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Continuous central venous oxygenation measurement by CeVOX in patients undergoing off-pump coronary artery bypass grafting

Introduction

Less invasive measurement of central venous O2 saturation(ScvO2) has shown to be a valuable alternative to the determination of mixed venous O2 saturation for monitoring of O2 supply/demand [1, 2]. The aim of this study was to compare ScvO2 measured continuously by the new CeVOX (Pulsion Medical System, Munich, Germany) device (CScvO2) with ScvO2 determined by blood gas co-oximetry (BScvO2).

Methods

Ten ASA III patients undergoing elective off-pump coronary artery bypass grafting were studied during the operation (OP) and during their ICU stay. In addition to the standard hemodynamic monitoring according to institutional policy, a CeVOX fiber-optic probe was introduced into a standard central venous catheter placed via internal jugular vein access. OP and ICU measurement started after in-vivo calibration of CeVOX. BScvO2 and CScvO2 readings were recorded at intervals of 30 min during OP and of 120 min during ICU. Data were statistically analyzed using Bland-Altman analysis, Pearson correlation and t test for the periods during OP, ICU, a set of three consecutive measurements during OP immediately after calibration (OPcal) and 4 hours later (OP4h) as well as immediately after calibration on the ICU (ICUcal) and 14 hours later (ICU14h). Trend analysis was performed, calculating differences (Δ) between consecutive measurements. P < 0.05 was considered significant.

Results

One hundred and twenty-nine matched sets of data were obtained (OP:n = 78, ICU: n = 51) with a wide range of ScvO2 values (BScvO2 = 48.0–91.0%, CScvO2 = 49.0–94.0%). The OP observation time was 4.0–6.5 hours and the ICU measurement sequence was 14.0–20.0 hours. Bland-Altman analysis revealed an overall mean bias ± 2SD (limits of agreement) of-0.7 ± 7.8% for CScvO2 – BScvO2 during OP and -1.1± 11.6% during ICU (Fig. 1). There was no significant difference between CScvO2 and BScvO2 (OP: P = 0.120, ICU: P = 0.167). The correlation coefficient(r2) for CScvO2 vs BScvO2 was 0.885 (OP) and0.592 (ICU). Statistics for OPcal' OP4hand ICUcal were comparable, whereas for ICU14hthe bias ± 2SD increased and r2 decreased (Table 1). Trend analysis showed no significant difference (OP: ΔBScvO2 = -1.3 ± 9.0%, ΔCScvO2 = -1.1 ± 8.6%, P = 0.663; ICU: ΔBScvO2 = -0.4 ± 6.8%, ΔBScvO2 = -0.4 ± 5.8%, P = 0.828).

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Figure 1

Table 1 Table 1

Conclusion

These preliminary results indicate that ScvO2 can be reliably assessed by CeVOX. Scheduled recalibration at intervals <14 hours may be mandatory.

References

  1. 1.

    Respiration. 2001, 685: 279-285. 10.1159/000050511

  2. 2.

    Acta Anaesthesiol Scand. 1998, 42: 172-177.

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Hofer, C., Ganter, M., Fodor, P. et al. Continuous central venous oxygenation measurement by CeVOX in patients undergoing off-pump coronary artery bypass grafting. Crit Care 10, P340 (2006). https://doi.org/10.1186/cc4687

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Keywords

  • Central Venous Catheter
  • Trend Analysis
  • Internal Jugular Vein
  • Consecutive Measurement
  • Hemodynamic Monitoring