Variation in phlebotomy techniques in emergency medicine and the incidence of haemolysed samples.

BACKGROUND: Phlebotomy is a potential cause of preanalytical errors. We have observed phlebotomy in routine practice in a busy Emergency Department, to see how current practice compares with optimal blood sampling. METHODS: Phlebotomy episodes were audited and compared with standard procedures. A computer-based search of the number of haemolysed samples from Emergency Medicine and hospital inpatients was reviewed. RESULTS: Four different ways of taking blood were observed: cannulation and a syringe (38%), cannula with evacuated tube and adaptor (42%), syringe and needle into vein (14%) and evacuated tube system used conventionally (6%). Where a syringe was used, two methods of transfer into the sample tube were observed; needle kept on with cap piercing (77%) and needle and evacuated cap both removed (23%). On 20 out of 50 phlebotomy episodes (40%), the potassium-EDTA tube was filled prior to the biochemistry serum gel tube. A search of the laboratory computer records for ward-based phlebotomy found 30 of 1034 samples were haemolysed (2.9%). In the 50 phlebotomy episodes in the Majors area of the Emergency Department, 24% produced a haemolysed sample (P < 0.0001). For samples taken from all areas of Emergency Medicine over a seven-day period, 52 of 485 were haemolysed (10.7%; P < 0.0001). CONCLUSIONS: This study has shown that phlebotomy techniques in the Emergency Department deviate from standard practice significantly. This may well be a reason for the much higher frequency of haemolysed samples and with the wrong order of collection the possibility of potassium-EDTA-contaminated samples.

The management of hyperkalaemia in the emergency department.

Life threatening hyperkalaemia (> 7.0 mmol/l) is commonly associated with acute renal failure. Moderate hyperkalaemia (6.1-6.9 mmol/l) is also common and well tolerated in patients with chronic renal failure. Renal failure is the most common cause of hyperkalaemia although other causes to consider include drugs (potassium sparing diuretics, angiotensin converting enzyme inhibitors), hyperglycaemia, rhabdomyolysis and adrenal insufficiency. Hyperkalaemia affects the cardiac conducting tissue and can cause serious arrhythmias including ventricular fibrillation and asystolic arrest. Therefore it is important to treat hyperkalaemia promptly in the emergency department. This paper evaluates the therapeutic options available for treatment of hyperkalaemia.