Update on new DAS guidelines 2015

In the foreword to NAP4 on page 5, we learn that life’s hardest experiences are like unpolished diamonds: tough; First comes the exam, then the lesson to be learned, says Martin Bromiley. At the excellent Scientific Meeting in Stratford it was apparent how DAS has seized the initiative on learning from past mistakes: with the aim of improving existing systems, to limit suboptimal human performance during the manipulations of a person’s airway that can risk compromising its integrity. In short, there must never be another life lost in the manner of Elaine Bromiley.
 
Our proposed revised guidelines for tracheal intubation due for release in 2015 will be examined across the globe for their wisdom and clarity, so we should ensure that every aspect has been cut and polished to the best of our collective ability. Here are my thoughts.
Working backwards from plan D: placement of a front of neck (FoN) airway should be a readily-made decision, being a previously well-rehearsed task undertaken with equipment that the whole team is familiar with.  Prof Levitan highlighted that excellent performance during stressful procedures is achieved through practising all of the individual fundamental steps until one gains a demonstrable competence. Clearly that competency will need to be maintained through regularly repeated practice; all of which seems like being licensed to fly a particular plane.
 
I now refer to the survey of the membership that I carried out with regard to their experience of the cannot-ventilate cannot-intubate (CICV) scenario (poster 106).  An intention to carry out tracheal intubation existed in the majority of the reported CICV cases which happened in an anaesthetic room in 45%.  In 30% the venue was theatre, perhaps suggesting that an airway difficulty had been anticipated.  The logbook data supplied by DAS members suggests that 8% of all cases undergo urgent tracheal intubation, from which we could estimate how many RSIs are performed annually.
CICV was resolved in 42% by a FoN airway. (Not all attempts at FoN airway succeeded as it was attempted in 56%).  Four methods were equally popular, but in 4 out of 10 occasions the access was achieved by a consultant surgeon. We will therefore need to consider, before those needs arise, who is best placed to carry out the didactic FoN access with the didactic device; and whether our anaesthetic room is big enough – so don’t overlook the usual WHO briefing just because it’s an urgent case!
 
Moving on to plan C, we really need to decide if waking up (or more simply restoring spontaneous respiration in) the patient is truly a realistic option that could prevent an adverse outcome, or in reality naive.
 
The new guidelines introduce the concept of using rocuronium instead of suxamethonium for neuromuscular blockade (NMB).  We can be more confident of sugammadex achieving pharmacological reversal of the NMB produced by rocuronium than of the spontaneous regression of suxamethonium in a heterozygote: and let’s face it; the only time that it matters that the sux hasn’t worn off is when you want it to.  The FDA has so far declined to allow the novel sugammadex into US medicine, but that may change soon and one imagines that the roc-sugammadex concept will prove popular in high BMI cases, and its role in RSI examined before long.
If we want to wake patients up, rather than just restore spontaneous respiration, then we should use hypnotics within the induction sequence that would enable us to do so. Midazolam in suitable dosage followed by alfentanil (15 – 30 micrograms/kg) would achieve this, but some volunteer studies might be required, and outside of Critical Care / Anaesthetic practice use of flumazenil attracts attention as a possible WHO never event ( number 10 ), which might account for the rarity of routine reversal of midazolam in clinical practice.  Neither the manufacturer of remifentanil, nor the manufacturer of naloxone have explored how much naloxone is required to antagonise remifentanil.
As an aside, in attempting to define an induction sequence that facilitated tracheal intubation in the absence of neuromuscular blockade, in Reading in 2001 we examined midazolam 70 micrograms/kg followed by remifentanil 2mcg/kg and propofol 1.25mg/kg.  Laryngoscopy and passage of a tracheal tube was easy enough, but inflation of the cuff balloon provoked coughing in a significant proportion.  Interestingly thiopentone and suxamethonium did not provide entirely satisfactory conditions in the control group. Warner OJ et al. British Journal of Anaesthesia 2001; 85: 318P
 
Given the complexities associated with defining a set of drugs that can be readily antagonised in a wide range of patients, I think that “waking the patient up” cannot be reliably achieved, and nor can restoring respiration with sugammadex be guaranteed to prevent harm from enduring hypoxia in circumstances associated with an obstructed airway.
Conversely, for what it’s worth, Prof Pandit found in 2001 that the overall efficiency of bag-valve-mask ventilation in 30 patients was unchanged after exhibiting vecuronium 1mg/kg.  Goodwin MWP et al Anaesthesia 2003; 58: 60 – 63
In the CICV survey, when paralysis was absent in 10 cases a NMB was given, but onset of relaxation only improved the situation in 50%.  In short, making sure that the patient is fully relaxed seems necessary and if that doesn’t ameliorate matters, press on with the didactic FoN.
However, despite deferring considerations of an induction sequence compatible with prompt wake-up for the future, I still believe that DAS should define the drugs used for rapid sequence induction and tracheal intubation, and this will of course require discussion with other interested parties such as the OAA and ED physicians.  I suggest this because of the desirable aim to make every step in the process best practice.
Fentanyl is familiar but the onset time of 3 - 4 minutes deserves to be taken into account. Remifentanil properly requires dedicated infusion apparatus and onset is slightly slower than alfentanil, which is perhaps the ideal intravenous opioid to reduce the dose of propofol required for induction.  If we are going to use rocuronium, it could be given early in the sequence to promote the yet more rapid onset of a modest dose ( facilitating earlier reversal by sugammadex if found to be appropriate ) although it stings in a small vein (include lidocaine iv flush?) and a securely-established infusion of intravenous fluid would need to be confirmed beforehand.  High BMI patients present a challenge, but it is possible to define that proximal occlusion at a point distant from the cannula causes flow to cease, commencing immediately once more on release.
 
It remains to be seen if the videolaryngoscope will render the facility afforded by the Intubating LMA redundant.
DAS now seems to lie at the centre of clinical excellence, the very breath of anaesthetic practice. The publication of the revised guidelines regarding the prime skill we claim to possess will put DAS very much in the spotlight, let’s make sure there are no flaws in this gem.
John Mackenzie