Changes in transcranial near-infrared spectroscopy values reflect changes in cardiac index during cardiac surgery.

To determine whether changes in transcranial near-infrared spectroscopy (NIRS) values reflect changes in cardiac index (CI) in adult cardiac surgical patients. Single-center prospective post hoc analysis. University hospital. One hundred and twenty-four adult patients undergoing cardiac surgery. In each patient, several CI measurements were taken, and NIRS values were collected simultaneously. We used a hierarchical linear regression model to assess the association between NIRS values and CI. We calculated a crude model with NIRS as the only factor included, and an adjusted model, where mean arterial pressure, end-tidal CO2 , and oxygen saturation were used as confounding factors. A total of 1301 pairs of NIRS and CI values were collected. The analysis of separate NIRS and CI pairs revealed a poor association, which was not statistically significant when adjusted with the chosen confounders. However, when the changes in NIRS from baseline or from the previous measurement were compared to those of CI, a clinically and statistically significant association between NIRS and CI was observed also in the adjusted model. Compared to the baseline and to the previous measurement, respectively, the regression coefficients with 95% confidence intervals were 0.048 (0.041-0.056) and 0.064 (0.055-0.073) in off-pump coronary artery bypass patients and 0.022 (0.016-0.029) and 0.026 (0.020-0.033) in patients who underwent cardiopulmonary bypass. In an unselected cardiac surgical population, the changes in NIRS values reflect those in CI, especially in off-pump coronary artery bypass patients. In this single-center post hoc analysis of data from a prospectively collected database of cardiac surgery patients, paired measurements of cardiac output and NIRS revealed that while there was a no correlation between individual paired measurements, a small correlation was found in changes in the two measurements from baseline values. This highlights a potential to utilize changes in NIRS from baseline to suggest changes in cardiac output in cardiac surgical populations.

Accuracy, Precision, and Trending Ability of Perioperative Central Venous Oxygen Saturation Compared to Mixed Venous Oxygen Saturation in Unselected Cardiac Surgical Patients.

OBJECTIVE: To determine whether central venous oxygen saturation (ScvO2) measurements could be used interchangeably with mixed venous oxygen saturation (SvO2) measurements in adult cardiac surgery patients. DESIGN: A single-center prospective observational study. SETTING: A university hospital. PARTICIPANTS: Eighty-five adult patients undergoing cardiac surgery. INTERVENTIONS: The study authors compared the oxygen saturations in 590 pairs of venous blood samples drawn from the pulmonary artery catheter (PAC) at three different time points during surgery and four different time points in the intensive care unit. They compared samples obtained from the distal pulmonary artery line (SvO2) to those drawn from the proximal central venous line of the PAC (ScvO2) with the Bland-Altman test and the four-quadrant method. MEASUREMENTS AND MAIN RESULTS: The mean bias between SvO2 and ScvO2 was -1.9 (95% confidence interval [CI], -2.3 to -1.5) and the limits of agreement (LOA) were -11.5 to 7.6 (95% CI, -12.5 to -10.7 and 6.8-8.5, respectively). The percentage error (PE) was 13.2%. Based on the four-quadrant plot, only 50% of the measurement pairs were in agreement, indicating deficient trending ability. CONCLUSION: ScvO2 values showed acceptable accuracy as the mean bias was low. The precision was inadequate; although the PE was acceptable, the LOA were wide. Trending ability was inadequate. The authors cannot recommend the use of ScvO2 values interchangeably with SvO2 measurements in the management of adult cardiac surgery patients.