Oxygen level with pneumonia

Checking your oxygen level is very important with pneumonia. Low oxygen levels with pneumonia are one of the most important indicators of a bad outcome with any pneumonia. In the last 15 years, I have treated hospitalized patients with pneumonia that had different degrees of problems with their oxygen levels. I am writing this article based on my personal experience as a doctor and a thorough review of relevant medical journals.

In this article, I will explain:

  1. How pneumonia affects your oxygen levels
  2. The comparison between two different ways of checking oxygen levels in pneumonia patients
  3. Different treatments needed for pneumonia based on different oxygen levels

If you would like to get an overview of what pneumonia is and learn about different types of pneumonia, read “Pneumonia types and symptoms.”

If you would like to understand what to expect when hospitalized for pneumonia, read this article.

How pneumonia affects your oxygen levels

When you have pneumonia, germs invade your lungs. Your immune system tries to get rid of these germs by attacking them using special proteins and white blood cells. The interaction between the germs, proteins, and white blood cells produce a pus-like fluid deep inside the lungs. These fluids fill up a portion of the air sacs inside your lungs.

A diagram showing the process by which germs, WBCs, and inflammatory fluids lead to low oxygen in the blood.
A diagram showing how germs and WBCs can lead to low oxygen in the blood

These air sacs are sites of air exchanges inside your lungs. Oxygen in drawn into the blood from the air inside the air sacs, and carbon dioxide is thrown out. Air sacs have very thin walls to allow the oxygen from the air to enter the blood vessels. Red blood cells help carry the oxygen from the lungs once it is inside the small blood vessels. However, the pus-like fluid makes it difficult for oxygen to enter the blood vessels, and thus your oxygen levels go down.

Initially, the areas of the lungs that aren’t affected try to compensate by increasing the blood flow and absorbing more oxygen. With mild pneumonia that can be treated at home, there are enough normal air sacs to maintain a regular oxygen level.

As the pneumonia gets more severe, it involves a larger area, and more pus-like fluids are produced. The larger the area of the lungs that are involved in this process, the greater the problem with oxygen absorption. So when pneumonia affects a large part of your lungs, you have oxygen absorption problems.

When a large portion of the air sacs are affected by pneumonia, the blood vessels inside the lungs try to divert more blood to the normal air sacs. To do this, they widen blood vessels going into normal air sacs and narrow the ones going into affected air sacs. When there are more affected air sacs than normal ones, this process becomes inefficient and difficult to maintain. The blood still going into affected air sacs makes oxygen levels go even lower.

How to check oxygen levels in pneumonia patients

There are two methods to check oxygen levels in pneumonia patients. We will discuss the advantages and disadvantages of both methods.

Here are the two ways of checking oxygen levels in pneumonia patients:

  • Non-Invasive pulse ox
  • Invasive arterial blood gas measurement

A non-invasive pulse oximetry, simply called a pulse ox, is used to check oxygen levels in pneumonia patients that are not very sick. This is an easy way to check the oxygen level and it can be done at the doctor’s office. It is a simple device that uses light to check the saturation of oxygen carrying red blood cells. After placing it around a finger, it transmits a light and analyzes how the light is absorbed while passing through your finger. Oxygen-carrying red blood cells are bright red, while ones without oxygen are a dull red. By analyzing the wavelength of the lights, the pulse oximeter exploits this color difference and gives out a percentage of oxygen-carrying red blood cells. Pulse oximetry only analyzes the color of the pulsating part of the finger. The pulsating part is the artery that carries fresh blood coming out of the heart.

A pulse ox is easy and fairly accurate when the oxygen level in the pneumonia patient is not too low. But it only gives you the saturation of oxygen carrying blood as a percentage, not the actual level of oxygen in the blood. Anything above 90% is acceptable, and higher than 95% is desirable, in pneumonia patients.

To check the actual oxygen level in pneumonia patients, you need the invasive test, an arterial blood gas analysis. In order to do this, they check for the pulsating artery, usually on your wrist. Then they insert a needle on that spot so that the needle is inside the artery. This test requires some skill, and is done by specifically-trained technicians or doctors. The arterial blood is then drawn up and sent to the lab for analysis. With this sample, they can actually measure the amount of oxygen in the blood. This is important for patients with pneumonia that are needing a lot of oxygen.

The arterial blood gas analysis is invasive, painful, and difficult to perform, but it is very accurate and very helpful in critically ill patients with pneumonia.

Different treatments needed for pneumonia based on different oxygen levels

Oxygen levels in pneumonia patients are very helpful in deciding how to treat pneumonia. We will look at a few different treatment options based on different oxygen levels.

Pneumonia with oxygen levels above 95% as measured by a pulse ox

These patients can be safely treated at home with antibiotics as long as they watch their symptoms. If they start to get more shortness of breath, they may have to call their doctor to recheck their oxygen levels. Oxygen levels in these pneumonia patients can be done with a pulse ox instead of the invasive blood gas test.

Pneumonia with oxygen levels above 90% but below 95%

Most patients in this category can be treated at home, but they need to be more vigilant. It may be a good idea to have these patients walk around with the pulse ox device on their fingers. If they remain above 90% even when walking, they are probably fine to go home. If the oxygen levels in these pneumonia patients drop down when walking, they may need to stay in the hospital overnight or go home with an oxygen treatment.

Pneumonia with oxygen levels less than 90%

These pneumonia patients will likely need hospitalization for further evaluation and treatment. They need to be given extra oxygen though a tube with two small prongs up their nostrils. After the extra oxygen, if the oxygen level in these pneumonia patients go up above 90%, they may be observed on the regular medical floor of the hospital.

Pneumonia with oxygen levels less than 90% despite extra oxygen

These pneumonia patients are very sick and may get worse quickly. They need to be watched very closely. In these patients, you can’t simply rely on a pulse ox. You need to know exactly how much oxygen is in the blood. Doctors will keep increasing the flow of oxygen until there is enough oxygen in the blood.

Pneumonia with low oxygen levels from a blood gas analysis despite a high flow of oxygen

These patients need the next level of care and are at a very high risk of having a bad outcome from their pneumonia. The first step to help increase the oxygen levels in these patients is called Bipap. Oxygen is forced in and out of their lungs with a machine connected to a tight-fitting mask.

If the oxygen levels are still not coming up to a satisfactory level, a tube needs to be placed down their throat and have it connected to a ventilator. These patients are treated in the ICU.

Pneumonia with low oxygen levels despite being on a ventilator

These patients are in real trouble. They may not make it out alive from the pneumonia. Sometimes, changing the settings of the ventilator may help. These patients need fast rates on the ventilator with a slightly higher pressure and less air. In a small fraction of patients, an artificial heart and lung machine may help them get through the hump while their lungs improve. The overall outcome is very poor when oxygen levels with pneumonia remain low despite being on a ventilator.

In conclusion, oxygen levels with pneumonia is a very important indicator of the severity of the illness. Oxygen levels can be measured invasively or non-invasively. The treatment of pneumonia and its outcome differ based on different oxygen levels.