Types of hypoxia

Question 1

Hypoxia definition

Answer 1

inadequate oxygen in a particular part or all of the body or at cellular level
often pathological
variations in arterial oxygen concentrations can be part of the normal physiology - hypoventilation training or strenuous exercise

Question 2

what is anoxia?

Answer 2

no oxygen at all

Question 3

classification of hypoxia

Answer 3

generalised

local

Question 4

types of hypoxia

Answer 4

inadequate oxygenation of blood in lungs 
pulmonary disease
venous to arterial shunts 
inadequate O2 transport to tissues 
inadequate tissue use of oxygen

Question 5

inadequate oxygenation of blood in lungs

Answer 5

hypoventilation

altitude hypoxia

Question 6

altitude hypoxia

Answer 6

barometric pressure of atmosphere is lower
oxygen molecules in air are further apart so oxygen content is lowered
reduction of available oxygen in the air at height reduces oxygen saturation in blood

Question 7

what is hypoxaemia ?

Answer 7

decreased availability of O2 in inhaled air

Question 8

hypoventilation

Answer 8

neurological weakness
trouble with bellows - movement of air
central drive of respiration centre suppressed

Question 9

what causes hypoventilation

Answer 9

opiate overdose
motor neuron disease 
severe neuropathy 
muscle weakness 
multiple system atrophy

Question 10

pulmonary disease

Answer 10

airway resistance - asthma
failure of respiratory membrane diffusion
volume of oxygen getting to airways is reduced
gas exchange failure - alveolar dysfunction or membrane dysfunction

Question 11

venous-arterial shunt

Answer 11

cardiac shunt
cyanotic congenital heart disease
mixing of arterial and venous blood
only occurs when right sided heart pressure increases and blood shunts from right to left

Question 12

inadequate O2 transport to tissues

Answer 12

decreased carrying capacity - low Hb - anaemia
generalised circulatory failure - shock
localised circulatory failure - acute MI or stroke

Question 13

cyanotic congenital heart disease

Answer 13

tetralogy of fallot
transposition of great arteries
ASD/VSD

Question 14

anaemia

Answer 14

less O2 carriage to tissue
measure oxygen saturation
less oxygen for target tissues/ organ/ cells

Question 15

oxygen saturation

Answer 15

% of which haemoglobin is saturation with oxygen

Question 16

inadequate tissue use of oxygen

Answer 16

burns

Question 17

CO poisoning

Answer 17

red colour
not cyanotic
oxygen sats appear unaffected

Question 18

what can cause cyanide toxicity?

Answer 18

burning rubber
pesticides 
battery manufacturing 
gold mining 
jewellery cleaning 
plastic, nylon and fumigant manufacturing 
almonds

Question 19

who gets cyanide toxicity?

Answer 19

35% of fire victims

Question 20

symptoms/ signs of cyanide toxicity

Answer 20

cyanosis 
low GCS 
normal oxygen saturations 
lactic acidosis 
low BP
low HR
high RR 
depressed mental activity - confusion and coma 
tissue and cell death - ischaemia 
reduced work capacity of muscles

Question 21

treatment for cyanide toxicity

Answer 21

amyl nitrate and sodium thiosulfate and sodium nitrate
goal to create methaemoglobin
hydroxocobalamin infusion - vitamin B12

Question 22

oxygen therapy

Answer 22

helpful if O2 is deficient

if alveolar O2 is increased O2 pressure gradient is increased

Question 23

type 1 respiratory failure

Answer 23

hypoxaemia - PaO2 <8kpa

normocapnia - PaCO2 <6kpa

Question 24

pathogenesis of type 1 respiratory failure

Answer 24

associated with damage to lung tissue which prevents adequate oxygenation of blood
remaining normal lung is sufficient to excrete carbon dioxide

Question 25

what causes type 1 respiratory failure?

Answer 25

``` low ambient oxygen/high altitude ventilation-perfusion mismatch - PE alveolar hypoventilation diffusion problems - pneumonia/ARDS right - left cardiac shunt ```

Question 26

type 2 respiratory failure

Answer 26

hypoxaemia - PaO2 <8kpa | hypercapnia - PaCO2 >6kpa

Question 27

pathogenesis of type 2 respiratory

Answer 27

due to alveolar hypoventilation | unable to get O2 into blood and CO2 out of it

Question 28

causes of type 2 respiratory failure

Answer 28

``` increased airway resistance reduced breathing effort decrease in area of lung available for gas exchange neuromuscular problems deformed/rigid/flail chest ```

Question 29

what causes increased airway resistance?

Answer 29

COPD asthma suffocation

Question 30

what causes reduced breathing effort?

Answer 30

drugs brainstem lesion extreme obesity

Question 31

what causes a decrease in area of lung available for gas exchange

Answer 31

chronic bronchitis

Question 32

what causes neuromuscular problems?

Answer 32

guillain-barre syndrome | motor neuron disease

Question 33

what causes deformed/rigid/flail chest?

Answer 33

kyphoscoliosis | ankylosing spondylitis

Question 34

how to treat respiratory failure

Answer 34

administer oxygen mechanical ventilation treat underlying condition - bronchodilators, steroids, antibiotics etc.

Question 35

different types of oxygen administration

Answer 35

venturi mask - 24% | rebreathe mask - 100%

Question 36

when can oxygen therapy be useful?

Answer 36

when there is inadequate oxygenation of blood | pulmonary disease

Question 37

how is respiration controlled?

Answer 37

central chemoreceptors peripheral chemoreceptors brainstem respiratory centres adjust rate and depth of respiration accordingly

Question 38

central chemoreceptors

Answer 38

respond to arterial PaCO2

Question 39

peripheral chemoreceptors

Answer 39

respond to PaCO2 and pH

Question 40

what should PaO2 be on oxygen?

Answer 40

should be 10kpa less than the % inspired O2 concentration

Question 41

what is anxiolysis?

Answer 41

level of sedation in which a person is relaxed and may be awake, caused by drugs to help relieve anxiety minimal sedation

Question 42

clinical features of COPD

Answer 42

``` chronically hypoxic chronically retain CO2 high CO2 and bicarbonate smoking history gaunt cachectic dyspnoea minimal cough increased minute ventilation pink skin pursed lip breathing accessory muscle use hyperinflation barrel chest decreased breath sounds tachypnoea ```

Question 43

complications of COPD

Answer 43

pneumothorax due to bullae and weight loss due to work of breathing

Question 44

management of COPD

Answer 44

no longer rely on detecting high levels of CO2 in their blood to stimulate respiration rather they rely on hypoxic drive need careful oxygen management - venturi devices target oxygen sats of 88-92% to avoid loss of ventilation stimulation which would cause hypercapnia and acidosis

Question 45

what to do if someone with COPD becomes acidotic with low O2 and high CO2

Answer 45

non-invasive ventilation

Question 46

clinical features of chronic bronchitis

Answer 46

``` chronic productive cough purulent sputum haemoptysis mild dyspnoea initially cyanosis hypoxaemia peripheral oedema - cor pulmonale crackles wheezes prolonged expiration ```

Question 47

complications of chronic bronchitis

Answer 47

secondary polycythemia vera due to hypoxaemia pulmonary hypertension due to reactive vasoconstriction from hypoxaemia cor pulmonale from chronic pulmonary hypertension

Question 48

asthma attack

Answer 48

``` inhalers not working raised respiratory rate tachycardia low PaO2 low PaCO2 normal pH ```

Question 49

opioid toxicity clinical features

Answer 49

``` reduced GCS reduced respiratory rate reduced ventilation high CO2 and low O2 pinpoint/ small pupils acidotic on ABG ```

Question 50

risk factor for opioid toxicity

Answer 50

excreted renally so CKD/ impaired renal function

Question 51

management for opioid toxicity

Answer 51

naloxone, corrects GCS

Question 52

pulmonary embolism

Answer 52

``` increases pulmonary vascular resistance decreased RV output reduced LV preload fall in CO hypoxia occurs due to VQ mismatch ```

Question 53

VQ mismatch in PE

Answer 53

reduced perfusion with normal ventilation

Question 54

treatment for PE

Answer 54

``` LMWH warfarin DOAC thrombolysis clot extraction ```

Question 55

guillain barre syndrome

Answer 55

acute inflammatory neuropathy | often have a history of gastronenteritis or flu-like illness weeks before onset of neurological symptoms

Question 56

clinical features of guillain barre syndrome

Answer 56

``` bilateral affects distal extremities first prior to progression 1/3 will experience respiratory failure requiring ventilation and airway protection hypercapnia and hypoxia are late signs falling oxygen sats low PaO2 high PaCO2 impending respiratory arrest ```

Question 57

testing in Guillain barre syndrome

Answer 57

regular spirometry to observe respiratory effort nerve conduction studies and lumbar puncture should be done lumbar puncture will show high protein

Question 58

pathogenesis of guillain barre syndrome

Answer 58

gastroenteritis or flu-like illness triggers an immune mediated attack on myelin sheaths due to molecular mimicry affects the motor and sensory nerves

Question 59

pneumonia presentation

Answer 59

high PaCO2 low PaO2 reduced alveolar expansion - hypoventilation crepitations at base

Question 60

treatment for pneumonia

Answer 60

``` IV antibiotics IV fluids oxygen analgesia chest physio ```