Oxygen therapy is generally administered at the lowest concentration needed to meet the patient’s clinical needs. This can be assessed by clinical observation, pulse oximetry (finger or forehead, non-invasive) and measurement of the patient’s arterial blood gases (by arterial puncture or indwelling arterial line- invasive), which measures arterial blood 02, C02, pH, 02 saturation and sometimes other parameters. There are numerous respiratory care devices used to administer varying oxygen concentrations. As with other drugs, too high (or too long) 02 concentrations can have possible adverse effects, such as oxygen toxicity and respiratory arrest in some patients.
It is uncommon to administer very high inspired 02 levels, however there are several clinical lifesaving indications for administering 100% or near 100% 02. Some clinical indications for 100% oxygen therapy at or near ambient pressure are cardiac arrest and sudden respiratory arrest (CPR), CO poisoning, smoke inhalation, poor local or systemic prefusion (low blood flow), low arterial O2 levels not corrected with lower O2 concentrations. 100% O2 can be administered to spontaneously breathing patients at ambient pressure or to those requiring assisted (patient is breathing) or controlled (patient not breathing) mechanical ventilation at intermittent positive pressure.
As mentioned in an earlier post, 100% O2 at elevated pressure is used with HBO (hyperbaric oxygen). Some clinical indications for HBO are carbon monoxide poisoning, wound and burn care when high ambient oxygen therapies are not effective or are unable to reach the affected tissue.
There are 2 medical oxygen standards - USP Oxygen (≥99.0%) and USP Oxygen 93 Percent (90 to 96%) which “...is oxygen produced from air by the molecular sieve process.”
A happy, healthy and successful New Year to all.
George Scott
