Changes in plasma calcium during septic shock.

Previous studies have documented a decrease in plasma calcium occurring early after trauma, haemorrhage and cardiac arrest. Therefore, changes in plasma calcium in an ovine experimental model of septic shock due to intraperitoneal sepsis were investigated. Subjects were volume-loaded with Ringer's lactate solution. Plasma calcium and albumin were measured before and 24 h after surgical induction of sepsis. Subjects were divided into two groups according to the severity of shock. Group 1 (n = 8) developed severe hyperdynamic sepsis with renal failure. Group 2 (n = 8) showed no change in blood pressure, cardiac output or renal function. Plasma calcium fell significantly in both groups, and was lower in Group 1 during sepsis (Group 1: 2.36 +/- 0.19 to 1.84 +/- 0.14 mmol l-1; Group 2: 2.34 +/- 0.12 to 2.01 +/- 0.13 mmol l-1; mean +/- SD; both P < 0.001). Plasma albumin fell during sepsis, and the reduction was greater in Group 1. The plasma calcium, corrected for albumin, was still significantly reduced and was similar in each group during sepsis (Group 1: 2.55 +/- 0.13 to 2.23 +/- 0.12 mmol l-1; Group 2: 2.50 +/- 0.08 to 2.27 +/- 0.09 mmol l-1; both P < 0.001). In this large animal model of septic shock, which reproduces the important features of clinical sepsis, there were significant decrements in uncorrected and corrected plasma calcium 24 h after the surgical induction of intraperitoneal sepsis. These changes may contribute to the pathophysiology of this condition.