Overview of Oxygenation and Perfusion

Oxygen therapy is the delivery of extra oxygen to those with conditions that cause hypoxemia, when oxygen levels in the blood are low; and hypoxia, which is when there is not enough oxygen at the tissue level to meet the needs of the body.

This includes patients with diseases that interfere with the lungs’ ability to absorb oxygen, like pneumonia, chronic bronchitis, emphysema, and pulmonary fibrosis; blood problems, like anemia, where the blood doesn't carry enough oxygen; and heart problems, like heart failure, where the heart has trouble pumping blood around the body.

Now, oxygen is considered a medication, so an order is needed.

An oxygen setup consists of an oxygen source and a delivery device. There are several sources for oxygen therapy. With a wall outlet, oxygen is delivered into each patient room from a central supply.

In contrast, an oxygen tank contains oxygen gas under pressure and is typically portable, so it can be carried along as the patient moves. However, this should be moved very carefully; if the tank tips over and the valve breaks open, pressurized oxygen can burst out forcefully and result in severe trauma. Oxygen tanks have a gauge that shows how much oxygen is left. There are also liquid oxygen systems which store oxygen as a liquid at very cold temperatures and then convert it to a gas for use. They are used either for bulk storage of oxygen for a hospital system or can be portable for home use for patients with high oxygen needs, where having a compact way to storge large amounts of oxygen is helpful.

Finally, oxygen concentrators pull in air from the atmosphere and selectively remove nitrogen to deliver air that is about 90 to 95% oxygen to the patient. These devices are easy to use and can deliver an unlimited amount of concentrated oxygen as long as they have a power supply. One caveat is that some units are designed to only deliver up to 5 liters of oxygen per minute, and so those aren’t a good fit for patients who have high-flow oxygen needs.

All oxygen sources are attached to a flow meter that indicates the flow rate, or the liters of oxygen leaving the device per minute. This usually falls somewhere between 1 and 15 liters per minute.

Now, the flow rate coming from the oxygen tank must be matched to an appropriate delivery device.