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Saturday, September 18, 2010

Suctioning: how deep do you go?

Your Question: I've actually looked in several places for this info before bugging you, but I can't seem to find it. How do you (or do you) measure how deep to place a suction catheter?

My preceptor asked me the other day just before I suctioned someone, and I wasn't really sure. I thought it should probably be to the depth of the carina, so I said I should measure from the sternal notch to the tip of the tube, but I was not terribly confident. It seemed to work fine. My preceptor just kinda eyeballed me.

My humble answer: First of all, any question any time is my policy. Your preceptor shouldn't give you a funny look because the purpose of clinicals is to learn. The same policy holds true at the RT Cave.

Actually, I think the sternal notch would be too deep. So that might explain the eyeball.

I actually think in RT school we were taught to go down to the corina. Actually, according to critical care nurse (, a study was performed and determined that up to 75% of those who suction patients regularly insert the suction catheter until they meet resistance.

And while studies like this show there is no conclusive evidence shallow tracheal suctioning is any better than deep tracheal suctioning, common sense might prevail here. However, other studies performed on animals has shown evidence of more necrosis and inflammation of tissues when deep suctioning was performed.

It is of my opinion, and the opinion of many of my colleagues, that banging into the corina with a narrow tip is not good practice. This is especially bad if the patient is on blood thinners such as coumadin, or if the patient has DIC. It can cause bleeding.

Other research shows it's not the actual suctioning process itself that causes most damage from suctioning, but the hitting of the corina with the suction catheter. To be blunt, this is common sense.

So what kind of trauma can deep suctioning do:
  • Epithelial denudement (stripping of the surface of the tissues in that area)
  • Hyperemia (more blood flow to damaged tissue due to increased tissue activity. In this case it's caused by tissue damage. It decreases oxygen and ph in that area. It also increases temperature and potassium ions in that area. Source: Wikepedia)
  • Loss of cilia (due to banging the corina and the act of suctioning itself)
  • edema (swelling of tissue)
  • fibrosis (generally caused by the repair process of damaged tissue)
  • granuloma formation (mass or nodule of caused by damaged tissue; infection)
According to critical care nurse, this damage can be made when tissue is sucked into catheter holes after the tissue is traumatized by the tip of the catheter banging into the corina. It can increase the risk of infection and bleeding.

As mentioned above, one study comparing deep and shallow suctioning of rabbits showed evidence of all the above types of damage in 100% of rabbits deep suctioned, and 0-10% in rabits shallow suctioned.

This is why it is important to suction gently:
  • Use special tipped catheters when possible
  • Use low levels of suction pressure when possible
Another thing to note is that intermittent suctioning has not been proven to reduce trauma. So again, it's not so much the suctioning process itself that causes damage to the patient, it's the tip of the catheter itself.

So there are generally four methods of inserting the suction catheter:
  1. Insert the suction catheter until you meet resistance and suction
  2. Insert catheter until you meet resistance, pull back 1cm, then suction
  3. Insert catheter to corina the first time you suction, note the cm mark at lip, and during subsequent attempts suction suction 1cm above where you met resistance the 1st time.
  4. Insert catheter 1cm beyond the end of the ETT. Insert suction catheter until the cm marker on ETT and suction catheter are aligned, and then insert 1cm further. Or, add the length of the ETT plus the adaper and add 1 cm. If ETT is shortened you'll have to adjust for this.
  5. Eyeball it. Just try not to hit the corina. This may be needed if tape or other obstructs view of cm markers on the ETT
Obviously method #4 above is the best, and the most often recommended. That's the method I use. I find that by using this method the process is still very successful. The cm mark you determine should be marked at the bedside so everyone who suctions that patient knows how deep to insert the catheter.

Unfortunately some of the newer suction catheters don't have cm marks, and in this case you'll have no choice but to use method #5. Where I work this is the method we use, considering we so happen to have unmarked catheters.

Whether or not I use intermittent suctioning pretty much depends on the situation and the patient. If there's copious (lots) or thick tenacious secretions I find it's better to not use intermittent suction.

However, common sense applies. If you have a little lady or child who becomes hypoxic (low spo2) while suctioning you'll want to use intermittent suctioning.

Many RTs will pre-oxygenate a patient prior to suctioning. Most studies (like this one) show this is effective and should be performed. After suctioning make sure you properly reconnect the patient to the ventilator.

Ideally, however, you'll want to use inline suction catheters in order to prevent the loss of PEEP and to prevent ventilator acquired pneumonia. Actually, best practice evidence suggests the use of inline suction catheters, and these are now common at Shoreline medical.

Lavage and suctioning (as I wrote here) at least once per shift has also been proven to reduce the risk of infection. This can be done using the port on the inline suction catheter. However, from time to time, especially if you suspect a plug in the ETT, the patient may need to be removed from the ventilator to perform a good lavage and suction.

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