10.頸動脈圧迫遮断時の眼動脈圧測定
-頸動脈結紮の耐容性に関する新しいチェック法
1984 年 13 巻 p. 57-61
詳細
1984 年 13 巻 p. 57-61
As a method of preoperative evaluation of the tolerance for carotid ligation, namely, of assessing intracranial collateral circulation, we have measured, using oculocerebrovasculometry(OCVM), the pressure of the ophthalmic artery with and without carotid compression and have calculated the ratio of the pressure of the ophthalmic artery to the systemic blood pressure (OAP/BrBP).
In those who presented no cerebral ischemic signs or EEG abnormalities with carotid compression, the OAP/BrBP ratio was 0.763±0.063 (mean±S.D., N: 18) without carotid compression, declining to 0.373±0.136 with ipsilateral carotid compression. The reduction of rCBF (three-dimensional measurement) with carotid compression in these nine cases remained around 10%. There was a good correlation between the %-reduction of the rCBF and the OAP/BrBP ratio, which were obtained under carotid compression (r: 0.758, N: 16, p<0.001).
One case manifested no cerebral ischemic signs or EEG abnormalities with preoperative carotid compression, but during the carotid endarterectomy procedure, she showed an ipsilateral decrease of alpha wave power without the appearance of slow waves with the carotid clamp. The preoperative rCBF was decreased with carotid compression in about 45% (59ml/100g/min., 81% of the normal value). In this case, the OAP/BrBP ratio with carotid compression was 0.313.
In another case, contralateral cerebral ischemic signs and ipsilateral EEG abnormalities (appearance of 6-7 Hz theta waves) developed with carotid compression. The reduction of rCBF with carotid compression was 51% (33 nit/100g/min., 45% of the normal value). In this case, the preoperative OAP/BrBP ratio was decreased remarkably to 0.114.
It is thought that in those whose OAP/BrBP ratio with carotid compression is above 0.3, the intracranial collateral circulation may have developed well and the ICA ligation may be tolerable. The lower limit of the OAP/BrBP ratio with carotid compression for tolerable ICA ligation is believed to be around 0.3.
