Oxygen Therapy Flashcards
What are the indications for oxygen therapy
- known hypoxaemia
- acutely unwell patients when hypoxaemia is likely
What are the two ways to measure oxygen levels
- oxygen saturation
- partial pressure of oxygen
How much percentage of oxygen in blood is bound to haemoglobin
97%
How can you measure the oxygen saturation levels
- Pulse oximetry (SpO2)
- direct from arterial blood sample - SaO2
how can you monitor the remain 3% of oxygen that is not bound to haemoglobin
- this is the partial pressure of oxygen in the blood referred to as PaO2 (kPa) or in mmHg
even if the SpO2 is 100% the PaO2 can continue to rise above normal why is this
When PaO2 drops, with will SaO2. When PaO2 rises, so does SaO2. When the SaO2 (or SpO2) reaches 100%, the haemoglobin is fully saturated. But more oxygen can still dissolve into the blood.
what factors shift the oxyhemoglobin curve right
- drop in pH
- hypercapnia (rise in CO2)
- rise in temperature
What factors shift the oxyhaemoglobin curve left
- drop in temperature
- decrease in CO2
- rise in pH
What information does the ABG give
- dissolved CO2
- pH
- amount of bicarbonate
- base excess
What is type 1 respiratory failure
If the PO2 is < 8KPa and the PaCO2 is normal, then refer to this as Type 1 Respiratory failure.
What is type 2 respiratory failure
If the PO2 is < 8KPa and the PCO2 is high, then we refer to this as Type 2 Respiratory failure.
What is pH
This is a measure of the amount of hydrogen ions
the more hydrogen ions….
the more acidotic the solution and the lower the pH
What is PaCO2
This is a ‘respiratory parameter’3 and measures the dissolved carbon dioxide in the blood.
what does reduced ventilation do
Reduced ventilation would lead to a rise in CO2, which creates more acid, lowering the pH