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

Introduction: 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.

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

Material and methods: 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.

Results: 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.

Conclusions: 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.