Top of Respiratory Table - ABG + O2 delivery

Question 1

When do you do ABG

Answer 1

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

Question 2

What do you comment on

Answer 2

Is it a type 1 or type 2 resp failure

Is patient retaining CO2

Question 3

What info is provided

Answer 3

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

Question 4

Why is VBG useful

Answer 4

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

Question 5

What is not accurate

Answer 5

O2

Question 6

When do you do ABG

Answer 6

Patient in shock / critical state

Shows pO2 accurately

Question 7

What is the base excess (used instead of bicarb)

Answer 7

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

Question 8

How do you analyse blood gas

Answer 8

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

Question 9

What do you want to know about patients condition

Answer 9

Is it acute or chronic

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

Question 10

What is acidotic

Answer 10

pH <7.35

Question 11

What is alkaloid

Answer 11

pH >7.45

Question 12

Is patient hyperaemic

Answer 12

O2 10.5-13.5

If on supplementary O2 PaO2 should be 10% of this

Question 13

What should CO2 be

Answer 13

4.5-6

Question 14

If CO2 increased

Answer 14

Suggest respiratory acidosis
OR
Resp compensating for metabolic alkalosis

Question 15

If CO2 decreased

Answer 15

Resp alkalosis
OR
Resp compensation for metabolic acidosis

Question 16

If CO2 decreased what will patient be doing

Answer 16

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

Question 17

Acidosis high CO2

Answer 17

Resp acidosis

Question 18

Acidosis low Co2

Answer 18

Hyperventilating to compensate for metabolic acidosis

Question 19

Aklaosis + low CO2

Answer 19

Resp alkalosis

Question 20

Alkalosis + high CO2

Answer 20

Don’t get

Question 21

What does BE / bicarb suggest if

Answer 21

Metabolic acidosis
or
Renal compensation for resp alkalosis

Question 22

If HCO3 very high

Answer 22

Suggest chronic process as takes time to rise

Question 23

What is important to remember

Answer 23

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

Question 24

When can this occur

Answer 24

Sepsis with reduced RR and lactic acid

Question 25

What does COPD cause

Answer 25

Chronic resp acidosis + compensator metabolic alkalosis

Question 26

REMEBER ROME

Answer 26

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

Question 27

Do Q

Answer 27

OK

Question 28

What are target sats

Answer 28

94-98% | Aim 88-92% if COPD / hypercapnia risk and monitor with ABG

Question 29

When do you not give O2

Answer 29

If no risk of hypoxia

Question 30

If patient critically ill e.g. anaphylaxis / shock

Answer 30

15l non-rebreathe mask even if COPD

Question 31

How do you deliver more O2

Answer 31

Increase FiO2 | Air we breath is only 28% so if higher conc more will diffuse into blood

Question 32

Is O2 a prescription

Answer 32

Yes

Question 33

How much O2

Answer 33

Titrate guided by sats and condition of patient | Humidify if long term at a high flow and tachy

Question 34

How much O2 in nasal cannula give

Answer 34

1-4l at 24-40% O2

Question 35

When would you never use a simple face mask

Answer 35

If hypercapnia or type 2

Question 36

What is Venturi good for

Answer 36

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

Question 37

What is non-rebreathe used

Answer 37

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

Question 38

When would you never use

Answer 38

Stable patient as hyperaemia dangerous due to free radical

Question 39

What must you do after

Answer 39

ABG

Question 40

Non-invasive ventilation

Answer 40

CPAP or BiPAP

Question 41

What does it do

Answer 41

Improve V/Q mismatch

Question 42

Invasive ventilation

Answer 42

If still no response

Question 43

What is optifldow

Answer 43

High flow nasal cannula used in ARDS / COVID | Can give 60-100% O2

Question 44

Estimated L of O2 and % O2 delivered

Answer 44

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

Question 45

Other factors to improve sats

Answer 45

Treat anaemia Improve CO Chest physic for V/Q mismatch

Question 46

What causes a respiratory acidosis

Answer 46

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

Question 47

What causes resp alkalosis

Answer 47

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

Question 48

What causes metabolic acidosis

Answer 48

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

Question 49

What do salicylate cause

Answer 49

Mixed | Early resp alkalosis and late metabolic acidosis

Question 50

What causes metabolic alksosi

Answer 50

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

Question 51

How is K affected by pH

Answer 51

``` Acidosis = K out of cells = hyperkalaemia Alkalosis = hypokalaemia ```

Question 52

What organs involved in maintaining pH

Answer 52

Lungs - Can retain or blow of CO2 changing pH in minutes Kidney - Excrete acid + regulate bicarb - Takes hours to days