Iatrogenic anaemia? A survey of venesection in patients in the intensive therapy unit.

In 30 consecutive patients admitted to the Intensive Therapy Unit, the volume of blood taken for investigations was recorded. Results were available for 26 patients. Total venesection volume averaged 336 ml. Venesection volume averaged 55.7 ml/day after the first 24 hours. The mean haemoglobin on admission was 11.5 g/d litre. Blood loss was related to both APACHE score and length of stay (APACHE.day), to the presence of arterial and central venous catheters, and to the need for mechanical ventilation. Iatrogenic blood loss of this magnitude will cause anaemia if it continues.