Interfascial Injection Pressure Depending on Type of Regional Anesthesia Needle

Area of Science:

• Anesthesiology
• Ultrasound-guided regional anesthesia
• Medical device engineering

Background:

• Accurate identification of interfascial spaces is critical for successful nerve block analgesia.
• Ultrasound-guided approaches present challenges, especially in obese or pediatric patients.
• Previous research explored methods for measuring injection pressures relative to fascial planes.

Purpose of the Study:

• To investigate the influence of needle tip design on injection pressures during ultrasound-guided peripheral nerve blocks.
• To compare pressure dynamics across different needle tip geometries (Facet, Facet S, Sprotte) in ex vivo porcine tissue.

Main Methods:

• Utilized a custom apparatus to continuously measure intraluminal injection pressures during saline delivery.
• Employed ultrasound-guided peripheral nerve block needles (22G, Pajunk) with three distinct tip designs.
• Analyzed pressure data during tissue penetration and interfascial hydrodissection in porcine thigh specimens.

Main Results:

• Injection pressures varied significantly across intramuscular, fascial puncture, and interfascial phases, with a distinct puncture peak.
• Needle geometry demonstrated a significant effect on pressures in all phases (p ≤ 9.2 × 10⁻⁵).
• The classical tip showed highest intramuscular/interfascial pressures, the sharp tip lowest puncture pressure, and the lateral tip lowest intramuscular/interfascial pressures.

Conclusions:

• Needle tip geometry substantially influences injection pressure dynamics in regional anesthesia.
• Classical tips are associated with higher fascia-penetration pressures; sharp tips with lower puncture pressures.
• Lateral tips are linked to the lowest intramuscular and interfascial pressures, potentially improving needle guidance.