Oxygen administration: Physiology, indications & equipment

Oxygen administration is a therapy to maintain adequate tissue oxygenation while minimizing cardiopulmonary work. There are a variety of reasons that cause doctors to initiate oxygen administration, that includes maintenance of oxygenation while providing anesthesia, increased metabolic demand, CO (carbon monoxide) exposure, treatment of headaches, supplementation due to affected oxygen exchange during the treatment of lung illnesses, and more are included in the reasons for its initiation¹

The atmosphere consists of approximately 21% oxygen at sea level. This percentage decreases in a near-linear fashion with an increase in altitude. O2 mask (non-rebreather, venti-mask, simple), or nasal cannula is used to deliver supplemental oxygen to the patient. In some cases, oxygen is added into BiPAP (bilevel positive airway pressure) or CPAP (continuous positive airway pressure) system. To deliver oxygen to intubated patients, ventilators are used.

Physiology and anatomy

The optimal oxygenation of the patients depends upon their airway anatomy. For instance, a trauma patient whose nasal passages are impeded by blood would be provided supplemental oxygen suboptimally using a nasal cannula while it might be hard to achieve oxygenation goals using CPAP or BiPAP system (i.e., sealed masks) for a patient with micrognathia.

The patient’s position must be upright while being provided with supplemental oxygen unless there is a contraindication to such positioning such as level of sedation, patient risk, anatomy, and trauma before the c-spine clearance.

Indications

Hypoxemia (decreased level of oxygen in the blood) is the most readily accepted indication for supplemental oxygenation. Oxygen saturation targets are 92 to 98% in a healthy patient. Values under 90% are considered to be low. Normal arterial oxygen is around 75 to 100 mm Hg². Low levels of oxygen in blood or hypoxemia show symptoms like tiredness, confused behavior, SOB (shortness of breath), and others that can even damage your body³.

For patients with chronic hypercapnic conditions, the values for oxygen saturation can be as low as 80%. These values are measured by pulse oximetry. In the critical care setting, pulse oximetry is far and widely used for monitoring oxygenation. Respiratory status of patients in ICU is also monitored by pulse oximetry⁴. But in cases of CO (carbon monoxide) or cyanide poisoning and anemia, pulse oximeter gives falsely elevated readings and is not an adequate indicator of perfusion.

There the three types of indications:

Chronic
Acute

Chronic

Chronic indications include:

COPD (chronic obstructive pulmonary disease). It refers to a group of diseases that cause breathing-related problems and airflow blockage. It has no cure but it can be treated^5.
Pulmonary fibrosis (which is caused by scarred tissues present deep in lungs. They become stiff and thick which can make it harder for the person to catch a breath and as result blood does not get properly oxygenated). Its symptoms include SOB, fatigue, clubbing, dry cough, aching muscles, and joints, etc,⁶.
Cystic fibrosis (It is an inherited disease in which sticky, thick mucus buildup that can damage many of the organs of the body). Its symptoms include continuous damage to the respiratory system and chronic digestive system problems⁷.
Sarcoidosis (It is a disease characterized by the growth of a tiny group of inflammatory cells in different parts of the body. Most commonly in lymph nodes and lungs. But it can also affect the heart, skin, eyes, and other organs)⁸.

Acute

These acute indications refer to medical emergencies that require high concentrations of oxygen in all cases. These cases include:

Shock
Sepsis (i.e., a possibly life-threatening condition caused by the body’s response to an infection)
Major trauma, cardiac arrest and during resuscitation (to provide adequate arterial oxyhemoglobin saturation)
Anaphylaxis (which is a potentially life-threatening and severe allergic reaction)
Cyanide and carbon monoxide (CO) poisonings
TRALI (transfusion-related acute lung injury: which is a rare but serious syndrome which is characterized by sudden acute respiratory distress following transfusion).

These acute indications refer to medical emergencies that may or may not require oxygen administration. These cases include:

Asthma (It causes repeated attacks of early morning or nighttime coughing, breathlessness, wheezing, and chest tightness⁹).
Bronchitis (It is caused when the airway of the lungs swell and produce mucus in the lungs10).
Acute heart failure, or heart failure exacerbations
Pulmonary embolism (It is a sudden blockage in the lung artery).

Equipment

Nasal cannula, transtracheal catheters, face Masks, and non-rebreathing masks are used for providing low flow oxygen administration. While HFNC (High flow nasal cannula) is used for high flow oxygen administration to the patients by medical professionals. CPAP and BiPAP are the masks that deliver continuous positive pressure oxygen to the patient. Bag-mask devices and ventilators aid in this process too. Neonatal incubators also provide supplemental oxygen but in a different way, it increases the concentration of oxygen in the interior chamber without directly providing oxygen to the patient.

Conclusion

In acute care settings, oxygen administration is one of the most common interventions and is widely used to treat acute and chronic medical conditions. Medical professionals should be familiar with the routes of oxygen administration, as the physiological effects of oxygen administration are considered to be the fundamental part of patient care.