I believe the left facing bevel is designed to give you a better view of the cords when inserting the tube by direct laryngoscopy.

Tracheal tubes were invented long before the concept of using bougies was thought of and much longer before fibreoptic brochoscopes were invented. In addition to improving the view, it facilitates passage through the vocal cords and makes obstruction less likely if the end impact the wall of a bronchus.

True, this explanation is cited in many textbooks without real evidence to support it. Left facing bevel on tracheal tube may have been important for intubations with the re-usable rubber tubes, but is it still necessary with modern transparent tubes? Easy intubations are easy with any bevel position. Difficult may require you to use an adjunct (bougie or a fibreoptic scope), so to cover difficult ones it may make more sense to have the bevel facing posteriorly.

It was meant for blind intubation

Agree with above answers.....

1. Improves vision of cords during intubation

2. Decreases effective horizontal size of ETT as it passes through cords, which are obviously narrower in the horizontal than vertical dimension

3. Facilitates nasal intubation via right nares, decreasing likelihood for turbinate interference..

David Grittith is correct. Remember this is abetter version, than the one used originally that did not have any bevel.

Of course, there are now tubes designed for railroading. The Parker tube has a backward facing bevel and the tip bends slightly to help it hug the bougie or flexible scope. Then there is the ETT specifically designed for blind passage via an intubating laryngeal mask. It has a soft, bullet-shaped tip. I have never experienced impingement on the cords using that tube over a flexible scope.

Bevel edge of the tracheal tube not only allows for better visibility of the glottic opening while intubating the trachea, it is also most difficult to get blocked on account of greater circumference.

Our glottic opening is oriented antero-posteriorly , intubating is like putting a coin in a piggy bank opening 1) bevel should face either left or right to avoid injury to cords 2) as most of us manipulate tube with right hand and through right side for all practical purpose left bevel has better orientation for blind intubation and better visualisation as well for direct laryngoscopy .

The trachea curves first ventrally and then dorsally and the bevel is one of the ETT- safety design items, making sure that even when the tip of the ETT lays against he tracheal wall it is not obstructed. With the bevel ventral or dorsal (i.e. anterior or posterior) this risk of tip occlusion would be potenially threatening. The ETT design has to follow safety issues before following some special placement desires (infact, most ETT's are placed without a scope or bougie).

Dr. McCulloch has mentioned the Parker tube which is specifically designed to avoid this problem when attempting blinded techniques such as when using a fiberoptic or bougie. I have used these multiple times and find them to do exactly what they claim. There is much less problem with railroading.

1) We have Murphy's eye to compensate for the eventuality of the tracheal tube tip leaning against the tracheal wall so no need for the bevel to be facing side-way.

2) In addition, experienced intubators rotate the tube's curve to the right during routine insertion, away from the line of sight, presenting the left facing bevel anteriorly. Bevel that is facing posteriorly would be take left position during insertion.

Consequently, posterior bevel position would improve the visibility of the cords and make it less likely to cause injury than left facing tube bevel even during intubations that don't require railroading.

To reduce the trauma of direct contact and easy passsing and placement of the tube....I guess