The effects of intraoperative hypothermia and cardiopulmonary bypass on trace metals and their protein binding ratios

Abstract

The ability of intraoperative hypothermia to modify the metabolic response to cardiopulmonary bypass (CPB) was assessed by serial alterations in iron, zinc and copper, and in their molar binding ratios to their respective transport proteins, in 20 male patients under-going elective coronary artery surgery and randomised to an operative blood temperature of 28 degrees C or 20 degrees C. Decreases in serum iron and zinc concentrations, typical of the acute phase response, were preceded by early rises. Significant alterations in the metal: protein molar binding ratios preceded significant changes in the serum concentrations of the metals and occurred earliest in the zinc: albumin binding ratio, which was apparent by the time of skin incision. An intraoperative temperature of 20 degrees C modified iron and zinc concentrations and their protein binding ratios during surgery but not in the post-operative period. These early changes in trace metals and their protein binding ratios are a simple and inexpensive method of quantitating the response to surgical injury and may be useful in assessing new interventions in cardiopulmonary bypass. An awareness of the trace element response to surgical injury is essential to avoid misdiagnoses of iron deficiency anaemia or zinc deficiency.