Simple face mask

The simple face mask (SFM) is a basic disposable mask, made of clear plastic, to provide oxygen therapy for patients who are experiencing conditions such as chest pain (possible heart attacks), dizziness, and minor hemorrhages. It is often set to deliver oxygen between 6–10 litres per minute (1.3–2.2 imp gal/min). 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 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 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 patients who have lost the ability to fully inhale. The effectiveness of the therapy can be continuously monitored using a pulse oximeter, though more clinically useful data can only by obtained by drawing arterial blood gas.