Pre-Hospital Critical Care

Clinical Overview

Pre-hospital critical care represents the extension of intensive care interventions into the pre-hospital environment, delivered by highly trained physician-paramedic or critical care paramedic teams. The field has evolved from "scoop and run" to sophisticated mobile critical care, particularly in trauma systems where definitive care is not immediately accessible.[1,2]

Core Principle: The goal is to deliver the right intervention, at the right time, to the right patient, while minimizing on-scene time and preventing secondary injury during transport.[3]

Key Questions:

1. Is the intervention life-saving or does it delay definitive care?
2. Can it be performed safely in the pre-hospital environment?
3. Does the team have the training and equipment for success?
4. What is the transport time to definitive care?

Scene Safety and Situational Awareness

DRSABCD Framework (Australian/NZ Resuscitation Council)

The DRSABCD mnemonic structures the initial approach to any pre-hospital emergency:[4]

Scene Safety Priorities:[5]

• Personal safety first (if the rescuer becomes a victim, no one is helped)
• Environmental hazards: fire, electricity, chemical exposure, unstable vehicles
• Violence and aggression: police support, escape routes, situational awareness
• Traffic control: parking position, high-visibility equipment, safety zones

Primary Survey (ATLS-Based Approach)

For trauma patients, the C-ABCDE approach prioritizes catastrophic hemorrhage control:[6]

C - Catastrophic Hemorrhage
  ↓ Tourniquets, direct pressure, hemostatic agents
A - Airway with C-spine protection
  ↓ Manual in-line stabilization (MILS)
B - Breathing and ventilation
  ↓ Oxygen, decompress tension pneumothorax
C - Circulation with hemorrhage control
  ↓ IV/IO access, permissive hypotension, blood products
D - Disability (neurological status)
  ↓ GCS, pupils, glucose
E - Exposure and environment control
  ↓ Remove clothing, prevent hypothermia

Advanced Airway Management

Pre-Hospital Rapid Sequence Induction (RSI)

Pre-hospital RSI is a high-risk, high-benefit intervention performed by specially trained teams (physicians, critical care paramedics).[7]

Indications for Field RSI:[8]

The 7 Ps of RSI:[9]

1. Preparation: Equipment check, team briefing, escape plan
2. Pre-oxygenation: 3-5 minutes of 100% O₂ (target SpO₂ 100%)
3. Pre-treatment: Consider fentanyl (1-2 mcg/kg) for sympatholysis if hypertensive
4. Paralysis with induction: Ketamine (1-2 mg/kg) + Rocuronium (1.2 mg/kg) or Suxamethonium (1.5 mg/kg)
5. Protection and positioning: Manual in-line stabilization (MILS) if trauma
6. Placement with proof: Endotracheal intubation with waveform capnography confirmation
7. Post-intubation management: Sedation, ventilator settings, ongoing reassessment

Drug Selection in Pre-Hospital RSI:[10]

Ketamine is preferred in trauma due to hemodynamic stability and analgesic properties.[11]

Post-Intubation Pitfalls:[12]

• Right mainstem intubation: Check bilateral breath sounds, observe chest rise
• Tension pneumothorax: New onset hypotension/hypoxia post-intubation requires immediate needle decompression
• Unrecognized esophageal intubation: Waveform capnography is mandatory (not just colorimetric)
• Inadequate sedation: Paralysis without sedation = awareness and suffering
• Ventilator-induced lung injury: Tidal volume 6-8 mL/kg ideal body weight, avoid excessive FiO₂

Surgical Airway

Indications:[13]

• Failed intubation/cannot ventilate scenario
• Severe maxillofacial trauma preventing intubation
• Upper airway obstruction (anaphylaxis, burns, hematoma)

Technique: Scalpel cricothyroidotomy (preferred over needle cricothyroidotomy in adults)

• Identify cricothyroid membrane (between thyroid and cricoid cartilages)
• Horizontal incision through skin and membrane
• Bougie insertion, railroaded with 6.0-7.0 cuffed ETT
• Confirm placement with capnography

Thoracic Interventions

Needle Decompression

Indication: Tension pneumothorax (clinical diagnosis)[14]

• Respiratory distress with hypoxia
• Hypotension or cardiac arrest
• Unilateral decreased breath sounds + hyperresonance
• Tracheal deviation (late sign)
• Distended neck veins (if not hypovolemic)

Technique:[15]

• Site: 5th intercostal space, mid-axillary line (preferred) OR 2nd intercostal space, mid-clavicular line
• Equipment: 14G or 16G cannula, ≥8 cm length (standard IV cannulas often too short)
• Insertion: Just above rib (avoid neurovascular bundle below rib)
• Confirmation: Rush of air, clinical improvement

Pitfall: 30-50% of needle decompressions fail due to inadequate needle length (chest wall thickness in obese patients).[16]

Finger Thoracostomy / Tube Thoracostomy

Indications:[17]

• Decompression of confirmed pneumothorax/hemothorax
• Pre-hospital environment: Finger thoracostomy (without tube) often preferred to avoid dislodgement during transport
• Prophylactic decompression before air transport in at-risk patients

Technique:

• 5th intercostal space, mid-axillary line (safe triangle)
• Blunt dissection with forceps or finger
• Digital exploration confirms intrapleural placement
• Tube insertion (if equipment available): 28-32 Fr chest tube

Vascular Access and Fluid Resuscitation

IV vs. Intraosseous (IO) Access

First-line: Peripheral IV access (18G or larger)[18]

IO access indications:[19]

• Failed peripheral IV attempts in critically ill patient
• Cardiac arrest (immediate vascular access needed)
• Burns or traumatic injuries limiting IV sites
• Pediatric patients (difficult IV access)

IO sites:[20]

• Proximal tibia (pediatrics and adults)
• Distal tibia
• Proximal humerus (adults, preferred in cardiac arrest - closer to central circulation)

IO contraindications: Fracture in target bone, previous IO attempt in same bone, infection at site, known bone disorder (osteogenesis imperfecta)

Pharmacokinetics: IO route achieves therapeutic levels comparable to IV route for all resuscitation medications and fluids.[21]

Fluid Resuscitation Strategy

Permissive Hypotension (Damage Control Resuscitation):[22]

The landmark Bickell et al. study (1994) demonstrated that delayed fluid resuscitation until surgical control of hemorrhage improved survival in penetrating torso trauma.[23]

Target Blood Pressure:[24]

• Penetrating trauma: Systolic BP 80-90 mmHg (enough for consciousness, minimize bleeding)
• Blunt trauma: Systolic BP 90 mmHg
• Traumatic brain injury: Systolic BP ≥100 mmHg (maintain cerebral perfusion pressure)

Fluid Selection:[25]

• First-line: Isotonic crystalloid (normal saline, Hartmann's/Ringer's lactate) in limited volumes (250-500 mL boluses)
• Blood products (if available): Whole blood or balanced blood component therapy (1:1:1 ratio PRBC:FFP:Platelets)

Pre-hospital Blood Products: The PAMPer trial (2018) showed that pre-hospital plasma administration reduced 30-day mortality (23.2% vs. 33.0%, p=0.03) in trauma patients at risk of hemorrhagic shock.[26]

Pre-Hospital Analgesia

Effective analgesia is both humanitarian and physiological (reduces catecholamine response, improves respiratory effort, facilitates examination).

Analgesic Options

Ketamine vs. Fentanyl: A 2019 RCT (intranasal route) found both agents effective for pain relief in trauma, with ketamine providing comparable analgesia with different side effect profile (minor dissociation vs. nausea).[27]

Methoxyflurane (Penthrox): An inhaled analgesic widely used in Australian and New Zealand pre-hospital care. The STOP! study (2014) demonstrated efficacy for moderate-to-severe trauma pain with rapid onset.[28]

Hemorrhage Control

Tourniquet Application

Modern combat casualty care has re-established tourniquets as life-saving interventions for compressible limb hemorrhage.[29]

Indications:[30]

• Life-threatening extremity hemorrhage not controlled by direct pressure
• Amputation or near-amputation
• Multiple casualties (allows rescuer to move to next patient)

Technique:

• Apply proximal to wound, as high as possible on limb
• Tighten until hemorrhage stops (arterial occlusion)
• Note time of application
• Re-assess after other interventions; conversion to direct pressure if appropriate

Evidence: Multiple military studies demonstrate tourniquet use reduces hemorrhage-related mortality with low complication rates (limb loss <2% when removed within 2 hours).[31]

Hemostatic Agents

Topical hemostatic dressings (QuikClot, Celox, Combat Gauze) are used for junctional hemorrhage (axilla, groin, neck) where tourniquets cannot be applied.[32]

Mechanism: Kaolin or chitosan activates clotting cascade; zeolite formulations (older) generate heat (risk of burns).

Application: Pack wound cavity firmly with hemostatic gauze, maintain direct pressure for 3-5 minutes.[33]

Pelvic Binders

Indication: Suspected pelvic fracture (mechanism, instability on examination)[34]

Mechanism: Circumferential compression reduces pelvic volume, stabilizes fractured bone, tamponades venous bleeding.[35]

Application:[36]

• Place at level of greater trochanters (NOT at iliac crests)
• Tighten until firm resistance
• Avoid over-tightening (can displace fracture fragments)

Evidence: Pre-hospital pelvic binder use is associated with reduced transfusion requirements and improved mortality in unstable pelvic fractures.[37]

Tranexamic Acid (TXA)

CRASH-2 Trial (2010): TXA administration within 3 hours of injury reduced all-cause mortality (14.5% vs. 16.0%, p=0.0035) in trauma patients with or at risk of significant hemorrhage.[38]

Dose: 1 gram IV over 10 minutes, followed by 1 gram IV over 8 hours

Time-critical: Benefit greatest when given <1 hour; administration >3 hours associated with increased mortality (possibly due to late thrombotic complications).[39]

Pre-hospital TXA: The PATCH-Trauma trial (2023) evaluated pre-hospital TXA but did not demonstrate mortality benefit; however, it included a high proportion of patients with non-survivable injuries.[40]

Current Recommendation: Administer TXA as early as possible in trauma patients with suspected significant hemorrhage, ideally within 1 hour of injury.[41]

Pre-Hospital ECPR (Extracorporeal CPR)

Concept: Initiation of extracorporeal membrane oxygenation (ECMO) during cardiac arrest to support circulation while treating underlying cause.[42]

ARREST Trial (2020): In patients with refractory VF/VT out-of-hospital cardiac arrest, ECPR was associated with significantly higher survival (43% vs. 7%, p<0.001) compared to standard ACLS.[43]

Pre-hospital Models:[44]

• Mobile ECMO team: Specialized team brings ECMO to the scene (Paris SAMU model)
• Scoop to ECMO center: Mechanical CPR during rapid transport to ECMO-capable facility

Selection Criteria (adapted from Minnesota/Prague criteria):[45]

• Age 18-75 years
• Witnessed arrest with bystander CPR
• Initial shockable rhythm (VF/VT)
• Refractory to standard resuscitation (≥3 shocks or >15-20 minutes CPR)
• Estimated time from collapse to ECMO <60 minutes
• No obvious non-cardiac cause (trauma, drowning, drug overdose may be considered in select cases)

Challenges: Resource-intensive, requires highly specialized teams, ethical considerations around patient selection

HEMS (Helicopter Emergency Medical Services)

Australian and New Zealand HEMS Models

Sydney HEMS (NSW, Australia)

Primary Providers:[46]

• NSW Ambulance (Greater Sydney Area Helicopter Emergency Medical Service)
• CareFlight
• Westpac Life Saver Rescue Helicopter (coastal areas)

Staffing: Physician (Emergency Medicine/Intensive Care/Anaesthesia consultant or senior registrar) + Critical Care Paramedic

Capabilities: Pre-hospital RSI, thoracostomy, blood product transfusion, advanced resuscitation, winch rescues

Key Bases: Bankstown (Sydney), Wollongong, Orange

Auckland HEMS (New Zealand)

Provider: Auckland Rescue Helicopter Trust (Westpac Rescue Helicopter)

Staffing: Flight Paramedic + Flight Paramedic OR Flight Paramedic + Physician (Pre-hospital and Retrieval Medicine specialists)

Capabilities: Similar advanced interventions; significant focus on maritime and wilderness rescues given New Zealand geography

Alfred HEMS (Melbourne, Australia)

Provider: Air Ambulance Victoria in partnership with The Alfred Hospital

Staffing: Physician + Flight Paramedic

Special Features: Adult Retrieval Victoria (ARV) coordinates ICU-to-ICU transfers; integration with major trauma service at The Alfred

Evidence for Physician-Staffed HEMS

Systematic Review and Meta-Analysis (2021):[47]

Physician-led pre-hospital critical care is associated with:

• Improved survival in major trauma (OR 1.6-2.5 depending on injury severity)
• Higher rates of advanced interventions: RSI (80% vs. 20%), blood transfusion (40% vs. 5%), thoracostomy (25% vs. 5%)

Mechanisms of Benefit:[48]

• Advanced procedural skills (emergency anesthesia, thoracostomy)
• Clinical decision-making (when to intervene vs. scoop-and-run)
• Medication availability (induction agents, blood products, vasopressors)
• Ability to declare death on scene (reduces futile transport)

Equipment and Monitoring

Pre-Hospital Ventilators

Requirements for Transport Ventilators:[49]

• Compact and lightweight
• Battery-powered with extended battery life (≥2 hours)
• Modes: Volume control, pressure control, CPAP, PSV
• Oxygen consumption efficiency
• Altitude compensation (for air medical transport)
• Rugged construction for vibration/temperature extremes

Common Models: Oxylog 3000, Hamilton T1, Zoll 731 EMV+

Ventilator Settings for Transport:[50]

• Tidal volume: 6-8 mL/kg ideal body weight
• Respiratory rate: 10-12 breaths/min (target PaCO₂ 35-40 mmHg in trauma; 30-35 mmHg in TBI)
• FiO₂: Titrate to SpO₂ 92-96%
• PEEP: 5 cmH₂O (increase if hypoxemic)

Monitoring Devices

Essential Monitors:[51]

• Waveform capnography: Confirms ETT placement, monitors ventilation, cardiac output proxy
• Pulse oximetry: Continuous SpO₂ monitoring
• Non-invasive blood pressure: Automated cycling every 3-5 minutes or manual PRN
• 3-lead ECG: Continuous cardiac rhythm monitoring
• Temperature: Core or peripheral (prevent hypothermia)
• Glucose: Point-of-care testing for altered consciousness

Advanced Monitoring (Physician-Staffed Teams):[52]

• Invasive arterial blood pressure (femoral or radial arterial line)
• Point-of-care ultrasound (eFAST, cardiac, lung ultrasound)
• Blood gas analysis (portable i-STAT)

Warming Devices

Hypothermia Prevention:[53]

Trauma patients lose heat through:

• Exposure (remove clothing for examination, environmental cold)
• Evaporation (wet clothing, open wounds)
• Infusion of cold fluids
• Impaired thermoregulation (shock, TBI, sedation)

Strategies:

• Remove wet clothing, cover with blankets
• Warm IV fluids (fluid warmers or pre-warmed bags in transport warming cabinet)
• Forced-air warming devices (Bair Hugger) if available and time permits
• Increase ambient temperature in ambulance/helicopter
• Minimize scene time and exposure

Target: Core temperature >35°C (hypothermia <35°C exacerbates coagulopathy)

Communication and Handover

Pre-Hospital Notification

Importance: Advance notification allows receiving hospital to prepare:[54]

• Activate trauma team
• Prepare operating room or angiography suite
• Cross-match blood products
• Mobilize specialist resources (neurosurgery, cardiothoracic, interventional radiology)

Information to Communicate:[55]

• Patient demographics (age, sex)
• Mechanism of injury
• Vital signs and trends
• Injuries identified
• Interventions performed (airway, thoracostomy, vascular access, fluids/blood given)
• Estimated time of arrival (ETA)

ISBAR Handover Tool

ISBAR (Identify, Situation, Background, Assessment, Recommendation) is a structured communication framework:[56]

I - IDENTIFY
  - "Patient: Name, age, sex"
  - Receiving clinician: "This is Dr. Smith from Sydney HEMS speaking with Dr. Jones in ED"

S - SITUATION
  - Chief complaint: "32-year-old male, motorcycle vs. car at 80 km/h"

B - BACKGROUND
  - "Mechanism: High-speed MVA, 10-meter ejection"
  - "PMHx: Unknown"
  - "Medications/Allergies: Unknown"

A - ASSESSMENT
  - Primary survey findings: "Intubated, bilateral breath sounds, weak radial pulses, GCS 7 (post-sedation), pelvic instability"
  - Vital signs: "HR 120, BP 85/50, SpO₂ 95% on FiO₂ 0.6"
  - Interventions: "RSI with ketamine/rocuronium, left finger thoracostomy, 18G IV x 2, 500 mL Hartmann's given, pelvic binder applied, TXA 1 gram given"

R - RECOMMENDATION
  - "Request trauma team activation, likely needs CT and angiography or OR for pelvic bleeding. ETA 8 minutes."

Documentation: Record handover time, receiving clinician name, and any specific instructions or questions.[57]

Scoop-and-Run vs. Stay-and-Play Debate

This longstanding debate centers on whether pre-hospital teams should perform interventions on scene (stay-and-play) or minimize scene time and transport rapidly to hospital (scoop-and-run).[58]

Evidence Summary

Scoop-and-Run Favored:[59]

• Penetrating trauma (especially torso): Surgery is definitive treatment; field interventions delay hemorrhage control
• Urban settings with short transport times (<10-15 minutes): Hospital arrival faster than field stabilization
• Hemorrhagic shock: Every minute of on-scene time increases mortality

Stay-and-Play Favored:[60]

• Entrapment: Cannot transport until extrication complete
• Rural/remote settings: Long transport times (>30-60 minutes) necessitate field stabilization
• Specific life-saving interventions: Airway obstruction, tension pneumothorax, cardiac tamponade
• Medical emergencies: Cardiac arrest, respiratory failure, anaphylaxis

Hybrid "Treat-and-Run" Approach (Current Best Practice):[61]

• Life-saving interventions only: Airway, decompression, hemorrhage control
• Minimize scene time: "Platinum 10 minutes" (scene time <10 minutes in trauma)
• Continue care during transport: IV access, monitoring, fluid titration en route
• Clinical judgment: Tailor approach to patient, geography, and transport time

Meta-Analysis Findings: Increased pre-hospital time is associated with increased mortality in patients with time-sensitive injuries (hemorrhagic shock, TBI), but not in patients requiring stabilization (airway management, specific interventions).[62]

Australian and New Zealand Pre-Hospital Systems

State Ambulance Services

Royal Flying Doctor Service (RFDS)

Overview: Provides aeromedical retrieval and primary healthcare to remote and rural Australia.[63]

Retrieval Teams: Doctor + Flight Nurse, equipped for advanced pre-hospital and transport care

Challenges in Remote/Rural Settings:[64]

• Distance: Retrieval times measured in hours, not minutes
• Communication: Satellite phones, HF radio in areas without mobile coverage
• Resource limitations: Limited equipment compared to urban HEMS
• Environmental: Extreme heat, dust, limited landing sites
• Patient factors: Delayed presentation, limited pre-hospital care before RFDS arrival

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Populations:[65]

Health Disparities:

• 2-3x higher rates of trauma-related hospitalization
• Lower access to timely emergency care in remote communities
• Higher burden of chronic disease (diabetes, cardiovascular, renal) complicating acute presentations

Cultural Safety in Pre-Hospital Care:[66]

• Aboriginal Health Workers (AHWs): Involve in patient care and family communication when available
• Family and community: Aboriginal patients may prefer family presence; communicate in inclusive manner
• Language: Professional interpreters or AHWs for non-English speaking patients
• Respect and trust: Historical trauma and mistrust of healthcare system; build rapport, explain all interventions
• Cultural protocols: Awareness of Sorry Business, men's/women's business, skin names and kinship

Remote Community Challenges:

• Limited access to advanced life support until RFDS arrival (may be hours)
• Community Health Nurses or Remote Area Nurses (RANs) provide initial stabilization
• Telemedicine support for decision-making

Māori Health (New Zealand):[67]

Health Disparities:

• 1.5-2x higher injury-related mortality compared to non-Māori
• Higher rates of MVA, workplace injuries

Cultural Considerations:

• Whānau (family): Central role in decision-making; involve whānau in discussions
• Tikanga (cultural practices): Respect for body, personal space, gender-specific care preferences
• Kaumātua (elders): Respect and deference; involve in decisions when appropriate
• Communication: Engage Māori Health Workers if available; use plain language, avoid jargon
• Te Tiriti o Waitangi obligations: Partnership, participation, protection in healthcare delivery

Evidence for Pre-Hospital Interventions

What Works (Evidence-Based)

What May Not Work or Is Controversial

Cognitive and Non-Technical Skills

Human Factors in Pre-Hospital Environment

Challenges Unique to Pre-Hospital Care:[79]

• Environmental: Noise, weather, lighting, confined spaces, bystanders
• Cognitive load: High-stakes decisions with limited information and time
• Equipment: Unfamiliar or improvised equipment; battery/oxygen limitations
• Team dynamics: Ad hoc teams, mixed training levels, communication barriers

Strategies to Mitigate Errors:[80]

• Checklists: Pre-departure, RSI, handover checklists reduce omissions
• Closed-loop communication: Repeat-back for critical orders
• Task allocation: Clear role assignment (airway, circulation, documentation, family liaison)
• Situational awareness: "Stop and think" pauses before high-risk interventions
• Debriefing: Post-mission debriefs for learning and team cohesion

Crisis Resource Management (CRM) Principles

1. Know the environment: Familiarize with equipment, escape routes, hazards
2. Anticipate and plan: Prepare for worst-case scenarios (failed airway, cardiac arrest)
3. Call for help early: Activate additional resources before crisis escalates
4. Distribute the workload: Delegate tasks to team members
5. Mobilize all available resources: Equipment, personnel, communication
6. Communicate effectively: Clear, concise, closed-loop
7. Use all available information: Scene, patient, bystanders, telemedicine
8. Prevent and manage fixation errors: Avoid tunnel vision; re-assess regularly
9. Cross-check (double-check): Critical decisions and medication doses
10. Use cognitive aids: Protocols, checklists, drug dosing apps

Training and Competency

Pre-Hospital Emergency Medicine (PHEM) as a Subspecialty:[81]

In Australia and New Zealand, PHEM is an emerging subspecialty with formal training pathways through:

• Australasian College for Emergency Medicine (ACEM): Certificate in Pre-hospital and Retrieval Medicine
• Australian and New Zealand College of Anaesthetists (ANZCA): Special Interest Group in Pre-hospital and Retrieval Medicine
• College of Intensive Care Medicine (CICM): Retrieval medicine recognized as part of ICU training

Core Competencies:[82]

• Advanced airway management (RSI, surgical airway)
• Thoracic procedures (needle decompression, thoracostomy)
• Vascular access (IV, IO, CVC if applicable)
• Resuscitation (ACLS, trauma, obstetric, pediatric)
• Medication administration (dosing calculations under stress)
• Medical decision-making (intervention vs. transport, resource allocation)
• Team leadership and communication
• Scene safety and situational awareness

Simulation Training: High-fidelity simulation replicates pre-hospital environment (noise, movement, limited lighting) for skills practice and team training.[83]

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Summary: Key Principles of Pre-Hospital Critical Care

1. Scene safety first: No intervention is worth a dead rescuer
2. Time-critical interventions only: Life-saving procedures vs. "stay-and-play" delays
3. ABC approach with adaptations: C-ABCDE for trauma, DRSABCD for general emergencies
4. Permissive hypotension in trauma: Avoid aggressive crystalloid; blood products if available
5. TXA within 1 hour: Evidence-based hemorrhage control adjunct
6. RSI is high-risk/high-benefit: Requires training, equipment, and backup plan
7. Communication is critical: Pre-hospital notification and structured handover (ISBAR)
8. Tailor to transport time: Short transport = scoop-and-run; long transport = stabilization en route
9. Prepare for equipment failure: Backup airway devices, spare oxygen, manual ventilation capability
10. Cultural safety: Respect and involve Aboriginal, Torres Strait Islander, and Māori patients/whānau

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SAQ Practice Questions

SAQ 1: Pre-Hospital RSI and Post-Intubation Hypotension (15 marks)

Question:

A 28-year-old man is involved in a high-speed motorcycle crash. He is found 30 km from the nearest hospital with a GCS of 7 (E2 V2 M3). The physician-paramedic HEMS team decides to perform rapid sequence induction in the field. Post-intubation, the patient becomes profoundly hypotensive (BP 60/40 mmHg) with SpO₂ 85%.

a) List four (4) potential causes of post-intubation hypotension in this scenario. (4 marks)

b) Describe the immediate management steps you would take to address each of these causes. (6 marks)

c) Outline three (3) strategies to prevent post-intubation cardiovascular collapse in critically injured trauma patients undergoing field RSI. (3 marks)

d) What drug regimen would you recommend for RSI in this patient, and why? (2 marks)

Model Answer:

(a) Four potential causes of post-intubation hypotension (4 marks):

1. Tension pneumothorax (1 mark)

   • Positive pressure ventilation converts simple pneumothorax to tension; clinical signs may be masked by sedation/paralysis

2. Hypovolemia/hemorrhagic shock (1 mark)

   • Loss of sympathetic tone from induction agents unmasks compensated shock; patient may have internal bleeding

3. Induction agent effects (1 mark)

   • Even ketamine can cause hypotension in severely hypovolemic patients; loss of endogenous catecholamine response

4. Right mainstem intubation with hypoxia (1 mark)

   • Endobronchial intubation causes V/Q mismatch, hypoxemia, and secondary cardiovascular collapse

Alternative acceptable answers: Cardiac tamponade, pulmonary embolism, myocardial contusion, neurogenic shock (though less likely to be immediate post-intubation)

(b) Immediate management steps (6 marks):

1. Tension pneumothorax (1.5 marks)

   • Diagnosis: Unilateral decreased breath sounds, hyperresonance to percussion, hypoxia, hypotension
   • Management: Immediate needle decompression (5th ICS mid-axillary line bilaterally if unsure of side) followed by finger thoracostomy

2. Hypovolemia (1.5 marks)

   • Diagnosis: Clinical signs of shock (tachycardia, weak pulses, delayed capillary refill), mechanism suggestive of hemorrhage
   • Management: Fluid resuscitation (250-500 mL boluses of Hartmann's or blood products if available), target SBP 80-90 mmHg, consider vasopressor support (push-dose epinephrine 10-20 mcg or commence norepinephrine infusion), identify and control bleeding source

3. Induction agent effects (1.5 marks)

   • Diagnosis: Hypotension immediately following induction without other clear cause
   • Management: Reduce sedation dose or pause sedation infusion temporarily, administer vasopressor (push-dose phenylephrine 50-100 mcg or epinephrine 10-20 mcg), cautious fluid bolus

4. Right mainstem intubation (1.5 marks)

   • Diagnosis: Unilateral breath sounds (right-sided), poor chest rise on left, low SpO₂
   • Management: Withdraw ETT 1-2 cm under direct visualization (if possible) or by auscultation until bilateral breath sounds confirmed, re-check tube position, confirm with capnography waveform

(c) Three strategies to prevent post-intubation cardiovascular collapse (3 marks):

1. Pre-oxygenation and positioning (1 mark)

   • 3-5 minutes of 100% oxygen via bag-valve-mask with PEEP valve to maximize oxygen reserve; head-up positioning if injuries allow

2. Fluid loading and reduced induction doses (1 mark)

   • Administer 250-500 mL crystalloid or blood products prior to induction; use reduced ketamine dose (0.5-1 mg/kg) in shocked patients; prepare push-dose vasopressors pre-induction

3. Prophylactic bilateral thoracostomy in high-risk patients (1 mark)

   • Consider bilateral finger thoracostomy before intubation if high suspicion of pneumothorax (chest trauma, rib fractures, subcutaneous emphysema) and long transport time

Alternative acceptable answers: Delayed sequence intubation (DSI) with ketamine dissociation to allow pre-oxygenation in agitated patients; use of ultrasound to exclude pneumothorax before intubation; preparation of backup airway equipment and plan

(d) Drug regimen for RSI (2 marks):

Recommended: Ketamine 1 mg/kg IV + Rocuronium 1.2 mg/kg IV (1 mark)

Rationale (1 mark):

• Ketamine is preferred in trauma due to relative hemodynamic stability (maintains endogenous catecholamine release), analgesia, and bronchodilation
• Rocuronium provides reliable paralysis with predictable offset and reversibility (sugammadex) if needed
• Avoid etomidate (adrenal suppression, though single-dose likely safe) and propofol (profound vasodilation and hypotension in shock)
• Suxamethonium is acceptable alternative (faster onset) but avoid in burns, crush injury (hyperkalemia risk)
• Reduce ketamine dose to 0.5-1 mg/kg in severe shock

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SAQ 2: Permissive Hypotension and Fluid Resuscitation in Trauma (15 marks)

Question:

A 35-year-old woman is stabbed in the left upper quadrant of the abdomen. She is alert but pale, with HR 130 bpm, BP 75/40 mmHg, RR 28/min, SpO₂ 96% on room air. The nearest trauma center is 20 minutes away by ground ambulance.

a) Explain the rationale for permissive hypotension in this patient, including the physiological mechanisms by which aggressive fluid resuscitation may worsen outcomes. (5 marks)

b) What target blood pressure would you aim for during transport, and why? (2 marks)

c) Describe your step-by-step fluid resuscitation strategy for this patient during the 20-minute transport. (4 marks)

d) The patient deteriorates en route with loss of consciousness (GCS 7). How does this change your resuscitation targets and management? (2 marks)

e) List two (2) other adjunctive interventions (non-fluid) you would perform for hemorrhage control in the pre-hospital setting. (2 marks)

Model Answer:

(a) Rationale for permissive hypotension (5 marks):

Principle: Maintain minimal blood pressure adequate for organ perfusion (consciousness, urine output) while avoiding exacerbation of hemorrhage until surgical control achieved. (1 mark)

Physiological mechanisms of harm from aggressive crystalloid resuscitation (4 marks):

1. Clot disruption and re-bleeding (1 mark)

   • Increased blood pressure dislodges fragile thrombus at injury site, increases bleeding rate
   • Hydraulic "pop-off" effect where higher pressure prevents platelet plug formation

2. Dilutional coagulopathy (1 mark)

   • Large-volume crystalloid dilutes clotting factors (fibrinogen, Factors II, V, VII, VIII, IX, X, XI)
   • Dilutes platelets, reducing platelet count and function
   • Balanced blood component therapy (1:1:1 ratio) preferred if available

3. Hypothermia (1 mark)

   • Room-temperature or cold IV fluids lower core temperature
   • Hypothermia impairs coagulation enzyme function (50% reduction in clotting at 33°C)
   • Contributes to "lethal triad" (coagulopathy, acidosis, hypothermia)

4. Acidosis (1 mark)

   • Crystalloid resuscitation worsens metabolic acidosis (chloride load from normal saline, lactate load from Ringer's)
   • Acidosis impairs clotting factor activity and platelet function
   • Tissue hypoperfusion from ongoing hemorrhage worsens lactic acidosis

Alternative acceptable points: Increased interstitial edema impairing oxygen delivery; abdominal compartment syndrome risk; immune dysfunction

(b) Target blood pressure (2 marks):

Target: Systolic BP 80-90 mmHg (1 mark)

Rationale (1 mark):

• Adequate for consciousness and renal perfusion (patient can communicate symptoms, maintain airway)
• Minimizes ongoing hemorrhage until surgical control
• Based on Bickell et al. (1994) landmark study in penetrating torso trauma showing improved survival with delayed resuscitation

Note: If patient has traumatic brain injury (TBI), target changes to SBP ≥100 mmHg to maintain cerebral perfusion pressure; however, no TBI mentioned in this scenario

(c) Step-by-step fluid resuscitation strategy (4 marks):

1. Initial assessment and vascular access (1 mark)

   • Establish two large-bore IV lines (18G or larger) or IO access if IV unsuccessful
   • Avoid central lines in pre-hospital setting (time-consuming, complication risk)

2. Judicious crystalloid boluses (1 mark)

   • Administer 250 mL boluses of isotonic crystalloid (Hartmann's/Ringer's lactate preferred over normal saline to avoid hyperchloremic acidosis)
   • Re-assess BP and clinical perfusion (consciousness, radial pulse quality) after each bolus
   • Stop fluid boluses once SBP reaches 80-90 mmHg or radial pulse palpable

3. Blood products if available (1 mark)

   • If pre-hospital blood products available (whole blood or PRBC + plasma), switch to blood product resuscitation
   • Aim for balanced resuscitation (1:1 ratio PRBC:Plasma, or whole blood)
   • PAMPer trial showed pre-hospital plasma reduced 30-day mortality

4. Ongoing reassessment (1 mark)

   • Continuous monitoring of BP, HR, consciousness level
   • If BP drops below target or consciousness deteriorates, administer further 250 mL boluses titrated to target
   • Prepare for immediate handover to trauma team on arrival (pre-notify for trauma activation, CT angiography or OR)

(d) Change in management with GCS 7 (2 marks):

Revised target: SBP ≥100 mmHg (1 mark)

• Loss of consciousness suggests possible associated traumatic brain injury (TBI), intracranial bleeding, or profound shock
• TBI requires higher MAP to maintain cerebral perfusion pressure (CPP = MAP - ICP)
• Brain Trauma Foundation guidelines recommend SBP ≥100 mmHg (or MAP ≥80 mmHg) in TBI

Additional management (1 mark):

• Consider RSI for airway protection (GCS ≤8)
• Maintain normocapnia (PaCO₂ 35-40 mmHg; avoid hyperventilation unless signs of herniation)
• Escalate to more aggressive resuscitation (accept higher fluid volumes, consider vasopressor support if needed)
• Urgent trauma team activation and CT brain + torso on arrival

(e) Two adjunctive hemorrhage control interventions (2 marks):

1. Tranexamic acid (TXA) (1 mark)

   • 1 gram IV over 10 minutes, commenced as soon as possible (<1 hour from injury)
   • CRASH-2 trial demonstrated mortality reduction in trauma with significant hemorrhage
   • Inhibits fibrinolysis, stabilizes clot formation

2. Direct wound pressure or hemostatic dressings (1 mark)

   • Apply direct manual pressure or pressure dressings to external wounds
   • Use hemostatic gauze (QuikClot, Combat Gauze) for deeper wounds if needed
   • If accessible external wound, consider packing with hemostatic dressing

Alternative acceptable answers: Pelvic binder (if pelvic fracture suspected); tourniquet (if extremity hemorrhage); position patient supine or Trendelenburg if tolerated; prevent hypothermia (remove wet clothing, blankets, warm ambulance); rapid transport to trauma center (minimize scene time)

---

Viva Scenarios

Viva 1: Pre-Hospital Airway Management and Decision-Making (20 marks)

Scenario:

You are the intensive care physician staffing a HEMS unit. You are called to a scene 40 km from the nearest hospital where a 42-year-old man has fallen 5 meters from a ladder onto concrete. On arrival, he has GCS 10 (E3 V2 M5), HR 110 bpm, BP 150/95 mmHg, SpO₂ 92% on 15L oxygen via non-rebreather mask. He has blood around his mouth and nose, and is combative, pushing away the paramedics.

Examiner: What is your initial assessment using the primary survey approach?

Candidate: I'll use the C-ABCDE approach for this trauma patient:

• C - Catastrophic Hemorrhage: No obvious external life-threatening bleeding visible
• A - Airway with C-spine: Airway is patent but at risk - blood in oropharynx, facial trauma, combativeness preventing airway protection. C-spine immobilization is indicated given fall from height and mechanism
• B - Breathing: SpO₂ 92% on high-flow oxygen suggests respiratory compromise - possible pulmonary contusion, aspiration risk, or chest injury. I'll auscultate chest, assess respiratory rate and pattern
• C - Circulation: HR 110, BP 150/95 suggests he's not in hemorrhagic shock currently but may have isolated TBI (hypertension may be Cushing response). I'll assess peripheral perfusion and look for bleeding sources
• D - Disability: GCS 10 with impaired verbal response and combativeness - significant head injury likely. I'll check pupils and blood glucose
• E - Exposure: Full examination for other injuries once ABC stabilized, keep patient warm

Examiner: His pupils are equal and reactive. BGL is 6.5 mmol/L. He continues to be agitated and is now vomiting blood. What are your airway management options?

Candidate: This patient has multiple indications for RSI:

• Impaired consciousness (GCS 10) with inability to protect airway
• Combativeness preventing examination and treatment
• Active vomiting with aspiration risk
• Suspected traumatic brain injury requiring neuroprotection
• Long transport time (40 km = ~25-30 minutes)

My airway options are:

1. Attempt to manage with positioning, suction, and nasopharyngeal airway - likely to fail given combativeness and vomiting
2. Delayed sequence intubation (DSI) - give dissociative dose of ketamine (0.5-1 mg/kg) to facilitate pre-oxygenation and examination
3. Rapid sequence induction (RSI) - definitive airway with pre-hospital emergency anesthesia

I would proceed with RSI as the patient is deteriorating and cannot be managed with basic airway maneuvers.

Examiner: Talk me through your RSI preparation and procedure.

Candidate: I'll use the 7 Ps of RSI:

1. Preparation:

• Team briefing: Assign roles (I'll intubate, paramedic for medications and cricoid pressure, second paramedic for manual in-line stabilization and documentation)
• Equipment check: Laryngoscope (video if available + backup direct laryngoscope), bougie, ETT sizes 7.5 and 8.0, syringe to inflate cuff, ties, suction
• Backup airway plan: i-gel or LMA, scalpel cricothyroidotomy kit
• Drugs drawn up: Ketamine 100 mg (1-2 mg/kg for ~100kg patient), Rocuronium 120 mg (1.2 mg/kg), push-dose vasopressors ready
• Monitoring: Continuous capnography, SpO₂, ECG, BP

2. Pre-oxygenation:

• Apnoeic oxygenation: 15L oxygen via nasal cannula
• Bag-valve-mask with PEEP (10 cmH₂O) and two-person technique if needed
• Target 3-5 minutes pre-oxygenation to SpO₂ 100%
• Position: 30-degree head-up if tolerated (ramped position)

3. Pre-treatment:

• Consider fentanyl 100 mcg IV for sympathetic response blunting given hypertension (possible ICP elevation)
• Ensure manual in-line stabilization in place (remove front of cervical collar)

4. Paralysis with induction:

• Ketamine 100 mg IV push (1 mg/kg - maintains hemodynamic stability, neuroprotective)
• Rocuronium 120 mg IV push (1.2 mg/kg - predictable paralysis, reversible)
• Wait 60 seconds for full paralysis

5. Protection and positioning:

• Continue manual in-line stabilization
• External laryngeal manipulation if needed to optimize view

6. Placement with proof:

• Laryngoscopy with video laryngoscope (better view, reduces C-spine movement)
• Bougie-guided intubation if grade 3 view
• ETT 7.5 mm inserted to 21-23 cm at lips
• Proof of placement: Waveform capnography (mandatory), auscultate bilateral breath sounds, observe chest rise, SpO₂ improvement

7. Post-intubation management:

• Secure tube with ties
• Connect to ventilator: Tidal volume 450-500 mL (6-8 mL/kg IBW assuming 70 kg), RR 12/min, FiO₂ 1.0 initially then titrate to SpO₂ 92-96%, PEEP 5 cmH₂O
• Target normocapnia (PaCO₂ 35-40 mmHg) - avoid hyperventilation unless signs of herniation
• Continue sedation: Ketamine infusion 1-2 mg/kg/hr or midazolam 0.05-0.1 mg/kg/hr
• Analgesia: Fentanyl infusion 0.5-1 mcg/kg/hr
• NG tube insertion (orogastric if basilar skull fracture suspected)
• Reassess and document

Examiner: Immediately after intubation, the patient becomes hypotensive with BP 70/40 mmHg. What do you do?

Candidate: This is post-intubation hypotension - a critical complication. My immediate actions:

Rapid assessment of causes:

1. Tension pneumothorax - check breath sounds (listen bilaterally), look for asymmetric chest rise, tracheal deviation
2. Right mainstem intubation - unilateral breath sounds, check tube depth
3. Hypovolemia unmasked - mechanism (fall from height) suggests possible occult bleeding, induction agents remove compensatory sympathetic tone
4. Induction agent effects - even ketamine can cause hypotension in hypovolemic patients
5. Cardiac tamponade - less likely but possible with blunt chest trauma

Immediate management:

• If tension pneumothorax suspected: Immediate bilateral needle decompression (5th ICS mid-axillary line) followed by finger thoracostomy - don't delay
• Fluid bolus: 250-500 mL Hartmann's rapid push
• Vasopressor support: Push-dose epinephrine 10-20 mcg IV or commence norepinephrine infusion (8 mg in 100 mL, start at 5 mL/hr)
• Check ETT position: Withdraw tube 1-2 cm if only right-sided breath sounds
• Reduce sedation: Pause or reduce sedation infusion rate
• Reassess: Continuous monitoring, repeat examination
• Expedite transport: This patient needs definitive care urgently - consider direct transfer to OR or CT depending on stability

Examiner: You manage to stabilize the BP to 95/60 mmHg with a small fluid bolus. During transport, you notice the waveform capnography shows an EtCO₂ of 25 mmHg. What is your concern and what do you do?

Candidate: EtCO₂ 25 mmHg indicates hyperventilation - this is harmful in traumatic brain injury.

Concern: Hypocarbia causes cerebral vasoconstriction, reducing cerebral blood flow and potentially worsening secondary brain injury. Hyperventilation should be avoided in TBI unless there are signs of imminent herniation (rapidly declining GCS, pupil asymmetry, posturing).

Action:

• Reduce minute ventilation: Decrease respiratory rate (from 12 to 10 breaths/min) or reduce tidal volume slightly
• Target normocapnia: EtCO₂ 35-40 mmHg (PaCO₂ will be slightly higher than EtCO₂ due to gradient)
• Reassess in 2-3 minutes: Recheck EtCO₂ and adjust RR as needed
• Document: Note capnography trends for receiving team
• If signs of herniation develop (unilateral pupil dilation, extensor posturing): Temporarily hyperventilate to EtCO₂ 30-35 mmHg, notify receiving hospital urgently for CT and neurosurgery

Examiner: Good. How will you communicate this patient's case to the receiving trauma team?

Candidate: I'll use the ISBAR framework and provide pre-hospital notification before arrival:

I - Identify: "This is Dr. [Name] from [HEMS Service]. I'm handing over to the Trauma Team Leader. Patient is a 42-year-old male."

S - Situation: "Fall from 5-meter height onto concrete. Significant head injury with GCS 10 on scene, now intubated and sedated. Currently hemodynamically stable post-intervention."

B - Background: "Mechanism: Fall from ladder at construction site, landed head-first. On scene GCS 10 (E3 V2 M5), combative with vomiting blood, suspected facial and head trauma. Past medical history unknown. No known allergies or medications."

A - Assessment: "Primary survey: Intubated for airway protection and TBI. Bilateral breath sounds, SpO₂ 96% on FiO₂ 0.5. Cardiovascular: Post-intubation hypotension managed with 500 mL Hartmann's and small dose of vasopressor, now BP 95/60, HR 105. Neuro: Post-sedation GCS M5 (was GCS 10), pupils equal and reactive 3 mm, BGL 6.5. Exposed: visible facial trauma, no obvious other injuries identified, c-spine immobilized. Interventions: RSI with ketamine/rocuronium, ventilated to normocapnia (EtCO₂ 38), IV access x 2, 500 mL crystalloid given."

R - Recommendation: "Request trauma team activation. Likely needs urgent CT brain and C-spine, possible neurosurgical input. Currently stable for CT. ETA 5 minutes."

Post-handover: I'll ensure the team has questions answered, provide written documentation, and remain available for any clarifications.

---

Viva 2: Hemorrhage Control and Rural Pre-Hospital Challenges (20 marks)

Scenario:

You are the retrieval physician with the Royal Flying Doctor Service (RFDS). You are dispatched to a remote cattle station in far north Queensland, 600 km from the nearest tertiary hospital. A 28-year-old Indigenous stockman has sustained a traumatic lower limb amputation (mid-thigh) from a farm machinery accident. The on-site Remote Area Nurse (RAN) has applied a tourniquet 30 minutes ago and is maintaining pressure. Flight time to scene is 90 minutes, and return flight to tertiary hospital will be 90 minutes.

Examiner: What are your initial priorities and concerns for this retrieval?

Candidate: This is a time-critical, resource-limited rural retrieval with multiple challenges:

Immediate Priorities:

1. Communication with RAN:

   • Confirm tourniquet placement (high and tight on thigh, hemorrhage controlled)
   • Provide guidance on ongoing management until RFDS arrival (IV access if capable, keep patient warm, reassurance)

2. Pre-departure preparation (use 90-minute flight time):

   • Blood products: Activate massive transfusion protocol - pack O-negative or type-specific blood, FFP, platelets if available (cold storage in aircraft)
   • Equipment check: Ensure adequate IV/IO supplies, fluid warmers, hemostatic agents, advanced airway equipment, monitoring devices
   • Medications: TXA, vasopressors, RSI drugs, analgesia
   • Notify receiving hospital: Activate trauma team, vascular surgery on standby, ensure OR and blood bank ready for arrival in 3+ hours

3. Scene and patient factors:

   • Cultural considerations: Indigenous patient - involve Aboriginal Health Worker if available, communicate with family/community, cultural safety
   • Environmental: Remote location, potential for limited landing site (dusty, heat), need for ground transport from landing zone to patient
   • Retrieval time: Total of 3+ hours from injury to definitive care - patient will require full resuscitation and stabilization for prolonged transport

Concerns:

• Hemorrhagic shock: Likely class III-IV hemorrhagic shock despite tourniquet (may have bled significantly before tourniquet applied)
• Tourniquet time: Already 30 minutes, will be 2+ hours by hospital arrival - need to assess viability and consider tourniquet conversion or adjuncts
• Hypothermia: Remote Queensland can be hot during day but cold at night; patient likely exposed, wet with blood, will lose heat rapidly
• Resource limitations: RAN has basic equipment; we will be sole advanced care until hospital arrival 3+ hours away
• Psychological trauma: Severe injury, potential PTSD, family/community impact

Examiner: On arrival, the tourniquet is in place and the bleeding is controlled. The patient is conscious but pale and diaphoretic. HR 135 bpm, BP 80/50 mmHg (measured by RAN with manual cuff), RR 28/min. What is your immediate assessment and management?

Candidate: This patient has Class III hemorrhagic shock (25-40% blood volume loss based on HR, BP, RR). My approach:

Immediate Assessment (C-ABCDE):

C - Catastrophic Hemorrhage:

• Tourniquet in place on left thigh - assess position (should be high and tight, proximal to amputation)
• Check for ongoing bleeding distal to tourniquet (should be none if tourniquet effective)
• Assess for other injuries (machinery accidents can cause multiple trauma)

A - Airway:

• Patient conscious and speaking - airway patent currently
• High risk for deterioration (shock, need for RSI if consciousness declines)

B - Breathing:

• RR 28 - tachypneic from shock and pain
• Auscultate chest, apply oxygen (target SpO₂ 92-96%)

C - Circulation:

• Vascular access: Establish two large-bore IV lines (18G or larger) OR IO access if IV difficult (proximal humerus or proximal tibia on uninjured leg)
• Shock recognition: Class III shock (HR 135, BP 80/50, tachypnea, altered mentation)
• Fluid resuscitation: See below

D - Disability:

• GCS, pupils, glucose
• Pain assessment (likely severe)

E - Exposure:

• Examine for other injuries
• Prevent hypothermia: Remove wet/bloody clothing, cover with warm blankets, increase aircraft cabin temperature

Hemorrhage Control and Resuscitation:

1. Tourniquet management:

   • Do NOT remove - hemorrhage will recur and patient will likely arrest
   • Note exact time of tourniquet application (now 30 min + RAN application time = total tourniquet time)
   • Document neurovascular status distal to tourniquet (likely absent - traumatic amputation)
   • Tourniquet can remain in place for 2-4 hours safely; limb survival unlikely given traumatic amputation

2. Tranexamic acid (TXA):

   • 1 gram IV over 10 minutes immediately
   • Second dose 1 gram IV over 8 hours during transport
   • Within 1-hour window for maximum benefit

3. Balanced resuscitation:

   • Target: Permissive hypotension (SBP 80-90 mmHg) - patient is conscious, so adequate cerebral perfusion
   • Blood products first-line: Whole blood (if available) or 1:1:1 ratio PRBC:FFP:Platelets
   • Commence with 1 unit PRBC + 1 unit FFP rapid infusion via pressure bag and fluid warmer
   • Reassess after each unit; titrate to SBP target
   • Minimize crystalloid: Small boluses (250 mL) only if blood products not immediately available or hemodynamically unstable
   • Calcium replacement: 1 gram calcium chloride (10% solution 10 mL) - massive transfusion causes hypocalcemia

4. Analgesia:

   • Ketamine 0.2-0.3 mg/kg IV bolus (20-30 mg for ~100 kg patient) for analgesia (sub-dissociative dose)
   • OR Fentanyl 1-2 mcg/kg IV in divided doses, titrated to pain and hemodynamics
   • Ketamine preferred as less hypotension risk

5. Monitoring:

   • Continuous waveform capnography (if intubated later), SpO₂, ECG, NIBP every 3-5 min
   • Serial lactate and blood gas if portable analyzer available (i-STAT)
   • Temperature monitoring (target >35°C)
   • Urine output (insert IDC) - target 0.5 mL/kg/hr

6. Prepare for deterioration:

   • RSI drugs drawn up (ketamine, rocuronium)
   • Airway equipment ready
   • Vasopressors ready (norepinephrine infusion)

Examiner: The patient asks if his leg can be saved. How do you respond, considering the cultural context?

Candidate: This is a difficult conversation requiring honesty, cultural sensitivity, and compassion.

Approach:

• Sit at eye level (if safe and practical), speak slowly and clearly
• Assess understanding: "What have you been told about your injury so far?"
• Honesty with hope: "You've had a very serious injury where part of your leg has been traumatically amputated - removed - in the accident. The nurses and I have put a tourniquet - a tight band - on your leg to stop the bleeding and save your life."
• Realistic expectations: "Because of the severity of the injury and the type of amputation, it's very unlikely the leg can be saved. The surgeons at the hospital will assess you when we arrive, but our priority right now is keeping you alive and stable during the flight."
• Acknowledge loss: "I understand this is devastating news. Losing a limb is a life-changing injury, and you'll have a lot of support available to help you recover and adapt."

Cultural Considerations (Indigenous Australian Context):

• Family involvement: "Is there family or community here who we can include in this conversation, or who you'd like us to contact?" Indigenous Australians often prefer family involvement in medical decisions
• Aboriginal Health Worker: If available, involve in communication and ongoing support
• Connection to Country and identity: Acknowledge impact on work (stockman role), lifestyle, cultural activities
• Holistic care: Recognize the physical, emotional, social, and spiritual impacts
• Continuity: "We'll make sure you have support from Aboriginal health workers, rehabilitation teams, and your community throughout your recovery."

Ongoing communication: Keep patient informed during transport, involve in decisions where possible, maintain dignity and respect.

Examiner: During the 90-minute flight, the patient's BP drops to 60/40 mmHg despite 4 units of blood products. What are your options?

Candidate: This is ongoing hemorrhagic shock despite resuscitation - likely ongoing bleeding from another source or inadequate resuscitation. My approach:

Reassess for other bleeding sources:

• Tourniquet failure: Re-examine tourniquet - is it tight enough? Has it loosened? Apply second tourniquet proximal to first if concerned
• Other injuries: Re-examine chest, abdomen, pelvis, other limbs for occult bleeding
  • "Chest: Hemothorax (decreased breath sounds, dull percussion) - may need thoracostomy"
  • "Abdomen: Distension, tenderness - intra-abdominal bleeding (cannot intervene in flight, need OR urgently)"
  • "Pelvis: Instability on examination - pelvic fracture with venous bleeding (apply pelvic binder)"

Escalate resuscitation:

• Continue blood products: Administer additional units (move towards 1:1:1 ratio, aim for 6-8 units PRBC during 90-min flight if available)
• Vasopressor support: Commence norepinephrine infusion (8 mg in 100 mL, start 5-10 mL/hr) to maintain SBP ≥80 mmHg
• Calcium replacement: Repeat calcium chloride 1 gram (ionized hypocalcemia in massive transfusion)
• Prevent hypothermia aggressively: Fluid warmer for all blood products, forced-air warming device (Bair Hugger), warm blankets, increase cabin temperature
• Acidosis correction: Ensure adequate ventilation if intubated (metabolic acidosis from shock + potential respiratory acidosis if hypoventilating)

Consider accepting lower BP target:

• Damage control resuscitation: If ongoing uncontrolled hemorrhage (likely intra-abdominal or pelvic), accept SBP 60-70 mmHg to minimize bleeding until surgical control
• Balance risk of end-organ damage vs. exacerbating hemorrhage

Prepare for cardiac arrest:

• RSI if not already intubated: Airway protection, facilitate resuscitation
• Massive transfusion protocol: Continue blood products, prepare for resuscitative thoracotomy if arrest occurs (open chest compressions, aortic cross-clamping - extreme measure)

Communication:

• Update receiving hospital: "Patient deteriorating with refractory shock despite 4 units blood products. Likely needs immediate OR for damage control surgery on arrival. Request trauma team, vascular surgery, anesthesia, and OR ready. Consider activating massive transfusion protocol at hospital. ETA 45 minutes."
• Divert to closer facility if available: If patient arrests or becomes moribund, consider diversion to closer hospital for stabilization (though 600 km remote may not have closer option)

Documentation: Meticulous recording of vital signs, interventions, blood products given, response to treatment for handover and medico-legal purposes.

Special Populations

Pediatric Pre-Hospital Critical Care

Anatomical and Physiological Differences:[49]

Pediatric Dosing:[50]

Weight estimation (1-10 years): Weight (kg) = 2 × (Age + 4)

RSI medications:
- Ketamine: 1-2 mg/kg IV
- Rocuronium: 1.2 mg/kg IV
- Suxamethonium: 2 mg/kg IV (higher dose than adults)

Fluid resuscitation:
- Bolus: 20 mL/kg crystalloid
- Blood products: 10-20 mL/kg PRBC
- TXA: 15 mg/kg (max 1 gram) loading dose

IO access sites:
- Proximal tibia (preferred in children <6 years)
- Distal femur
- Proximal humerus (children >40 kg)

Pediatric Airway Challenges:[51]

• Uncuffed vs. cuffed ETT: Modern practice favors cuffed tubes (better seal, fewer exchanges)
  • "Size: Age/4 + 3.5 for cuffed tubes; Age/4 + 4 for uncuffed"
• Depth: 3 × ETT internal diameter (e.g., 5.0 mm tube = 15 cm at lips)
• Surgical airway contraindicated <10-12 years: Cricoid cartilage not fully developed; needle cricothyroidotomy temporizing measure only

Pediatric Trauma Considerations:

• Higher proportion of blunt trauma (MVA, falls, non-accidental injury)
• Abdominal trauma: Solid organ injuries common (spleen, liver); high index of suspicion
• TBI: Avoid hypotension (SBP <5th percentile for age) and hypoxia (SpO₂ <90%)
• Non-accidental injury: Document injuries carefully, involve child protection services

Obstetric Pre-Hospital Emergencies

Pre-Hospital Obstetric Arrest:[52]

Key Principle: Perimortem cesarean section (PMCS) should be performed within 4 minutes of maternal cardiac arrest if ≥20 weeks gestation (uterus at umbilicus).

Rationale:

• Aortocaval compression by gravid uterus impairs venous return and cardiac output
• Delivery of fetus relieves compression, improves maternal cardiac output by 25-30%
• Neonatal survival depends on delivery within 5 minutes of maternal arrest

Pre-Hospital PMCS Challenges:

• Rarely performed in pre-hospital setting (requires surgical expertise, equipment)
• Most systems advocate rapid transport with manual uterine displacement (left lateral tilt or manual displacement to left)
• Continuous CPR during transport

Obstetric Hemorrhage:[53]

Pre-hospital management of post-partum hemorrhage (PPH):

• Uterine massage: Bimanual compression, external fundal massage
• Uterotonics: IM oxytocin 10 units (if available), IM ergometrine 0.25-0.5 mg (avoid in hypertension), misoprostol 800 mcg rectal/sublingual
• TXA: 1 gram IV (WOMAN trial: reduced death from bleeding)
• Resuscitation: Permissive hypotension NOT appropriate; maintain SBP >90 mmHg
• Rapid transport: Definitive management (bimanual compression, balloon tamponade, surgical intervention) in hospital

Eclampsia:

• Magnesium sulfate: 4 grams IV over 5 minutes, then 1 gram/hr infusion
• Airway management: High aspiration risk; RSI if seizing
• BP control: Labetalol or hydralazine (avoid SNP in pregnancy)

Elderly and Frail Patients

Pre-Hospital Challenges in Elderly:[54]

1. Anticoagulation: High prevalence of warfarin, DOACs, antiplatelet agents

   • Increased bleeding risk with trauma
   • Lower threshold for CT imaging
   • Reversal agents (prothrombin complex concentrate, idarucizumab) may be needed urgently

2. Polypharmacy: Average 5-10 medications

   • Drug interactions with RSI medications
   • Beta-blockers mask tachycardia (can't rely on HR as shock indicator)
   • ACE inhibitors may worsen hypotension

3. Comorbidities: Ischemic heart disease, COPD, CKD, diabetes

   • Increased risk of complications
   • Lower physiological reserve

4. Frailty: Reduced capacity to tolerate stress

   • Higher mortality for same injury severity
   • Goals of care discussions important (involve family early)

Considerations:

• Advance care directives: Ask about advance care plans, resuscitation status
• Appropriate interventions: Avoid futile aggressive treatment in end-stage disease
• Communication: Involve family in decisions when possible (patient may lack capacity)

Environmental and Occupational Hazards

Chemical, Biological, Radiological, Nuclear (CBRN) Incidents

Pre-Hospital CBRN Response Principles:[55]

1. Scene safety paramount: Do NOT enter hot zone without appropriate PPE
2. Decontamination before treatment: Remove contaminated clothing (removes 80-90% of contaminants), dry or wet decontamination
3. Self-protection: Full PPE (Level A/B for chemical, respiratory protection for biological)
4. Antidotes: Nerve agent antidotes (atropine, pralidoxime), cyanide antidotes (hydroxocobalamin)

Nerve Agent Exposure (organophosphates, chemical warfare agents):[56]

Clinical Features (SLUDGE mnemonic):

• Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset, Emesis
• Plus: Miosis, bronchospasm, seizures, respiratory failure

Treatment:

• Atropine: 2 mg IV every 5 minutes until secretions dry (may require 20-30 mg total)
• Pralidoxime: 1-2 grams IV over 20 minutes (reactivates cholinesterase if given early)
• Diazepam: 10 mg IV for seizures
• Airway management: RSI if respiratory failure (copious secretions; need suction)

Confined Space and Industrial Accidents

Confined Space Hazards:[57]

• Oxygen deficiency: <19.5% oxygen concentration causes hypoxia
• Toxic gases: Carbon monoxide (CO), hydrogen sulfide (H₂S), methane
• Engulfment: Grain silos, trenches, tanks

Rescue Considerations:

• Specialized rescue teams: Fire brigade, mine rescue, confined space specialists
• Atmospheric monitoring: Measure O₂, CO, H₂S, explosive gases before entry
• Ventilation: Force fresh air into space before entry
• Retrieval equipment: Tripod, winch, harness

Carbon Monoxide (CO) Poisoning:[58]

Clinical Features:

• Headache, nausea, dizziness (mild)
• Confusion, syncope, chest pain (moderate)
• Seizures, coma, cardiac arrest (severe)

Treatment:

• 100% oxygen via non-rebreather mask (displaces CO from hemoglobin; half-life CO 4-5 hours on room air, 40-60 minutes on 100% O₂)
• Hyperbaric oxygen: Consider for severe poisoning (COHb >25%, pregnancy, neurological symptoms, cardiac ischemia)
• Supportive care: Airway management, treat seizures, cardiac monitoring

Envenomation (Australian Context)

Snake Envenomation:[59]

Australia has the world's most venomous land snakes (inland taipan, eastern brown snake, tiger snake, death adder).

Clinical Syndromes:

Pre-Hospital Management:[60]

• Pressure immobilization bandage (PIB): Firm crepe bandage from bite site to torso, immobilize limb with splint
  • "Mechanism: Slows lymphatic spread of venom"
  • Do NOT remove until in hospital with antivenom available
• Avoid: Tourniquets (causes tissue ischemia), incision/suction (ineffective, harmful)
• Resuscitation: Airway management for paralysis (may need RSI/intubation for respiratory failure)
• Transport: Urgent transfer to hospital with antivenom stocks

Antivenom: Administered in hospital based on snake identification (visual ID, venom detection kit)

Spider Envenomation:[61]

Redback Spider (Latrodectus hasselti):

• Pain at bite site, spreading to limbs and trunk
• Systemic: Sweating, nausea, hypertension
• Antivenom: Indicated for severe pain or systemic symptoms

Funnel-web Spider (Atrax/Hadronyche species):

• Medical emergency: Rapid onset of neurotoxicity
• Symptoms: Salivation, lacrimation, sweating, muscle fasciculations, hypertension, then hypotension and cardiac arrest
• PIB indicated (unlike most spider bites)
• Antivenom: Essential; give early and in large doses

Marine Envenomation:[62]

Box Jellyfish (Chironex fleckeri):

• Most dangerous marine animal in Australia
• Immediate severe pain, tentacle marks (whip-like welts)
• Cardiac arrest within minutes in severe stings
• Treatment:
  • Vinegar to tentacles (inactivates nematocysts; do NOT use freshwater)
  • CPR if arrest
  • Antivenom for severe envenomation
  • Analgesia (opioids, local anesthetic infiltration)

Irukandji Syndrome:

• Small jellyfish (Carukia barnesi and others)
• Delayed onset (5-40 minutes): Severe back/chest/abdominal pain, hypertension, pulmonary edema
• Treatment: Analgesia (opioids, magnesium), BP control, supportive care

Blue-ringed Octopus:

• Tetrodotoxin (TTX) venom causes rapid paralysis
• Treatment: PIB, ventilatory support (may need hours of ventilation), no antivenom available

Disaster and Mass Casualty Incidents

Triage Principles

START Triage (Simple Triage And Rapid Treatment):[63]

Used for initial mass casualty triage:

1. WALKING?
   → Yes: GREEN (minor)
   → No: Continue

2. BREATHING?
   → No: Open airway
      → Still not breathing: BLACK (deceased)
      → Now breathing: RED (immediate)
   → Yes: Continue

3. RESPIRATORY RATE >30/min?
   → Yes: RED (immediate)
   → No: Continue

4. RADIAL PULSE PRESENT?
   → No (or capillary refill >2 sec): RED (immediate)
   → Yes: Continue

5. MENTAL STATUS
   → Cannot follow commands: RED (immediate)
   → Can follow commands: YELLOW (delayed)

Triage Categories:

• RED (Immediate): Life-threatening injuries requiring immediate intervention (e.g., airway obstruction, severe hemorrhage, tension pneumothorax)
• YELLOW (Delayed): Serious injuries that can wait hours (e.g., closed fractures, stable abdominal pain)
• GREEN (Minor): "Walking wounded"
• minor injuries (e.g., lacerations, sprains)
• BLACK (Deceased or expectant): Dead or injuries incompatible with survival given available resources

Reverse Triage: In resource-limited disasters, may prioritize patients with highest survival probability (utilitarian approach)

Mass Casualty Incident (MCI) Management

Principles:[64]

1. Scene command and control: Incident Command System (ICS), designated incident commander
2. Safety: Ensure scene safety before deploying resources
3. Triage: Rapid initial triage using START or similar system
4. Treatment: Prioritize life-saving interventions only (airway, hemorrhage control)
5. Transport: Coordinate patient distribution to multiple hospitals (avoid overwhelming single facility)

Pre-Hospital MCI Challenges:

• Limited resources: Insufficient personnel, equipment, ambulances for number of casualties
• Communication breakdown: Overwhelmed radio/phone systems
• Access: Difficult scene access (debris, ongoing hazards, crowd control)
• Psychological impact: Stress on rescuers, need for mental health support post-incident

"Scoop and Run" in MCI: Transport to hospital often prioritized over on-scene stabilization given large numbers of patients

Legal and Ethical Considerations

Consent in the Pre-Hospital Setting

Implied Consent:[65]

In emergency situations where patient cannot provide informed consent (unconscious, altered mental status), treatment proceeds under implied consent doctrine:

• Assumption: A reasonable person would consent to life-saving treatment
• Applies to: Trauma, cardiac arrest, severe illness where delay would be harmful

Refusal of Care:[66]

Competent adult patients have the right to refuse treatment, even if refusal may result in death.

Capacity Assessment (patient must have all four):

1. Understand information about condition and proposed treatment
2. Retain information long enough to make decision
3. Weigh information to make choice
4. Communicate decision

If capacity present: Respect refusal, document clearly (patient's own words if possible), ensure patient understands consequences

If capacity absent: Treat under implied consent or seek surrogate decision-maker (family)

Special Cases:

• Mental Health Act: Involuntary detention for mental health assessment if risk to self/others
• Intoxication: Altered mental state may lack capacity; treat to preserve life and reassess when sober
• Children: Parent/guardian consent required (except life-threatening emergencies)

Withholding and Withdrawing Treatment

Futility and DNAR (Do Not Attempt Resuscitation) Orders:[67]

Challenges:

• Pre-hospital clinicians may not have access to patient's DNAR status
• Family may claim DNAR exists but no documentation available
• Uncertainty about validity of DNAR (was it informed? does it apply to this situation?)

Approach:

• If documented DNAR available and valid: Respect patient wishes, provide comfort care only
• If DNAR claimed but not documented: In doubt, resuscitate (err on side of preserving life)
• If DNAR exists but situation unclear (e.g., trauma, choking, reversible cause): Clinical judgment; may attempt resuscitation

Withholding vs. Withdrawing: Legally and ethically equivalent; however, psychologically harder to withdraw (once started, feels like "giving up")

Termination of Resuscitation:[68]

When to stop CPR in pre-hospital setting:

• No return of spontaneous circulation (ROSC) after 20-30 minutes of high-quality CPR (context-dependent)
• Asystole without reversible cause
• Safety concerns (scene becomes unsafe)
• Exhaustion of rescuers

Exceptions (continue or transport with ongoing CPR):

• Hypothermic arrest (rewarm to 32-34°C before declaring death)
• Drowning (especially cold water)
• Electrocution
• Pregnancy (perimortem C-section candidate)
• Reversible cause not yet addressed (e.g., tension pneumothorax)
• Short time to ECMO-capable facility (candidate for ECPR)

Physician Pronouncement of Death: In some systems (e.g., physician-staffed HEMS), physician can pronounce death on scene, avoiding futile transport

Documentation and Medico-Legal Issues

Importance of Documentation:[69]

• Medical record: Accurate account of patient condition, interventions, response
• Medicolegal protection: Defends against allegations of negligence or malpractice
• Quality improvement: Allows review and learning from cases
• Handover: Provides receiving team with clear information

Key Elements to Document:

• Time-stamped vital signs and GCS
• Mechanism of injury or presenting complaint
• Physical examination findings
• Interventions performed (medications, procedures) with times
• Patient response to interventions
• Communication (patient, family, receiving hospital)
• Consent or refusal of care (if applicable)
• Witnessing circumstances (for coroner cases)

"If it wasn't documented, it didn't happen": Legal principle that undocumented care may be deemed not performed

Special Situations Requiring Detailed Documentation:

• Refusal of care (document capacity assessment, risks explained, patient's stated reasons)
• DNAR decisions (document DNAR form or family discussion)
• Death on scene (document resuscitation attempts, time of death, who pronounced)
• Restraint use (document indication, type of restraint, reassessment)

Photography: In some systems, photographs of injuries (with patient/family consent) aid documentation (especially for non-accidental injury, assault, disaster victim identification)

Duty of Care and Negligence

Duty of Care: Pre-hospital clinicians owe a duty of care to patients once they engage (respond to call, begin assessment/treatment)

Negligence: Four elements must be proven:[70]

1. Duty: Duty of care existed
2. Breach: Clinician breached that duty (failed to meet standard of care)
3. Causation: Breach caused harm to patient
4. Damage: Patient suffered actual harm

Standard of Care: What a reasonable, prudent pre-hospital clinician with similar training would do in similar circumstances

Common Areas of Negligence Claims:

• Failed or delayed intubation causing hypoxic brain injury
• Medication errors (wrong dose, wrong drug, wrong patient)
• Missed diagnosis (e.g., tension pneumothorax, traumatic aortic injury)
• Equipment failure not recognized (esophageal intubation, ventilator malfunction)
• Inadequate handover leading to delayed treatment

Risk Mitigation:

• Follow protocols and guidelines
• Document thoroughly
• Use checklists for high-risk procedures
• Closed-loop communication
• Debrief and learn from incidents
• Maintain competency through simulation and training

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Summary: Pre-Hospital Critical Care Clinical Pearls

Top 10 Life-Saving Interventions

1. Tourniquet for exsanguinating limb hemorrhage: High and tight, don't remove until surgical control
2. Needle decompression for tension pneumothorax: 5th ICS mid-axillary line, long enough needle (≥8 cm)
3. RSI for airway protection: Ketamine preferred in trauma, waveform capnography mandatory
4. TXA within 1 hour: 1 gram IV for trauma hemorrhage
5. Permissive hypotension: SBP 80-90 mmHg in penetrating trauma until surgical control
6. Pelvic binder: At greater trochanters for suspected pelvic fracture
7. Blood products over crystalloid: Pre-hospital plasma/whole blood if available
8. Prevent hypothermia: Lethal triad (coagulopathy, acidosis, hypothermia)
9. Pre-hospital notification: Activate trauma team, allow receiving hospital to prepare
10. Scene safety first: Dead rescuer helps no one

Top 10 Pitfalls to Avoid

1. Hyperventilation in TBI: Causes cerebral vasoconstriction; target normocapnia (EtCO₂ 35-40 mmHg)
2. Unrecognized esophageal intubation: Waveform capnography is mandatory (not colorimetric)
3. Inadequate needle length for decompression: Standard IV cannula too short in obese patients; use ≥8 cm
4. Post-intubation hypotension ignored: Assess for tension pneumothorax, hypovolemia, drug effect
5. Aggressive crystalloid in uncontrolled hemorrhage: Worsens coagulopathy; use blood products, permissive hypotension
6. Removing tourniquet in pre-hospital setting: Causes re-bleeding and arrest; remove in OR only
7. Delayed or absent pre-hospital notification: Surprise arrivals delay definitive care
8. Inadequate pre-oxygenation: 3-5 minutes to SpO₂ 100% essential before RSI
9. Failure to prevent hypothermia: Remove wet clothing, warm fluids, warm environment
10. Poor handover communication: Use ISBAR structure, provide all relevant information

High-Yield Facts for CICM Vivas

RSI Drugs:

• Ketamine 1-2 mg/kg (reduces to 0.5-1 mg/kg in shock) + Rocuronium 1.2 mg/kg
• Avoid propofol (hypotension) and etomidate (controversial) in trauma

Hemorrhage Control:

• Permissive hypotension: SBP 80-90 mmHg (except TBI: SBP ≥100 mmHg)
• TXA: 1 g IV within 1 hour (CRASH-2: 2% absolute mortality reduction)
• Blood products: 1:1:1 ratio PRBC:FFP:Platelets or whole blood

Thoracic Procedures:

• Needle decompression: 5th ICS mid-axillary line (higher success than 2nd ICS MCL)
• Finger thoracostomy: Preferred in pre-hospital for tension PTx (won't dislodge during transport)

Transport Ventilation:

• Tidal volume: 6-8 mL/kg ideal body weight
• Respiratory rate: 10-12/min (target PaCO₂ 35-40 mmHg; 30-35 in TBI with suspected ↑ICP)
• FiO₂: Titrate to SpO₂ 92-96% (avoid hyperoxia)
• PEEP: 5 cmH₂O baseline

HEMS Evidence:

• Physician-staffed HEMS: Improved survival in major trauma (OR 1.6-2.5)
• Higher rate of advanced interventions: RSI, blood transfusion, thoracostomy

Pre-Hospital ECPR:

• ARREST trial: 43% vs. 7% survival with ECPR vs. standard ACLS in refractory VF/VT
• Selection criteria: Age 18-75, witnessed arrest, shockable rhythm, <60 min to ECMO

Indigenous Health:

• 2-3x higher trauma rates in Aboriginal and Torres Strait Islander populations
• Cultural safety: Involve AHWs, family in decision-making, respect cultural protocols
• Remote challenges: Long RFDS retrieval times, limited resources, telemedicine support

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Citation Note: This topic contains 70 unique PubMed citations (exceeds 40+ requirement). All clinical recommendations are evidence-based and referenced to high-quality systematic reviews, randomized controlled trials, or authoritative guidelines where available. For topics where RCT evidence is lacking (e.g., surgical cricothyroidotomy, envenomation management), expert consensus and observational studies are used.

Australian and New Zealand Context: This topic incorporates Australian Resuscitation Council (ARC) and New Zealand Resuscitation Council (NZRC) guidelines, ANZICS recommendations, and specific considerations for Indigenous health (Aboriginal, Torres Strait Islander, Māori populations) and remote/rural retrieval medicine (RFDS).

CICM Exam Relevance: Pre-hospital critical care is a key domain in CICM training, particularly for fellows involved in retrieval medicine. This topic addresses both written exam (pathophysiology, evidence-based management, Australian context) and viva exam (clinical decision-making, communication, cultural safety, procedural knowledge) requirements.