventilation leading to mucus plugging and atelectasis.

• Increase frequency of deep breathing exercises and physio.

• Consider chest physiotherapy and mucolytics.

• Nebulised saline if available, mobilise as tolerated.

• Avoid sedation or excessive opioids which suppress respiratory drive.

He now appears drowsy and confused. What are the possible causes, and how would you investigate and treat them?

• Causes include opioid toxicity, CO₂ retention, sepsis, or silent aspiration.

• Check recent drug chart for timing and dosing of opioids and gabapentinoids.

• Perform ABG to assess for hypercapnia.

• If opioid toxicity suspected: withhold opioids, consider low-dose naloxone infusion.

• Rule out metabolic derangements or head injury with bloods and review fall notes.

In Scenarioville, NIV is unavailable. What strategies can you use to prevent further deterioration?

• Maximise conservative oxygenation strategies: upright position, HFNC if present.

• Incentive spirometry, chest physio, early mobilisation with OT/physio.

• Avoid oversedation; reduce opioid burden by switching to adjuvants like ketamine.

• Consider low-dose morphine infusion only with continuous monitoring.

What clinical indicators would push you toward intubation in this elderly patient, and what additional considerations must you make?

• Refractory hypoxia (SpO₂ <85% despite supplemental oxygen)

• Hypercapnic respiratory failure with acidosis (pH <7.25)

• GCS decline <9 or unprotected airway

• In elderly: anticipate prolonged ventilation and potential for poor recovery

• Must coordinate with retrieval early if prolonged ventilation expected

The tertiary center recommends retrieval. Describe your preparation.

Optimise Before Transfer:

• Ensure analgesia is stabilised with clear dosing plan

• Secure IV access (2x 18G if possible), check all lines are labelled and patent

• Ensure documentation includes vitals trend, neurovascular status, last analgesic dose

Communications:

• Use structured ISBAR for verbal handover

• Clarify current O₂ needs, airway status, recent deterioration episodes

• Inform family of expected transfer time and risks involved

Logistics and Practicalities:

• Prepare medication list, CXR/CTs in digital or printed format

• Notify receiving facility of any ACPs or limitations of care

• Secure monitoring devices for en route use (SpO₂, BP if possible)

What specific monitoring do you consider essential during transfer, and how would you implement it in a rural environment?

• Continuous SpO₂ monitoring with alarms enabled

• Manual BP monitoring every 15–30 minutes if automatic not available

• Sedation/agitation scoring every 30 minutes (e.g., RASS scale)

• Clear escalation plan for hypoxia or agitation

How do you plan analgesia during the transfer, and what contingencies do you include?

• Convert PRN dosing to scheduled prior to departure

• Provide pre-drawn rescue doses (e.g., 2.5mg morphine SC with instructions)

• Include medication list with dosing history for transfer team

• Avoid initiating new sedating agents unless retrieval team is trained in monitoring

What are the key clinical and physiological risks of transferring this patient by air, and how would you mitigate them?

• Hypobaric hypoxia: exacerbates respiratory failure → maximise oxygenation pre-flight

• Barotrauma risk: assess for pneumothorax before flight (CXR or POCUS)

• Equipment dislodgement: secure IV/O₂ lines and label medications

• Mitigation: fly with oxygen supply, appropriate staff, and detailed transfer notes

Family members question the need for transfer. How do you explain it empathetically but clearly?

• "Your father’s injuries need advanced support we don’t have here. This includes access to respiratory machines, surgical specialists, and a team that manages rib fracture complications daily."

• Emphasise patient safety, continuity of care, and importance of timely intervention to prevent deterioration.

Key Exam Phrases:

• "In the elderly, multimodal analgesia helps reduce opioid burden and delirium risk"

• "Respiratory support and pain management are co-dependent in rib fractures"

• "Early coordination with retrieval avoids crisis-driven decisions"