In response to regional anesthesia in the austere environment: Lessons learned from current out-of-hospital practice

To the Editor:

With great interest, we read the article by Anderson et al recently published in your esteemed journal. ¹ The authors have done a commendable job carrying out the research and drafting the article meticulously. While going through the article, we came across some points of concern and would like to highlight them through this correspondence.

In this scoping review, the authors have tried to explore the feasibility and efficacy of regional anesthesia techniques in out-of-hospital settings. After analyzing the article, we found that the authors haven’t discussed the volume and concentration of the local anesthetic agents in the study. ¹ Proper estimation of local anesthesia dose (volume and concentration) is important in reducing the risk of local anesthetic systemic toxicity (LAST).^2,3 Similarly, the discussion lacks information about an airway-securing tool (including the difficult airway cart) and an intravenous lipid emulsion essential to manage LAST.^2,4,5 Though the authors have not commented on the above, readers may be interested to know the same. We fully agree with the authors’ opinion to consider a regional anesthesia technique based on a risk versus benefit ratio. However, it is surprising to find some high-risk blocks, such as interscalene and infraclavicular brachial plexus blocks, being administered by the researchers. These blocks can cause phrenic nerve palsy and respiratory compromise, so they should be carefully administered in polytrauma patients (with hemo- or pneumothorax), especially in out-of-hospital settings.^6,7 Furthermore, most blocks were administered by landmark guidance, which can have a much higher complication rate than the visualized approach and would be disastrous in such critical patients. Interscalene block has an especially high rates of complications with landmark guidance due to proximity to critical structures such as the spine and vertebral artery, leading to such complications as total spinal anesthesia and LAST. Though reported only in one case report, using ultrasound guidance for the block will reduce the risk of such complications. ⁸ Erector spinae plane block is an emerging block for treating pain due to chest injury, which is common in such settings and can be a good option for pain management. ⁹

Although the authors have discussed nerve damage, diagnosing such a complication is difficult unless follow-up cases are done in the above setting.^10,11 Further, complications due to nerve blocks may be inadequately represented because they may be attributed to trauma itself, or the patient may not have survived. The authors have mentioned that emergency medical service nurses and paramedics can administer regional blocks such as the fascia iliaca nerve block safely. ¹ However, readers would like to know how 1 day of training for an emergency medical service nurse is sufficient for administering regional blocks compared with years of training by anesthesia/emergency residents.

To conclude, we appreciate the efforts by Anderson et al, and we are hopeful that the points mentioned herein will be informative for readers.