Blood Gasses Flashcards
Acid
A substance that can donate H ions when dissolved in water
Base
A substance that’s can accept H ions
pH
The negative log of the H+ ion concentration, can use pH to calculate H+ ion concentration
Acidosis
<7.35
Alkalosis
> 7.45
Hypercapnia
Increased CO2 in blood
Henderson-Hasselbahch Equation
Expresses acid-base relationships in a mathematical formula
What do the lungs do during the regulation of acid-base balance?
Carbon dioxide, the end product of most aerobic metabolic processes, easily diffuses out of the tissue where it is produced and into the plasma and red cells and surrounding capillaries.
What do the kidneys do during acid-base balance?
The kidneys regulate the excretion of both acid and base, making them an important player in the regulation of acid-base balance. Specifically the kidney’s main role is to reabsorb HCO3, from the glomerular filtrate in the proximal tubules.
pH reference range
7.35 - 7.45
pCO2 (mm Hg) reference range
35 - 45
HCO3- (mmol/L) reference range)
22 - 29
Total CO2 Content (mmol/L)
23 - 27
pO2 (mmol/L)
85 - 105
What are the four parameters to asses a patients oxygen status?
- Oxygen Saturation (SO2)
- Fractional Oxyhemoglobin (FO2Hb)
- Trends in oxygen saturation assessed by transcutaneous (TC) and pulse oximetry (SpO2)
- Amount of O2 dissolved in plasma (pO2)
What occurs when an oxygen dissociation curve shifts to the right?
- Increased H ions (decreased pH)
- Increased Carbon Dioxide (pCO2)
- Increased temperature
- Increased 2,3-DPG
What occurs when an oxygen dissociation curve shifts to the left?
- Decreased H ions (Increased pH)
- Decreased Carbon Dioxide (pCO2)
- Decreased temperature
- Decreased 2,3-DPG
Which two forms can O2 exist in blood?
(1) Free dissolved gas - same form as water
(2) Bound to Hb
What is measured by Potentiometry?
pH and pCO2
What is the methodology of Potentiometry?
Measures a comparison of an indicator electrode to a reference electrode.
What is measured using amperometry?
PO2
What is the methodology of amperometry?
Measures a reduction in oxygen which leads to a flow of current between the cathode and anode.
Once collected, how soon should a blood gas sample be ran?
Within 15 to 30 minutes depending on the hospital policy.
Otherwise, cell metabolism continues to take place using up O2 and giving off CO2 which results in decreased O2 and increased CO2 resulting in a decreased pH.
What happens if the sample is not held within an airtight container?
Air O2 150 mm Hg, sample if < 150 mm Hg, will take in O2 from the air, Air CO2 is near 0 and the sample will lose CO2 to the air, resulting in a decrease in H+ and an increase in pH.
