Drowning

Epidemiology and causes:

  • 0.7% of all deaths (500,000 per year) is due to drowning.
  • Common in young boys.
  • Epilepsy increases the risk of drowning by ~15 times.
  • Long QT syndrome may contribute to ~30% of drowning.
  • 10-30% of drowning is also contributed by drugs and toxins.

** Appropriate to do basic examinations (eg ECG, ask for epilepsy history) after patient recovers to uncover any potential causes

  • Prevention of drowning is far more better than treatment

Definition

  • Drowning: respiratory compromise due to submersion (water over the head) or immersion (water splashed to face).
  • Submersion/immersion incidents WITHOUT drowning should be called water rescue.
  • Avoid terms like near drowning or dry/wet drowning.

Pathophysiology

  1. Breath holding until the inspiratory drive is too high to resist.
  2. Hypoxemia causes laryngospasm but this is only transient.
    – It was previously thought that laryngospasm may lead to “dry drowning” but it is now considered patient is more lilkely to die from alternative causes prior to submersion (i.e suspect for any homicide)
  3. Aspiration
  4. Washout of surfactant and destruction of alveolar membrane (leading to alveolar edema)
  5. Atelectasis and V/Q mismatch
  6. Hypoxemia from impaired gas exchange and unable to inspire.
  7. Cardiac arrest

Hypothermia in drowning may be neuroprotective, although paradoxically hypothermia can cause coagulopathy, worsen acidosis, bradyarrythmias (sinus bradycardia, AV block) and VF

  • Use of resuscitation drugs for cardiac arrest in hypothermia is less effective due to less responsive heart in hypothermia.
  • Guideline suggests rewarming the patient until the core temperature >30 degrees.

No difference between fresh and salt water aspiration.

Initial resuscitation

  • Unless cardiac arrest, ABC is used as drowning is primarily due to lack of oxygen.
  • 5 rescue breaths instead of 2 since water in airways can impair the effective alveolar expansion.
  • Compression only CPR is inadequate in drowning.
  • Most common complication is the regurg of wter from stomach leading to aspiration. Abdominal thrusts to expel water should be avoided.

1

Care in ED

  • Without respiratory compromise
    – O2 with nasal cannula, monitor for at least 6 hours because most resp.distress in 4-8 hours of the submersion incident.
  • With resp.compromise and stuporous:
    – Intubation & mechanical ventilation
    – NG tube inserted to decompress the stomach and prevent aspiration (due to regurg of water from stomach)
    – Lung protective strategy should be used (tidal volume 6-8 mL/kg of IBW with high PEEP due to shunt physiology)

    – Due to hypoxemia, mixed acidosis (respiratory and metabollic) is frequent but should not be routinely treated.
  • What if patient’s status become worsened?
    – Consider complications from mechanical ventilation (DOPES: displacement, obstruction, PTX, equipment and
    stacked breaths)
    – Toxicologic screen

ICU care

  • Treat as in ARDS with lung protective ventilation.
  • Local pulmonary injury may not resolved sufficiently, so avoid weaning intubation until after 24 hours even when gas exchange may appear normal.
  • Routine abx for pneumonia is not indicated.
    – Atelectasis and pulmonary edema maybe mistaken for pneumonia in CXR.
    – Pneumonia in drowning patients is normally due to nocosomial pathogens in prolonged intubation, but can be due to aspiration of polluted fluid.
    – if consolidation remains/new one occurs around day 3-4 after the edema resolves, consider pneumonia in a drowning patient.

    From radiopaedia.org, ARDS like CXR in drowning with pulmonary edema (may mimic pneumonia)
  • Steroids use in reducing lung injury is controversial.
  • Therapeutic hypothermia? Role in drowning has been extrapolated from studies in adults’ cardiac arrest.
    – Latest AHA guideline on PALS suggests hypothermia is not better than normothermia in children with cardiac arrest.
    – In adults, latest AHA guideline states that TTM can be done (between 32 to 36 celcius) for at least 24 hours in ROSC after cardiac arrest.

Complications

  1. SIRS is common and should not be treated.
  2. Sepsis
  3. Renal failure

Prognosis

  • Most patients are young so if early first aid is provided, <6% need medical attention in a hospital.
  • Even if patient is in cardiac arrest, chance of ROSC is better due to the age of the patient.
  • However, neurological impairment risk increases as drowning time increases.
    – >5 minutes 50-60%
    – >10 minutes 80-100%
  • Delayed out-of-hospital resuscitation and prolonged in-hospital resuscitation also leads to higher risk of neurological impartment.

Take home messages:

  1. Breathing should be priority in drowning. 5 breaths instead of 2 only. Compression only CPR is NOT adequate in cardiac arrest due to drowning.
  2. Neurological compromise chance increases once you are drowned >5 minutes.
  3. Even with no resp.compromise, patients need to be monitored for at least 6 hours as most resp.distress happen 4-8 hours post-submersion.
  4. Lung protective strategy when mechanically ventilating the patient. Routine NaHCO3 is not indicated.
  5. Weaning of intubation in ICU should be done only after 24 hours of monitoring. Local pulmonary injury may not recovery sufficiently.
  6. Routine abx for pneumonia prophylaxis in drowning is not indicated. Role of steroids is controversial.

References:

  1. David Szpilman, M.D., Joost J.L.M. Bierens, M.D., Ph.D.,, Anthony J. Handley, M.D., and James P. Orlowski, M.D. Drowning. N Engl J Med 2012;366:2102-10
  2. F Eduardo Martinez, Andrew J Hooper. Drowning and immersion injury. Anaesthesia and intensive care medicine 2014.
  3. Near drowning, treat approach. BMJ 2015
  4. 2015 AHA Updates For CPR and ECC
  5. Summary of the main changes in Resuscitation Guidelines. ERC Guidelines 2015
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