The Diagonal Vector (DIVE) Approach for Lumbar Plexus Block - A Comparison with Chayen's Technique.

Purpose: Substantial understanding of anatomic landmarks remains mandatory for regional anesthesia procedures of the lower limbs, even in times of ultrasound-guided techniques. Theoretically, applying a diagonal vector (DIVE) from the posterior superior iliac spine towards the spinous process of lumbar vertebra 3 leads to a higher error tolerance and closer nerve approximation when compared to Chayen's approach. The purpose of this study was to compare both techniques regarding clinical applicability, accuracy and risk profile.

Patients and methods: Lumbar plexus block was performed bilaterally according to Chayen's technique and the DIVE method in embalmed bodies donated to science. The posterior medial half of the psoas major muscle was predefined as the puncture target area. Essential anatomical landmarks were labelled, photographed and a computer-aided analysis of the images was conducted. Both approaches were compared regarding the puncture success rate, spatial nerve approximation and complications such as vessel or kidney punctures.

Results: Both techniques were applied bilaterally on 34 embalmed bodies (50% male, mean age ± standard deviation 82 ± 8 years, height 167 ± 10cm) and led to similar success rates of a psoas muscle hit (Chayen vs DIVE 86.3% vs 82.8%). DIVE punctures were more often localized in the medial third of the psoas (p<0.001), whereas the risk for vessel or kidney punctures was similar (p=0.473; p=0.367, respectively).

Conclusion: Punctures according to the DIVE method resulted in a higher puncture accuracy compared to Chayen's technique with comparable practicability and risk profile. When using the DIVE Block, a window for a successful puncture can be expected between a quarter and a third of the PSIS- L3SP distance.