Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MBChB Yr 3 OSCES > Blood Gas Analysis > Flashcards

Blood Gas Analysis Flashcards

1
Q

What does a normal PaCO2 in a hypoxic asthmatic patient suggest?

A

Sign they are tiring and need ITU intervention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does a very low PaO2 in a patient who looks completely well, is not short of breath and has normal O2 saturation suggest?

A

Likely a venous sample and not arterial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What should the PaO2 be on air in a healthy patient?

A

> 10 kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

If a patient is receiving oxygen therapy, what should their PaO2 be?

A

PaO2 should be approximately 10kPa less than the % inspired concentration / FiO2 (i.e. 40% oxygen would be expected to have a PaO2 of approximately 30kPa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does it mean if a patient has PaO2 <10 kPa on air?

A

Hypoxaemic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does it mean if a patient has PaO2 <8 kPa on air?

A

Severely hypoxaemic & in respiratory failure. Next look at the PaCO2 to determine if it type 1 or 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the ABG in type 1 respiratory failure?

A
  • Hypoxaemic (<8 kPa)

- Normocapnic (PaCO2 <6.0 kPa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the ABG in type 2 respiratory failure?

A
  • Hypoxaemia (PaO2 <8 kPa)

- Hypercapnia (PaCO2 >6.0 kPa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does type 1 respiratory failure occur?

A

Ventilation/perfusion (V/Q) mismatch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are 2 types of V/Q mismatches leading to type 1 respiratory failure & give examples of each?

A
  1. Reduced ventilation & normal perfusion: pulmonary oedema, bronchoconstriction
  2. Reduced perfusion with normal ventilation: pulmonary embolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does type 2 respiratory failure occur?

A

Alveolar hypoventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Give 4 examples of when hypoventilation occurs leading to type 2 respiratory failure?

A
  1. Increased resistance as a result of airway obstruction (COPD)
  2. Reduced compliance of the lung tissue/chest wall (pneumonia/rib fractures/obesity)
  3. Reduced strength of the respiratory muscles (Guillain–Barré / motor neurone disease)
  4. Drugs acting on the respiratory centre reducing overall ventilation (opiates)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe an ABG in respiratory acidosis?

A
  • pH: decreased
  • CO2: increased
  • HCO3-: normal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe an ABG in respiratory alkalosis?

A
  • pH: increased
  • CO2: decreased
  • HCO3-: normal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe an ABG in respiratory acidosis with metabolic compensation?

A
  • pH: normal/decreased
  • CO2: increased
  • HCO3-: increased
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe an ABG in respiratory alkalosis with metabolic compensation?

A
  • pH: normal/increased
  • CO2: decreased
  • HCO3-: decreased
17
Q

What is the carbonic acid equation?

A

CO2 + H2O H2CO3 (carbonic acid) HCO3- + H+

18
Q

Describe an ABG in metabolic acidosis?

A
  • pH: decreased
  • HCO3-: decreased
  • CO2: normal
19
Q

Describe an ABG in metabolic alkalosis?

A
  • pH: increased
  • HCO3-: decreased
  • CO2: normal
20
Q

Describe an ABG in metabolic acidosis with respiratory compensation?

A
  • pH: decreased
  • HCO3-: decreased
  • CO2: decreased
21
Q

Describe an ABG in metabolic alkalosis with respiratory compensation?

A
  • pH: increased
  • HCO3-: increased
  • CO2: increased
22
Q

What does a high base excess (> +2mmol/L) indicate?

A

Higher than normal amount of HCO3- in the blood, which may be due to a primary metabolic alkalosis or a compensated respiratory acidosis

23
Q

What does a low base excess (< -2mmol/L) indicate?

A

Lower than normal amount of HCO3- in the blood, suggesting either a primary metabolic acidosis or a compensated respiratory alkalosis

24
Q

Describe the ABG in a mixed acidosis/alkalosis?

A

CO2 & HCO3- will be moving in opposite directions (↑ CO2 & ↓ HCO3- in mixed respiratory & metabolic acidosis)

25
Q

List 5 causes of respiratory acidosis?

A
  1. Respiratory depression (opiates)
  2. Guillain-Barre: paralysis leads to an inability to adequately ventilate
  3. Asthma
  4. Chronic obstructive pulmonary disease (COPD)
  5. Iatrogenic (incorrect mechanical ventilation settings)
26
Q

What is a definition of respiratory acidosis?

A

Inadequate alveolar ventilation leading to CO2 retention

27
Q

What is a definition of respiratory alkalosis?

A
  • Excessive alveolar ventilation (hyperventilation) resulting in more CO2 than normal being exhaled
  • PaCO2 is reduced & pH increases causing alkalosis
28
Q

List 6 causes of respiratory alkalosis?

A
  1. Anxiety: often referred to as a panic attack
  2. Pain: causing an increased respiratory rate
  3. Hypoxia: resulting in increased alveolar ventilation in an attempt to compensate
  4. Pulmonary embolism
  5. Pneumothorax
  6. Iatrogenic (excessive mechanical ventilation)
29
Q

What is an anion gap used for?

A

To work out if the metabolic acidosis is due to increased acid production or ingestion vs decreased acid excretion or loss of HCO3–

30
Q

List 3 causes of a metabolic acidosis with increased anion gap?

A
  1. Diabetic ketoacidosis (↑ production)
  2. Lactic acidosis (↑ production)
  3. Aspirin overdose (ingestion of acid)
31
Q

List 3 causes of a metabolic acidosis with a decreased anion gap?

A
  1. GI loss of HCO3- (diarrhoea, ileostomy, proximal colostomy)
  2. Renal tubular acidosis (retaining H+)
  3. Addison’s disease (retaining H+)
32
Q

How do you work out the anion gap?

A

Anion Gap = Na+ – (Cl- + HCO3-)

33
Q

What is the definition of metabolic alkalosis?

A

Decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations

34
Q

List 3 causes of a metabolic alkalosis?

A
  1. GI loss of H+ ions (vomiting/diarrhoea)
  2. Renal loss of H+ ions (loop & thiazide diuretics/heart failure/nephrotic syndrome/cirrhosis/Conn’s syndrome)
  3. Iatrogenic: addition of alkali (milk-alkali syndrome)
35
Q

List 2 causes of a mixed respiratory & metabolic acidosis?

A
  1. Cardiac arrest

2. Multi-organ failure

36
Q

List 3 causes of a mixed respiratory & metabolic alkalosis?

A
  1. Liver cirrhosis with diuretic use
  2. Hyperemesis gravidarum
  3. Excessive ventilation in COPD

MBChB Yr 3 OSCES (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions