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Changes in cerebral oxygenation based on intraoperative ventilation strategy
Elisabeth Dewhirst1, Hina Walia1, Walter P Samora2
1Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA, Elisabeth.Dewhirst@nationwidechildrens.org.
Medical Devices (Auckland, N.Z.)
|August 14, 2018
Summary
Cerebral oxygenation (rSO2) monitoring using NIRS shows a slight decline during hypocarbia in adolescents. This decrease is reversible with increased oxygen levels, highlighting ventilation
Area of Science:
- Anesthesiology
- Physiology
- Medical Technology
Background:
- Cerebral oximetry (regional oxygen saturation, rSO2) monitors brain oxygenation using near-infrared spectroscopy (NIRS).
- rSO2 changes can precede pulse oximetry, aiding early detection of clinical deterioration.
- Ventilation parameters, such as CO2 levels, can influence cerebral oxygenation measurements.
Purpose of the Study:
- To evaluate the impact of intraoperative mechanical ventilation changes on cerebral oxygenation (rSO2) in adolescents.
- To assess how transitions between normocarbia and hypocarbia, with varying fractions of inspired oxygen (FiO2), affect rSO2.
- To determine the reversibility of ventilation-induced rSO2 changes.
Main Methods:
- Near-infrared spectroscopy (NIRS) was used to monitor cerebral and tissue oxygenation in 30 adolescents.
- Measurements were taken during four ventilation phases: normocarbia/low FiO2, hypocarbia/low FiO2, hypocarbia/high FiO2, and normocarbia/high FiO2.
- Paired t-tests compared rSO2 values between sequential ventilation phases.
Main Results:
- Cerebral oxygenation (rSO2) decreased significantly from 83% ± 8% during normocarbia to 79% ± 8% during hypocarbia (p < 0.01).
- Increasing FiO2 partially reversed the rSO2 decline during hypocarbia (81% ± 9%).
- rSO2 returned to baseline levels (83% ± 8%) upon returning to normocarbic conditions with high FiO2. Tissue oxygenation remained stable.
Conclusions:
- Hypocarbia during general anesthesia in adolescents leads to a statistically significant, albeit slight, decrease in cerebral oxygenation (rSO2).
- The reduction in rSO2 associated with hypocarbia is readily reversible by increasing supplemental oxygen levels.
- Cerebral oximetry is sensitive to changes in ventilation, specifically CO2 levels.
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