Week 10 (ABG Analysis)

Question 1

What are the two main tools to measure blood gas levels?

Answer 1

1. Pulse oximetry: non-invasive

2. ABG Analysis: invasive

Question 2

What does a pulse oximeter measure?

Answer 2

Oxygen saturation and heart rate

Question 3

What does an ABG analysis measure?

Answer 3

Oxygen and carbon dioxide levels in blood, oxygen saturation, blood pH and bicarbonate levels

Question 4

Oxygen is transported to and from the lungs in the blood in what two forms?

Answer 4

1. Oxyhemoglobin (98.5%)

2. Oxygen molecules dissolved in the blood (1.5%)

Question 5

SaO2 measured by…

Answer 5

Arterial blood gas sample

Question 6

SpO2 measured by…

Answer 6

Pulse oximetry

Question 7

What are the normal PaO2 levels

Answer 7

80-100 mmHg

Question 8

Define hypoxemia

Answer 8

Abnormally low oxygenation of arterial blood (low pao2/sao2)

Question 9

Define hypoxia

Answer 9

When o2 delivery to tissues is inadequate to maintain normal tissue oxygenation/meet metabolic needs (hypoxemia is one cause of tissue hypoxia)

Question 10

What are the normal PaCo2 levels

Answer 10

35-45 mmHg

Question 11

What are the pH values

Answer 11

7.35 - 7.45

Question 12

What are the normal HCO3 levels

Answer 12

22-26 mmol/L

Question 13

What are the normal base excess levels

Answer 13

-2 + 2 mEq/l

Question 14

When pao2 and spo2/sao2 are low…

Answer 14

Insufficient oxygen to tissues is transported and delivered to the tissues

Question 15

Pulse oximetry disadvantage

Answer 15

Inaccurate in low saturation levels and with poor peripheral circulation (cold weather)

Question 16

Consequences of acute hypoxaemia

Answer 16

Tachycardia, increased CO, arrhythmias, hypotension

Question 17

PaO2 (80-100mmHg) = SaO2 (?)

Answer 17

95-100% - normal

Question 18

PaO2 (<80mmHg) = SaO2 (?)

Answer 18

<95% - hypoxaemia

Question 19

PaO2 (<60mmHg) = SaO2 (?)

Answer 19

<90% - respiratory failure

Question 20

What is fiO2

Answer 20

% of oxygen the person breaths

Question 21

What equation do you use to interpret a person’s level of oxygenation

Answer 21

P/F ratio

PaO2/Fio2

Question 22

Normal range of P/F ratio

Answer 22

350-450

Question 23

Low Paco2 is

Answer 23

Hypocapnia

Question 24

Pathophysiology of hypercapnia

Answer 24

increase in CO2 level in the blood (hypercapnia) > decrease in blood pH > stimulates central chemoreceptors > stimulates phrenic and intercostal nerves > increase respiratory muscle activity > increase depth/rate of respiration (alveolar hyperventilation) until normal PaCO2 and pH levels are restored

Question 25

BE increases in... and decreases in...

Answer 25

Metabolic alkalosis | Metabolic acidosis

Question 26

Base excess is

Answer 26

Amount of acid required to restore 1L of blood to its normal pH at a PaCo2 of 40mmHg

Question 27

HYPOventilation

Answer 27

High PaCO2 -> acidosis

Question 28

HYPERventilation

Answer 28

Low PaCO2 -> alkalosis

Question 29

Hypoventilation means

Answer 29

Not breathing effectively - breathlessness, chest tightness

Question 30

Hyperventilation means

Answer 30

Breathing more than we should - SOB (25-40RR)

Question 31

Acidaemia is

Answer 31

Low pH level in blood pH<7.35

Question 32

Alkalaemia

Answer 32

High pH level in blood pH>7.45

Question 33

PaCO2 >45

Answer 33

Acidosis

Question 34

PaCO2 <35

Answer 34

Alkalosis

Question 35

HCO3 <22

Answer 35

Acidosis

Question 36

HCO3 >26

Answer 36

Alkalosis

Question 37

Symptoms of acidosis

Answer 37

Headache, sleepiness, confusion, loss of consciousness, SOB, coughing, increased HR, seizures, weakness, nausea, vomiting, diarrhoea

Question 38

Symptoms of alkalosis

Answer 38

confusion, light-headedness, coma, head tremor, twitching, prolonged spasms, nausea, vomiting

Question 39

Uncompensated

Answer 39

(pH abnormal) – other system is normal

Question 40

Partial

Answer 40

(pH towards normal but not yet normal) – other system is opposite but pH like main system

Question 41

Complete

Answer 41

(pH now restored back to normal) – other system is opposite

Question 42

Implications: reduced O2 movement

Answer 42

Low paO2 or lower paO2 than should be given for the FiO2 | Low P/F ratio

Question 43

Implications: reduced CO2 movement

Answer 43

High PaCO2/respiratory acidosis