Spread of Injectate After Combined Deep Serratus Anterior and Superficial Parasternal Intercostal Plane Injections: A Cadaver Study to Evaluate Their Utility in Breast Surgery
Bibliographic record
Abstract
BACKGROUND: Analgesia for breast surgery by a single peripheral nerve block is challenging as breast tissue receives innervation from multiple sources. In this cadaveric study, we evaluated the injectate spread of combined superficial parasternal intercostal plane (PIP) and deep serratus anterior plane (SAP) injections in the tissues relevant for breast surgery analgesia. METHODS: We performed ultrasound-guided dye injections in 18 hemithoraces. 20 mL of methylene blue solution was injected into the superficial PIP at the fourth rib. Following that, 20 mL of black India Ink solution was injected in the SAP at the fourth rib at the midaxillary line. We dissected the specimens, 15 min post-injection to visualize dye dispersion. Staining of the intercostal nerves from each injection was measured by counting the number of intercostal spaces and nerves stained. RESULTS: For PIP injections, the cranial spread of injectate was observed up to the second intercostal nerve involving the anterior cutaneous branch in 14/16 (87.5%) with caudal spread to the fifth intercostal nerve in 15/16 (94%). In addition, the staining of the medial and lateral pectoral nerves was noted in 14/16 (88%) of the specimens. For the SAP dye injections, the cranial spread of injectate was observed up to the lateral cutaneous branch of the third intercostal nerve level in 9/16 (56%) of specimens and caudal spread up to the lateral cutaneous branch of the sixth intercostal nerve in 14/16 (88%) specimens. CONCLUSIONS: This study demonstrated extensive spread of dye injectate with combined PIP and SAP injections involving anterior and lateral cutaneous branches of intercostal nerves and lateral and medial pectoral nerves. This study demonstrates an alternative analgesic approach to provide perioperative analgesia for breast surgery. EDITORIAL COMMENT: This cadaver study demonstrates that combining deep serratus anterior block with parasternal intercostal plane block provides reliable injectate spread to the cutaneous branches of intercostal nerves. In a clinical setting, this could provide comprehensive analgesia for the breast. Compared with paravertebral blocks, the combination of two fascial plane blocks may offer a technically less challenging alternative with a lower risk of complications.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".