Near-Drowning and Submersion Injury

Quick Answer

What are the critical anaesthetic considerations for near-drowning victims?

Near-drowning (submersion with survival >24 hours) causes severe hypoxic brain injury, pulmonary complications, and often hypothermia. Key principles:

1. Immediate resuscitation - ABC approach; rescue breathing even before chest compressions if asystole
2. Hypothermia management - "No one is dead until they are warm and dead" - rewarm to 32-35°C before terminating resuscitation
3. Cerebral protection - Avoid hyperthermia; maintain normocapnia; consider therapeutic hypothermia (32-34°C) for 24 hours post-cardiac arrest
4. Pulmonary management - Expect ARDS; surfactant washout; mechanical ventilation with lung-protective strategy
5. No role for routine corticosteroids or prophylactic antibiotics - Treat infections if they develop
6. Electrolyte disturbances - Usually mild; freshwater vs saltwater distinction largely theoretical
7. Prognosis - Based on submersion time, water temperature, time to effective CPR, GCS

Clinical Pearl: The most critical factor in near-drowning outcome is the duration of hypoxia, not the type of water (fresh vs salt). "Wet" vs "dry" drowning is an outdated concept - nearly all submersion victims aspirate some liquid. The priority is immediate oxygenation and circulation, not specific fluid type management.

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Clinical Overview

Epidemiology

Global and Australian burden:

Australian context:

• Summer months (Dec-Feb) peak incidence
• Alcohol implicated in 20-30% of adult drowning deaths
• Remote/Indigenous communities higher rates
• Tourism-related drowning (international visitors at beaches)

Risk factors:

Pathophysiology

The drowning process:

Key concept: Only small volumes of aspirated fluid (1-3 mL/kg) cause significant lung injury. This equals 70-210 mL for 70 kg adult. Volumes >22 mL/kg rarely survive to hospital.

Freshwater vs saltwater - is there a difference?

Clinical Pearl: The "freshwater vs saltwater drowning" distinction has little clinical relevance in modern practice. The pathology and management are essentially identical. Both cause surfactant washout, alveolar-capillary membrane damage, and ARDS. Do not waste time determining water type.

Pulmonary pathophysiology:

Systemic effects:

Classification of Severity

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Prehospital and Initial Management

Rescue and Immediate Care

First principles:

Modified BLS for drowning:

• Traditional sequence: Call → Compression → Breathing
• Drowning sequence: Airway → Breathing → Compressions → Defibrillation
• Reason: Hypoxia is primary problem; 5 rescue breaths before compressions
• If hypothermic, handle gently (risk of VF with rough movement)

Key differences from standard ALS:

C-Spine Consideration

When to immobilise:

• Suspected diving injury
• Signs of trauma (head injury, fall from height)
• Focal neurological deficit
• Unreliable history (intoxication, young child)

When not to immobilise:

• Witnessed non-traumatic submersion (child in pool)
• No signs of trauma
• Reliable history of non-diving submersion

Rationale: Unnecessary immobilisation delays effective CPR and rescue breathing.

Hypothermia Management in the Field

Stages of hypothermia:

"Nobody is dead until they are warm and dead"

Continue resuscitation until:

• Core temperature >32-35°C
• AND no response to resuscitation
• OR asystole for >20 minutes after reaching 35°C
• OR potassium >12 mmol/L (irreversible cellular death)

Survival with good neurological outcome has been reported with:

• Core temps as low as 14°C
• Submersion times up to 66 minutes (cold water)
• CPR durations >6 hours with ECMO rewarming

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Hospital Management

Emergency Department

Initial assessment:

Immediate interventions:

Rewarming techniques:

ECMO/CPB for hypothermia:

• Most effective rewarming method
• Can achieve 1-2°C/min rewarm
• Provides circulatory support
• Survival with good neurological outcome documented
• Requires rapid deployment

Respiratory Management

Oxygenation targets:

• SpO2 >94-96%
• PaO2 >80 mmHg
• Avoid hyperoxia (toxic to lungs and brain)

Ventilation strategy:

• Lung-protective ventilation
• Tidal volume 6-8 mL/kg (ideal body weight)
• Plateau pressure <30 cmH2O
• PEEP 5-15 cmH2O (recruit atelectatic alveoli)
• FiO2 wean to maintain SpO2 94-96%
• Consider prone positioning if severe ARDS

Special considerations:

• High risk of gastric distension (air swallowing) - decompression
• Risk of ARDS developing 24-72 hours later even if initially clear
• Bronchospasm common - bronchodilators
• Secretions - suctioning, physiotherapy

ECMO for respiratory failure:

• Refractory hypoxaemia despite maximal ventilation
• VV-ECMO for isolated respiratory failure
• VA-ECMO if cardiac support also needed
• Consider early transfer to ECMO centre

Cerebral Protection

Pathophysiology of hypoxic brain injury:

• Primary insult: Hypoxia during submersion
• Secondary insult: Reperfusion injury, excitotoxicity, inflammation
• Prevention of secondary injury is key

Management strategies:

Therapeutic hypothermia (TTM):

• Indication: Cardiac arrest with ROSC, unresponsive
• Target: 32-34°C for 24 hours, then slow rewarm
• OR 36°C for 24 hours (similar outcomes)
• Start ASAP (within 6 hours)
• Shivering control: sedation, paralysis if needed
• Avoid hyperthermia (>37.5°C) at all costs

Sedation and analgesia:

• Propofol ± remifentanil
• Ventilated patients require adequate sedation
• Consider neuro-monitoring (processed EEG)

Cardiovascular Management

Common abnormalities:

• Hypotension (myocardial depression, hypovolaemia)
• Arrhythmias (hypothermia, electrolytes, acidosis)
• Myocardial stunning

Management:

• Fluid resuscitation if hypovolaemic
• Inotropes/vasopressors as needed (noradrenaline first-line)
• Treat arrhythmias (correct temperature, electrolytes first)
• Echocardiogram if cardiac dysfunction suspected

Electrolyte and Metabolic Management

Expected abnormalities:

Freshwater vs saltwater electrolyte differences:

• In practice, these are minor and transient
• Do not base management on water type
• Monitor and correct electrolytes based on lab values

Infection Prophylaxis and Treatment

Prophylactic antibiotics:

• NOT recommended routinely [5]
• Consider if: Grossly contaminated water (sewage), retained foreign body, lung abscess

Infection surveillance:

• Daily CXR
• Sputum culture if ventilated
• Blood cultures if fever
• BAL if VAP suspected

Pneumonia treatment:

• If develops, treat according to hospital protocol
• Cover typical and atypical organisms
• Consider fungal coverage if immunocompromised or severe

Corticosteroids

No proven benefit:

• Do not reduce cerebral oedema effectively
• Do not improve pulmonary outcomes
• Increase infection risk
• NOT recommended in near-drowning [6]

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Prognosis and Outcome Prediction

Poor Prognostic Factors

The "triple jeopardy" of poor prognosis:

1. Submersion >5-10 minutes
2. No immediate bystander CPR
3. Arrest to ROSC >30 minutes

Favourable Prognostic Factors

Neurological Prognostication

Timing:

• Do not prognosticate in first 24 hours
• Hypothermia delays assessment
• Wait until rewarmed and off sedation

Predictive tests:

• Clinical examination (GCS, pupillary, motor response) - most important
• SSEPs (bilateral absent N20 predicts poor outcome)
• EEG (burst suppression, status epilepticus poor)
• Imaging (CT/MRI brain - global oedema poor)
• Biomarkers (NSE, S100B - limited utility)

Important: No single test is definitive; integrate multiple modalities

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Communities

Disproportionate burden:

Contributing factors:

• Geographic remoteness (delayed emergency response)
• Limited water safety education
• Higher rates of recreational swimming in unsafe locations (rivers, dams)
• Alcohol-related drowning
• Lack of fencing around natural water bodies
• Overcrowded housing (pool access)

Cultural considerations:

Prevention and education:

• Culturally appropriate water safety programs
• Swimming lessons in remote communities
• Community pool fencing programs
• Alcohol harm reduction
• Child supervision education

Māori Health (Aotearoa New Zealand)

Epidemiology:

• 2-2.5× higher drowning rates than non-Māori
• Younger age at drowning
• Higher male predominance

Water safety:

• Rivers and beaches culturally significant
• Water-based recreation common
• Water safety education in te reo Māori

Cultural considerations:

• Whānau involvement in care decisions
• Tikanga around water and death
• Karakia and spiritual support
• Māori Health Workers essential

Te Tiriti obligations:

• Equity in water safety outcomes
• Culturally appropriate prevention programs
• Māori health workforce development

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ANZCA Final Examination Focus

High-Yield Topics

Written examination:

Viva scenarios:

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Assessment Content

SAQ 1: Near-Drowning Management (20 marks)

Question:

A 6-year-old child is brought to the Emergency Department after being found at the bottom of a swimming pool. She was estimated to be submerged for 5-7 minutes. Bystander CPR was commenced after 2 minutes. Paramedics intubated at the scene. On arrival, her core temperature is 31°C, GCS is 3 (E1, V1, M1), pupils are fixed and dilated. She has return of spontaneous circulation.

a) What are the immediate priorities in managing this child? (8 marks)

b) Describe your approach to rewarming. (6 marks)

c) What is the role of therapeutic hypothermia in this patient, and how would you implement it? (6 marks)

Model Answer:

a) Immediate Priorities (8 marks):

Airway and breathing (2 marks):

• Confirm ETT position (auscultation, EtCO2, CXR)
• Secure ETT; ventilate with lung-protective strategy
• SpO2 target >94%; PaCO2 35-45 mmHg
• CXR to assess tube position and pulmonary status

Circulation (2 marks):

• Maintain BP; target MAP >60-70 mmHg (age appropriate)
• Inotropes if needed (noradrenaline)
• Arterial line for monitoring
• ECG monitoring (arrhythmias common with hypothermia)

Temperature management (2 marks):

• Active rewarming required (core temp 31°C)
• Remove wet clothing; dry patient
• Warm blankets; warmed room
• Warmed IV fluids; warm humidified ventilator gases
• Target 32-35°C before considering prognostication

Neurological (1 mark):

• GCS documented; pupillary assessment
• C-spine clearance (witnessed pool submersion - may not need immobilisation)
• Prevent secondary brain injury

Other (1 mark):

• Nasogastric tube (gastric distension common)
• Urinary catheter (monitor output, temperature)
• Blood tests: FBC, electrolytes, glucose, lactate, CK, coagulation
• Blood gas (acidosis, oxygenation)

b) Rewarming Approach (6 marks):

Active external rewarming (2 marks):

• Warm air blankets (Bair Hugger) - torso initially
• Warm packs to axillae, groin
• Warm room (24-26°C)
• Remove all wet clothing immediately

Active internal rewarming (2 marks):

• Warmed IV fluids (40-42°C) - all fluids warmed
• Warmed humidified oxygen/ventilator gases
• Heated ventilator circuits
• Goal: 1-2°C/hour rewarm rate

ECMO consideration (2 marks):

• If cardiac instability or unable to maintain perfusion
• Most effective rewarming method (1-2°C/min)
• Provides cardiac support
• Consider early if: Temp <28°C, cardiac arrest, haemodynamic instability
• Transfer to ECMO centre if not available

c) Therapeutic Hypothermia (6 marks):

Role (2 marks):

• Indicated: Post-cardiac arrest with ROSC, unresponsive
• Neuroprotective: Reduces metabolic demand, excitotoxicity, inflammation
• Evidence: Improved neurological outcomes in adults (controversial in children but recommended)
• Target: 32-34°C for 24 hours OR 36°C for 24 hours

Implementation (4 marks):

• Start ASAP (within 6 hours of arrest)
• Current temp 31°C - maintain at 32-34°C rather than active rewarm
• Surface cooling: Cooling blankets, ice packs (avoid shivering)
• IV cooling: Cold IV fluids initially (4°C) - rapid induction
• Intravascular cooling catheter if available
• Monitor core temperature continuously (oesophageal, bladder)
• Shivering control: Sedation (propofol), meperidine, buspirone, paralyse if refractory
• Rewarm slowly after 24 hours: 0.25-0.5°C/hour
• Avoid hyperthermia >37.5°C at all costs

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SAQ 2: Prognostication in Near-Drowning (20 marks)

Question:

An 18-year-old man is admitted to ICU after near-drowning in a river. He was submerged for approximately 15 minutes and received immediate bystander CPR. He achieved ROSC after 20 minutes. He is currently ventilated, sedated, with a core temperature of 36.5°C. His GCS is 3 (E1, V1, M1), pupils are fixed and dilated. pH is 7.12, lactate 8.5 mmol/L.

a) What factors suggest a poor prognosis in this patient? (8 marks)

b) When and how would you prognosticate neurological outcome? (6 marks)

c) What factors might suggest a better-than-expected outcome? (6 marks)

Model Answer:

a) Poor Prognostic Factors (8 marks):

Submersion factors (2 marks):

• Submersion time 15 minutes (prolonged)
• Time to ROSC 20 minutes (delayed)

Clinical features (3 marks):

• GCS 3 (very low)
• No eye opening (E1)
• No verbal response (V1)
• No motor response (M1)
• Fixed dilated pupils (ominous sign)

Physiological factors (2 marks):

• Severe acidosis (pH 7.12)
• High lactate (8.5 mmol/L) - severe tissue hypoperfusion
• Core temp 36.5°C (warm water drowning - worse prognosis than cold water)

Age factor (1 mark):

• Adult (children generally have better outcomes)

b) Prognostication Timing and Method (6 marks):

Timing (2 marks):

• Delay prognostication at least 24-48 hours
• Must be rewarmed (already at 36.5°C)
• Must be off sedation for clinical assessment
• Hypothermia delays metabolism of sedatives

Clinical assessment (2 marks):

• GCS (must be off sedation ≥24 hours)
• Pupillary light reflex
• Corneal reflexes
• Motor response to pain (presence of withdrawal vs flaccid)
• Brainstem reflexes (gag, cough, oculocephalic, oculovestibular)

Investigations (2 marks):

• SSEPs: Bilateral absent N20 predicts poor outcome with high specificity
• EEG: Background activity; burst suppression; seizures
• CT brain: Sulcal effacement, loss of grey-white differentiation, herniation
• MRI brain: Diffusion restriction (DWI) - prognostic value at 3-5 days
• Biomarkers: NSE, S100B (limited additional value over clinical)

c) Favourable Factors (6 marks):

Immediate response factors (2 marks):

• Immediate bystander CPR (started right away)
• Achieved ROSC (20 minutes - prolonged but achieved)
• Age 18 (young adult - better neuroplasticity than older adult)

Potential confounders (2 marks):

• Sedation currently confounding GCS
• Pupils may still be affected by sedative agents
• Need reassessment off sedation

Unknown factors (2 marks):

• Water temperature unknown (if cold water, may have neuroprotection)
• Quality of CPR unknown
• Possible shorter actual submersion than estimated
• Young brain has better recovery potential than elderly

Important caveat:

• Children can have unexpectedly good outcomes despite poor initial signs
• Prolonged observation (days) warranted before prognosticating
• No single factor is absolute predictor

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Viva Scenario: Hypothermic Drowning

Scenario:

You are called to the Emergency Department to assist with a 45-year-old man pulled from a mountain lake after 25 minutes submersion. He is in cardiac arrest. Core temperature is 28°C.

Examiner: "How would you manage this patient?"

Candidate Response:

"This is a hypothermic cardiac arrest following drowning. The key principle is 'no one is dead until they are warm and dead.' My management would be:

Immediate priorities:

1. Continue CPR - Do not stop resuscitation for hypothermic patient
2. Advanced airway - Intubate with RSI; protect airway; prevent aspiration
3. Ventilation - 100% O2; adequate tidal volumes; avoid hyperventilation
4. Rewarming - This is critical and must start immediately

Specific hypothermia management: At 28°C, this patient has severe hypothermia. The cardiac arrest may be secondary to hypothermia itself rather than irreversible hypoxic brain injury. I would:

• Active external rewarming: Remove wet clothes immediately; warm blankets; Bair Hugger; warm room
• Active internal rewarming: Warmed IV fluids (40-42°C); warm humidified ventilator gases
• ECMO/CPB: This is the most effective option and I would activate this immediately if available. At 28°C with cardiac arrest, extracorporeal rewarming offers the best chance of survival with good neurological outcome. Can achieve 1-2°C/min rewarming.

Alternative if no ECMO:

• Body cavity lavage - warm peritoneal lavage, pleural lavage, gastric lavage
• Thoracotomy with mediastinal lavage (if other methods failing)

Monitoring:

• Core temperature (oesophageal or bladder) - continuous
• ECG - watch for Osborn J waves, arrhythmias, VF
• Blood gas - ABG (interpret at patient's temperature or corrected)
• Electrolytes - especially potassium (if >12 mmol/L, suggests cellular death and poor prognosis)

When to stop resuscitation: Only if:

• Rewarmed to 32-35°C AND
• Asystole persists for >20 minutes after reaching target temp OR
• Potassium >12 mmol/L (indicates irreversible cell death)

Post-resuscitation (if ROSC):

• Therapeutic hypothermia 32-34°C for 24 hours OR maintain 36°C
• Lung-protective ventilation (ARDS likely)
• Cerebral protection measures
• ICU admission

The cold water actually offers protection - I've seen cases of good neurological outcomes after 40+ minute submersion in cold water with effective rewarming."

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References

1. World Health Organization. Global report on drowning: preventing a leading killer. Geneva: WHO; 2014.
2. Royal Life Saving Society - Australia. National Drowning Report 2023. Canberra: RLSSA; 2023.
3. Australian Water Safety Council. Australian Water Safety Strategy 2016-2020. Sydney: AWSC; 2016.
4. Modell JH. Drowning. N Engl J Med. 1993;328(4):253-256. PMID: 8417322
5. Szpilman D, Bierens JJ, Handley AJ, Orlowski JP. Drowning. N Engl J Med. 2012;366(22):2102-2110. PMID: 22646632
6. Datta A, Tipton MJ. Respiratory responses to cold water immersion: neural pathways, responses, and implications. Med Sport Sci. 2006;50:103-118. PMID: 16998671
7. Royal Life Saving Society - Australia. National Drowning Report: Aboriginal and Torres Strait Islander People. Canberra: RLSSA; 2023.
8. Golden FS, Tipton MJ, Scott RC. Immersion, near-drowning and drowning. Br J Anaesth. 1997;79(2):214-225. PMID: 9349151
9. Orlowski JP. Drowning, near-drowning, and ice-water drowning. JAMA. 1988;260(3):390-391. PMID: 3379745
10. Bierens JJ, van der Velde EA, van Berkel M, van Zanten JJ. Submersion in the Netherlands: prognostic indicators and results of resuscitation. Ann Emerg Med. 1990;19(12):1390-1395. PMID: 2240753
11. Kolar M, Krsnakova L. [Neurological and psychopathological findings after near-drowning]. Cesk Psychiatr. 1990;86(4):244-250. PMID: 2288214

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File generated for ANZCA Final Examination preparation. Last updated: 2026-02-03