Superior Laryngeal Nerve Block for Intubation in Patients With COVID-19.

Abstract

Coronaviruses are thought to primarily spread via respiratory droplets and close or direct contact. Transmission is also possible through prolonged exposure to high concentrations of virally infected aerosols in a relatively closed environment.1 Once generated, these aerosols reportedly remain suspended in the air for up to 3 hours.2 Certain clinical procedures such as intubation and extubation are particularly known to generate potentially contagious aerosols that could infect medical personnel.3 Canelli et al4 recently invented an “aerosol box,” a barrier that can be easily fabricated, to reduce the risk of viral transmission and infection via exposure to contaminated aerosols for clinicians performing intubation- and extubation-related procedures. This barrier consists of a transparent plastic cube that encases the patient's head, with 2 circular ports through which clinicians can insert their hands to manage the airway with minimal exposure. However, this box restricts hand mobility and requires prior training before use in actual clinical procedures.5Ponnappan et al6 analyzed their preliminary experience using the aerosol box during 30 endotracheal intubations performed by anesthesiologists at the Institute of Liver and Biliary Sciences, New Delhi. The mean experience of the anesthesiologists involved in that study was 5.3 years after completion of anesthesia training. Successful intubation was achieved in 38.1% of cases during the first attempt. A second attempt was required in 28.6% of cases, and removal of the aerosol box was required in 28.6% of cases because of poor vision and/or inadequate space to facilitate proper airway management. In difficult intubation cases in which it was necessary to intubate while spontaneous ventilation was maintained, success rates while using the aerosol box would have likely decreased significantly.Reducing coughing during intubation could contribute to a reduction in viral transmission and exposure among health care workers. Coughing can be reduced by several techniques such as the administration of nebulized lidocaine to anesthetize the airway or intravenous boluses of opioid agonists for cough suppression, among others. In our hospital, we use moderate sedation with midazolam and fentanyl for patients with suspected difficult intubation or airway management. Once the patient is adequately sedated, a bilateral superior laryngeal nerve (SLN) block (SLNB) can be performed to further reduce coughing during intubation, because the block effectively prevents contraction of the cricothyroid muscle. The block can be performed percutaneously without ultrasound guidance (Figure). Therefore, even when the need for emergent intubation unexpectedly becomes apparent, it can be performed relatively easily and quickly. The SLN provides sensation to the upper part of the larynx (and lower part of the pharynx).7–10 SLNB has been used to facilitate awake endotracheal intubations during endoscopic laryngeal surgeries.11,12 Alessandri et al13 reported that SLNB reduced cough and discomfort during awake fiber-optic intubations. However, this block can be associated with potential complications, including intravascular injection and nerve damage. Nevertheless, we believe that cough suppression via bilateral SLNB can be a useful approach for reducing aerosol generation during airway management (ie, intubation). It must be mentioned that appropriate personal protective equipment still remains necessary for adequate protection at all times, particularly during this pandemic.We do not have any experience intubating patients infected with SARS-CoV-2, the virus that causes the novel coronavirus disease 2019 (COVID-19). However, we are of the opinion that SLNB is likely to be effective in reducing coughing and aerosol generation during difficult airway management in patients with COVID-19.