A young obese woman with asthma prsents with tachypnoea, tachycardia and a low grade temperature (on antibiotics)
1.
Acute compensated respiratory alkalosis
Additional high anion gap (35.5)
mild hypokalaemia
elevated lactate
2.
Hyperventilation causing respiratory alkolosis and hpokalaemia (shift), indicates some respiratory reserve
Lactic acidosis due to salbutamol, dehydration, sepsis
3. Poor prognostic factors:
older age
chronic severe asthma
high values for inflammatory laboratory markers – ESR/CRP
asthma exacerbated by pneumonia – radiologically proven
relatively low nutritional status – low albumin
Features of severe asthma:
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:
PEF <33% best or predicted
SpO2 < 92%
PaO2 < 60 mmHg
Normal PaCO2 35-45 mmHg
Silent chest
Cyanosis
Feeble respiratory effort
Bradycardia
Dysrrhythmia
hypotension
exhaustion
confusion
coma
Acute severe asthma
Any one of:
PEF 33–50% best or predicted
RR > 25/min
HR > 110/min
Inability to complete sentences in 1 breath
4. Disposition Factors
Medical
Social