Which treatment is essential for someone who has experienced a shallow water blackout?

Administering 100% oxygen by mask is crucial for someone who has experienced a shallow water blackout because this condition is typically caused by hyperventilation, which can lead to a rapid drop in carbon dioxide levels in the body. When a person hyperventilates, they may take in more oxygen than their body can utilize, resulting in a state of hypoxia (lack of adequate oxygen in the tissues) that causes loss of consciousness when they hold their breath under water.

Providing 100% oxygen helps to rapidly increase the amount of oxygen available to the body's tissues, counteracting the effects of hypoxia and promoting quicker recovery. This treatment is particularly important because shallow water blackouts can occur without warning, and the individual may not be able to breathe effectively on their own once they regain consciousness. Thus, oxygen therapy is essential in facilitating recovery and preventing potential complications associated with prolonged hypoxia.

Other suggested treatments, such as putting ice on the victim or encouraging them to drink water, do not adequately address the immediate need for oxygenation and can potentially complicate the person's condition. Waiting for them to regain consciousness without proactive measures can be dangerous, as they may require immediate medical intervention if their state does not improve rapidly.