Description

Intracranial aneurysm coil embolization is a widely accepted treatment for unruptured aneurysms, but the procedure is frequently accompanied by hemodynamic instability, particularly episodes of hypotension and hypertension, which may increase the risk of neurological or cardiovascular complications. Continuous and reliable arterial blood pressure monitoring is therefore critical during the periprocedural period.

The conventional standard of care has been invasive arterial blood pressure (IABP) monitoring using a radial arterial catheter. Although IABP provides accurate real-time hemodynamic data, it is associated with procedural risks such as bleeding, hematoma, arterial occlusion, distal ischemia, infection, and patient discomfort. These risks are particularly relevant in patients undergoing neuroendovascular procedures where vascular access and anticoagulation may already increase complication risk.

The ClearSight™ system (Edwards Lifesciences, Irvine, CA, USA) is a non-invasive continuous blood pressure monitoring device that uses a finger cuff based on the volume clamp method and pulse contour analysis. Previous studies have validated its use in a variety of surgical and perioperative settings, including obese patients, vascular surgery, and cardiac surgery \[Kim et al., 2014; Maheshwari et al., 2018; Bugarini et al., 2021; Chapalain et al., 2024\]. However, its role as a primary monitoring modality during neuroendovascular procedures has not been fully established.

This randomized controlled trial (NOVA study) is designed to determine whether non-invasive continuous blood pressure monitoring (NVBP) can serve as a safe and effective alternative to radial IABP in patients undergoing coil embolization for unruptured intracranial aneurysms. Patients will be randomized in a 1:1 ratio to receive either NVBP monitoring (experimental arm) or standard IABP monitoring (control arm). All participants will also undergo cerebral oxygenation monitoring with O₃® Regional Oximetry (Masimo, CA, USA) to detect potential cerebral desaturation events.

In the NVBP group, invasive arterial pressure will not be obtained from a radial catheter but may be secondarily recorded from a femoral arterial catheter used for the endovascular procedure itself. Importantly, the femoral arterial waveform will not be displayed to the anesthesiologist but will be recorded by nursing staff to ensure patient safety and allow for event adjudication if NVBP and IABP values diverge significantly.

The primary endpoint of this study is the intraoperative incidence of hemodynamic events, defined as episodes of hypotension (mean arterial pressure \<65 mmHg sustained for ≥1 minute) or hypertension (systolic blood pressure \>120 mmHg sustained for ≥1 minute). Secondary endpoints include vasopressor and antihypertensive drug use (type, dose, frequency), incidence of cerebral desaturation events (≥20% reduction from baseline or absolute rSO₂ \<50), ICU admission and length of stay, overall hospital length of stay, 30-day mortality, reoperation rate, and incidence of major postoperative complications (neurologic, cardiovascular, or acute kidney injury).

To minimize performance bias, intraoperative management will follow a standardized anesthetic protocol including induction with propofol, rocuronium, and remifentanil; maintenance with sevoflurane (1 MAC); ventilation targeting normocapnia; and postoperative reversal and extubation criteria. Clinical decision-making for vasoactive drug administration will follow predefined thresholds based on both blood pressure and rSO₂ monitoring criteria.

This study aims to provide pilot-level evidence on whether NVBP can reduce the need for radial arterial catheterization without compromising intraoperative safety or postoperative outcomes. If successful, NVBP may represent a less invasive, safer, and patient-friendly monitoring option for neurointerventional procedures, with broader implications for perioperative practice in patients where invasive arterial access is either undesirable or technically challenging.