Brain tissue oxygen pressure monitoring in awake patients during functional neurosurgery: the assessment of normal values.

Local brain tissue oxygen (ptiO2) monitoring is frequently applied in patients at risk for cerebral ischemia. To identify ischemic thresholds, the normal range of local brain tissue oxygen pressure (ptiO2) values needs to be established. Ideally, such normal values are determined in healthy and awake subjects, so as to eliminate the possible influences of anesthetics on cerebral physiology or ptiO2.

Abnormal responses of the human cerebral microcirculation to papaverin during aneurysm surgery.

Background And Purpose: The role of the cerebral microcirculation in delayed ischemia after subarachnoid hemorrhage remains obscure. To test the hypothesis that cerebral arterioles have a reduced capacity to dilate after subarachnoid hemorrhage, we studied the microvascular responses to papaverine (PPV) in patients undergoing aneurysm surgery. Method- In 14 patients undergoing aneurysm surgery, the diameter changes of cortical microvessels after topical application of PPV were observed using orthogonal polarizing spectral imaging.

Continuous real-time visualization of the human cerebral microcirculation during arteriovenous malformation surgery using orthogonal polarization spectral imaging.

Objective: After excision of an arteriovenous malformation (AVM), intracerebral hemorrhage or edema can develop, most probably resulting from hyperperfusion. Changes in the perinidal cerebral microvessels probably play a role in the development of this complication but have not been well studied so far. In this study, microvascular changes associated with resection of an AVM were observed and quantified intraoperatively using orthogonal polarization spectral imaging.

Direct observation of the human cerebral microcirculation during aneurysm surgery reveals increased arteriolar contractility.

Background And Purpose: The effects of aneurysmal subarachnoid hemorrhage on morphology and function of the cerebral microcirculation are poorly defined, partly due to the lack of suitable techniques to visualize the microvessels in vivo. We used orthogonal polarization spectral (OPS) imaging on the brain cortex during aneurysm surgery to directly observe the small cortical blood vessels and quantify their responses to hypocapnia.

Methods: In 16 patients undergoing aneurysm surgery, the diameter changes of small cortical vessels (15 to 180 microm) were observed using OPS imaging.

Intraoperative monitoring of brain tissue oxygen and carbon dioxide pressures reveals low oxygenation in peritumoral brain edema.

Brain edema and swelling often complicate surgery for brain tumors. Its pathophysiology is unclear, as is the relationship with brain tissue oxygenation. Our hypothesis was that brain edema around tumor is cytotoxic type caused by impaired local tissue oxygenation due to increased local tissue pressure.