Acute Careniche
A 24-year-old woman is admitted with an exacerbation of asthma. After an hour of nebulised salbutamol and ipratropium and oral prednisolone she is speaking in full sentences, her respiratory rate is 22 breaths per minute and her oxygen saturation is 96% on room air. A venous gas taken when the cannula was inserted shows pH 7.44, pCO2 32 mmHg, bicarbonate 22 mmol/L and lactate 2.9 mmol/L. Your registrar asks you to make sure she is not retaining carbon dioxide. Which one of the following should you do to settle that question?