Comparison of peripheral blood saturation with brain oxygenation in patients undergoing thoracic surgery

Near-infrared spectroscopy (NIRS) is a non-invasive method of regional tissue oxygenation measurement. Intraoperative use of NIRS to monitor brain oxygenation (BO) during surgery might be beneficial to identify cerebral desaturations.

To compare peripheral blood saturation (SpO₂) with BO measurements and evaluate the utility of BO in thoracic surgery.

We took BO and SpO₂ measurements in a group of 100 patients undergoing standard thoracic surgery. Measurements were made every 15 minutes. The Mann-Whitney U test was used to compare study groups. Spearman's rank correlation coefficient was used to determine correlation between studied parameters.

We found a negative correlation between patients' age and BO at the beginning of surgery. Operations lasted between 30 and 200 minutes. We found a positive correlation between BO and SpO₂ between 15 and 90 minutes of surgery. Subsequently, BO remained at a low level while SpO₂ returned to baseline values. Higher minimum SpO₂ values were noted in patients undergoing left-sided procedures.

Cerebral oxygenation does not return to baseline values until the end of the surgery as opposed to the SpO₂. Furthermore, both SpO₂ and BO correlate negatively with the overall duration of thoracic surgery. In addition, after 90 minutes of surgery, SpO₂ stopped reflecting brain oxygenation.