Cerebral oxygenation monitoring using near infrared spectroscopy during one-lung ventilation in adults

Background :Changes in oxygenation occur during one-lung ventilation (OLV) due to intrapulmonary shunt. Although arterial oxygenation is generally adequate, there are no studies evaluating the effect of these changes on cerebral oxygenation.
Materials and Methods :Cerebral oxygenation (rSO₂ ), heart rate (HR), blood pressure (BP), oxygen saturation (SaO₂ ), and end-tidal carbon dioxide (ETCO₂ ) were prospectively monitored during OLV in adults. Cerebral oxygenation was monitored using near infrared spectroscopy. No clinical decisions were made based on the rSO2 value. BP and HR were the inspired oxygen concentration was adjusted as needed to maintain the SaO₂ ≥ 95%.
Results :The study cohort included 40 adult patients. 18,562 rSO₂ values were collected during OLV. The rSO₂ was ≥ baseline at 3,593 of the 18,562 data points (19%). The rSO2 was 0-9 ≤ baseline in 7,053 (38%) of the readings, 10-19 ≤ baseline in 4,084 (22%) of the readings, and 20-29 ≤ baseline in 3,898 (21%) of the readings. 2,599 (14%) of the rSO₂ values were less than 75% of the baseline value. Thirteen patients (32.5%) had at least one rSO2 value that was less than 75% of the baseline. Eight patients (20%) had rSO₂ values less than 75% of baseline for ≥ 25% of the duration of OLV. These patients were older (63.7 ± 10.2 vs 54.6 ± 9.8 years, P < 0.025), weighed more (95.8 ± 17.4 vs 82.6 ± 14.6 kgs, P =0.038), and were more likely to be ASA III vs II (7 of 8 versus 25 of 32, relative risk 1.75) than the remainder of the cohort.
Conclusions :Significant changes in rSO2 occur during OLV for thoracic surgical procedures. Future studies are needed to determine the impact of such changes on the postoperative course of these patients.

Keywords
Cerebral oxygenation, near infrared spectroscopy, one-lung ventilation, thoracic surgery, thoracoscopy