Jugular Bulb Desaturations During Propofol Anesthesia in Neurosurgical Procedures

We read with interest the article by Jansen et al. (¹) concluding that, during propofol anesthesia administration with normoventilation, 50% of patients with brain tumor showed signs suggestive of cerebral hypoperfusion. However, under a propofol/opioid anesthesia for cerebral aneurysm clipping, we seldomly observe jugular desaturations (i.e., jugular saturation [SjO₂] less than 50%) that cannot be attributed to a PaCO₂ less than 32 mm Hg or to a mean arterial pressure less than 90 mm Hg. Especially the role of PaCO₂ on jugular desaturations should be better analyzed. We noticed from their data that PaCO₂ was lower (although not significantly) in the propofol compared with the isoflurane-group and was more just around 32 mm Hg, which might already reach the critical level of cerebral hypoperfusion for some patients. Therefore, we think that the conclusion should include a warning for the use of even moderate hyperventilation during propofol/opioid anesthesia in neurosurgical patients.

A second remark concerns the respective depth of anesthesia in both groups. As the dose-dependent change of global cerebral metabolism induced by both anesthetics is essential for the correct interpretation of SjO₂ data, it is crucial to know whether depth of anesthesia was equal in both groups. Currently available Bispectral Index electroencephalogram monitoring offers the best method to evaluate depth of anesthesia, and therefore we think that all current (and future) studies comparing the effects of different anesthetics on SjO₂ should include BIS monitoring.

Cathy De Deyne MD, PhD

Raf De Jongh MD

René Heylen MD, PhD

Michel Struys MD, PhD