Guidelines for Management of Severe Asthma
DEFINITION
Near Fatal
Asthma
Raised PaCO2 and/or requiring mechanical
ventilation with raised inflation pressures
Life
Threatening
Asthma
Any one of the following in a patient with
severe asthma:
Acute severe
asthma
Any one of:
•
•
•
•
•
•
•
•
•
•
•
•
•
Moderate
asthma
exacerbation
•
•
•
•
PEF <33% best or predicted
SpO2 <92%
PaO2 <8 kPa
normal PaCO2 (4.6 - 6.0 kPa)
silent chest
cyanosis
feeble respiratory effort
bradycardia
dysrhythmia
hypotension
exhaustion
confusion
coma
PEF 33-50% best or predicted
respiratory rate > 25/min
heart rate > 110/min
inability to complete sentences in one
breath
• Increasing symptoms
• PEF >50-75% best or predicted
• no features of acute severe asthma
ADMISSION CRITERIA
z Immediate ICU admission is warranted in patient with
„ Near fatal asthma
„ Life-threatening asthma
z ICU admission is advisable in patient with severe acute asthma,
especially when not responding to initial therapy.
z If a patient is not admitted to the ICU, always remind the
medical / nursing staff in the general ward to inform the ICU
team for reassessment if patient’s condition worsen.
MANAGEMENT
Pharmacological Treatment
z Beta-2-agonist
„ Inhaled salbutamol 6 to 8 puffs via spacer, can be repeated
as frequently as 5-10 minute intervals.
„ Consider IV infusion of salbutamol in refractory cases.
z Anticholinergics
„ Add ipratropium bromide 4 to six puffs via spacer every 4
hourly to b2 agonist for acute severe or life threatening
asthma or those with a poor initial response to beta 2
agonist therapy.
z Steroid
„ Start hydrocortisone 100mg Q6H IV
„ May change to oral prednisolone (40-50mg daily) if patient
can take it orally
„ Resume / start inhaled steroid as soon as patient is
stabilized.
z Magnesium Sulphate
„ Consider giving a single dose of IV MgSO4 (10mmol over
20mins) in refractory cases regardless of serum Mg level.
z Amiophylline
„ Controversial, narrow therapeutic range with significant
side effects.
„ Use IV aminophylline only after consultation with senior.
z Antibiotics
„ Routine prescription of antibiotics is not indicated.
NIV
„ No clear guidelines or evidence, maybe tried if no
contraindications.
„ Need close monitoring for deterioration
Indications for Intubation
„ Confusion / Coma
„ SpO2 < 92% despite 100% oxygen
„ Increasing respiratory acidosis
„ Bradycardia / dysrhythmia
„ Hypotension
„ Exhaustion
™ Requires an integrative clinical assessment
™ Decision to proceed to intubation should be made before the
patient is in extremis
Ventilatory Strategies
z Aim is to avoid dynamic hyperinflation
z Controlled hypoventilation, maximise expiratory time
z
z
z
z
z
z
Small TV, 6-8ml/kg
Slow respiratory rate, 8-12 breaths/min
Low I:E ratio, e.g. 1:4
Minimise extrinisic PEEP
Permissive hypercapnia
May need heavy sedation +/- muscle paralysis
z Aim intrinsic PEEP <12cmH2O, plateau pressure <25 cmH2O
DISCHARGE CRITERIA
„ PEF >50% best or predicted
„ Diurnal variation < 40%
„ Symptomaticlly improved
Last update : 2006