2024.2 Day 2 VIVA 13

Pain Medicine

You are a Rural Generalist Anaesthetist in Scenarioville for a gynaecology list. A 28-yearold woman with chronic pelvic pain and anxiety is scheduled for a diagnostic laparoscopy. She has had no previous general anaesthetics and has a BMI of 31. She currently takes Oxycodone SR 20 mg twice daily and Paroxetine 40 mg daily. The surgeon indicated that the procedure is just a "look around" and that she will have no post-operative pain.

Please outline your pre-anaesthetic assessment.

History taking priorities:

  • Detailed pain history - onset, character, severity, impact on function

  • Anxiety assessment - triggers, previous management, panic attacks

  • Drug history - tolerance, withdrawal symptoms, side effects

  • Previous anaesthetic exposure - family history of complications

  • Functional capacity assessment - exercise tolerance, activities of daily living

Physical examination focus:

  • Airway assessment - obesity increases difficult airway risk

  • Cardiovascular fitness - BMI 31 may impact respiratory reserve

  • Respiratory examination - baseline function crucial for laparoscopy

  • Neurological baseline - chronic pain patterns, anxiety manifestations

Specific concerns for this case:

  • Chronic opioid use - tolerance, hyperalgesia, withdrawal risk

  • SSRI therapy - serotonin syndrome risk, bleeding tendency

  • Obesity - positioning challenges, respiratory compromise

  • Anxiety - cooperation, PONV risk, emergence issues

Risk stratification:

  • ASA classification likely II-III

  • High PONV risk (female, anxiety, opioids, laparoscopy)

  • Moderate difficult airway risk

  • Significant postoperative pain risk despite surgeon's expectations

The surgeon says there will be no post-operative pain. How do you respond?

Challenge this assumption politely

  • Laparoscopy causes visceral and somatic pain

  • CO2 insufflation causes diaphragmatic irritation

  • Chronic pain patients have altered pain processing

  • Opioid tolerance requires higher analgesic doses

What specific risks does her chronic opioid use present?

  • Opioid-induced hyperalgesia - paradoxically increased pain sensitivity

  • Tolerance requiring higher perioperative doses

  • Withdrawal symptoms if inadequate replacement

  • Respiratory depression risk with additional opioids

  • Delayed emergence and cognitive effects

  • Pitfall: Underestimating withdrawal onset (6-12 hours for SR preparations)

How would you assess her functional capacity given her chronic pain?

  • Detailed activity history - stairs, housework, exercise

  • Employment status and limitations

  • Sleep quality and fatigue patterns

  • Previous hospitalisations for pain management

  • Cardiorespiratory fitness indicators

  • Scenarioville limitation: Limited exercise testing facilities

What investigations would you consider?

  • FBC - baseline haemoglobin, platelet function (SSRI effects)

  • UEC - baseline renal function

  • ECG - anxiety may cause arrhythmias, drug effects

  • Consider echocardiogram if poor functional capacity

  • Scenarioville context: Basic pathology available, limited cardiac investigations

How do you optimise her pre-operatively?

  • Continue regular medications including opioids

  • Anxiolytic premedication - avoid over-sedation

  • PONV prophylaxis planning

  • Positioning aids for obesity

  • Clear explanation to reduce anxiety

  • Critical consideration: Cannot delay surgery significantly in rural setting

Describe your anaesthetic technique and intraoperative concerns for this laparoscopic procedure.

Anaesthetic technique:

  • General anaesthesia with IPPV mandatory for laparoscopy

  • RSI not required - adequate fasting assumed

  • Balanced technique - volatile agent, opioids, muscle relaxants

  • Multimodal analgesia from induction

Airway management:

  • ETT essential for controlled ventilation

  • Size 7.0-7.5mm appropriate for female

  • Consider difficult airway backup plans

  • LMA contraindicated due to high airway pressures

Positioning considerations:

  • Steep Trendelenburg position required

  • Arms tucked, padded pressure points

  • Anti-slip mattress essential

  • Monitor eye pressure, facial oedema

Ventilation strategy:

  • Pressure-controlled ventilation preferred

  • PEEP to maintain recruitment

  • Monitor peak and plateau pressures

  • Adjust for CO2 absorption from insufflation

Monitoring priorities:

  • Standard ASA monitoring

  • Arterial line not routinely required

  • Capnography essential - CO2 absorption monitoring

  • Neuromuscular monitoring for reversal

What are the specific hazards of steep head-down positioning?

  • Increased intracranial pressure - cerebral oedema, raised IOP

  • Cardiovascular effects - increased preload, afterload

  • Respiratory compromise - reduced FRC, atelectasis

  • Airway oedema - laryngeal, conjunctival swelling

  • Risk of ETT displacement or kinking

  • Time limitation: Usually tolerated <4 hours

  • Pitfall: Not recognising duration limits in obese patients

The peak airway pressures are 45 cmH2O. What's your management?

  • Check depth of anaesthesia and muscle relaxation

  • Exclude mechanical causes - ETT position, blockage, biting, circuit disconnection

  • Reduce CO2 insufflation pressure if possible

  • Switch to pressure-controlled ventilation

  • Accept higher CO2 if necessary (permissive hypercapnia)

  • Consider recruitment manoeuvres

  • Critical threshold: Peak pressures >50cmH2O concerning

  • Scenarioville limitation: No advanced ventilation modes available

Saturation drops to 88% during insufflation. Your response?

  • Immediate 100% oxygen

  • Check positioning - anti-Trendelenburg temporarily

  • Recruitment manoeuvre - sustained inflation

  • Reduce CO2 pressure if surgeon agrees

  • Rule out pneumothorax, bronchospasm

  • Consider abandoning procedure if persistent

  • Critical action: Do not hesitate to flatten patient

How do you manage her chronic opioid tolerance intraoperatively?

  • Higher opioid doses required - 2-3x normal

  • Consider alternative analgesics - ketamine, dexmedetomidine

  • Regional techniques where possible - TAP block

  • Avoid complete opioid substitution

  • Monitor for withdrawal signs

  • Scenarioville context: Limited regional anaesthesia options

What PONV prophylaxis would you use?

  • Multimodal approach essential - 3-4 agents

  • Ondansetron 4-8mg, dexamethasone 4-8mg

  • Droperidol 0.625-1.25mg (if available)

  • Avoid propofol TIVA (limited pumps in Scenarioville)

  • Consider scopolamine patch

  • High-risk patient: Female, anxiety, opioids, laparoscopy

The patient wakes up in severe pain (8/10) and is vomiting. How do you manage this situation?

Immediate pain assessment:

  • Validate pain scores - chronic pain patients reliable reporters

  • Differentiate surgical vs gas pain

  • Check positioning, bladder distension

  • Review intraoperative analgesic doses

Pain management strategy:

  • Higher opioid doses due to tolerance

  • Multi-modal approach - paracetamol, NSAIDs if appropriate

  • Consider ketamine for hyperalgesia

  • Patient-controlled analgesia if available

  • Regional blocks - TAP or wound infiltration

PONV management:

  • Different class antiemetic if prophylaxis failed

  • Metoclopramide 10mg IV

  • Cyclizine 50mg IV

  • Ensure adequate hydration

  • Consider dexmedetomidine for anxiolysis

Monitoring requirements:

  • Continuous SpO2 monitoring

  • Regular pain and sedation scores

  • Vital signs every 15 minutes initially

  • Consider HDU if respiratory compromise

Her respiratory rate is 8/min and she's sedated. What's your concern?

  • Opioid overdose in tolerant patient

  • Synergistic effects with benzodiazepines/other sedatives

  • Residual anaesthetic effects

  • CO2 retention from laparoscopy

  • Immediate action: Reduce/cease opioids, consider naloxone

  • Scenarioville limitation: No HDU for close monitoring

  • Critical decision: May need retrieval for higher care

Pain remains 7/10 despite 20mg morphine equivalent. Next steps?

  • Ketamine 0.5mg/kg bolus, then infusion

  • Regional anaesthesia - bilateral TAP blocks

  • Gabapentinoids for neuropathic component

  • Liaise with chronic pain service (via telehealth)

  • Consider clonidine for sympathetic effects

  • Avoid: Excessive opioid escalation

  • Pitfall: Not recognising opioid-induced hyperalgesia

She continues vomiting despite multiple antiemetics. Management?

  • Check for surgical complications - bleeding, perforation

  • Exclude other causes - UTI, gastroenteritis

  • Propofol subanaesthetic dose if available

  • Steroids if not already given

  • Acupuncture/pressure if trained staff available

  • Scenarioville context: Limited consultant support available

When would you consider retrieval to the capital city?

  • Persistent respiratory depression requiring continuous monitoring

  • Uncontrolled pain despite maximal therapy

  • Suspected surgical complications

  • Intractable vomiting causing dehydration

  • Patient/family request for specialist care

  • Critical timing: 2-hour retrieval time must factor into decisions

How do you discharge plan for this patient?

  • Continue regular opioid prescription

  • Multimodal analgesia regime

  • Clear instructions for escalation

  • Follow-up with GP and chronic pain service

  • PONV medication for home

  • Scenarioville context: Limited community support services

  • Essential: Clear pain management expectations with patient and family

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