Aortic Diseases, Cardiac Surgical Procedures, Aortic Aneurysm, Thoracic, Delirium - Postoperative, Postoperative Complications (Cardiopulmonary), Postoperative Complications, Cerebrovascular Circulation
Conditions
Keywords
Optic nerve sheath diameter, Selective antegrade cerebral perfusion, Ascending aortic surgery, Circulatory arrest, Cardiopulmonary bypass, Postoperative delirium, Nursing Delirium Screening Scale, Transcranial Doppler ultrasonography, Middle cerebral artery mean flow velocity, Near-infrared spectroscopy, Suppression ratio, Cerebral protection
Brief 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.
Detailed description
This single-center prospective study will enroll adults undergoing elective or urgent ascending aortic surgery with planned axillary artery cannulation. Participants are grouped according to whether release of the aortic cross-clamp is required to construct the distal anastomosis, and therefore whether selective antegrade cerebral perfusion is applied. Group membership follows from the intraoperative surgical requirement and is not assigned by the investigators. All participants receive a single protocol-specified general anesthesia and ventilation regimen, identical in both groups, so that variables known to act on optic nerve sheath diameter, in particular arterial carbon dioxide tension, volatile agent concentration and airway pressure, are held constant. Because this regimen is assigned by the protocol, the study is registered as interventional. Bilateral optic nerve sheath diameter and optic nerve diameter will be measured by ultrasonography, and middle cerebral artery mean flow velocity by transcranial Doppler, at three time points: before anesthesia induction (T0), at the end of surgery after hemodynamic stabilization in the operating room (T1), and at postoperative hour 24 in the intensive care unit (T2). Regional cerebral oxygen saturation by near-infrared spectroscopy and the electroencephalographic suppression ratio derived from bispectral index monitoring will be recorded intraoperatively. Delirium will be screened at postoperative hour 24 using the Nursing Delirium Screening Scale (Nu-DESC), with a total score of 2 or more considered a positive screen. The primary outcome is the change in bilateral mean optic nerve sheath diameter across T0, T1 and T2, evaluated as the group-by-time interaction in a linear mixed-effects model.
Interventions
DIAGNOSTIC_TESTOptic 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.
DIAGNOSTIC_TESTTranscranial 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.
Sponsors
Koşuyolu Kartal Heart Training and Research Hospital
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Outcomes Assessor)
Masking description
Participants, the surgical team and the anesthesia team are not masked, since the cerebral protection strategy is visible intraoperatively. Optic nerve sheath and optic nerve diameter measurements at postoperative hour 24, and offline review of stored ultrasound images, are performed by an assessor masked to arm allocation. Delirium screening at postoperative hour 24 is performed by a nurse or investigator masked to arm allocation. Statistical analysis is performed on a coded dataset in which arm labels are masked until the primary analysis is complete.
Intervention model description
All participants receive the same protocol-specified general anesthesia and ventilation regimen, which constitutes the assigned intervention and is identical in both arms. Participants are not allocated to arms by the investigators. Arm membership is determined by whether release of the aortic cross-clamp is required to construct the distal anastomosis, which follows from the extent of the aortic pathology and the geometry of the graft. Participants in whom the cross-clamp is released undergo systemic circulatory arrest with selective antegrade cerebral perfusion; participants in whom the anastomosis can be completed with the cross-clamp maintained do not. The study is classified as interventional because the anesthetic and ventilatory regimen is assigned by the protocol, not because the cerebral protection strategy is assigned.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Age 18 years or older * Planned or urgent, hemodynamically stable ascending aortic surgery, including supracoronary ascending aortic replacement, aortic root replacement (Bentall procedure) or valve-sparing root surgery (David procedure), limited to cases involving the ascending aortic segment * Perfusion planned through axillary artery cannulation * Written informed consent
Exclusion criteria
* History of intracranial procedure or intracranial pathology * Previous carotid intervention, or carotid artery stenosis of 50 percent or more on preoperative Doppler ultrasonography * Advanced chronic obstructive pulmonary disease, defined clinically as advanced stage disease with long-term oxygen therapy or a history of frequent exacerbations * Baseline arterial carbon dioxide tension of 55 mmHg or higher on preoperative arterial blood gas analysis * Ocular pathology, ocular surgery or ocular trauma that could affect measurement of the optic nerve sheath or optic nerve, including glaucoma and retinal detachment or fibrosis * Severe preoperative neurological deficit, including major stroke or severe dementia, or active psychiatric illness * Hemodynamic instability, or a requirement for extracorporeal membrane oxygenation or intra-aortic balloon counterpulsation, of a degree that prevents measurements during the first 24 postoperative hours * Known contraindication to any component of the protocol-specified anesthesia regimen
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in bilateral mean optic nerve diameter (OND) over time | From before anesthesia induction to postoperative hour 24 | Optic nerve diameter in millimetres, measured at the same level as the sheath diameter between the outer margins of the nerve, excluding the sheath. Three measurements per eye are averaged and the mean of the two eyes is the participant value. 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. Measurements are obtained before anesthesia induction, at the end of surgery after hemodynamic stabilization in the operating room, and at postoperative hour 24 in the intensive care unit. |
| Change in middle cerebral artery mean flow velocity measured by transcranial Doppler | From before anesthesia induction to postoperative hour 24 | Mean flow velocity in centimetres per second in the M1 segment of the middle cerebral artery, insonated through the temporal window at approximately 45-55 mm depth. Three consecutive stable measurements per side are averaged and the bilateral mean is the participant value. The endpoint is the trajectory across the three time points, evaluated as the group-by-time interaction in a linear mixed-effects model. This analysis is exploratory. Measurements are obtained before anesthesia induction, at the end of surgery after hemodynamic stabilization in the operating room, and at postoperative hour 24 in the intensive care unit. |
| Change in regional cerebral oxygen saturation measured by near-infrared spectroscopy | From before anesthesia induction to the end of surgery | Bilateral regional cerebral oxygen saturation as a percentage, recorded by near-infrared spectroscopy with adhesive frontal sensors. Baseline value, nadir value, percentage change from baseline, number of desaturation episodes at or beyond a 20 percent relative fall from baseline, and total duration of desaturation in minutes are recorded for each side. Values are recorded before anesthesia induction, before cardiopulmonary bypass, before and after selective antegrade cerebral perfusion, at the end of cardiopulmonary bypass, and at the end of surgery. |
| Proportion of participants with a positive delirium screen (Nu-DESC >=2) | At postoperative hour 24 | Delirium screened with the Nursing Delirium Screening Scale, a five-item observational scale scored 0 to 2 per item for a total range of 0 to 10, where higher scores indicate more delirium features. A total score of 2 or more is a positive screen. Screening is performed once the participant is sufficiently awake and communicative; where deep sedation precludes assessment the screen is repeated at an appropriate time and the delay recorded. |
| Number of participants with a clinical neurological event | From end of surgery to hospital discharge, up to 30 days | Composite of stroke, transient ischemic attack, seizure, or a new focal neurological deficit, ascertained from clinical records and bedside neurological examination. Each component is reported separately in addition to the composite. Events are recorded from the end of surgery to hospital discharge. |
| Cumulative intraoperative electroencephalographic suppression time | From before anesthesia induction to the end of surgery | Total time in minutes for which the electroencephalogram is suppressed, derived from continuous bispectral index monitoring with an adhesive frontal sensor. Suppression time is accumulated from anesthesia induction to the end of surgery and reported in total and separately for the period of cardiopulmonary bypass and, where applicable, for the period of selective antegrade cerebral perfusion and systemic circulatory arrest. Higher values indicate a longer cumulative duration of an isoelectric electroencephalogram. The proportion of participants with any recorded suppression is reported alongside the duration. |
Countries
Turkey (Türkiye)
Contacts
CONTACTEbru Girgin Dinc, M.D., DESAIC
Outcome results
None listed