Top of Respiratory Table - ABG + O2 delivery Flashcards

1
Q

When do you do ABG

A
Any deteriorating patient
Acute exacerbation of chest
Impaired consciousness 
Poor resp effort
Signs of hypercapnia 
Certain conditions - DKA
Sats <92%
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2
Q

What do you comment on

A

Is it a type 1 or type 2 resp failure

Is patient retaining CO2

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3
Q

What info is provided

A
pH
pCO2 and pO2
Electrolyes - Na / K 
Lactate
Hb
Base excess
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4
Q

Why is VBG useful

A

Accurate for pH and pCO2
Less pain and less risk
Useful in cardiac arrest (diff reference values)

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5
Q

What is not accurate

A

O2

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6
Q

When do you do ABG

A

Patient in shock / critical state

Shows pO2 accurately

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7
Q

What is the base excess (used instead of bicarb)

A

The amount of acid needed to restore blood to original pH
Increases alkalosis
Decreases acidosis

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8
Q

How do you analyse blood gas

A
What is patient's condition 
Is patient acidotic or alkalemic 
Is patient hypoxic
What has happened to PaCO2
What has happened to BE / bicarbonate
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9
Q

What do you want to know about patients condition

A

Is it acute or chronic

e.g. resus will have mixed metabolic and resp acidosis due to inadequate ventilation + lactic acid

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10
Q

What is acidotic

A

pH <7.35

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11
Q

What is alkaloid

A

pH >7.45

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12
Q

Is patient hyperaemic

A

O2 10.5-13.5

If on supplementary O2 PaO2 should be 10% of this

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13
Q

What should CO2 be

A

4.5-6

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14
Q

If CO2 increased

A

Suggest respiratory acidosis
OR
Resp compensating for metabolic alkalosis

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15
Q

If CO2 decreased

A

Resp alkalosis
OR
Resp compensation for metabolic acidosis

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16
Q

If CO2 decreased what will patient be doing

A

Hyperventilating
Rare if normal RR / spontaneous breathing
More common in mechanical ventilation

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17
Q

Acidosis high CO2

A

Resp acidosis

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18
Q

Acidosis low Co2

A

Hyperventilating to compensate for metabolic acidosis

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19
Q

Aklaosis + low CO2

A

Resp alkalosis

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20
Q

Alkalosis + high CO2

A

Don’t get

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21
Q

What does BE / bicarb suggest if

A

Metabolic acidosis
or
Renal compensation for resp alkalosis

22
Q

If HCO3 very high

A

Suggest chronic process as takes time to rise

23
Q

What is important to remember

A

Can get mixed blood gas
- Low pH = acidic
- High PaCO2 = suggest resp acidosis
Low HCO3 = alkalosis

24
Q

When can this occur

A

Sepsis with reduced RR and lactic acid

25
Q

What does COPD cause

A

Chronic resp acidosis + compensator metabolic alkalosis

26
Q

REMEBER ROME

A

Resp = opposite

  • Low pH and high CO2 = acid
  • High pH and low CO2 = alkalosis

Metabolic = equal

  • Low pH and low bicarb = acid
  • High pH and high bicarb = alkalosis
27
Q

Do Q

A

OK

28
Q

What are target sats

A

94-98%

Aim 88-92% if COPD / hypercapnia risk and monitor with ABG

29
Q

When do you not give O2

A

If no risk of hypoxia

30
Q

If patient critically ill e.g. anaphylaxis / shock

A

15l non-rebreathe mask even if COPD

31
Q

How do you deliver more O2

A

Increase FiO2

Air we breath is only 28% so if higher conc more will diffuse into blood

32
Q

Is O2 a prescription

A

Yes

33
Q

How much O2

A

Titrate guided by sats and condition of patient

Humidify if long term at a high flow and tachy

34
Q

How much O2 in nasal cannula give

A

1-4l at 24-40% O2

35
Q

When would you never use a simple face mask

A

If hypercapnia or type 2

36
Q

What is Venturi good for

A

Accurate FiO2
24, 28 and 40%
Used in COPD to deliver controlled O2

37
Q

What is non-rebreathe used

A

Critically ill
Can technically give 100% O2
Usually 60-905 O2 with 10-15l
Stops you breathing in own CO2

38
Q

When would you never use

A

Stable patient as hyperaemia dangerous due to free radical

39
Q

What must you do after

A

ABG

40
Q

Non-invasive ventilation

A

CPAP or BiPAP

41
Q

What does it do

A

Improve V/Q mismatch

42
Q

Invasive ventilation

A

If still no response

43
Q

What is optifldow

A

High flow nasal cannula used in ARDS / COVID

Can give 60-100% O2

44
Q

Estimated L of O2 and % O2 delivered

A
1L = 24%
2L = 28% 
3L = 32%
4l = 36%
10L = 60%
If moving up therapy must ensure delivering higher FiO@
45
Q

Other factors to improve sats

A

Treat anaemia
Improve CO
Chest physic for V/Q mismatch

46
Q

What causes a respiratory acidosis

A
Reduced CO2 eliminate
Opiates - reduce RR
Chest trauma / pneumothorax - impaired breathing 
GBS / MG - impaired muscle
Obstruction - FB 
COPD
Asthma
47
Q

What causes resp alkalosis

A
Hyperventilation 
- Anxiety / pain / shock
PE 
Early aspirin (salicylate) overdose 
Fever
Liver failure
48
Q

What causes metabolic acidosis

A
Prolonged diarrhoea - lose HCO3 
MUDPILE
- Methanol
- Ureaemia - CKD 
- DKA
- Paracetamol
- Iron 
- Lactic acid
- Ethanol 
- Sacyilate (late)
49
Q

What do salicylate cause

A

Mixed

Early resp alkalosis and late metabolic acidosis

50
Q

What causes metabolic alksosi

A

Diuretic
Prolonged vomit
Admin bicarb
Diseases causing hypokalaemia = Conn’s

51
Q

How is K affected by pH

A
Acidosis = K out of cells = hyperkalaemia 
Alkalosis = hypokalaemia
52
Q

What organs involved in maintaining pH

A

Lungs
- Can retain or blow of CO2 changing pH in minutes

Kidney

  • Excrete acid + regulate bicarb
  • Takes hours to days