Drowning: pulmonary changes

– Process of primary respiratory impairment resulting from submersion/immersion in a liquid medium

– Spectrum of presentation based on severity :

1. Asymptomatic – no cough, or dyspnea, normal vital signs, no pulmonary findings

2. Mild – cough or dyspnea present, pulmonary findings present, possible both hypoxia or hypothermia

3. Moderate to severe – cough and dyspnea present, pulmonary findings present, hypoxia present, possible hemodynamic instability and hypothermia

4. Cardiac arrest

The immediate physiologic response to drowning is breath holding. This can be followed by involuntary laryngospasm with entry of fluid into oropharynx and larynx. Alternatively, if laryngospasm does not occur, drowning individual will begin gasping for air and reflexively coughing with entrainment of water into the airway. Presence of liquid – air interface at the entrance of the airway prevents patient from breathing air and aspiration of liquid occurs. Fluid entering airway results in alveolar dysfunction (increased permeability, surfactant dysfunction) and hypoxia. With continued exposure to fluid, further deterioration occurs leading to pulmonary edema, decreased lung compliance, atelectasis, bronchospasm and ventilation perfusion mismatch. Hypoxia and hypercapnia lead to neurological dysfunction and arrhythmia.