Do peripheral blood counts have any prognostic value following trauma?

Abstract

Background: both lymphocytosis and lymphopenia have been observed following trauma and each has been claimed to predict mortality. An understanding of the early temporal changes in leucocyte counts may help to explain why such discrepancies have been found. The purpose of this study was to determine the early serial changes in peripheral leucocyte counts following injury. Methods: a whole blood cell counter was used to measure serial total leucocyte, granulocyte, lymphocyte and monocyte counts from 20 patients in the first 3 h following blunt injury. Four to six peripheral blood samples were taken from each subject and grouped into 20 min intervals. Results: granulocytosis, lymphocytosis and monocytosis were evident within 40 min of injury. A biphasic granulocyte and monocyte response was observed in the first 3 h following trauma. Lymphocytes showed a linear resolution towards normal (regression coefficient −0.022; p<0.01) with some individuals developing a lymphopenia. No correlation with injury severity was observed. Conclusion: rapid mobilisation and subsequent redistribution of leucocytes occurs early following injury. Temporal changes will affect any predictive value of circulating leucocytes and studies must be precise with respect to blood sampling time.