Abstract SNACC-84

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The association between ocular blood flow measured by laser speckle flowgraphy during aortic arch surgery with selective cerebral perfusion and postoperative cerebral complication

Hayashi H, Okamoto M, Kawanishi H, Matsuura T, Kawaguchi M
Nara Medical University, Kashihara, Nara, Japan

Introduction: During complex repair of aortic arch, selective cerebral perfusion (SCP) is widely accepted as standard neuroprotective procedures. However, postoperative cerebral complication is still a major sequela of cardiovascular surgery, especially aortic arch surgery. Postoperative cerebral complication can be caused by hypoperfusion and embolism. Impaired ocular perfusion indicates reduced cerebral blood flow because the ophthalmic artery arises from the carotid artery. The relationship between postoperative cerebral complication and ocular circulation remains unclear. Laser speckle flowgraphy (LSFG) allows a non-contact method of determining ocular blood flow. Therefore, the purpose of this prospective study is to investigate whether there is a significant correlation between the ocular blood flow measured by LSFG and postoperative cerebral complication.
Methods: The protocol in this study was approved by the institutional ethics committee. Fourteen patients undergoing elective aortic arch surgery under SCP were enrolled in the study. Anesthesia was maintained with propofol or sevoflurane and fentanyl. Nonpulsatile flow (2.4-3.0 L/min/m2) and a heparin-coated membrane oxygenator were used for cardiopulmonary bypass (CPB). SCP was performed after the aortic arch has been opened and continued until all branches of the arch were reconstructed. LSFG technique (Softcare Ltd, Japan) was used to measure intraoperative blood flow in the optic nerve head. The mean blur rate (MBR), an indicator of blood flow, in the optic nerve head were assessed intraoperatively at the following 4 points; (1) 30 minutes after the induction of anesthesia (baseline), (2) 30 minutes after the beginning of CPB, (3) 30 minutes after the beginning of SCP, (4) 60 minutes after cessation of CPB. Postoperative cerebral complication including convulsion and paralysis were also recorded. The MBR in optic nerve head was compared between patients with cerebral complication and patients without cerebral complication. The data are shown as mean±standard deviation. Wilcoxon signed-rank tests were applied to assess differences in the MBR between the patients with and without postoperative cerebral complication. The significant difference was set at p<0.05.
Result: Patients ranged in age from 59 to79 years (mean 68 years). There were 5 males and 9 females. In all patients, the MBR in the optic nerve head could be measure through the operation. The MBR were (1) 21.2±6.2, (2) 16.5±6.9, (3) 12.6±3.8, (4) 23.0±5.8, respectively. Four patients had postoperative cerebral complication including convulsion in 3 patients and paralysis due to cerebral infarction in one patient. The MBR during SCP in patients with and without postoperative cerebral complication were 14.1±5.4 and 11.9±10.7, respectively. There was no statistical difference between the MBR during SCP in patients with postoperative cerebral complication and that in patients without postoperative cerebral complication.
Conclusion: Ocular circulation measured by LSFG is applicable for cardiovascular surgery with SCP. The result of this preliminary study cannot conclude the association between ocular circulation and cerebral complication because small number of patients included in this study.

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