Cerebral oxygen saturation, transcranial Doppler ultrasonography and stump pressure in carotid surgery

Abstract

Transcranial Doppler ultrasonography (TCD) of the middle cerebral artery (MCA), light-reflective cerebral oximetry and measurement of internal carotid artery stump pressure were compared as methods of monitoring cerebral perfusion during carotid surgery in 33 patients. Median cerebral oxygen saturation was 70 (range 62-85) per cent and TCD-measured mean blood velocity 42 (range 19-91) cm/s before carotid cross-clamping, falling to 68 (53-83) per cent and 16 (0-50) cm/s respectively on application of the clamps (P < 0.001). Stump pressure correlated closely with MCA blood velocity 30 s after the start of cross-clamping (rs = 0.58, P < 0.001), but not with cerebral oxygen saturation. A fall of 5 per cent or more in cerebral oxygen saturation following cross-clamp application was predicted by a decrease in mean MCA blood velocity of at least 60 per cent. Changes in cerebral oxygen saturation correlated significantly with systolic blood pressure throughout the perioperative period (rs = 0.41, P < 0.001). Significant falls in cerebral oxygenation were not predicted by low stump pressure but were associated with large reductions in the mean MCA blood velocity measured by TCD.

Alterations in cerebral autoregulation and cerebral blood flow velocity during acute hypoxia: rest and exercise

“…Cerebral NIRS has been shown to track changes in jugular venous bulb saturation in healthy volunteers under conditions of hypoxia (27) and has also been validated compared with PET scanning, with 133 Xe washout methods, and with internal carotid artery stump pressures (46). Previous studies have shown that change in NIRS provides a good measure of the proportion of blood that is oxygenated; it does not, however, distinguish how much blood is in the arterial or venous part of the vascular bed (23).…”

Cerebral hypoperfusion during hypoxic exercise following two different hypoxic exposures: independence from changes in dynamic autoregulation and reactivity

“…In the human brain, however, NIRS-determined capillary oxygenation is functionally related to the balance between arterial and internal jugular venous oxygen saturation (34). Cerebral NIRS has been shown to track changes in jugular venous bulb saturation in healthy volunteers under conditions of isocapnic hypoxia (24) and has also been validated compared with positron emission tomography scanning (37), with 133 Xe washout methods (39), and with internal carotid artery stump pressures (47). Moreover, a recent report indicates that de- Fig.…”

Diagnostic Criteria and Yield of Real-Time Transcranial Doppler Monitoring of Intra-Arterial Reperfusion Procedures

“…TCD is a widespread inexpensive tool that can detect intracranial stenoses, occlusions, collaterals, microemboli, hypoperfusion, and hyperperfusion in extracranial carotid revascularization procedures and in acute stroke patients. [7][8][9][10][11][12][13][14] TCD monitoring head frames are radiolucent, with only transducers and knob-locks leaving recognizable small imprints on subtracted angiographic images. These radio-opaque parts can be removed or placed out of plane for standard projections, making application of TCD monitoring feasible during IA reperfusion procedures.…”

“…ТКДГ является широко распространенным недорогим методом, позволяющим обнаруживать стенозы, окклюзии, наличие коллате-ралей, регистрировать микроэмболы во внутричереп-ных артериях, определять зоны гипо-и гиперперфузии при проведении экстракраниальной реваскуляризации сонных артерий и у пациентов с острым инсультом [7][8][9][10][11][12][13][14]. Головные устройства для проведения ТКДГ-мониторинга пропускают рентгеновское излучение, только передатчики и ручки-замки оставляют неболь-шой узнаваемый след на изображениях субтракци-онной ангиографии.…”