Lateral Decubitus Positioning Increases Pleura-Plexus Distance in Ultrasound-Guided Supraclavicular Brachial Plexus Targeting.

INTRODUCTION

To evaluate whether lateral decubitus positioning increases the pleura-plexus distance at the supraclavicular level and to characterize its role as a modifiable anatomical factor relevant to ultrasound-guided interventions.

METHODS

This prospective observational ultrasound study included 90 adults comprising individuals with complex regional pain syndrome, cervical spine stenosis, and healthy controls. Pleura-plexus distance was measured at end expiration in three standardized positions: semi-reclined supine, 45° lateral tilt, and lateral decubitus. Positional effects were assessed using mixed repeated-measures analysis of variance, and associations with demographic variables were examined using correlation and multivariable linear regression.

RESULTS

Pleura-plexus distance increased progressively across positions in all groups. Compared with the semi-reclined position (0.37-0.46 cm), lateral decubitus positioning more than doubled the distance (0.82-1.04 cm; p < 0.001), with a significant group interaction. Body mass index independently predicted pleura-plexus distance in the lateral position (+0.028 cm per kg/m2, p < 0.001), whereas age was not significantly associated.

CONCLUSIONS

Lateral decubitus positioning was consistently associated with increased pleura-plexus distance at the supraclavicular level across all study groups. These findings suggest that patient positioning represents a measurable and potentially modifiable anatomical factor that may influence anatomical conditions relevant to ultrasound-guided supraclavicular procedures.