Brainscape's Knowledge GenomeTM

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


See full index

MD4003 OSCEs > ABGs > Flashcards

ABGs Flashcards

1
Q

1kPa=

A

7.5mmHg

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

Acid buffers?

A

Proteins
Hb
** Carbonic acid or bicarbonate **

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

Anion gap=

A

(Na + K ) - (Cl + HCO3)

Cations - anions

Normal= 10-18mmol/L

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

Lactic acid accumulation in..

A

Shock
Infection
Hypoxia

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

Urate accumulation in..

A

Renal failure

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

Ketone accumulation in…

A

DM, alcohol

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

Causes of metabolic alkalosis?

So increase in pH and HCO3

A

Vomiting
K+ depletion (in diuretics)
Burns
Ingestion of base

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

In respiration, CO2 is blown of so an increase in RR…

A

Increase ventilation and decreases CO2 plasma levels (e.g. compensation for metabolic acidosis)

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

Causes of respiratory alkalosis?

A

Results of hyperventilation in..

  • Stroke
  • SAH
  • Meningitis

Also: Anxiety, altitude increase, pregnancy, PE, drugs

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

Normal pH?

A

7.35-7.45

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Normal pO2?

A

12-13kPa

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

Normal pCO2?

A

4.5-5.6kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Normal bicarbonate (standard)?

A

22-26mmol/l

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is stand bicarbonate calculated?

A

From the actual bicarbonate but assuming 37degrees and a paCO2 of 5.3kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

_____ + CO2 ____ < –> H+ + _____-

A

H2O + CO2 H2CO3 < –> H+ + HCO3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Risk of high 02 delivery ?

A

In COPD = Hypercapnic respiratory failure

Generates free radicals
–> Lung toxicity
Result? Collapse of alveoli due to atelectasis + irritation to mucous membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Normal alveolar-arterial (A-a) gradient?

A

Less than 3kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the P/F ratio?

A

PaO2 / FiO2

Should be >50

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

pH is in proportion to…

A

HCO3 / pCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Causes of hyperventilation?

A

Acute severe asthma
PE
Pulmonary oedema
Anxiety

21
Q

Approach to assessing ABGs?

A
  1. Assess oxygenation and pO2
  2. Assess pH
  3. Determine the primary problem
  4. Is compensation occurring?
22
Q

Increased anion gap signals..

A

Metabolic acidosis

23
Q

Metabolic causes of increased acid load

A

Bodies own production
Ingestion (exogenous source)
Failure of excretion by the kidneys

24
Q

Types of shock

A

Cardiogenic
Septic
Hypovolaemic
Anaphylactic

25
Q

How does the body’s produce acid in excess leading to metabolic acidosis

A

LACTIC ACIDOSIS
Hypoperfusion (of whole body in shock and part of body in embolus)
Leading to anaerobic metabolism –> Lactic acidosis

KETOACIDOSIS
Imbalance of insulin and glucagon –> High glucose
E.g. Uncontrolled DM, alcoholic ketoacidosis and starvation ketoacidosis

26
Q

Causes of lactic acidosis?

A

Hypopersion (shock or embolus)
Severe hypoxia
Severe convulsions (resp arrest)
Strenuous exercise (dehydration)

27
Q

Renal cause of metabolic acidosis?

A

Kidney function: Resorbs filtered bicarbonate + regenerates bicarbonate consumed by buffering

Acute and chronic renal failure (increases anion gap)
Renal tubular acidosis (normal gap)

28
Q

Normal anion gap causes in metabolic acidosis?

A

Diarrhoea

Renal tubular acidosis

29
Q

Where does the cut secrete HCO3?

A

Below the pylorus

In stomach HCl is excreted

30
Q

Why is there a normal anion gap in diarrhoea?

A

Increase in: HCO3- loss and H+ gain
+ Volume depletion

Volume depletion = RAAS activation = Cl retained

So lo HCO3 is replaced by Cl

31
Q

Respiratory compensation for metabolic acidosis

A

Must lower pCO2, therefore RR much increase to blow of excess CO2
e.g. Kussmaul respiration

32
Q

What is kussmaul respiration?

A

A laboured deep, rapid pattern of breathing

33
Q

What are the two stages of metabolic alkalosis?

A 
Initiating process (commonly Loss of H+ ions)
Maintaining process
34
Q

Two ways that H+ is lost in the initiating process of metabolic alkalosis?

A

From the gut (above the pylorus)

From the kidney (furosemide and thiazide)

35
Q

How is metabolic alkalosis maintained?

A

A process which impairs the kidneys to excrete bicarbonate

e.g. Cl depletion group. When Cl- in the renal tubular fluid is LOW, bicarb is resorb to maintain electrical neutrality

36
Q

Difference between type I and type II respiratory failure?

A

Type 1 (Hypoxaemic)

  • Oxygenation failure (PaO2 decrease)
  • PaO2 <8kPa
Type II (Hypercapnic)
-Ventilatory failure (PaO2 decrease, PaCO2 increase, pH decrease)
37
Q

Normal TV

A

10ml/kg

38
Q

Acid base disturbance in vomit?

A

Metabolic alkalaemia

Initiating process:
Loss of HCl from stomach

Maintaining process:
When kidneys resorb Na+ in tubule, HCO3- moves with it. Normally would be Cl- BUT in vomit this is depleted

39
Q

Osmolality equation?

A

2K+ + 2Na+ + Glucose + Urea

40
Q

What is myasthenia gravis?

A

Myasthenia gravis is a chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles, which are responsible for breathing and moving parts of the body, including the arms and legs. The name myasthenia gravis, which is Latin and Greek in origin, means “grave, or serious, muscle weakness.

–> Respiratory acidosis

41
Q

If the patient is receiving oxygen therapy their PaO2 should be approximately 10kPa less than the % inspired concentration / FiO2

So a patient on 40% oxygen would be expected to have a PaO2 of approximately ???

A

30kPa

42
Q

When does Type 1 Resp Failure occur?

A

Indications: Hypoxaemia (PaO2 <8kPa) with normocapnia (PaCO2 < 6kPa)

Due to V/Q mismatch

E.g.

  • Reduced ventilation and normal perfusion e.g. pulmonary oedema and bronchoconstriction
  • Reduced perfusion with normal ventilation e.g. PE
43
Q

When does Type 2 Resp Failure occur?

A

Indications: Hypoxaemia (PaO2 <8kPa) with hypercapnia (PaCO2 > 6kPa)

Due to alveolar hypoventilation

E.g.

  • Increase resistance due to airway obstruction e.g. COPD
  • Reduced compliance of the lung tissue/chest wall (e.g. pneumonia/rib fractures/obesity)
  • Reduced strength of the respiratory muscles (e.g. Guillain–Barré / motor neurone disease)
  • Drugs acting on the respiratory centre reducing overall ventilation (e.g. opiates)
44
Q

Indications of a mixed acidosis/alkalosis?

A

In these circumstances, the CO2 and HCO3– will be moving in opposite directions (e.g. ↑ CO2 ↓ HCO3– in mixed respiratory and metabolic acidosis).

45
Q

Causes of resp acidosis?

A

Respiratory depression (e.g. opiates)
Guillain-Barre – paralysis leads to an inability to adequately ventilate
Asthma
Chronic obstructive pulmonary disease (COPD)
Iatrogenic (incorrect mechanical ventilation settings)

46
Q

Causes of respiratory alkalosis?

A

Anxiety – often referred to as a panic attack
Pain – causing an increased respiratory rate
Hypoxia – resulting in increased alveolar ventilation in an attempt to compensate
Pulmonary embolism
Pneumothorax
Iatrogenic (excessive mechanical ventilation)

47
Q

A decreased anion gap indicates decreased acid excretion or loss of HCO3– (overall decrease in acid)
E.g?

A

GI loss of HCO3— diarrhoea, ileostomy, proximal colostomy
Renal tubular acidosis (retaining H+)
Addison’s disease (retaining H+)

48
Q

Causes of metabolic alkalosis?

A

Gastrointestinal loss of H+ ions – vomiting/diarrhoea

Renal loss of H+ ions – loop and thiazide diuretics / heart failure / nephrotic syndrome / cirrhosis / Conn’s syndrome

Iatrogenic – addition of alkali (e.g. milk-alkali syndrome)

MD4003 OSCEs (19 decks)

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