Highly conservative phlebotomy in adult intensive care--a prospective randomized controlled trial

Anaemia in critically ill patients is common and phlebotomy associated blood loss may contribute towards this anaemia. The aims of this study were twofold. Firstly, a survey was conducted to provide a summary of current phlebotomy practices within Australian intensive care units. A standardized telephone survey was aimed at Australian intensive care units registered with Australia and New Zealand Intensive Care Society (ANZICS) and questions regarding phlebotomy procedures directed at nursing staff. Secondly, a prospective randomized controlled trial aimed to assess the impact of a highly conservative phlebotomy procedure on haemoglobin concentration in intensive care patients. Patients admitted to our own intensive care unit were randomized using a sealed envelope technique to either a highly conservative phlebotomy group, or standardized controls. Blood was taken according to strict protocols and recorded along with haemoglobin concentration daily. The survey demonstrated that 16% of Australian units return deadspace volumes from in-line arterial sets and no unit routinely used paediatric-sized blood collection tubes. Using our highly conservative protocol, median phlebotomy-associated blood loss was reduced by over 80% (40 ml vs 8 ml P<0.001). Mean haemoglobin fell from 13.7 g/dl to 11.7 g/dl in controls (P=0.002) and from 12.7 g/dl to 11.5 g/dl (P=0.074) in our study group. We conclude that highly conservative phlebotomy is feasible in a critical care unit and is associated with a reduction in blood loss.