Pseudohypoxaemia In

She was diagnosed as having bronchitis and was given intravenous cefuroxime and gentaAbstract micin with improvement. However, on the Patients with acute leukaemia may have second day she complained of an irritating dry spuriously low arterial oxygen tensions cough and dyspnoea. Physical examination of (PaO2). The markedly increased numbers the respiratory and cardiovascular systems reof white blood cells in these patients rapmained unchanged and she was not cyanosed. idly consume dissolved plasma oxygen reThe chest radiograph remained normal. An sulting in dramatically decreased PaO2 and arterial blood gas sample gave tensions of P2 calculated oxygen saturations. The case 4.4 kPa, pH 7.44. P2 7.0 kPa, HCO3 23.5 history is reported of a patient with a white with calculated oxygen saturation of 78.7%. blood count of 191 000/mm in whom mulBecause the arterial blood gas tension showed tiple arterial blood gas measurements severe hypoxaemia and the patient was dysdocumented hypoxaemia out of propnoeic, she was intubated and placed on a portion to the clinical picture. Pulse mechanical ventilator. Pseudohypoxaemia was oximetry was used to confirm higher suspected. She was weaned off the respirator haemoglobin oxygen saturations and to and extubated on the same day. Repeat arterial establish the spuriously low plasma oxygen blood gas analysis while she was breathing tensions in this patient. oxygen via a mask at 10 l/min revealed P2 6.3 (Thorax 1997;52:394–395) kPa, pH 7.35, P2 4.3 kPa, HCO3 19.7 with calculated oxygen saturation 79.8%. The