[Temporary clipping and cerebral blood flow in patients with cerebral aneurysms].
脳動脈瘤患者における一時クリッピング中の局所脳血流変化：H2吸入法による術中評価
Abstract
In 15 patients with cerebral aneurysms, regional cerebral blood flow (RCBF) was monitored intraoperatively using the H2 inhalation technique during temporary vessel occlusion testing. Following temporary clipping, RCBF fell below critical thresholds in the majority of cases. Upon clip removal from the internal carotid and middle cerebral arteries, marked reperfusion hyperemia was recorded at 298 ± 55 ml/100 g × min. Despite these hemodynamic changes, the rate of postoperative complications attributable to temporary clipping did not increase, suggesting that complication development depends on the duration of cerebral ischemia and the integrity of the blood-brain barrier.
Mechanism
Temporary arterial clipping induces cerebral ischemia with RCBF dropping below critical levels; reperfusion upon clip removal triggers marked hyperemia. Postoperative complications appear linked to ischemia duration and blood-brain barrier integrity rather than the hyperemic response itself.
Bibliographic
- Authors
- Asaturian GA, Semeniutin VB, Maslennikova LS, Panutsev VS, Sergienko SK
- Journal
- Zh Vopr Neirokhir Im N N Burdenko
- Year
- 2006
- PMID
- 17125074
Tags
Delivery context
In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.
Safety notes
See also: