how do you know how far to advance the ET tube?

[RussianJoo]

just wondering if there's a formula based on pt's height on how far to advance the Et tube past the vocal cords. I know it should be 3 to 4 cm above the Carina but you know that only once you get a CXR. So is there a science to it or just advance the tube a few cm's passed the vocal cords, and listen to the lungs to make sure you hear breath sounds b/l?



as always thanks guys.

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[Bertelman]

For peds, there is a formula based on age. Adults, generally 20-21 cm for women, 22-23 cm for men.

I go based on visual confirmation. There's a dot on an adult ETT, and a series of lines on pedi tubes. I align the dot (or the double line hatch) with the cords, which generally puts the balloon 2 cm below the cords. There is a fair amount of variability of tooth to cords distance, so I don't rely on predictions. The dot's not that easy to see in the larynx, so generally I push until the balloon passes the cords, then push a little more.

You know you're too deep if peak pressures are high or the SpO2 is less than you might expect. You should also confirm breath sounds bilaterally. Same can be said for chest rise, though I can't say I could reliably discern unilateral chest rise.

 

[IlDestriero]

For the really little guys, sometimes I listen as I mainstem the tube, than pull back slowly until I'm on the Carina with BBS again, than pull back another cm or so. It can be quite variable. As for seeing unilateral chest movement, you often can see that in children.
There was a study on this in kids, I'll try to look it up.

 

[lazylikeapanda]

peds age/12 + 12 = tube distance

 

[Bertelman]

peds age/12 + 12 = tube distance

That must not take into consideration neonates or infants. I'd be close to main-stemming most of the little ones at 12.

I think the other formula is maybe 3 x ET size, so a 3.0 tube goes 9, 4 goes 12, etc.

I could be wrong.

 

[lazylikeapanda]

wrote the equations wrong
age/2 +12 = tube length for kids >3years old

Bertelman ur right, you can also estimate length by multiplying tube size by 3

 

[Impromptu]

Just started my first peds rotation, and 3X the ETT size is generally correct.
This is level at the upper gums (not everyone has teeth, and lips are quite variable). Always confirm with breath sounds and direct visualization of the cuff going past the vocal cords just 1-2 cm.

 

[proman]

I go based on visual confirmation. There's a dot on an adult ETT, and a series of lines on pedi tubes. I align the dot (or the double line hatch) with the cords, which generally puts the balloon 2 cm below the cords.

This is exactly what I use. It works well. And I get to use my fancy stethoscope.

 

[rsgillmd]

I'm with Bertelman on this one. As he mentioned about the lines on the kids tubes, and the tube size x 3 formula as a double check. On occasion, I've done what ID said -- main stem and then pull back a little.

I never really noticed the dot on the adult ETT. Probably because I never looked for it. So in an adult I just note where the cuff disappears below the cords and push another 2 cm past this.

 

[Code Brown]

just wondering if there's a formula based on pt's height on how far to advance the Et tube past the vocal cords. I know it should be 3 to 4 cm above the Carina but you know that only once you get a CXR. So is there a science to it or just advance the tube a few cm's passed the vocal cords, and listen to the lungs to make sure you hear breath sounds b/l?



as always thanks guys.

Just advance a couple of cm past the cords... but if for some reason you aren't sure, save yourself (and the patient) the CXR and take a quick look with a fiberoptic scope...

 

[RussianJoo]

thanks guys. I was just wondering if there was some science or formal envolved.. One of the critcal care fellows asked me since I am an anesthesia resident, I told him you can tell either by a CXR or with a fiberoptic scope otherwise you can't really tell you just stick the tube in, and listen for b/l breath sounds and you're done. So I posted on here to make sure I wasn't missing anything.

 

[jennyboo]

Adults above 5 feet: 21-23 cm at the teeth

Kids: 3 x ETT size

What I would tell the pulm/CC fellow is to place it at 22cm to begin with and then adjust according to auscultation and then x-ray like they already do. The tendency of the inexperienced or less experienced intubator is to push the tube in too far and mainstem it. If they know to set it at 22cm it's a good start.

 

[fakin' the funk]

thanks guys. I was just wondering if there was some science or formal envolved.. One of the critcal care fellows asked me since I am an anesthesia resident, I told him you can tell either by a CXR or with a fiberoptic scope otherwise you can't really tell you just stick the tube in, and listen for b/l breath sounds and you're done. So I posted on here to make sure I wasn't missing anything.

For your fictional "average 70kg patient" the measurements are supposed to be:
Teeth-to-vallecula: 10cm
Epiglottis: 2cm
Epiglottis-to-VC: 3cm

So, teeth-to-VC is supposedly 15cm. Add 3cm for the cuff, and 1-2 cm for the ETT distal to the cuff, and 20-22cm at the teeth for most adults is a good starting point.

Then, with ~6cm of subglottic ETT protruding into a 10-12cm trachea, your tip should be 4-6cm above the carina.