Optimal tilt: The search for the perfect angle for robot-assisted pelvic surgeries

Robotic pelvic surgeries offer distinct advantages regarding intraoperative manoeuvrability and post-operative outcomes. However, the steep Trendelenburg position required for these procedures presents significant physiological challenges. The optimal angle that minimises complications while maintaining surgical efficacy remains undefined.

A prospective, randomised comparative study was conducted involving 100 patients undergoing robotic radical prostatectomy ( n = 50) and robotic hysterectomy ( n = 50). The primary objective was to assess variations in intraocular pressure (IOP) and optic nerve sheath diameter (ONSD) at varying degrees of tilt. The secondary objective was to evaluate haemodynamic stability and surgical feasibility. Patients were randomised in a 1:1 ratio to either a reduced or standard tilt group for their respective procedures.

Haemodynamic parameters, including diastolic blood pressure (DBP), mean arterial pressure and arterial DBP, were significantly lower in the 15° and 20° tilt groups. ONSD measurements were marginally higher in prostatectomy patients (4.9 mm) versus hysterectomy patients (4.8 mm) ( P = 0.075). Significant variations in IOP, intracranial pressure and ONSD were observed between hysterectomy groups (15° and 20°) and prostatectomy groups (20° and 25°), with peak parameters typically occurring mid-surgery. Receiver operating characteristic analysis demonstrated superior sensitivity of IOP over ONSD for distinguishing conditions during hysterectomy. Minimal surgical difficulty was achieved at 20° tilt.

While traditional practices favour angles between 30° and 45°, this study demonstrates that lower angles provide safer alternatives without compromising surgical visualisation. Rather than adhering to a universal rigid angle, we recommend an individualised approach: initiating procedures at moderate tilts (15° for hysterectomy and 20° for prostatectomy) and increasing the angle only if patient-specific anatomical constraints dictate the need for greater exposure.