Proposed Formulae for Determining Blood Transfusion Requirements in Children with Severe Anaemia

Abstract

Background: Blood replacement remains a crucial component of the treatment of severe anaemia irrespective of the cause. The transfusion of an adequate amount of blood is important to prevent under- or over-transfusion. Existing formulae used for the calculation of blood transfusion requirements, while being useful, still have deficiencies. The current study aims to evolve simple formulae that can be used in calculating the volume of packed red blood cells (PRBC) required for attaining a specific packed cell volume (PCV) level.

Method: A total of 172 patients with severe anaemia [PCV of <20] were recruited for the study. They all received 15 ml/kg of PRBCs irrespective of their pre-transfusion PCV. Post-transfusion PCV was determined at least, six hours after the completion of blood transfusion. The three simple formulae were subsequently derived by using the blood volume transfused, the mean weight of the patients and their mean pre- and post-transfusion PCVs.

Result: The three formulae obtained in determining the volume of PRBC required in transfusions were as follows: (a) 1ml/kg of packed cells would increase PCV by 0.9 percent, (b) 1.1 ml/kg of packed cells would increase PCV by one percent, and (c) (target PCV x weight x k (0.55) / pre-transfusion PCV).

Conclusion: The three formulae should aid the calculation of required volume of PRBCs transfusion in severe anaemia aiming at a target PCV. The maximum target PCV should however, not exceed 30 percent and the PCV differential should not exceed 13.3 when using these formulae.

Key words: Formulae; Blood transfusion; Severe anaemia.

Nigerian Journal of Paediatrics Vol.31(1) 2004: 25-28