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Posts tagged Airway.

All Things Endotracheal

There have been some interesting papers recently exploring all-things endotracheal, relevant to anaesthesiologists, intensivists and emergency physicians alike.

Some challenge long-accepted dogma (ETT size), others confirm natural trends (cuffed paediatric tubes), or delve into ventilation physiology long forgotten by some of us (the ventral shift...).

Here's a brief stroll through five articles that may challenge your practice.

Choose smaller...

First, Karmali & Rose challenge the dogma surrounding endotracheal tube sizing in adult anaesthesia. They explore both the functional consequences of ETT size, good and bad, as well as the implications for airway trauma.

They describe how a modern ETT ≥ 6.0mm ID will accomodate most intraluminal devices, and in fact smaller sizes might even facilitate some airway procedures. Similarly, inspiratory and expiratory flow dynamics of smaller ETTs are inconsequential for most fit and healthy patients.

Noting that there is wide individual variation in tracheal dimensions, such that some patients are poorly served by a traditional ETT-size choice, they highlight the correlation between ETT size and airway trauma, hoarseness and sore throat, noting that for many patients a 'large' ETT offers little practical benefit.

"Instead of opting for ‘the largest tube that the larynx will comfortably accommodate’, we perhaps should consider using the smallest tube which permits the safe conduct of anaesthesia."

For routine anaesthesia of ASA 1 & 2 patients, an ETT sized 6.0-7.0 mm is probably the best balance between ventilation needs and airway trauma.

Don't cough

Yang et al.'s high quality meta-analysis explores the use of intravenous lidocaine/lignocaine to reduce a common, but potentially significant post-operative problem: coughing on extubation. Both coughing (reported incidence 15-94%) and post-operative sore throat (21-72%) are common among surgical patients.

This meta-analysis of 16 trials (though only 1,516 total subjects) showed a significant reduction in cough RR 0.64 (0.48-0.86 & NNT=5), and post-operative sore throat RR 0.46 (0.32-0.67), though no difference in laryngospasm, adverse events or time to extubation when using modern volatile agents.

However, they could make no clear recommendation of optimal timing or dose of lidocaine – although past reviews had found suggestion of a dose-effect, settling on 1.5 mg/kg as the best choice (Clivio et al. 2019).

Regardless, a simple intervention with peri-operative IV lidocaine reduces coughing on extubation and reduces post-operative sore throat, without any apparent increase in adverse events.

Read on for more ETT tidbits...

Five things I love about the C-MAC

Ah, videolaryngoscopes – wonderful toys increasingly common in operating rooms, intensive care units and emergency departments throughout the world.

After the first video laryngoscope was conceived by New York emergency physician Jon Berall in 1998, commercial success quickly followed with the 2001 Glidescope (designed by a vascular surgeon nonetheless!). Our love of the videolaryngoscope has grown ever since.

Like many anaesthetists and anesthesiologists I've used several different videolaryngoscopes over the past few years. The character that sets apart the videoscopes I like to use from those I do not is how well they enhance airway techniques I use every day rather than requiring a new technique specific to their device.

Overwhelmingly this comes down to how similar the laryngoscope is to a standard Macintosh blade rather than inventing a whole new shape. While there may be theoretical (or even real!) benefits to increasing the angle of the blade or adding extra conduits, when I have a difficult airway I want to augment the tools and techniques I use every day rather than change to something completely different. (When I want to change to something completely different I'll pick up a fibreoptic bronchoscope or something sharp!)

Read more...

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