Blood gas analysis and pulse oximetry Flashcards
What is the normal pH range of blood?
7.35-7.45
What is the six-step approach to interpret blood gas?
- How is the patient?
- Is that patient hypoxaemic?
- What is the pH?
- What has happened to the PaCO2?
- What has happened to the bicarbonate?
- Are there any other important values to consider?
When the lungs are functioning normally a partial pressure of 21kPa O2 gives an arterial PaO2 of what?
10-13kPa
As a rule of thumb the PaO2 should be about** X ** less than the inspired concentration
10
How is the numerical value of pH scale related to the concentration of hydrogen ions?
inversely, a decrease in blood pH suggests an increase in hydrogen ions
Too much CO2 will do what to pH?
Decrease it because CO2 + H2O= H + HCO3
Hyperventilation causes a ….
respiratory alkalosis
Normally an increase in the concentration of hydrogen ions in the blood causes what?
Hyperventilation to blow off CO2 and increase the pH
Under normal circumstances- what is the bicarbonate level?
22-26
How long does metabolic compensation take?
Days
What is the base excess?
measure of the amount of excess acid or base in the blood as a result of metabolic derangement
A patient with a base excess of +8 would require what to return pH to normal?
8mmol of strong acid
A patient with a base excess of -8 would require what to return pH to normal?
8 mmol of a strong base
A base excess more negative than -2 suggests what?
metabolic acidosis
A base excess more positive than +2 suggests what?
metabolic alkalosis
