Viva - Asthma

Question 1

Define asthma

Answer 1

Chronic inflammatory disorder of airways

Characteristic reversible airway obstruction on spirometry

FEV1/FVC <65%
FEV1< 70% predicted
Increased by 12% with bronchodilator

Question 2

Presentation of asthma

Answer 2

Breathless
Wheeze
Cough

Diurnal variation
Worse at night

May be history of atopy (eczema, rhinitis)
Exposure of occupations allergens

Worsened by smoke/NSAID/Aspirin/Bete blockers

Question 3

Pathophysiology of asthma

Answer 3

Chronic inflammation of airways

Smooth muscle hypertrophy

Goblet cell hyperplasia

Increased airway reactivity, mucosal oedema, excess secretion

Leads to bronchospasm and mucous plugging —> scarring, collagen

Question 4

Moderate asthma

Answer 4

Increasing symptoms
PEFR 50-75% of best
No severe features

Question 5

Severe

Answer 5

PEFT 33-50%
RR 25/min
HR>110
Can’t complete sentence

Any one

Question 6

Life threatening

Answer 6

Clinical. Ix
Altered mental stage. PEFR<33%
Exhaustion. SpO2 <92%
Arrhythmia. PaO2 <8
Hypotension. Normal CO2 4.5-6.0
Cyanosis
Silent chest
Poor Resp

Question 7

Near fatal

Answer 7

Raised CO2

MV with raised inflation pressures

Question 8

Tx - immediate A-B

Answer 8

ABCDE
High risk of deterioration

Liaise with resp

Airway - O2, aim stats 94-98%

Tube if poor resp effort, drowsiness, confusion, resp arrest, exhaustion

B - ABG and CXR (PTx)

Nebuliser salbutamol 2.5-5 mg
Neb ipratropium 250-500mcg
Steroids 40mg pred po (100mg hydro)
Mg 2g over 20 minutes

iv salbutamol
Aminophyloine 5mg/kg load

No role for Abx, Montelukast, Heliox (though it may reduce WOB)

Question 9

Things to bare in mind on induction

Answer 9

Use ketamine (smooth muscle relax)
Avoid Atracurium (histamine)

Question 10

Management, circulation

Answer 10

They are intravascularly deplete
CO worsened by reduced venous return by high thoracic pressures

Some fluid resus and careful induction
Monitor electrolyte imbalance (salbutamol and low K)

Question 11

Once tubed what vent strategies

Answer 11

There is high airways resistance, obstructs exp flow and breath stacking and air trapping -> dynamic hyperinflation

Causes barotrauma and CV depression

Vent strategies
Low PEEP (<80% of intrinsic PEEP )
Careful use of extrinsic PEEP reduces gradient from drop in airway pressures and reduce WOB
Measure iPEEP on expiration hold

Prolonged exp time, IE ratio 1:2 to 1:4

Controlled hypovent with permissive hypercapnoea (as long as pH>7.2)
Low Tidal volumes
Slow rate 10-14
Pplat 30cmH2O

Temporary disconnect and decompression

Question 12

Other drugs to think of

Answer 12

Ketamine - phencyclidine derivative, NMDA antag, bronchodilator
Induction AND infusion

Volatiles - sevoflurane

VV ECMO refractory asthmaticus

Question 13

NIV in asthma

Answer 13

Inconclusive Cochran’s review
Not really used
If you do, low threshold

Question 14

Risk factors for near fatal asthma

Answer 14

Previous ICU admission with MV
Oral steroid or theophylline
Increase b2 use
Poor compliance with steroids
Age over 40 years
Altered perception of dyspnoea

Question 15

Define and classify brittle asthma

Answer 15

Type 1 >40%diurnal variation in PEFR for 50% of the time despite tx

Type 2 Sudden severe attack on background of “well controlled@