Education

The Sellick Manoeuvre: maybe you’re doing it wrong…
I was NEVER going to write a post about cricoid pressure (it didn’t appear at all in “101 Tips for Anaesthetic Nurses”).
It always seemed so…fundamental to practice as an Anaesthetic nurse that there was nothing left to say. Recent controversies in relation to the application of cricoid pressure in the #FOAMed world left me appreciating that this wasn’t the case, especially as the arguments presented didn’t seem to address all the shades of gray…

 

The Sellick Manoeuvre, better known as “Cricoid Pressure”, was first described in 1961 by Dr Brian Sellick in a paper titled Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia – preliminary communication.

The application of pressure to the cricoid cartilage was advocated by Sellick following use of the technique on 26 “high risk” patients during induction and intubation. In 23 cases, no signs of aspiration or regurgitation of gastric contents was found at all during intubation, and in 3 cases regurgitation of gastric contents followed the release of cricoid pressure.

In 1961 there was routine use of high tidal volumes (greater than 10ml/kg), trendelenberg (head down) positioning during intubation, and use of barbituate anaesthesia. (The original “planes of anaesthesia” model described the physiological effects of inhaled ether and was easily modified when barbituates came into practice. With current pharmacology practice has changed so much that neither physiological model has much relevance).

For the next 40 years, the Sellick Manoeuvre was accepted practice in Anaesthetics, Intensive Care and Emergency particularly for non-fasted patients or during rapid sequence intubations. This is despite changes to the practice of anaesthesia (and intubation techniques).

However, in the early 2000’s, some aspects of the use of the Sellick Manoeuvre were found to be not as simple as first thought.

Damage to the cricoid, lateral movement of the oesophagus (not posterior occlusion as intended) and triggering of reflexative relaxation of the lower oesophageal sphincter causing regurgitation may all be physiological responses to the application of the Sellick Manoeuvre (Yao, Fontes and Malhotra, 2012).

Not to mention the difficulty in visualisation of the glottis for the laryngoscopist as a result of mobilisation of the larynx, with associated reduction in first-pass intubation.

In fact, a related technique called BURP (Backward, Upward, Rightward Pressure) was developed to improve visualisation of the glottis and therefore improve the incidence of first-pass intubation.

 
(This man has some serious manoeuvres, but they’re not right either)
http://tomselleck.tv-website.com/
 

There has been controversy recently within the #FOAM world in relation to the routine application of the Sellick Manoeuvre during intubation and the evidence for or against. Much of the obvious preferences centre around the difficulty in obtaining first-pass intubation due to impaired visualisation. As the chance of aspiration from gastric regurgitation from all causes is reduced by successful intubation, improving the glottic view is the focus of this blog.

The prevailing thought-leader opinion seems to be passionately and firmly in the belief that the use of cricoid pressure is not justified in routine clinical practice. Opinion had been divided into “tribes”: eg. use of the Sellick Manoeuvre may be justified in anaesthesia, but not in intensive care or emergency. Interestingly, College Fellowship exams of all three colleges require that the Sellick Manoeuvre be applied (or at least considered) for intubation scenarios.

Academia (somewhat more staid than #FOAM) seems firmly out to lunch on the matter. Several sources suggest the use of the Sellick Manoeuvre can neither be recommended nor discouraged, citing benefits, drawbacks, and unknowns.

So where does that leave us?

Before throwing the baby out with the bath water, it might be good to look at what the Sellick Manoeuvre actually involves.

Importantly, Sellick’s description of the technique specifies that pressure should be applied via the index finger, after the cricoid carilage has been palpated between the thumb and the 2nd finger (Sellick, 1961: 405). The original Sellick article does not specify which hand should be used or on which side of the patient the person applying pressure should stand. The thumb and two finger technique was the method I was taught, using the right hand (I’m very left handed), standing on the patient’s right.

The Sellick Manoeuvre was one of the first things I learned as a junior Anaesthetic nurse.I was taught by an Anaesthetic nurse, not by an Anaesthetist. Successful demonstration of Cricoid Pressure during a rapid sequence induction was the end point of my preceptorship in Anaesthetics (after a shift and a half).

Looking after the airway is ultimately the Anaesthetist’s responsibility, but it is also the primary reason for the Anaesthetic nurse’s role. If you ask them during their more honest moments, most Anaesthetic nurses will tell you that they don’t really work that hard for their wages. Except during emergencies such as difficult airways. It’s what they have to know, in order to appropriately do, and when.

Over time I have had many opportunities to apply cricoid pressure during difficult airways for prolonged periods. When tired, it is natural to drag your hand (and the larynx) towards you. This can make a difficult airway harder. The last thing you want is to be responsible for a difficult airway. This is your incentive to communicate with the laryngoscopist, to find out what the view of the larynx is like, to make adjustments.

Since I started, I have seen a variety of Anaesthetists, Intensive Care and Emergency specialists and Senior Registrars demonstrate Cricoid Pressure to junior nurses and residents, or attempt to assist each other…

…and they don’t do it very well.

It’s kind of surprising. Anyone other than another Anaesthetic nurse seems to stand either side of the patient or uses either hand, or uses more digits than thumb and first two fingers. Some just…mash…

The lack of practice, consistency and established communication between intubator and assistant mean that it is difficult to know if applying pressure to the cricoid is achieving anything.

It means it is difficult to know if the person applying pressure is moving the larynx laterally, or whether the patient has a deviated trachea.

It means it is difficult to know if the person applying cricoid pressure is applying enough or too much pressure (and the lack of standardisation in technique means it is near impossible to ever ascertain what too little or too much even means).

I’m not suggesting for a moment that there are arcane skills amongst Anaesthetic nurses that no-one else can learn. But I am suggesting that if a group of professionals perform something like the Sellick Manoeuvre repeatedly and as consistently as possible and we still don’t know if it helps or not…

 

Then have it both ways…

Assess the patient and the conditions. Is there another way? Do you and the person you ask to place pressure on the cricoid have the same expectations? Now is a good time to find out…

Put it on. Try it.

Assess the view. See the glottis? Left, right or anterior? Tell the person assisting.

If it helps, leave it on.

If it doesn’t help, you can always take it off.

 

 

 

 

 

 

Bhatia, N.; Bhagat, H.; Sen,I. (2014) Cricoid Pressure: Where do we stand? Journal of Anaesthesiology Clinical Pharmacology Jan-Mar; 30(1): 3–6.

Sellick, B.A. (1961) Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia – preliminary communication. Lancet (2): 404-406 accessed via www.hneed.com/storage/Original%20Sellick%20Article%201961.pdf

Yao, F.F.; Fontes, M.L.; Malhotra, V. (2012) Intraoperative Management in Yao and Artusio’s Anesthesiology: Problem-Oriented Patient Management (7th Edition). Lippincott Williams & Wilkins. accessed via https://www.inkling.com/store/book/yao-artusio-anesthesiology-fonte-malhotra-7th

 

 

 

 

 

 

 

 

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The Magic Numbers: The Soldier’s 5 of Arterial Blood Results (Lesson 1)

So you want to interpret your patient’s arterial blood results but it seems a lot to learn and you’re not sure where to start?

Here’s the Soldier’s 5 version:

 

  1. 35 and 45 are the two ‘Magic’ numbers to remember
  2. pH should be 7.35 to 7.45. Lower than 7.35 is acidotic, greater than 7.45 is alkalotic (determining a respiratory or metabolic cause is a bit more complicated – see point 2)
  3. pCO2 should be 35 mmHg to 45 mmHg. Lower than 35 mmHg can drive a respiratory alkalosis, higher than 45 mmHg can drive respiratory acidosis (if pCO2 is normal then a deranged pH has a metabolic cause or is compensated)
  4. Sodium (Na) should be 135 mmol/L to 145 mmol/L. Lower than 135 is hyponatraemia, higher than 145 is hypernatraemia
  5. Potassium (K) should be 3.5 mmol/L to 4.5 mmol/L.(*) Lower than 3.5 is hypokalaemia, higher than 4.5 is hyperkalaemia.

 

 

Interpreting blood results isn’t something that nurses should be afraid of. Don’t be afraid to have a go – talk to the staff you’re working with and ask them to help. Practice makes perfect.

 

If you think you’ve found something abnormal on your patient’s blood work, report it. In the worse case, it’s a great learning opportunity.

 

 

(*) some texts suggest a potassium of 5.2 mmol/L is the upper end of normal.

 

The values listed for Sodium and Potassium are the blood values – intracellular (or cytosol) values are almost perfectly reversed. This prevents osmosis of water into the cell.

 

 

A Soldier’s 5 is good for Clinicians, too

I spent some 6 years as an Army reservist in the Australian Army. Several aspects of my time (and training) have helped me in my career in both Anaesthetic and Intensive Care nursing. I’ll address some of these in future posts.

 

Perhaps the most relevant of these is the concept of the “Soldier’s 5”. It is a choice of 5 seconds, 5 minutes or 5 points that a soldier needs to know NOW.

An example might be using a new weapon:

  1. the pointy end (towards the bad guy)
  2. the safety (how not to hurt yourself)
  3. the trigger (how to actually fire the thing)
  4. The aiming reticle (how to aim it)
  5. Where the ammunition goes and how to re-attach magazines (how to keep the thing going)

Of course in the real world, a soldier would ideally have lessons on new equipment before heading into battle.

 

Much like healthcare.

 

The benefit of the “Soldier’s 5” is that the method can be used from simple points with new practitioners through to more complex tasks with experienced practitioners.

 

A clinical example might be:

 

  1. Synchronous Intermittent Mandatory Ventilation (SIMV) is a form of positive pressure ventilation
  2. SIMV requires the patient breathe through an ETT
  3. It can be volume or pressure controlled (set volume OR pressure)
  4. SIMV allows a set number of breaths/minute but will “Synchronise” with spontaneous breaths
  5. SIMV generally allows PEEP and Pressure Support adjustment

 

It works with auditory and kinetic learners, and the short points can be recorded by visual learners.

 

The “Soldiers 5” is generally highly repeatable: once used, the learner can rapidly become the teacher.

 

Of course, there is no scope for in depth understanding or for learner questioning, so a thorough follow up session relating theory to practice with an educator is recommended.