The simple face mask is a basic disposable mask, made of clear plastic, to provide oxygen therapy

Oxygen therapy

Oxygen therapy is the administration of oxygen as a medical intervention, which can be for a variety of purposes in both chronic and acute patient care...

 for patients who are experiencing conditions such as chest pain

Chest pain

Chest pain may be a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the pain is non-cardiac in origin, this is often a diagnosis of exclusion made after ruling out more serious causes of the pain.-Differential...

 (possible heart attacks), dizziness

Dizziness

Dizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....

, and minor hemorrhages. It is often set to deliver oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 between 6-10 litres per minute. This mask is only meant for patients who are able to breathe on their own, but who may require a higher oxygen concentration than the 21% concentration found in ambient air. Patients who are unable to breathe on their own are placed on a medical ventilator

Medical ventilator

A medical ventilator can be defined as any machine designed to mechanically move breatheable air into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently....

 instead.

The final oxygen concentration delivered by a simple face mask is dependent upon the amount of room air that mixes with the oxygen the patient breathes. The air mixing is determined by how much air any individual is breathing at the moment, combined with the fit of the mask. Because of the variability in these factors, the final oxygen concentration is uncontrolled. A venturi

Venturi mask

The venturi mask, also known as an air-entrainment mask, is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy. Venturi masks are considered high-flow oxygen therapy devices. This is because venturi masks are able to provide total inspiratory flow at a...

 device attached to the mask can be used to control to some degree the concentration of oxygen delivered, usually this is used to prevent respiratory depression in emphysema

Emphysema

Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...

 patients who have lost the ability to fully inhale

Inhalation

Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....

. The effectiveness of the therapy can be continuously monitored using a pulse oximeter

Pulse oximeter

A pulse oximeter is a medical device that indirectly monitors the oxygen saturation of a patient's blood and changes in blood volume in the skin, producing a photoplethysmograph. It is often attached to a medical monitor so staff can see a patient's oxygenation at all times...

, though more clinically useful data can only by obtained by drawing arterial blood gas

Arterial blood gas

An arterial blood gas is a blood test that is performed using blood from an artery. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery at the wrist, but sometimes the femoral artery in the groin or...

.