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[The effect of postural changes on cerebral hemodynamics during general anesthesia]
1Abteilung für Anaesthesiologie, Universitäts-Krankenhaus Eppendorf, Hamburg.
Der Anaesthesist
|September 1, 1990
Summary
Anesthesia can lower blood flow velocity in the middle cerebral artery (MCA) when patients are moved to a head-elevated position. This finding is crucial for understanding cerebral blood flow (CBF) regulation during anesthesia.
Area of Science:
- Anesthesiology
- Neuroscience
- Medical Imaging
Context:
- Anesthesia can impair the body's ability to regulate blood flow, especially to the brain, when body position changes.
- Sudden changes in position, like moving from horizontal to head-elevated, can decrease cerebral perfusion pressure and cerebral blood flow (CBF), posing risks for patients with cerebrovascular disease.
Purpose:
- To compare the effects of changing from a horizontal to a head-elevated position on middle cerebral artery (MCA) blood flow velocity (BFV) in patients under different levels of steady-state anesthesia.
- To assess the utility of Transcranial Doppler sonography (TCD) in monitoring relative changes in CBF during positional changes under anesthesia.
Summary:
- The study investigated MCA blood flow velocity (BFV) in 30 patients (ASA I) at two anesthesia levels (isoflurane 1.0% vs. 0.4%) during a positional change from horizontal to 35-40 degrees head-elevated.
- In the higher anesthesia group (1.0% isoflurane), significant reductions were observed: systolic BFV decreased by 25% (79 to 59 cm/s) and mean BFV by 33% (52 to 35 cm/s) immediately after repositioning.
Impact:
- Findings indicate that anesthesia depth influences the cerebrovascular response to positional changes.
- Transcranial Doppler sonography (TCD) effectively monitored changes in cerebral hemodynamics, highlighting the potential for BFV monitoring to detect alterations in CBF during anesthesia and surgery.