Single versus two-level superficial parasternal intercostal plane block: cadaveric evaluation of injectate spread with needle tip position on anterior surface of costal cartilage.

Abstract

Superficial parasternal intercostal plane blocks have grown in clinical use for cardiac surgery as a targeted fascial plane block for median sternotomy. Despite this, there remains no consensus on technique for optimal parasternal spread of injectate. The primary objective of this cadaveric study was to evaluate parasternal spread of injectate of single versus two-level superficial parasternal intercostal plane injections with the needle tip positioned on the anterior surface of the costal cartilage. We performed 10 single-level injections at T4 and 10 two-level injections at T3 and T5 on alternating sides in 10 fresh frozen cadavers. All injections were ultrasound guided with a parasagittal ultrasound probe orientation and an in-plane needle orientation. Anatomic dissections were performed immediately following injections. Parasternal spread of injectate was greater with two-level injections at T3 and T5 costal cartilages than with single-level injections at the T4 costal cartilage, with two-level injections consistently spreading to the T2-T5 intercostal spaces. Median (Q1, Q3) intercostal space spread for single-level injections was 2.0 (2.0-2.5). Median (Q1, Q3) intercostal space spread for two-level injections was 4.0 (4.0-4.375). Two-level injections with the needle tip located on the anterior surface of the costal cartilage resulted in improved parasternal spread compared with single-level injections.