Lidocaine nebulization for airway topical anesthesia can be improved by diminish ex-cannula lost and alkalization

Abstract

Lidocaine nebulization is noninvasive, safe, and easy to perform. However, it does not provide adequate anesthesia due to the following reasons: 1. There is a high wastage of lidocaine aerosol, with at least 70 % of the lidocaine aerosol being lost from the cannula. This loss of lidocaine results in a lower amount of inhaled lidocaine, which is insufficient to provide adequate anesthesia. 2. The commercial lidocaine preparation has a low penetrating potency. The onset of anesthesia is directly related to the amount of local anesthetic in the lipid-soluble form. However, there are only a few lipid-soluble prototypes in the commercially available lidocaine cartridges. This is because the lidocaine is purposely formulated as acidic solutions (with pH levels between 3.5 and 5.5) in order to enhance the solubility and stability of the anesthetic salts. To address these issues and improve lidocaine anesthesia potency while reducing wastage, a “Y” type cannula was used for aerosol inhalation. Additionally, 1/5 vol of 5 % sodium bicarbonate solution was added to 2 % lidocaine to enhance the pH value to 7.2. This alkalized lidocaine nebulization provides an effective topical anesthesia for bronchoscopy.