resp failure

Question 1

what is resp failure

Answer 1

syndrome of inadequate gas exchange due to dysfunction to 1+ of
[nervous system, resp muscle, pulmonary]

Question 2

example of issue with [nervous system, resp muscle, pulmonary]

Answer 2

[nervous system= CNS
resp muscle=diaphragm
pulmonary=airway disease/circulation

Question 3

risk factors to resp failure
chronic vs acute

Answer 3

chronic= COPD/CF

acute=infection/pancreatitis

Question 4

what is ARDS

Answer 4

Acute respiratory distress syndrome

Question 5

how to diagnose ARDS

Answer 5

Berlin definition
timing- within 1 week

chest imaging- bilateral opacities (lung more white)

origin of edema -not due to cardiac failure

oxygenation(P/F) (PaO2/FIO2) mmHg-
mild= 200-300
moderate= 100-200
severe= <100

Question 6

Ventilation and perfusion across the lung- bottom on lung

Answer 6

bottom lung:
-ventilation (increased)
-alveoli smaller and more compliant

perfusion (increased)
-more recruitment
-less resistance
-high flow rate

Question 7

what are the different zones of the lungs and ventilation
perfusion matching

Answer 7

Zone 1=apex
PA>Pa>Pv

Zone 2
Pa>PA>Pv

Zone 3=base
Pa>Pv>PA

PA=alveoli pressure
ventilation/perfusion

Question 8

define compliance and elastance

Answer 8

compliance= tendency to distort under pressure
△v/△p

elastance = tendency to recoil to original volume
△P/△V

-think PEV

Question 9

how to calculate minute ventilation (L/min) and what it is

Answer 9

gas entering and leaving lungs

tidal volume x breathing frequency (breaths/min)

Question 10

how to calculate alveolar ventilation (L/min) and what it is

Answer 10

gas entering and leaving the alveoli

[tidal volume- dead space] x breathing frequency (breaths/min)

Question 11

what is type 1/hypoxemic resp failure and cause

Answer 11

PaO2 <60
Failure of O2 exchange

-Increased shunt fraction (QS/QT )
- Due to alveolar flooding
- Hypoxemia refractory=no improvement to supplemental oxygen administration

Pulmonary HOE
-hypertension
-oedema
-embolism

Question 12

what is type 2/hypercapnic resp failure and cause

Answer 12

(PaCO2 >45):
Failure to exchange or remove CO2

-Decreased alveolar minute ventilation (V A )
- Dead space ventilation

airway obstruction/weak muscles

Question 13

what is type III resp failure (perioperative resp failure)

Answer 13

Increased atelectasis (incomplete lung inflation) due to low functional residual capacity

-can be hypoxaemia / hypercapnoea
-Prevention: anesthetic or operative technique

Question 14

what is Type IV Respiratory Failure: Shock

Answer 14

pt- intubated and ventilated
during (Septic) shock

Ventilation increases thoracic pressure which affects the heart
Reduces LV afterload, Increased RV pre and after load

Question 15

cause of ARDS pulmonary vs extra-pulmonary

Answer 15

pulmonary- trauma/aspiration

extra-pulmonary- pancreatitis/transfusion

both: INFECTION

Question 16

what is the issue with lung injury in relation to gas exchange

Answer 16

Alveolar-capillary units become damaged and leaky,
distance for gas exchange increases,
reducing efficiency of gas exchange.
Reduced O2 available.

exacerbate by inflammatory response

Question 17

resp failure- therapeutic intervention

Answer 17

1. treat underlying disease
   bronchodilators/steroids/Ab
2. resp support
3. multi organ support

Question 18

resp support in clinical management for ARDS from mild to severe

Answer 18

All:
-fluid management
-low volume ventilation
-increasing PEEP

Mod/Sev=
-prone positioning
-neuromuscular blockade

severe:
ECMO

Question 19

what is ecmo

Answer 19

extracorporeal membrane oxygenation

Question 20

ARDS pathogenesis

Answer 20

1. Poor gas exchange
   Inadequate oxygenation
   Poor perfusion
   Hypercapnoea

2.Infection-Sepsis

3.Inflammation

4. Systemic effects

Question 21

ventilation- cons

Answer 21

-Minute ventilation- PaCO2 control

-Alveolar recruitment (PEEP)

-V/Q mismatch -Ventilation without gas exchange vice-versa

-VENTILATOR INDUCED LUNG INJURY-> DRIVING PRESSURE

Question 22

what is the Murray score and what each would mean

Answer 22

guiding escalation of therapy

0 = normal
<2.5 =Mild
>2.5 = Severe ARDS
3= ECMO

(averagescore on all 4 parameters:
P/F ratio, CXR, PEEP, Compliance

Question 23

national ARDS approach

Answer 23

1.telephone/online referral
murray score 3+ or
pH<7.2

2.consultant case review
3. transfer imaging
4. advice
5. retrieval and transfer
6.ongoing management

Question 24

ECMO issues

Answer 24

-time to access/consideration of referral

-obtaining access-subclavian/femoral
-clotting/bleeding

Question 25

who to treat vs exclusion criteria

Answer 25

inclusion
-Murray 3+,
positive pressure ventilation not appropriate (eg. sig tracheal injury)

exclusion
-sign co-morbidity (dependency to ECMO