2-6

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2-6. EFFECTS OF RESCUE BREATHING

Rescue breathing consists of two phases. In the first phase, the rescuer blows a breath into the casualty's lung. This replaces the casualty's normal inhalation. Once the inhalation phase is completed, the rescuer breaks his seal over the casualty's airway. This allows the casualty's body to exhale on its own.

a. Inhalation Phase. Once the rescuer seals the casualty's airway so that air cannot escape, he blows air into the casualty's airway (usually though the casualty's mouth). The pressure from the rescuer's breath forces air through the rest of the respiratory tract and causes the alveoli to expand. This causes in the lungs as a whole to expand. When the lungs expand, they cause the rib cage (chest) to rise and the diaphragm to flatten somewhat.

b. Exhalation Phase. When the rescuer removes his mouth from the casualty (breaks the seal over the casualty's airway), the higher air pressure in the casualty's respiratory system causes air to rush from the airway and into the atmosphere. The rib cage and the diaphragm resume their normal positions (the chest falls and the diaphragm pushes into the chest cavity by resuming its dome-like shape). These actions result in air being forced out of the lungs, just as in normal exhalation.

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