1994 Fiscal Year Final Research Report Summary
The application of retinal fluorescein angiography to brain circulation monitoring.
| Project/Area Number |
04454392
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
麻酔学
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| Research Institution | Yokohama City University |
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Principal Investigator |
TAKITA Shinji Yokohama City University, School of Medicine, Instructor, 医学部・救命救急センター, 助手 (70236389)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIYAMA Mitsugu Yokohama City University, School of Medicine, Associate Professor, 医学部・救命救急センター, 助教授 (60046084)
SOGA Kouta Yokohama City University, School of Medicine, Instructor, 医学部・救命救急センター, 助手 (80244507)
OKUMURA Fukuichiro Yokohama City University, School of Medicine, Professor, 医学部, 教授 (50028487)
ANDOH Tomio Yokohama City University, School of Medicine, Assistant Professor (00193110)
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| Project Period (FY) |
1992 – 1994
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| Keywords | retinal fluorescein angiography / brain ischemia / air embolism / cardiopulmonary bypass / cerebral circulation / brain death |
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| Research Abstract |
We studied on usefulness of retinal fluorescein angiography (RFA) for intraoperative diagnosis of brain air embolism associated with cardiopulmonary bypass and for diagnosis of absence of cerebral circulation in brain death patients.
For the first purpose, we developed a canine model of brain air embolism, in which sequential RFA could be performed by the injection of fluorescein isothiocyanate dextran through common carotid artery without accumulation of fluorescein dye, and a certain amount of air was injected through common carotid artery to induce retinal air embolism. In this model, retinal air emboli were detected when more than 0.1 ml of air was injected. We found that while arterial obstruction by air emboli was relieved within 1 min after air injection in normotensive animals, the occlusion persisted more than 3 min when mean arterial pressure was reduced to 50 mmHg. These results indicated that air embolism could cause significant brain ischemia under hypotensive conditions like emergence from cardiopulmonary bypass. In addition, we utilized a hand-held retinal camera to perform RFA during open heart surgery. We tried seven patients without any adverse reactions and found that this method is applicable to anesthetized patients but needs some improvements such as larger magnification and combined video system for simultaneous diagnosis in intraoperative use.
For the second purpose, we also used the hand-held retinal camera for RFA in four patients diagnosed with brain death. Retinal circulation was detected by RFA in all cases, suggesting that blood flow in ophthalmic artery, the first intracranial branch of internal carotid artery, is preserved even after cerebral circulation ceases, or retinal circulation is maintained by collateral circulation from external carotid artery in the condition of brain death. In either case, RFA does not seem to be useful for differential diagnosis of presence or absence of cerebral circulation in brain death.
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