Calibration of pulse contour continuous cardiac output analysis

Introduction

We evaluated the effect of the calibration interval on the reliability of pulse contour cardiac output (COpc) measurement [1].

Methods

Eleven patients were investigated for over 10 hours using two COpc monitors simultaneously. One COpc (COpcCAL) monitor was calibrated hourly, while the other (COpcNOCAL) was calibrated once initially without any further calibration. COpcCAL was compared with COpcNOCAL.

Results

A total of 116 pairs of cardiac output measurement was obtained. After 3 hours, the correlation between COpcCAL and COpcNOCAL was r² = 0.85, P < 0.0001, bias ± SD was -0.43 ± 0.87 ml/minute; after 6 hours, r² = 0.68, P = 0.0064, bias ± SD was -0.83 ± 1.39 ml/minute; after 10 hours, r² = 0.70, P = 0.0026, bias ± SD was -0.81 ± 1.21 ml/minute. See Figures 1 and 2.

Figure 1

Line regression between COpcCAL and COpcNOCAL.

Figure 2

Bland–Altman plot of COpcCAL and COpcNOCAL. Solid line, bias; dashed lines, ± 2 SD.

Conclusion

The calibration interval has no effect on the reliability of the COpc measurement.