Water enters and stimulates laryngospasm

End

Vagally-mediated pulmonary vasoconstriction => pulmonary hypertension
Atelectasis
Reduced lung compliance
Ventilation-perfusion mismatch
Progressive hypoxia/hypercapnia
Cardio-respiratory arrest

Hypoxia/hypercapnia

In 80–90%, stimulates gasp and aspiration

10–20% maintain laryngospasm until cardiac arrest; most have some fluid in the lungs following arrest

Fresh water
Water absorbed into capillaries from alveoli, disrupts surfactant

Salt water
Water moves from capillaries into alveoli and interstitium, dilutes/washes out surfactant