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Angiotensin converting enzyme inhibition, CBF autoregulation, and ICP in patients with normal-pressure hydrocephalus
J F Schmidt1, A R Andersen, O B Paulson
1University Clinic of Neurosurgery, Rigshospitalet, Copenhagen, Denmark.
Insights
Normal pressure hydrocephalus patients showed intact cerebral blood flow (CBF) autoregulation. Captopril lowered blood pressure but maintained autoregulation, suggesting benefits in hypotensive anesthesia for CBF.
Area of Science:
- Neurosurgery
- Neurology
- Pharmacology
Background:
- Normal pressure hydrocephalus (NPH) affects cerebral blood flow (CBF) and intracranial pressure (ICP).
- Understanding CBF autoregulation is crucial for managing NPH patients, especially during anesthesia.
Purpose of the Study:
- To investigate cerebral blood flow (CBF) autoregulation in patients with normal pressure hydrocephalus (NPH).
- To assess the effects of Captopril on CBF, intracranial pressure (ICP), and CBF autoregulation in NPH patients.
Main Methods:
- CBF autoregulation and ICP were monitored in 14 NPH patients.
- Mean arterial blood pressure (MABP) and ICP were measured.
- Global CBF changes were estimated using the arterio-venous oxygen difference method.
- The effect of oral Captopril (50 mg) on CBF, ICP, and autoregulation was studied in 8 patients.
Main Results:
- CBF autoregulation was present in 13 out of 14 NPH patients (p < 0.01).
- The lower limit of autoregulation was 86% of baseline perfusion pressure.
- Captopril administration reduced MABP by 16 mmHg but did not alter ICP or CBF.
- Autoregulation was preserved post-Captopril, with the lower limit decreasing by 19 mmHg.
Conclusions:
- NPH patients generally exhibit preserved CBF autoregulation.
- Captopril effectively reduces MABP without compromising ICP, CBF, or autoregulation.
- Captopril may be beneficial for NPH patients undergoing hypotensive anesthesia due to maintained autoregulation.
Abstract:
Fourteen patients with normal pressure hydrocephalus had the autoregulation of cerebral blood flow (CBF) and intracranial pressure (ICP) investigated. In 8 of the patients the effect of Captopril on ICP and CBF was also investigated. The mean arterial blood pressure (MABP) was 109 mmHg (intra-arterially), and ICP was 11 mmHg (intraventricularly). Changes in global CBF were estimated by the arterio-venous oxygen difference method. The autoregulation of CBF was present in 13 of the patients (p less than 0.01). The lower limit of CBF autoregulation was 86% of the baseline perfusion pressure. One hour after 50 mg of captopril perorally, MABP was reduced 16 mmHg, and ICP and CBF were unchanged. The autoregulation was maintained and the lower limit was decreased 19 mmHg. Thus patients would be expected to benefit from captopril treatment in hypotensive anaesthesia.