Dose-dependent characteristics of intravenous calcium therapy for hypocalcemic critically ill trauma patients receiving specialized nutritional support.

OBJECTIVE

The purpose of this investigation was to evaluate the dose-dependent characteristics of intravenous calcium gluconate therapy for hypocalcemic critically ill patients.

METHODS

The dose-dependent characteristics of 2 g versus 4 g of intravenous calcium gluconate therapy were evaluated in 25 critically ill, adult multiple trauma patients with hypocalcemia. The calcium gluconate was infused at a rate of 1 g/h for both groups. Patients weighed within 90% to 120% of ideal body weight, had normal renal function, did not receive diuretic therapy, and did not have anasarca.

RESULTS

Fifteen patients with mild hypocalcemia (serum ionized calcium concentration [iCa] 1-1.12 mmol/L) were given 2 g of calcium gluconate. Ten patients with moderate to severe hypocalcemia (iCa <1 mmol/L) were given 4 g. Each dosage group had a significant (P < or = 0.001) increase in iCa (from 1.07 +/- 0.05 to 1.17 +/- 0.05 mmol/L and from 0.92 +/- 0.08 to 1.16 +/- 0.11 mmol/L, respectively). Each dosage group retained about half of the dose in the exchangeable calcium space (P = NS between groups), but the higher dosage group retained significantly more elemental calcium overall (81 +/- 38 versus 201 +/- 50 mg, respectively, P < or = 001). Serum ionized calcium concentrations achieved a plateau without a further decline in iCa by 10 h after completion of the infusion for each dosage.

CONCLUSION

About half of the administered elemental calcium dose was retained for each dosage group, with the higher dose (4 g) resulting in significantly more elemental calcium retention in the exchangeable calcium space. An iCa determination performed about > or =10 h after the completion of the calcium gluconate infusion should be sufficient time to ensure equilibration of iCa to assess the efficacy of the therapy. This mode of calcium therapy serves as an effective means for providing calcium to the acutely hypocalcemic, critically ill, multiple trauma patient.