Does adding transversus thoracic muscle plane block reduce pain following mastectomy?

“For all the happiness mankind can gain, 

Is not in pleasure, but from rest from pain.” – John Dryden

Addition of transversus thoracic muscle plane block to pectoral nerves block provides more effective perioperative pain relief than pectoral nerves block alone for breast cancer surgery. DOI:https://doi.org/10.1093/bja/aew449

Enhanced Abstract:

Background. The pectoral nerves (PECS) block cannot block the most internal mammary region, whereas a transversus thoracic muscle plane (TTP) block can. The combination of PECS and TTP blocks may be suitable for anterior chest surgery. This study includes patients undergoing mastectomy to assess whether the combination of PECS and TTP blocks provides better analgesia than PECS block alone.

Methods. Seventy adult female patients undergoing unilateral mastectomy under general anaesthesia were randomly allocated to receive either the combination of PECS block plus TTP block (PT group, n=35) or the PECS block only (C group, n=35). The primary outcome measure was visual analog scale pain score. Secondary outcomes were the sensory level loss confirmed by cold tests and additional analgesic drugs within 24 h after the operation.

Results. The visual analog scale pain scores were lower in the PT group than the C group (P<0.0001). The use of postoperative additional analgesic drugs was also lower lower in the PT group than that in the C group (P<0.0003). In the majority of patients in the PT group, sensory loss was confirmed in both the anterior and the lateral branches of thoracic nerves (Th2–6) but there was no sensory loss on anterior branches for PEC only block (P<0.0001). There were no drop outs in the study. All the patients recruited in the study were included in the conclusion.

Conclusion. Compared with PECS block alone, the combination of PECS and TTP blocks provides better effective perioperative pain relief for breast cancer surgery.

Analysis and thoughts.

Pros:

  1. Focus of the trial was clear and there were well defined primary and secondary outcomes.
  2. Both the groups were similar at the start of the trial and were treated in the same way except for the difference in the block they received.
  3. Technically, the study had adequate sample size and statistical analysis in terms of tests and methods was meticulous.
  4. All the possible relevant clinical outcomes were considered.

Cons:

  1. The method of randomisation was not stated.
  2. Blinding was not stated at all. Robust randomisation and blinding are particularly important in studies like this in which the outcome measure is subjective.
  3. It was not clear who performed the blocks. Like any other clinical skill, PECS and TTP blocks have a learning curve. There potentially could be an operator’s bias if different people of varied skill levels perform these procedures making one group worse than other.
  4. Standard deviation (SD) for VAS score (40 mm) was derived from the pilot cases which were very few in number (8 cases) to give more realistic SD

My take on this study:

  1. There is growing evidence of relationship between breast cancer recurrence and opioid use. Hence it would be nice to have a regional anaesthetic technique at hand to limit opioid requirements.
  2. There is also some evidence that regional blocks may reduce incidence of post mastectomy chronic pain (nearly 20% cases developed chronic pain).
  3. Chest wall blocks are more peripheral and can be safer than epidural, para-vertebral in terms of nerve damage and pleural punctures.
  4. To employ this technique in my practice and locally there is a need for acceptance and hands-on training.
  5. TTP block being a very new introduction to the list of volume blocks needs further review of its risk benefit analysis but PEC blocks have been shown to be effective in many studies and can be employed for most of the breast operations effectively.

Summary by Dr Kunal Joshi

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