Blood Gasses

Question 1

Acid

Answer 1

A substance that can donate H ions when dissolved in water

Question 2

Base

Answer 2

A substance that’s can accept H ions

Question 3

pH

Answer 3

The negative log of the H+ ion concentration, can use pH to calculate H+ ion concentration

Question 4

Acidosis

Answer 4

<7.35

Question 5

Alkalosis

Answer 5

> 7.45

Question 6

Hypercapnia

Answer 6

Increased CO2 in blood

Question 7

Henderson-Hasselbahch Equation

Answer 7

Expresses acid-base relationships in a mathematical formula

Question 8

What do the lungs do during the regulation of acid-base balance?

Answer 8

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.

Question 9

What do the kidneys do during acid-base balance?

Answer 9

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.

Question 10

pH reference range

Answer 10

7.35 - 7.45

Question 11

pCO2 (mm Hg) reference range

Answer 11

35 - 45

Question 12

HCO3- (mmol/L) reference range)

Answer 12

22 - 29

Question 13

Total CO2 Content (mmol/L)

Answer 13

23 - 27

Question 14

pO2 (mmol/L)

Answer 14

85 - 105

Question 15

What are the four parameters to asses a patients oxygen status?

Answer 15

• 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)

Question 16

What occurs when an oxygen dissociation curve shifts to the right?

Answer 16

• Increased H ions (decreased pH)
• Increased Carbon Dioxide (pCO2)
• Increased temperature
• Increased 2,3-DPG

Question 17

What occurs when an oxygen dissociation curve shifts to the left?

Answer 17

• Decreased H ions (Increased pH)
• Decreased Carbon Dioxide (pCO2)
• Decreased temperature
• Decreased 2,3-DPG

Question 18

Which two forms can O2 exist in blood?

Answer 18

(1) Free dissolved gas - same form as water

(2) Bound to Hb

Question 19

What is measured by Potentiometry?

Answer 19

pH and pCO2

Question 20

What is the methodology of Potentiometry?

Answer 20

Measures a comparison of an indicator electrode to a reference electrode.

Question 21

What is measured using amperometry?

Answer 21

PO2

Question 22

What is the methodology of amperometry?

Answer 22

Measures a reduction in oxygen which leads to a flow of current between the cathode and anode.

Question 23

Once collected, how soon should a blood gas sample be ran?

Answer 23

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.

Question 24

What happens if the sample is not held within an airtight container?

Answer 24

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.