Blood volume measurements using an integrated fiberoptic monitoring system in a porcine septic shock model.

Abstract

To compare the accuracy of an integrated fiberoptic monitoring system using transpulmonary thermo-dye dilution technique to measure blood volume (BV) with standard method using chromium-51-tagged erythrocytes in septic shock. Prospective blinded animal laboratory study. University department of anesthesiology. Thirty-five anesthetized and mechanically ventilated pigs (21.4 +/- 2.2 kg) were investigated over a period of 6 hrs. Septic shock was induced with fecal peritonitis (0.75 g . kg per body weight autologous feces). A central venous catheter was used for injection of the indicator dyes. BV was measured by detecting indocyanine green using a 4-Fr aortic catheter with an integrated fiberoptic and thermistor connected to a computer system for calculation of transpulmonary indicator dilution BV (BVTPID). Cr-tagged erythrocytes were used as standard method of BV measurement (BV-Cr). Hemodynamic treatment scheme was aimed at maintenance of a central venous pressure of 12 mm Hg. Data were analyzed using Bland-Altman analyses. One hundred and five data pairs of simultaneous BV measurements were yielded during hemodynamic stability with a mean BVTPID of 64.2 +/- 17.8 mL . kg. Mean BV-Cr was 83.1 +/- 17.0 mL . kg. Linear regression equation was BVTPID = 0.58 x BV-Cr + 15.8 (r = .56, p < .01). Mean bias was 18.9 mL . kg (95% confidence interval, 15.7-22.1 mL . kg), with limits of agreement of -13.9 to 51.7 mL . kg. Transpulmonary indicator dilution for blood volume measurement agrees moderately with standard method using Cr-tagged erythrocytes in porcine septic shock.