Cerebral oxygenation monitoring using near infrared spectroscopy during controlled hypotension

Controlled hypotension (CH) is used to limit intraoperative blood loss and decrease the need for homologous transfusions. Despite the efficacy of the technique, hypotension has the potential to affect cerebral perfusion and oxygen delivery. There are no data providing a direct measurement of cerebral oxygenation during this technique.

The current study prospectively evaluated cerebral oxygenation during CH using near infrared spectroscopy. Nineteen patients ranging in age from 6 to 18 years were enrolled in the study. CH was provided using a combination of intravenous opioids and sevoflurane supplemented with labetolol as necessary.

There were a total of 268 readings obtained from the cerebral oximeter. The baseline cerebral oximeter reading was 81+/-8% on the right and 82+/-7% on the left. During CH (mean arterial pressure of 65-69, 60-64, 55-59, and <54 mmHg), the right cerebral oximeter values were 80+/-9, 78+/-8, 78+/-10, and 84+/-9%, respectively while the left cerebral oximeter values were 79+/-7, 80+/-7, 78+/-8, and 78+/-8%, respectively. Of the 268 readings, there were 11 points (4%) at which either the left or right cerebral oximeter was 10-19 less than the baseline value and no points at which the reading was 20 or more from the baseline value.

Our preliminary data with a measurement of cerebral oxygenation demonstrates the safety of CH within the accepted mean blood pressure recommendations of 55-65 mmHg.