respiratory failure

Question 1

what is acute resp failure called?

Answer 1

acute respiratory distress syndrome

Question 2

why is there limited data on acute respiratory distress syndrome? (ARDS)

Answer 2

Because it has heterogenous presentations and also the policies for ventilations and management when someone presents with it vary a loott

Question 3

is ARDS common? is it fatal?

Answer 3

yes and yes (30-40% mortality) more serious in oolder people- more fatal

Question 4

critical features to classify as ARDS

Answer 4

TIMING: needs within 1 week from new clinical insult or worsening

sides: both sides

needs to not be fully explained by smth like heart failure (problem needs to stem from lungs)

Question 5

cseverity classifications and how do you manipulate internationa numbers for uk numbers?

Answer 5

mild
moderate
severe

numbers on slide divided by approx 6.5

Question 6

what is ventilation and perfusion in this context?

Answer 6

ventilation refers to alveolar gas exchanges

perfusion is the blood flow in pulmonary capillaries

Question 7

which part of the liung is there more ventilation and why

Answer 7

at the bottom because there is

Question 8

what are the two types of resp failure

Answer 8

type 1: hypoxia (failure to get oxygen)
type 2: hypercapnea (failure to remove co2)

Question 9

CAUSES of type 1 resp failure

Answer 9

1)increased shunt fraction (QS/ QT) HEART failure - this is hypoxemia refractory to supplemental oxygen (independant - to suppl oxygen bc it has to do with blood circulation)

2) ALVEOLAR FLOODING (aspiration of smth - acid,-> membrane doesnt work-> oedema, fluid bc heart failure! or scarred membrane fron othe rreason

pulmonary oedema
pulmonary embolism
pulm hypertension

Question 10

2 types of causes for type 2 resp failure

Answer 10

1) decreased alveolar minute ventilation (air getting to alveoli less- due to slow breathing- unconsious ect)_

2) dead space ventilation- less air getting to alveoli due to contriction of airways (asthma, COPD)

nervous syst
neuromuscular
muscle failure
chest wall deformity

Question 11

what are some drugs that have already been tested for resp failure adn didnt rl work

Answer 11

steroids, salbutamol (surfactant) , surfactant, N-Acetylcysteine (cheap and easy) , neutrophil esterase inhibitor, GM-CSF, statins

Question 12

some of the treatments being tried out now

Answer 12

keratinocyte growth factor (repair factor)

mesenchymal stem cells (ex-vivo benefit) (cells loosely connected in extracellular matrix)

steroids- going back to this

Question 13

how much evidence is there on ARDS

Answer 13

not much- see ipad for what 3 key studies are syaing

Question 14

what is a relevant sub- phenotype sin patients that has been associated with ARDS outcomes

Answer 14

hyper and pro inflammatory endotypes, hyperinflammatory patients do worse (these are sort of patent differences- form person to person- medcine is headed in that more personalized management way)

Question 15

why is it important to research these sub phenotypes

Answer 15

so we can treat the specific parts of disease better for each one

Question 16

three types of therapeutic intervention (in terms of the aspect of your disease being targeted)

Answer 16

treating underlying disease
repspiratory support
multiple organ support

Question 17

what drugs do you treat underlying disease with

Answer 17

• treating underlying disease:
  bronchodilators
  pulmonary vasodilators

steroids
antibiotics
antivirals

systemic drugs (immunotherpies n other)
Pyridostigmine
Plasma exchange
IViG
Rituximab

Question 18

approaches for repsiratory support

Answer 18

Physiotherapy
Oxygen
Nebulisers (inhaling a drug)
High flow oxygen
Non- invasive ventilation

Mechanical ventilation
Extra-corporeal support (Extra corporeal membrane oxygenation - ECMO: you remove blood, oxygenate it and oout back in to support heart AND lungs- very high risk)

Question 19

multiple organ support approaches and organ systems to target

Answer 19

Cardiovascular support
Fluids
Vasopressors
Inotropes

**Pulmonary vasodilators**

Renal support
Haemofiltration
Haemodialysis

Immune therapies
Plasma exchange
Convalescent plasma

Question 20

what is the order of respiratory support interventions as ARDS gets progressively worse

Answer 20

1) conservative fluid management and low volume ventilation
2) increasing positive end expiratory pressure (like an air stent into lungs trying to recruit as many alveoli as possible)
3) neuromuscular blockage and if its not working well prone them
4) inhaled pulmonary vasodilator
5) ECMO

Question 21

the sequelae (consequences) of ARDS

Answer 21

-POOR GAS EXCHANGE : poor oxygenation and perfusion, hypercapnoea

• infection: sepsis
• inflammation - inflammatory responce

-systemic effects (sleep, heart, kidney ect due to v high co2, you can die of multi organ failure)

Question 22

what are the 4 types of ventilation

Answer 22

volume controlled
pressure controlled
assisted breathing modes
advanced ventilatory modes

Question 23

which type of ventilation is not used in uk and why?

Answer 23

pressure controlled ventlation because its dangerous to control pressures bc lung may colapse (see pressure volume loop)

Question 24

how does the patient volume loop change form normal to ARDS lung

Answer 24

moves down and to the right

Question 25

how is compliance depicted/ quantified in / from a pressure volume loop

Answer 25

its the incline of the extrapolation of the straight line of inspiration

Question 26

what does UIP stand for and signify

Answer 26

upper inflection point its the top part before the straight line becomes flatter on the inspiration side of loop (bottom). it signifies that after this pressure the alveoli need disproportionately lagre amounts of pressure to fill

Question 27

what is LIP

Answer 27

lower inflection point: lowest pressure at which there can be optimal alveolar recruitment

Question 28

what colour is air in CT

Answer 28

black - more black: better

Question 29

what is lung ct used to see

Answer 29

if theres air in lumgs or if they are not properly ventilated

Question 30

what do you use lung iltrasound for

Answer 30

see if fluid or air infectin or stuff like that

Question 31

what is the murray score

Answer 31

score used to guide escalation of therapy (determine who needs escalation/ refferal)

Question 32

factors involved in murray score

Answer 32

1) oxygen levels 2) CXR (x-ray scan)- how many quadrants are infiltrated 3) PEEP - the more you need the more points 4) compliance - the more the better

Question 33

how do you calculate murray score

Answer 33

add up all points and divivde by 4 (average of the 4 factors)

Question 34

score range - normal- needing ecmo

Answer 34

0= nrpmal 1-2.5 mild 2.5 severe 3- ecmo

Question 35

can patients get ecmo in every hospital in UK?

Answer 35

NO, there are 6 centeres that deal with this stuff

Question 36

what is the national ARDS aproach

Answer 36

since onmly 6 national centres, when someone has murray score >3 or really low ph (<7.2) 1) telephone or online repheral 2) consultant case review 3) send imaging 4) advice from special hospital 5) retrieval if needed- take them to the other hospitl by ambulance 6) transfer back to your hospital after ecmo/ special management 7) continue treatment on your hospital tll they get better

Question 37

what is another case in which you should give ecmo (other than murray score >3)

Answer 37

when positive pressure ventilation is not appropriate for ex due to significant tracheal injury

Question 38

who should you NOT gibe ecmo to

Answer 38

1) someone who wouldnt be able to continue active treatment after ecmo due to a significant co morbidity (this also could mean they could become dependent to ecmo) 2) someone who would get a disability that theyr enot ok with getting

Question 39

success rate of ecmo in uk?

Answer 39

very high

Question 40

why may success rate of ecmo in uk be better than other countries

Answer 40

bc very refinedcriteria on who gets ecmo

Question 41

how does ecmo work?

Answer 41

1) CANNULA THROUGH IVC 2) blood goes from IVC into a centrifugal pump (has little magnet to spin inside to reduce sheer stress: make sure layers are not separating) 3) then sent to oxygenator where pure oxygen is passed across the top of the membrane and blood turns from purple/ blue to bright red 4) blood inserted back into RIGHT heart (so lungs are nooot bypassed)

Question 42

what evidence is there for ecmo in literature and in uk clinical data?

Answer 42

literature: not that much evidence, 1 big trial started was stopped and data not stat sign buttt in uk lower mortality shown than lit- maybe bv of selection criteria so ecmo used widely in uk

Question 43

disadvantages od f ecmo

Answer 43

- prob with equity- centres are only 6 spread so u might live far and spend longer time getting there- getting sicker - technically hard - haemodynamics, clotting and bleeding, access to internal jugular and other veins ect - very expensive