In Response

摘要

We thank Patel et al1 for their shared enthusiasm and comments on our recent review of regional anesthesia in cardiac surgery focusing on chest wall fascial plane blocks.2 Patel et al1 are particularly interested in simplifying chest wall blocks for minimally invasive anterior thoracotomy incision through performing a combination of pectoralis II (PECS II) or serratus anterior plane (SAP) with a pecto-intercostal fascial plane (PIF) block. The authors believe that the brachial plexus (medial and lateral pectoral nerves) does not contribute to nociception with incisions involving anterior or lateral thorax.1 In our review, we emphasize that it is unclear as to what extent blocking the branches of the brachial plexus contributes to postoperative analgesia compared to the intercostal nerves.2 We hypothesized that, because thoracotomy requires resection of the muscle planes, it is likely that blockade of these nerves contributes to postoperative analgesia to a much greater extent than with simple mastectomy.2 Although primarily motor, medial, and lateral pectoral nerves also carry sensory fibers innervating pectoralis muscles, both basic and clinical literature on this subject are scarce. Because pectoralis I (PECS I)/PECS II is usually performed through a single injection site, the number of injections proposed in our review is in fact the same as proposed by Patel et al.1 Since at present, there is no evidence to support either theory and this type of incision does involve violation of the pectoralis muscle, we believe that medial and lateral pectoral nerves should be blocked to achieve better analgesia. We do not completely disagree with the proposed by Patel et al1 because, as is evident from our table, we also suggest unilateral erector spine plane (ESP) block for this type of incision, which would not provide pectoralis nerve coverage. A comparison of these different approaches for minimally invasive anterior thoracotomy incision in a form of a randomized controlled trial may answer this dilemma. While we propose a combination of PECS II and SAP for minimally invasive right thoracotomy (typically robotic mitral surgery), Patel et al1 suggest that it is unnecessary to perform both blocks because they are targeting the same nerve branches (lateral cutaneous intercostal nerves) and that SAP block alone is sufficient to provide analgesia for this type of surgical incision. We agree that the SAP block would most likely cover all intercostal branches required to achieve analgesia for robotically assisted mitral valve surgery if the volume administered is sufficient to reach higher dermatomal levels and cover the left robotic arm port incision, which is usually at the third intercostal level. Because of the relative simplicity of the PECS II/SAP combination, we believe that performing both blocks would ensure adequate spread both cranially and caudally to cover all incisions (ports) and chest tube sites. As with the previous example, ESP block can be used as an alternative. A clinical trial is needed to compare the efficacy of the proposed approaches. Patel et al1 also raise an important consideration of anticoagulation and fascial plane blocks. Unfortunately, in case of fascial plane blocks, there are no specific recommendations and guidelines in the setting of patients receiving antithrombotic or thrombolytic therapy, and it is suggested that decision-making should be guided by assessment of site compressibility, vascularity, and consequences of bleeding.3 A practice advisory was recently published classifying the bleeding risk with some of the chest wall blocks described in our review, which may help in individual risk assessment.4 We avoid making specific recommendations about the coagulation study cutoff values because we lack evidence to support such recommendations. In our practice, all patients in whom we perform the blocks receive anticoagulation in a form of intravenous heparin before cardiopulmonary bypass and are revers