Glottic Opening Appearance is Not Sufficient for Every Endotracheal Intubation

Abstract

We read with interest the article by Altun et al. 1 as the difficult airway is a life-threatening emergency, and predicting difficult intubation is an issue that especially anesthesiologists and Ear, Nose, and Throat (ENT) surgeons, have been working on for years.We want to contribute to this issue and criticize the authors' research.An ENT surgeon performed indirect laryngoscopy (IL), and patients classified as Grade 3 to 4 were assumed to have a difficult airway. 2 However, approximately 80% of patients classified as Grade 3 to 4 actually have easy intubation, and 6% of patients classified as Grade 1 to 2 have difficult intubation. 2 This can be explained by the different characteristics of the laryngoscopes used for IL and endotracheal intubation. The absence of a static image throughout the IL due to the swallowing-coughing may also cause this situation.Patients with neck movement limitation were excluded from the study. However, a significant relationship was shown between neck movement limitation and the presence of a difficult airway on patients who underwent IL. 2 Also, patients with a history of radiotherapy to the head-neck region and with abnormal larynx anatomy due to laryngeal surgery were excluded from the study. However, these patients often come with difficult airway in head and neck anesthesia practice. 3 As a matter of fact, the authors indicated that they did not encounter any Grade 4 patients. However, 13% of patients were classified as Grade 3 to 4 in a similar study. 2 An anesthesiologist performed direct laryngoscopy (DL), and only patients classified as Cormack-Lehane (CL) Grade to 4 were assumed to have a difficult airway. However, 25% of patients even classified as CL Grade 1 to 2 are difficult to intubate. 2 This is because the difficulty of visualizing the glottis opening and the difficulty of intubation are two different concepts. A small percentage of anesthetists have sufficient information about CL classification, although it is frequently used to classify the laryngeal appearance. 4 Possible causes are confusion with other commonly used similar classifications such as the Mallampati and uncertainties between CL grades. And personal factors such as the anatomy of the patient, the force applied by the clinician during laryngoscopy, the skill and experience of the clinician also affect the CL grade. 4 Visual analog scales (VAS) are psychometric response scales with dozens of variants used to measure subjective characteristics or attitudes. 5 VAS scores corresponding to CL grades, IL grades, and ultrasonographic measurements were presented in table 3. However, the authors should explain which VAS score was used in the study and its intent.

In response to the letter to the editor regarding “Comparison of the intubation success rate between the intubating catheter and videolaryngoscope in difficult airways: a prospective randomized trial”

“…Even experienced clinicians have difficulty in directing the endotracheal tube to the vocal cords and performing successful intubation, even in the case of easy laryngoscopy in pediatric patients. 3 Considering the Cormack-Lehane (CL) results of our study, the author claimed that the Frova Intubation Catheter (IC) is indicated in cases where the laryngoscopy view is unsatisfactory. Video laryngoscope used in adult patients with difficult intubation improves the CL score.…”