Oxygen therapy is used to treat individuals whose lungs are not oxygenating their blood well enough. This can happen with a number of conditions including obstetric emergencies for mothers and respiratory distress for neonates. Oxygen therapy is typically employed when a patient's spO2 falls below 90%. SpO2 is the fraction of the arterial blood's hemoglobin which is carrying oxygen. Low SpO2 indicates that the body's tissues are not receiving as much oxygen as they should.
Mechanism of Action
The lungs' alveoli and their surface area allows diffusion of oxygen from the air to the bloodstream where hemoglobin molecules carry it to the body's tissues. When this process is unable to fully oxygenate the blood using the 20% oxygen in air, additional oxygen can help. Higher concentrations of oxygen lead to faster diffusion into the blood stream.
Oxygen is generally separated out from air using a zeolite column. This can happen at the bedside, at the hospital level, or at centralized processing facilities. Bedside concentrators allow tubing to supply oxygen to the patient. Hospital-level concentrators will be piped to individual wards. Alternatively, oxygen can be compressed and bottled for use near the patient. Oxygen bottles are also often used as backup for hospital systems.
At the patient, this high oxygen concentration gas will be mixed with air to provide the appropriate level to the patient. An adult might need 3 liters per minute while a neonate may need less than one. It is important to adjust oxygen levels specifically for a patient as oxygen disolved in the blood but not attached to hemoglobin is toxic and can lead to blindness in neonates through retinopathy.
Current Use in High-Resource Settings
Well-equipped hospitals typically have O2 piped to wards as well as backup concentrators or cylinders in place. Patients are monitored to ensure their oxygenation is appropriate using pulse oximetry. Oxygen is readily available in both labor and delivery wards as well as for neonatal resuscitation and wards.
Application in Low-Resource Settings
Where O2is available in low-resource settings, it is mostly by concentrator and O2cylinders. Where power is available, concentrators are often more economical than cylinders in the long run. A single oxygen source can be used in a patient ward to support several patients simultaneously where necessary. Lack of equipment and staff can make monitoring oxygen levels difficult.
Related Technologies in Development
Oxygen flow and concentration meter