Oxygen Toxicity in Intensive Care Unit- A Deadly Possibility

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Oxygen Toxicity In Intensive Care Unit- A Deadly Possibility

Oxygen as the Main Drug 

The most important drug, as COVID-19 proved, for human beings is good old oxygen. We all saw the escalation of oxygen need amongst nations around the globe. The naturally available oxygen was not simply concentrated enough to be beneficial alone. The whole society started reaching out for alternatives to oxygen cylinders for pulmonary health. The main players, in the end, turned out to be oxygen concentrator devices and oxygen cylinders.  

Oxygen Concentrators & Oxygen Cylinders as a Source of Oxygen

We have come to appreciate the positives as well as the limitations of both the oxygen generator options. The population has certainly evolved in their views regarding the necessity of both these devices. The oxygen concentrator market has seen unparalleled growth in the post-COVID-19 era. Similarly, oxygen cylinders have also evolved in their safety profile. 

The current population understands the benefits of having oxygen sources stored away in their homes. You can get a portable oxygen concentrator to take in oxygen on the go. Similarly, the home oxygen units help the patients feel better at home and have a lesser need to go to the emergency room for breathlessness caused by COPD.  

While the general populace is using oxygen concentrators and oxygen cylinders only when necessary or as prescribed by their physician, there is another group that uses oxygen regularly. 

Oxygen Generator Device Used in Intensive Care Unit

The oxygen therapy given in the ICU is monitored by the whole team of experts. ICU workers monitor the patient metrics and then move the treatment accordingly. It stands to reason that patients in ICU are prescribed oxygen therapy for hypoxemia. The patients are often given highly concentrated oxygen in conjunction with invasive ventilation. 

Invasive ventilation and high concentration oxygen can help the patient improve their blood oxygen level. As a result of the intensive treatment, the patient’s organs receive the proper amount of oxygen as oxygen administration reduces the oxygen tension in the blood. Once the optimal level of oxygenation has been achieved, the responsibility of the ICU team includes titration of the oxygen level. The physicians can eventually stop the oxygen administration. 

What if the Oxygen Administration Surpasses the Required Oxygen?

There are times when the patient’s blood oxygen levels have reached more than 92% oxygen level and the FIO2 level continues to stay higher than 0.5 for more than 24 hours at normal atmospheric pressure. The condition results in slow oxygen toxicity.

In another condition, the atmospheric pressure is higher, in the range of 1.6-4, and with more FIO2 levels but the time of application is smaller. The faster toxicity is referred to as high-pressure O2 poisoning.

What Happens in Oxygen Toxicity?

The damage starts from the cellular level and then escalates to a level where the mortality rate increases significantly. It is important to remember that the oxygen provided in the ICU is high grade and high pressure, the home oxygen concentrator units cannot normally supply high-pressure oxygen to the patients. 

The patient experiences a series of events when the oxygen levels become higher. 

  1. Reactive oxygen species form because of the high oxygen level as the cells create free radicals when O2 is converted to H2O inside the cells.
  2. The oxidative stress increases by way of reactive oxygen species presence (ROS). 
  3. The antioxidants try to curb the damage cascade initiated by the ROS. 
  4. The damaging ROS impact the lining of the alveoli. This in turn ends up damaging the gas exchange barrier of the capillaries. 
  5. Next, the inflammation initiates pulmonary edema as the inflammatory fluid collects within the alveoli. 
  6. The ROS further attracts more immune reactions from the WBCs. 
  7. Thin cell layers become more oxidized and the ROS continue to proliferate. 
  8. Next, the cells to repair the lining start accumulating. 
  9. After there is an excessive secretion from the alveolar type II cells and even more monocyte arrival, the final stage arrives. 
  10. In the last stage of oxygen toxicity, the cells start creating more collagen and the lung space becomes thicker (bad for oxygen exchange). The lung ultimately gets fibrotic. 

Clinical Appearance of the Oxygen Toxicity 

The cellular cascade results in the following symptoms in the patient. Remember low-level oxygen toxicity mainly destroys the lung tissue as the oxygen is first exposed to the lungs. The blood oxygen level has not gotten a chance to feel the effects yet. We see: 

  1. Breathlessness
  2. Burning in throat 
  3. Chest discomfort
  4. Painful respiration. 

The high-pressure oxygen toxicity shows up as the following because blood and as a result, all the other organs are now exposed to high levels of oxygen. 

  1. Seizures
  2. Nausea
  3. Dizziness
  4. Disorientation 
  5. Mood changes
  6. Vision disturbance
  7. Muscular twitches
  8. Coma

Careful Consideration Of Oxygen Use 

The ICU personnel must remain alert about the oxygen levels of the different admitted patients. A brief increase in oxygen can lead to dangerous consequences for the patient. Oxygen administration should not only be highly monitored, but it is also best if the patient is properly evaluated for their oxygen needs as the oxygen in ICU is highly concentrated.