Selective Antegrade Cerebral Perfusion and Perioperative Optic Nerve Sheath Diameter in Ascending Aortic Surgery

Condition(s) studied

Investigational drug(s) / intervention(s)

Optic nerve sheath and optic nerve diameter ultrasonography: Ocular ultrasonography with a linear probe of approximately 7-13 MHz, participant supine with the head neutral, eyelids closed, sterile transparent dressing and gel, minimal probe pressure. Optic nerve sheath diameter is measured in the transverse plane 3 mm posterior to the entry of the optic nerve into the globe. Three measurements per eye are averaged, and the mean of the two eyes is recorded. Performed at T0, T1 and T2.

Transcranial Doppler ultrasonography: Transcranial Doppler ultrasonography with a 2 MHz pulsed-wave probe. The M1 segment of the middle cerebral artery is insonated through the temporal window at approximately 45-55 mm depth, bilaterally where a window is obtainable. Three consecutive stable mean flow velocity measurements are taken per side and averaged. Performed at T0, T1 and T2, and where technically feasible during selective antegrade cerebral perfusion and/or circulatory arrest.

Study summary

In ascending aortic surgery the distal anastomosis may be constructed with the aortic cross-clamp maintained, or, where the extent of the aortic pathology and the geometry of the graft require it, after release of the cross-clamp during a period of systemic circulatory arrest. Both are established surgical approaches. Where the cross-clamp is released, selective antegrade cerebral perfusion (SACP) is an established cerebral protection technique and is applied for that purpose. Where release of the cross-clamp is not required, systemic circulatory arrest is avoided and SACP is not applied. Optic nerve sheath diameter (ONSD) measured by ocular ultrasonography is a non-invasive marker of raised intracranial pressure. Cardiopulmonary bypass may increase blood-brain barrier permeability through hypoperfusion, non-pulsatile flow, hemodilution and systemic inflammation, predisposing to cerebral edema. Perioperative increases in ONSD have been reported after open heart surgery and have been associated with postoperative delirium. Data on how SACP influences perioperative ONSD dynamics in ascending aortic surgery, and whether such changes relate to postoperative delirium, are limited.

Eligibility

Primary outcome measure(s)

• Change in bilateral mean optic nerve sheath diameter (ONSD) over time — From before anesthesia induction to postoperative hour 24
  Optic nerve sheath diameter in millimetres, measured by ocular ultrasonography 3 mm posterior to the entry of the optic nerve into the globe in the transverse plane. Three measurements are obtained per eye and averaged; the mean of the right and left eye values is the participant value. Higher values indicate a larger sheath diameter and are interpreted as consistent with a higher intracranial pressure. The endpoint is the trajectory across the three time points, evaluated as the group-by-time interaction term in a linear mixed-effects model with a random intercept for participant.

Trial sites (1)

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