Which is better? BURP or bimanual? Is cricoid pressure of any use?
Sellick described cricoid pressure in 1961. How useful is it? Well it’s purpose is to minimise the passive movement of gastric contents into the oropharynx and the potential aspiration of those contents, during rapid sequence intubation. How good is it? I was recently asked this at an Airway Workshop and I had to say for what we have, it’s pretty good. BUT the evidence is not that great!
In fact some of the newer evidence now says, it may be detrimental and can affect intubation. It can further affect ventilation of the patient!
Initially the recommended pressure was 44Newtons which is equivalent to 4.5kg (10 pounds). At this pressure it was found that there was occlusion of the glottis in 50% of patients in one study (Anaesthesia 2000 march 263-268). To be fair, the conditions in this study, which was a small one (n=30) were somewhat artificial and not really reflecting the real scenarios.
In other studies where the effect of cricoid pressure on actually passing a tube through the cords was looked at. It was found that in a small number of cases, the cricoid pressure affected the ability to pass the tube (Anaesthesia 2007 May;62; 456-9). In those cases where the tube was getting stuck at the level of the glottis i.e. at the posterior cartilages, where usually a 90 degree rotation of the tube would relieve the issue, cricoid pressure made this more difficult.
In an MRI study looking at cricoid pressure, there was direct visualisation of the hypo-pharynx being occluded when cricoid pressure was applied (Anesth Analg 2009. Nov; 109;1546).
The correct use of cricoid pressure is of utmost importance, and the ability to use it to minimise the chance of aspiration remains to be tested. There is certainly evidence that it can make intubation far more difficult than no cricoid pressure being applied (J Emerg Med 2001 Jan 20;29-31) and if there is a difficulty in intubating then cricoid should be relaxed or even released.
There needs to be some idea of how much pressure needs to be used. There is no formal teaching in this area. The original 4.5kg of pressure is now not used and 2kg or 20N of pressure is recommended, but how do you guarantee this? How do you know how much pressure is being applied at any one time? When I’m tubing I ask for cricoid. How do I know if that cricoid is appropriate and if it’s affecting the intubation?
The BURP manoeuvre was established in 1993 by Knill and its purpose is to improve the view of the cords during laryngoscopy. People still get it wrong. It is the person intubating that is to apply this pressure, not someone else. The Backward,Upward to the Right Pressure must be applied to suit that person intubating.
In a study that compared the BURP technique with bimanual manipulation in cadavers (Ann Emerg Med 2006 Jun;47;548-55), it was found that bimanual manipulation improved the POGO (percentage of glottic opening) more than BURP or cricoid.
What is bimanual manipulation? It is simply putting external pressure on the thyroid cartilage and moving it whilst inserting the tip of the laryngoscope into the vallecula. The effect is that it assists the tip of the blade in reaching deeper into the vallecula and thus assists in elevating the epiglottis.
So a few things to remember here.
Be careful with cricoid pressure. There is a place for it in bag-valve mask as long as it is not too aggressive. It may however hinder intubation and even ventilation. So if you are encountering issues with intubation, or the patient is difficult to ventilate, release the cricoid and see if there is a resolution.
Cricoid plus BURP together may make intubation far more difficult.
Bimanual manipulation may be an effective technique.
Hi Peter,
Interesting discussion – thanks. I had a read of the Ann Emergency Med 2006 study you referenced and a few other articles. It seems, in particularly in that article, that both cricoid (to the cricoid c) and BURP (to the thryoid c) have been defined as “assistant” provided pressure whereas bimanual manipulation (to the thryoid c) is defined as operator provided pressure, then taken over by the assistant who maintains it.
It does not surprise me that bimanual manipulation was clearly superior in the study. Other than that the actual direction of bimanual applied pressure is not defined – it i sufficiently vague because it essentially is whatever direction/pressure the operator finds maximises their view of the cords.Common sense isn’t it?
It is quite possible of course that this pressure being applied in bimanual manipulation is in fact backwards and/or upwards and/or right as as such may be still using the elements of BURP. The key difference is the operator is applying it and then the assistant takes over.
Looking at the great uncertainty from the studies re whether cricoid actually prevents any passive regurgitation and reasonably good evidence that it can worsen view and is indeed inferior to Bimanual in terms of obtaining a good view, I suspect the time of cricoid may be drawing to an end.
Bimanual manipulation by the operator which is then maintained by the assistant does seem the way forward. The pressure/direction applied in bimanual may in fact use aspects of BURP in its application.
Dr Arnie Senthi
WA
Dear Dr Senthi
I agree, cricoid is really an antiquated procedure that we are clinging onto. I see its use being slowly withdrawn. One of the issues with the BURP, is that originally this manoeuvre was meant to be done by the person intubating and given over to the assistant, but has been misapplied over the years.
We are doing some work on cricoid at the moment. I’m hoping to see its use relaxed soon.
I must admit I’m also looking forward to us all getting rid of laryngoscopes and being able to get instruments that give us a direct view of the larynx. This is another antiquated thing we do. I’m not sure why we continue to use instruments that don’t give us the best chance of performing this all important procedure.
Peter
good points Peter. It does seem odd with our available technology that we still only use more advanced airway devices when we get in trouble. Using a laryngoscope is almost like an old school right of passage.
Arnie
I also think the concept of the assistant initiating any maneuver (cricoid or BURP) on their own without initial guidance from the operator is a flawed concept particularly in the ED setting.
In theatre where anaesthetic techs do this many times a day, they may over time develop a reasonable idea of how to apply pressure in a way that might generally be of benefit to the intubator. However a particular ED nurse assisting an intubation once every month would likely be highly unreliable and ineffective in their pressure and direction application.
So particularly in ED, it seems logical and appropriate that the intubator should initiate the pressure (while looking down the airway) and then have the assistant maintain it.