Under pressure: Endotracheal tube cuffs

Under pressure: Endotracheal tube cuffs

Under pressure: Endotracheal tube cuffs

1267 570 Jo Park-Ross

What’s the problem?

The average internal diameter of an adult trachea is 1,5 – 2 cm and this doesn’t leave much room for expansion. Over-inflated cuffs could be killing off tracheal mucosa by restricting blood flow, causing problems such as tracheal stenosis: a long term condition which will need a multi-disciplinary team and some expensive surgery to fix, if it is fixable. This is money we shouldn’t be wasting, and avoidable morbidity we could be sparing our patients.

There are 3 commonly used clinical methods for inflating cuffs:

1. Palpation: Inflate cuff with air. Feel cuff between fingers. Decide the cuff feels right.

2. Pre-determined volume: Inflate cuff with pre-determined amount of air (10ml,15ml,20ml?).

3. Minimal leak: Inflate cuff. Listen for air leak during ventilation. Decide the leak is ‘minimal’.

It was demonstrated in multiple studies that even anaesthetists in theatre (whether experienced or not) were not able to achieve acceptable pressure range using clinical methods alone. Working in the out-of-hospital sphere or the emergency centre, we do not have the luxury of a quiet working environment so these methods are likely even less reliable in our environment. On top of this, a cuff inflated to pressures within the ‘safe zone’ feels a lot softer than I expected, and used less air than I had been taught to use.

Gold Standard = Cuff Pressure Manometer

 

What are we aiming for?

Screen Shot 2015-07-29 at 11.18.21 PM

Screen Shot 2015-07-29 at 11.14.29 PM

Visual demonstration of air-filled cuff pressure in flight:

A 50ml syringe to simulate the internal diameter of an adult trachea (it has a 3cm internal diameter, which is larger than an adult trachea). The manual cuff pressure manometer was attached to air filled ETT cuff via the extension set.

 

1. Before take off:

Cuff inflated to within safe limits.

1. Aircraft on ground

 

2. Half way through our climb to altitude (Cabin altitude 3770 ft)

Cuff pressure is already well outside of safe limits.

climbing_final skitch

 

3. Cruising altitude (cabin altitude 6470 ft)

Cuff pressure is almost 3 times the safe upper limit.

3__At_altitude_-_6470_ft

 

4. Reset the cuff pressure to within safe limits at cruising altitude

(cabin altitude 6470 ft)

4__Reset_at_altitude

5. Half way on the descent (cabin altitude 3230 ft)

Cuff is well below the low pressure limit – potential for aspiration increased

5__descending_after_reset_at_altitude

Saline for aeromedical transfers?

So, you’ve been told replacing the air with saline is second best. There are a few reasons why this isn’t true.

1. This is not what an ETT cuff is designed for or the approved usage as tested by the manufacturer

2. It is impossible to remove all of the air and replace it with saline, so there will be expansion (and increased pressure on the mucosa) with even a small increase  in altitude. I have tried this personally over and over in a simulated airway, and there is always a residual bubble.

3. Once the cuff is full of saline, you can no longer measure the pressure: if you cannot guarantee the pressure the cuff is exerting on your mucosa, as you cannot measure the pressure then why do it?

4. The exchange itself: despite your best effort with your faithful suction, there will be some aspiration of secretions that have likely sat around the tube for as long as your patient has been intubated. Are you willing to expose your patients to this unnecessary aspiration? There is also a possible risk for adverse events such as accidental extubation or right main bronchus intubation if the procedure is not well controlled.

5. That tube will be most likely be exchanged as the ICU won’t keep water in the cuff: this exposes the patient to risk of an adverse event such as aspiration.

So please, in ALL of your intubated patients – remember the cuff.

 

 

Want to read more?

A little more about air transport of the critically ill

Some South African literature on the subject:

http://t.co/iF4vfdwDsr

http://www.samj.org.za/…/samj/article/download/4469/3124

 

 

References

 
Bhatti NI1, Mohyuddin A, Reaven N, Funk SE, Laeeq K, Pandian V, Mirski M, Feller-Kopman D. Cost analysis of intubation-related tracheal injury using a national database. Otolaryngol Head Neck Surg. 2010 Jul;143(1):31-6. PMID: 20620616.

 
Peters JH1, Hoogerwerf N. Prehospital endotracheal intubation; need for routine cuff pressure measurement? Emerg Med J. 2013 Oct;30(10):851-3. PMID: 23100319.

 
Hurford WE. Some comments on the cuff. Respir Care. 2011 Oct;56(10):1625-6. PMID: 22008403.
 
Lizy C1, Swinnen W, Labeau S, Poelaert J, Vogelaers D, Vandewoude K, Dulhunty J, Blot S. Cuff pressure of endotracheal tubes after changes in body position in critically ill patients treated with mechanical ventilation. Am J Crit Care. 2014 Jan;23(1):e1-8. PMID: 24382623.

 
Haas CF1, Eakin RM2, Konkle MA2, Blank R3. Endotracheal tubes: old and new. Respir Care. 2014 Jun;59(6):933-52; discussion 952-5. PMID: 24891200.

 
Stauffer JL, Olson DE, Petty TL. Complications and consequences of endotracheal intubation and tracheotomy. A prospective study of 150 critically ill adult patients. Am J Med. 1981 Jan;70(1):65-76. PMID: 7457492.

 
Parwani V1, Hoffman RJ, Russell A, Bharel C, Preblick C, Hahn IH. Practicing paramedics cannot generate or estimate safe endotracheal tube cuff pressure using standard techniques. Prehosp Emerg Care. 2007 Jul-Sep;11(3):307-11. PMID: 17613904.

 
Berra L1, Sampson J, Fumagalli J, Panigada M, Kolobow T. Alternative approaches to ventilator-associated pneumonia prevention. Minerva Anestesiol. 2011 Mar;77(3):323-33. PMID: 21150848.

 
Hoffman RJ1, Parwani V, Hahn IH. Experienced emergency medicine physicians cannot safely inflate or estimate endotracheal tube cuff pressure using standard techniques. Am J Emerg Med. 2006 Mar;24(2):139-43. PMID: 16490640.

Jo Park-Ross

Flight paramedic, #FOAM enthusiast.

All stories by:Jo Park-Ross
5 comments
  • great article here Jo!
    yes RFDS Qld and most other Australian aeromedical services changed to cuff manometers many years ago for all the reasons that you cite

    We stopped using saline in cuffs when ICU folks kept telling us that the saline would lead to cuff deterioration and rupture.

  • James DuCanto, M.D. 12th August 2015 at 01:16

    I caution saline in the cuffs–let me explain. I had an opportunity at the end of an endoscopic procedure to utilize an inflation gun with saline (used for dilating closed ducts during ERCP)–and the cuff on the Mallinkrodt tube was able to tolerate 2.5 ATM before rupture. That’s 36.75 psi, or 1900 mm Hg, 2583 cm H2O. Ouch. Could be bad news if you did not monitor cuff pressure. Best do it right–that’s all I’m saying.

  • During mechanical ventilation, endotracheal tube cuff pressure should be maintained within proper range. We investigated the effect of frequent adjustment on cuff pressure in 27 mechanically ventilated patients.

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Jo Park-Ross

Flight paramedic, #FOAM enthusiast.

All stories by:Jo Park-Ross