Acute Severe Asthma

Question 1

In a patient you suspect to have acute severe asthma, what are the key points in the history?

Answer 1

Precipitant: infection, travel or exercise?
Usual and recent Rx?
Previous attacks and severity: ICU admissions?
Best PEFR

Question 2

In pt with acute severe asthma, what are the key investigations?

Answer 2

PEFR
ABG - PaO2 normal or slightly low
PaCO2 low = normal
If PaCO2 elevated, send to ITU for ventilation
Bloods: FBC, U&E, CRP, blood cultures
CXR to rule out pneumothorax/pulmonary oedema

Question 3

What are the features of severe asthma?

Answer 3

PEFR <50%
RR >25
HR >110
Can’t complete sentences in one breath

Question 4

What are the features of life threatening asthma

Answer 4

PEFR <33%
SpO2 <92%, PaCO2 >4.6kPa, PaO2 <8kPa 
Cyanosis
Hypotension
Exhaustion, confusion
Silent chest, poor respiratory effort
Tachy/brady/arrhythmias

Question 5

What are the differentials of acute severe asthma

Answer 5

Acute exacerbation of COPD
Pneumothorax
Pulmonary oedema

Question 6

What are the admission criteria?

Answer 6

Life threatening attack

Features of severe attack persisting despite initial Rx

Question 7

When could you discharge if admission was not necessary?

Answer 7

May discharge if PEFR >75% 1h after initial Rx

Question 8

Discharge when

Answer 8

Been stable on discharge meds for 24h

PEFR is >75% with diurnal variability <25%

Question 9

Discharge plan

Answer 9

TAME pt 
Checked inhaler technique
PO steroids for 5d
GP appointment within 1 week
Respiratory outpt clinic appointment within 1 month

Question 10

Management of acute severe asthma - O2, nebs and steroids

Answer 10

Sit up
100% O2 via non-rebreathe mask, aim for sats 94-98%
Nebulised salbutamol 5mg (every 15min or 10mg continuously/ hour) & ipratropium 0.5mg 4-6hrly
Hydrocortisone 100mg IV or prednisolone 40-50mg PO or both
Write “no sedation” on drug chart

Question 11

Mx of life threatening asthma

Answer 11

Inform ITU
MgSO4 2g IVI over 20mins
Nebulised salbutamol every 15mins

Question 12

If improving:

Answer 12

Monitor SpO2 - aim 92-94%, PEFR
Continue pred 40-50mg for 5 days OD
Nebulised salbutamol every 4 hours

Question 13

IV Rx if no improvement within 15-30min

Answer 13

Neb salbutamol every 15 min (monitor ECG)
Continue ipratropium 0.5mg 4-6hrly
MgSO4 2 IVI over 20min
Salbutamol IVI 3-20ug/min
Consider aminophylline - load 5mg/kg IVI over 20 min unless already on theophylline
Continue 0.5mg/kg/hr
Monitor levels 
ITU transfer for invasive ventilation

Question 14

Monitoring of acute severe asthma

Answer 14

PEFR every 15-30 min
- pre and post beta-agonist
SpO2: keep >92%
ABG if initial PaCO2 normal or higher