Optimal Head Rotation for Ultrasound- Guided Internal Jugular Vein Cannulation in Obese Patients: A Prospective Observational Study

Background: Ultrasound-guided internal jugular vein (IJV) cannulation is standard practice, but the risk of accidental common carotid artery (CCA) puncture persists, especially in obese patients. Head rotation manoeuvres aim to improve IJV accessibility but may increase IJV-CCA overlap. The optimal degree of head rotation to minimise this overlap although studied in normal patients remains largely underexplored in obese patients. Aims: To determine the head rotation angle (15°–60°) that maximizes IJV diameter while minimizing IJV-CCA overlap in obese patients (BMI ≥25 kg/m²). Material and Methods: Sixty obese patients were stratified by BMI (Group 1: 25–29.9; Group 2: 30–39.9; Group 3: ≥40) in the pre-operative room. In supine position with 15° Trendelenburg tilt, right IJV and CCA were imaged using 5–12 MHz linear probe at cricoid level. Transverse and anteroposterior diameters of the right sided IJV and CCA and their overlap were measured using real time ultrasound at 15°, 30°, 45° and 60° of head rotations. Results: IJV-CCA overlap increased significantly with rotation: 34.9% (with15°) to 55.3% (with 60°) (P<0.001). Overlap was highest in Group 3 (BMI ≥40). No significant change in IJV diameter was observed. The safest rotation was ≤45° for BMI 30–39.9 and ≤60° for BMI 25–29.9. Conclusion: Head rotation >45° in obese patients significantly increases CCA puncture risk. Ultrasound-guided cannulation at ≤45° is recommended for BMI ≥30 kg/m². Keywords: Internal jugular vein, Obesity, Ultrasound guidance, Head rotation, Common carotid artery