Case (58)

[Dr.A.al-sheeq]

A 50ys old femal with chronic asthma is admitted with nausea -vomiting and shortness of breath .she had been treated with erythromycin by her GP for chest hnfection as she was allergic to penicilllin . Her usual medication is a long acting beta-2 agonist  an inhaled steroid and theophyllin
On examination she is shaking and anxious but able to complete full sentences . she has a respiration rate of 28|min pulse of 120|min  blood pressure 140|70 mmhg and temperture of 36c ....O2 saturation 97% on air . Examination of her chest reveals equal air entry with little evaidence of wheez . Her peak flow is 400 (best 450)
blood gas (on air)
pH 7.36
PO2 11.4 kpa
PCO2  4.3 kpa
HCO3   25 mmol|l
  

what is likely cause of her symptoms ?
what is the most important test ?

[Aduka]

1. Cause of symptoms is theophylline toxicity secondary to erythromycin course as erythromycin is an enzyme inhibitor.
2. Test serum theophylline levels.