Question

At a restaurant, a customer chokes on a piece of food. You put your arms around the person's waist and use your fists to push up on the person's abdomen, an action called the Heimlich maneuver. a. How would this action change the volume of the chest and lungs? b. Why does it cause the person to expel the food item from the airway?

Short answer

Pushing the diaphragm up reduces lung volume and increases pressure, forcing air to expel the obstruction.

Step-by-step solution

Understanding the Heimlich maneuver

The Heimlich maneuver involves placing your arms around the person's waist and using your fists to push up on the person's abdomen. This technique is used to help expel an obstruction from a choking person's airway.

Chest and lung volume - Part A

When you push up on the person's abdomen, it forces the diaphragm upwards. The diaphragm is a large, dome-shaped muscle at the base of the lungs. By pushing it up, you reduce the space in the chest cavity and therefore reduce the volume of the lungs.

Reason for expelling the food - Part B

The reduction in lung volume causes a rapid increase in the pressure inside the lungs. According to Boyle's Law, which states that pressure and volume of a gas have an inverse relationship, this increased pressure forces air up the windpipe and can push the obstructing food or object out of the airway.

Key concepts

Chest and Lung Volume

When performing the Heimlich maneuver, you apply pressure to a person's abdomen. This action pushes the diaphragm upwards. The diaphragm is a domed muscle at the base of the chest cavity.

By pushing it upwards, you decrease the space inside the chest cavity. Less space means the lungs will have less room to expand, and thus their volume decreases. This decreased volume inside the lungs is crucial for the next step in helping a choking person.

Diaphragm Function

The diaphragm plays a key role in breathing.

Normally, when you inhale, the diaphragm moves downward, creating more space in the chest cavity and allowing the lungs to expand. This movement decreases pressure in the lungs, letting air flow in.

When you perform the Heimlich maneuver, you do the opposite. The upward force on the diaphragm reduces chest cavity space and lung volume, which increases the pressure inside the lungs. This increased pressure is vital for expelling anything that's blocking the airway.

Boyle's Law

Boyle's Law states that the pressure and volume of a gas have an inverse relationship. This means when you decrease the volume of a gas, its pressure increases, and vice versa.

During the Heimlich maneuver, when you make the lung volume smaller by pushing the diaphragm up, the pressure inside the lungs goes up.

This high pressure is what forces the air up the windpipe, and ideally, it pushes the blocked object (like food) out of the airway. This is the scientific principle that makes the Heimlich maneuver effective for helping someone who is choking.