ABG and Oxygen

Question 1

what is hypoxia

Answer 1

lack of oxygen in the tissues

Question 2

what is hypoxaemia

Answer 2

low oxygen levels in the blood

Question 3

what causes anaemic hypoxia

Answer 3

lack of Hb

Question 4

what causes perfusion hypoxia

Answer 4

poor CO (cardiac output)

Question 5

what causes toxic hypoxia

Answer 5

failure to release O2 at tissue level

Question 6

what causes hypoxaemic hypoxia

Answer 6

low pO2 and SaO2

Question 7

what is pO2

Answer 7

partial pressure of oxygen- oxygen saturation in blood plasma

Question 8

what range of pH is classed as acidaemia

Answer 8

<7.35

Question 9

define acidosis

Answer 9

process causing excess acid to be present in the blood

Question 10

what does acidosis not necessarily cause

Answer 10

acidaemia

Question 11

what pH range is classified as alkalaemia

Answer 11

> 7.45

Question 12

define alkanosis

Answer 12

process causing excess base to be present in the blood

Question 13

what are CO2 changes related to

Answer 13

respiratory changes

Question 14

what are HCO3 changes related to

Answer 14

metabolic changes

Question 15

which compensation is slow and which is fast

Answer 15

respiratory compensation fast, met slow

Question 16

which out of CO2 and HCO3 is an acid and which is a base

Answer 16

CO2 acid, HCO3 base

Question 17

what do opposite codes (high/low) mean

Answer 17

compensation

Question 18

what do matched codes mean

Answer 18

primary abnormality

Question 19

what can cause resp acidosis with metabolic compensation

Answer 19

chronic type 2 resp failure; COPD, CF, Kyphoscoliosis

Question 20

what can cause metabolic acidosis with resp compensation

Answer 20

sepsis, poisoning, drugs, lactate

Question 21

what causes uncompensated resp acidosis

Answer 21

acute type 2 resp failure

Question 22

what causes decompensated resp acidosis

Answer 22

acute or chronic type 2 resp failure

Question 23

what is the anion gap

Answer 23

difference between primary measured cations (Na+ and K+) and primary measured anions (CL- and HCO3-)

Question 24

what is the commonest cause of a high anion gap

Answer 24

infection

Question 25

what organ controls bicarbonate

Answer 25

kidneys

Question 26

what organs control CO2

Answer 26

lungs

Question 27

how does the body react to acidosis

Answer 27

breathing fast- hyperventilating- to get rid of CO2

Question 28

what is metabolic compensation for resp acidosis

Answer 28

kidney stores bicarbonate

Question 29

what is the resp compensation for metabolic alkanosis

Answer 29

maintain CO2 and reduce resp rate

Question 30

what is type 2 resp failure

Answer 30

hypoxia and hypercapnia

Question 31

what is hypercapnia

Answer 31

too much CO2

Question 32

what is SpO2

Answer 32

percutaneous oxygen saturation (detected with a pulse oximeter)

Question 33

what is SaO2

Answer 33

arterial blood oxygen saturation

Question 34

why is venous blood darker than arterial

Answer 34

as deoxygenated haemoglobin in darker in colour

Question 35

what is PaO2

Answer 35

amount of oxygen dissolved in arterial blood plasma

Question 36

what is the amount of oxygen dissolved in the blood proportional to

Answer 36

the partial pressure of oxygen

Question 37

what is FiO2

Answer 37

fraction of inspired oxygen

Question 38

what is the only cause of hypoxia

Answer 38

hypoxaemia

Question 39

why is too much oxygen a bad thing

Answer 39

poisons people, unable to detect changes in pO2, can develop into hypercabia (CO2 retention)

Question 40

in what type of patient should you suspect type two resp failure

Answer 40

COPD

Question 41

who else is at risk of type 2 resp failure

Answer 41

scoliosis, neuromuscular deficiency, hyper obese

Question 42

how does excess oxygen cause V/Q mismatching

Answer 42

reverses reactive vasoconstriction in areas of poor ventilation, improves perfusion but not ventilation

Question 43

what is the haldane effect

Answer 43

when CO2 occupies the empty binding sites on Hb (acidotic)

Question 44

what happens when patients with the haldane effect are given high FiO2

Answer 44

pushes CO2 out of Hb and into system

Question 45

what is normal respiration driven by

Answer 45

CO2 chemoreceptors

Question 46

what does chronic hypercarbia lead to

Answer 46

desensitisation of these receptors- making oxygen chemoreceptors control respiration

Question 47

why should COPD patients (with chronically compensated CO2 levels) not be put on

Answer 47

as they are not dependant on hypoxic drive and when in resp failure and put on high oxygen the CO2 in their blood will rise via the haldane effect, V/Q mismatch, and via the removal/reduction of the hypoxic drive

Question 48

patients with chronically poor localised ventilation can be sensitive to what

Answer 48

oxygen- V/Q mismatch

Question 49

what is a good marker for oxygen sensitivity

Answer 49

CO2 retention

Question 50

what are the symptoms of hypoxaemia

Answer 50

altered mental state, cyanosis, dyspnoea, tachypnoea, arrhythmias

Question 51

when does hypoxaemia cause death

Answer 51

around 2.7 kPa

Question 52

what is the bets SaO2

Answer 52

sepsis= 85-95% | critical care= 100%

Question 53

what causes anaemic hypoxia

Answer 53

deficiencies (iron, vit b, folate)

Question 54

what causes toxic hypoxia

Answer 54

toxins- cyanide, CO, arsenic, alcohol, popper

Question 55

what is hypoxic hypoxaemia caused by

Answer 55

low inspired oxygen concentration; alveolar hypoventilation, impaired diffusion, shunt, dead space, V/Q mismatch

Question 56

what causes low inspired oxygen concentration

Answer 56

anaesthetic gases, altitude

Question 57

what causes alveolar hypoventilation

Answer 57

opiates, anaphylaxis, obesity, kyphoscoliosis, anaesthetic, foreign body in lung

Question 58

what is impaired diffusion

Answer 58

failure of the alveolar-endothelial interface

Question 59

what can cause impaired diffusion

Answer 59

interstitial thickening (pulmonary fibrosis, lymphangitis, sarcoidosis), vascular dysfunction (pulmonary vasculitis, endothelial malignancy)(blood vessels to big/damaged)

Question 60

what is shunting

Answer 60

perfusion without ventilation

Question 61

what is dead space

Answer 61

ventilation with perfusion

Question 62

what causes dead space

Answer 62

PE, po vasculitis, po hypertension

Question 63

describe the V and Q in lug apex

Answer 63

good v poor q

Question 64

describe the V and Q in lug base

Answer 64

poor v good q

Question 65

what is DO2

Answer 65

global oxygen delivery (total amount of oxygen delivered to tissues per minute)

Question 66

what conditions are patients given all the oxygen

Answer 66

cardiac arrest, severe trauma, severe sepsis, anaphylaxsis