O2 Sat Help

Published

What is the rationale for ordering O2 to maintain SaO2 over 90%?

Up Vote Up Vote ×
Specializes in Acute Care, Rehab, Palliative.

Tell us what you think the reason for the order would be.

Up Vote Up Vote ×
Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Welcome to AN! The largest online nursing community!

We are happy to help...but we need to know what you think first. What semester are you in?

Why would it be important to be sure the patients OXYGENATION be above a certain level?

Up Vote Up Vote ×
Specializes in Cath/EP lab, CCU, Cardiac stepdown.

Ask yourself what is normal range of oxygen saturation, then what does oxygen saturation measure

Up Vote Up Vote ×

The patient has pneumonia and O2 sats were running 84%. My response would be that we need to maintain the above 90% for adequate perfusion and to avoid hypoxemia.

Up Vote Up Vote ×
Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
The patient has pneumonia and O2 sats were running 84%. My response would be that we need to maintain the above 90% for adequate perfusion and to avoid hypoxemia.
Her organs can be perfused with blood lacking oxygen....you want the O2 sat >90% to endure proper oxygenation of the vital organs and to prevent injury to vital organs from the hypoxia.

Low oxygen saturation is also called hypoxemia, reduced oxygenation of the arterial blood.

The causes of low blood oxygen saturation

  • inspired air does not contain enough oxygen (high altitudes, inhaling poorly oxygenated gases, breathing in an enclosed space)
  • the patient hypoventilates (the respiratory center is inappropriately stimulated by an overdosage or neurological damage as in increased intracranial pressure, diabetic ketoacidosis, end-stage respiratory failure of chronic obstructive pulmonary disease)
  • there is insufficient blood volume to carry hemoglobin oxygen (massive hemorrhage)
  • blood, for some reason, is able to bypass the lungs (arteriovenous shunt)
  • the surface area of the lung tissue has been damaged so gas exchange is impaired (alveolar capillary diffusion abnormality of emphysema, fibrosis or pulmonary edema; ventilation-perfusion mismatch as in asthma, chronic bronchitis or pneumonia).

Low oxygen concentration, in and of itself, merely means that the amount of oxygen being carried in the blood by the red blood cells is low. However, if it continues for any length of time it proceeds to another much more serious condition called hypoxia which is reduced oxygen available to the cells and tissues of the body. Hypoxia is a lack of oxygen from any cause and results in an increased respiratory rate, restlessness, impaired judgment, tachycardia, dyspnea and cyanosis. Cells and tissues cannot thrive for very long without any oxygen at all.

Up Vote Up Vote ×

So, I was on the right track...I think.

Up Vote Up Vote ×
Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

for the most part but you said perfusion...the organs can be just "perfused" with blood that doesn't' have oxygen but to prevent damage you need to ensure proper/adequate oxygenation.

Up Vote Up Vote ×

Perfusion is blood flow, specifically, arterial flow to the capillary bed. Arterial thrombus, arteriosclerosis, or compartment syndrome are examples of perfusion problems.

Deep venous thrombosis is not a perfusion problem.

Notice there is nothing about what's being carried in those vessels except blood. Oxygenation is a different matter.

Up Vote Up Vote ×

Thank you for the help : ) I understand it much better now.

Up Vote Up Vote ×
Specializes in Emergency Department.

There is also the oxygen dissociation curve to look at. Read up on that with the idea of tissue oxygenation in mind as described above and you'll understand why you often see orders to maintain a SpO2 level >90% or even >92%.

Up Vote Up Vote ×

Also consider this, which is very, very often missed: When you assess SpO2, what is that? It's the percentage of RBCs that are saturated with oxygen. You're getting one (slightly indirect) measure of oxygen delivery to the tissues.

I say, "indirect" because you can't rely solely on SpO2 to let you know how tissue oxygenation is going. Why? Because it doesn't tell you how much oxygen is being delivered.

Why not? Think about it. (Ooooh, we love critical thinking around here!)

If you have a patient with a hematocrit of 40 and an SpO2 of 99% and a patient with a hematocrit of 30 and an SpO2 of 99%, who's delivering more oxygen to his tissues? Right, the first guy; the second guy has only 3/4 as much oxygen being carried to his cells, because his crit is 3/4 of the first guy's. Another guy with a hematocrit of 20 and an SpO2 of 99% is carrying only half the amount of oxygen as the first guy.

Never, never forget to look at both measures of oxygen-carrying capacity.

Up Vote Up Vote ×
+ Join the Discussion