Hypoxemia: Oxygen Therapy and Ventilation/Perfusion (VQ) Mismatches

Hypoxemia is an abnormally low concentration of oxygen in the blood which can lead to dire consequences when left unmanaged. In most patients with hypoxemia, the application of supplemental oxygen is a quick bandaid therapy that is often applied to counteract the problem. However, have you ever applied supplemental oxygen to a patient experiencing hypoxemia and there has been a minimal effect? Have you ever wondered why the application of supplemental oxygen works in some patients but not others? It all comes down to what is causing the hypoxemia and understanding the pathophysiology behind a ventilation/perfusion (VQ) mismatch.

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Chest X-Ray Interpretation in 7 Easy Steps!

chest xray analysis

It is important to understand that when a chest x-ray is taken, light is absorbed according to the density of what it passes. We have different densities within our bodies ranging from bone, to tissue, to fluid, to air. This results in a monochrome display ranging between white to black. There are three distinct things you should look for on a chest x-ray and they all rhyme: Continue reading

Oxygen Flow Rate and FiO2: Understand the Relationship!

Oxygen, we all need it! We do not need a lot of it under normal circumstances, with 0.21 being the fraction of inspired oxygen (FiO2) of room air. FiO2 is defined as the concentration of oxygen that a person inhales.  The air that we inhale on a day to day basis is made up of 21% of oxygen, 78% of nitrogen and 1% of trace elements such as argon, carbon dioxide, neon, helium and methane. For the purposes of this article, fractions and percentages will be used interchangeably for ease of explanation.  Continue reading

Respiratory Failure: Type 1 or Type 2?

To recap the last blog post about oxygen saturations versus PaO2:

  • Respiration is the process of gas exchange, both at the alveoli to blood interface and blood to cellular tissue interface
  • Oxygen has to bind to haemoglobin in order to be effectively transported around the body, but must dissociate from the haemoglobin prior to be taken up by the cells
  • The amount of haemoglobin in the body that has oxygen attached is measured via oxygen saturations while the amount of oxygen freely floating in the blood unattached to haemoglobin is measured via PaO2
  • When we experience a failure to oxygenate, we have a problem with our oxygen
  • A decrease in oxygen saturations below 90% will cause the body to increase it’s ventilatory effort as a compensatory mechanism
  • A failure to oxygenate is known as type 1 respiratory failure, defined as a decreased PaO2 with a normal carbon dioxide level

In this blog post, we are going to discuss type 1 and type 2 respiratory failure in detail and explore which pathophysiological respiratory conditions lead to which type of failure. Continue reading

The Importance of Counting Respiratory Rate

Having attended numerous MET calls and code blues over the years, there is a trend that becomes quite noticeable. Despite the blood pressure, heart rate and oxygen saturations trending up or down; the respiratory rate predominantly stays the same right up to the point just before the MET call or code blue is called. Continue reading