title: Apparent hyperkalaemia from blood sampled from an arterial cannula.
abstract: Blood samples were obtained from a radial artery cannula in a 60-yr-old man during coronary artery surgery. Serum potassium concentrations of 9.3, 8.4, and 7.4 mmol litre(-1) were obtained. A simultaneous venous blood sample gave a serum potassium concentration of 4.4 mmol litre(-1). The ECG was unchanged. After the arterial cannula was repositioned, subsequent blood samples gave expected ranges of serum potassium concentration. We suggest that the initial arterial cannula position caused a high shear rate in the blood when samples were withdrawn, causing haemolysis and hyperkalaemia.
authors.affiliation: Boyle Department of Anaesthesia, St Bartholomew Hospital, West Smithfield, London EC1A 7BE, UK. vmehta1971@hotmail.com
authors.forename: V
authors.initials: V
authors.lastname: Mehta
authors.forename: Z
authors.initials: Z
authors.lastname: Ahmed
mesh_terms: D001800:Blood Specimen Collection / Q000379:methods*; D005189:False Positive Reactions; D006801:Humans; D006947:Hyperkalemia / Q000175:diagnosis*; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D017534:Radial Artery