Submersion Injury

A. Presentation

Important elements in history:

• SOB, cessation of breathing
• Persistent cough
• History of possible aspiration of foreign bodies
• Loss consciousness at any time
• Vomiting
• Coincident alcohol or drug use
• Past medical history of
  - Syncope/Acute coronary syndrome
  - Epilepsy
  - DM/hypoglycemia
  - Psych history (esp suicide/depression)
  - Neuromuscular disorder

 

4 categories of patients initially

1. Dead
2. Cardiopulmonary compromised
   - Cardiopulmonary arrest
   - arrhythemia
   - ARDS
3. Symptomatic
   - altered vital signs
   - anxious appearance
   - dyspnoea/tachypnoea
   - metabolic acidosis
   - altered LOC or neurological deficit
4. Asymptomatic

B. Investigation

Arterial blood gases

Most reliable in asymptomatic or mildly symptomatic.

Needed to exclude hypoxia

 

FBC, U&E

Baseline

 

Coagulation, Urinalysis

If indicated

 

Blood alcohol, urine toxicology screen

If indicated

 

Chest X-ray

For evidence of aspiration, pulmonary oedema, segmental atelectasis suggesting FB aspiration

May be normal (see Acute Respiratory Distress Syndrome)

 

Cervical spine X-ray, non-contrast head CT

If head injury suspected

 

C. Treatment

Initially

ABCs

100% O2 (i.e. 15L O2 non-rebreathing mask)

Intubate at earliest opportunity if necessary

Neck immobilization if face/head injury present or history of diving

Rewarming

Secondary survey

 

Later

Asymptomatic patients

---> If ABG and Xray normal, discharge after 6-8 hours of obs.

Mild symptoms

---> If symptoms improve, and ABG and Xray are normal, discharge after 6-8 hours of close obs.

---> If history of significant immersion, keep for longer

Patients requiring intubation or those with cardiopulmonary compromise

---> ICU admission

Discharged patients must return immediately if they develop dyspnoea, cough, or fever.

 

Others

PEEP has been shown to improve ventilation

   [By shifting interstitial pulmonary water into the capillaries]

   [By increasing lung volume via delayed airway closure during expiration]

   [By increasing the diameter of airways to improve ventilation]

Cough and bronchospasm

---> treat aggressively with nebulised salbutamol

 

 

Tubes

Endotracheal intubation (and PEEP) may be required when

• Altered LOC, reduced cough reflex
• PaO2 of 60-80mmHg on 100% O2 (i.e. 15L O2 non-rebreathing mask)
• PaCO2>45mmHg
• Deteriorating blood gas result
• In alert cooperative patients, try CPAP/BiPAP first.

Nasogastric tube

Urinary catheter placement

• Assessment of urine output
• Rewarming of hypothermic patients via continuous bladder lavage

Warm peritoneal lavage in severely hypothermic patient

Warmed IV fluids

Warmed inspired air

Extracorporeal blood re-warming in severely hypothermic patient

 

D. Other notes

 

Mechanism

Death is by prolonged hypoxemia

Target organ of injury is the lung. Injury to other systems is secondary to hypoxia and acidosis.

There may be concomitant head or spinal cord injury

Fluid aspiration causes (via vagus) pulmonary vasoconstriction and hypertension.

 

Freshwater immersion

---> Water moves rapidly across the alveolar-capillary membrane

---> water adds to circulation, surfactant destoryed

---> atelectasis, decreased compliance, V/Q mismatch (up to 75% shunting)

 

Saltwater immersion

---> Surfactant washout, rapid exudation of plasma

---> decreased compliance, direct alveolar-capillary basement membrane damage

---> V/Q mismatch

 

Other mechanism

Aspiration of vomitus, sand, silt, sewage can lead to

• Occulsion
• Bronchospasm
• Pneumonia
• Abscess
• Pneumonitis

Pulmonary oedema can be:

• Post-obstructive pulmonary oedema following laryngospasm
• Neurogenic following hypoxic neuronal injury

 

Chain of events

1. Initial gasp/aspiration (into hypopharynx)
2. Hyperventilation
3. Voluntary apnoea and variable degree and duration of laryngospasm
4. Hypoxemia (and acidosis)
      [Due to laryngospasm and lung damage]
5. Cardiac arrest / CNS ischemia

Relaxation of the airway due to asphyxia can happen

   - just before cardiac arrest

   - with or after cardiac arrest

 

Different types of drowning

When airway relaxes before cardiac arrest, water fills the lung

---> wet drowning (80-90% of cases)

When laryngospasm continues until cardiac arrest, no aspiration

---> dry drowning (10-20% of cases)

 

Cold water immersion

Sudden rapid immersion reducing core temp to <30C may have bradycardia, slow metabolism and preferential shunting, which may be protective.

In most immersions, hypothermia is gradual

---> high risk of VF and neurologic injury

---> Thus aggressive rewarming

No resuscitation should be abandoned until the patient has been warmed to at least 30C.

 

Epidemiology

Male:Female - 12:1 for boat-related, 5:1 for non-boat-related

Female children predominate in bath tub drowning

 

Peak incidence in 2 groups:

   <4 year olds

   15-24 year olds

 

Other information

• 33degrees - thermal neutral - heat loss equals heat production
• <25degrees C ---> significant risk of hypothermia
• Bathtub drowning ---> possible child abuse

 

Differential diagnosis

Head/neck trauma

Arrhythmia

Seizure

Hypothermia

 

Complications

Significant complication - ARDS in the 12-24 hours after submersion.

Neurological injury

Pneumonia/pneumonitis

Multiple organ system failure (MOSF)

Acute tubular necrosis (ATN) (secondary to hypoxemia)

Myoglobinuria

Hemoglobinuria

 

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Things to revise/add later:

Bibliography: "eMedicine On The Go"

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