Sux vs Roc – why Sux still holds an edge in RSI

The debate over  the optimal paralytic in RSI continues in my view, albeit many consider its over and declared Rocuronium to be the clear winner. My aeromedical service has replaced vecuronium with rocuronium but still kept suxamethonium/succinylcholine, mainly due to familiarity for it in RSI by all our doctors and nurses.

But this months anaesthesia journal reading revealed another gem from Japanese authors

Effects of Muscle Relaxants on Mask Ventilation in Anesthetized Persons with Normal Upper Airway Anatomy

Aya Ikeda, M.D.,* Shiroh Isono, M.D.,† Yumi Sato, M.D.,‡ Hisanori Yogo, M.D.,‡ Jiro Sato, M.D.,§

Teruhiko Ishikawa, M.D.,† Takashi Nishino, M.D.

Anesthesiology ,Sept 2012.

ABSTRACT

Background: Recent studies suggest advantages of muscle relaxants for facemask ventilation. However, direct effects of muscle relaxants on mask ventilation remain unclear because these studies did not control mechanical factors influencing ventilation. We tested a hypothesis that muscle relaxants, either rocuronium or succinylcholine, improve mask ventilation.

Methods: In anesthetized adult persons with normal upper airway anatomy, tidal volumes during facemask ventilation were measured while maintaining the neutral head and mandible positions and the airway pressures of a ventilator before and during muscle paralysis induced by either rocuronium (n  14) or succinylcholine (n 17). Tidal volumes of oral and nasal airway routes were separately measured with a custom-made oronasal portioning full facemask. Behavior of the oral airway was observed by an endoscope in six additional subjects receiving succinylcholine.

Results: Total, oral, and nasal tidal volumes did not significantly change at complete muscle paralysis with rocuronium. In contrast, succinylcholine significantly increased total tidal volumes at 60 s after its administration (meanSD; 4.22.1 vs. 5.4  2.6 ml/kg, P  0.02) because of increases of ventilation through both airway routes. Abrupt tidal volume increase occurred more through oral airway route than nasal route. Dilation of the space at the isthmus of the fauces was endoscopically observed during pharyngeal fasciculation in all six subjects.

Conclusions: Rocuronium did not deteriorate facemask ventilation, and it was improved after succinylcholine administration in association with airway dilation during pharyngeal fasciculation. This effect continued to a lesser degree after resolution of the fasciculation

OKAY? I am sure some of you are saying : SO WHAT Minh? My take home messages are the attention to fine details in airway management and are reinforced by this article.

  1. Note the predominant nasal route during face mask ventilation. IMPORTANT to note as placing oral and nasal airways during difficult BVM will help!
  2. Note how suxamethonium not rocuronium dilated the pharyngeal airway during fasciculation. IMPORTANT TIP – a more OPEN AIRWAY GIVES YOU AN EDGE IN THE CRITICAL INTUBATION

CAVEATS : The study was performed in an elective setting. No airway maneuvers or optimal positioning were performed. Dose of Rocuronium was 0.6mg/kg and Sux 1mg/kg but neuromuscular monitoring was performed until Train of four stimulation response was absent.

12 Comments
  1. Interesting Minh. I wonder what the results would have been if the roc dose was closer to the acknowledged induction dose of 1.2mg/kg?

    We are just starting to have the roc vs sux argument. We currently have the choice of roc (1.2mg/kg induction, 0.6mg/kg ongoing) or sux (1.5mg/kg). Starting to think about just roc.

    Cheers,

    Ben.

  2. Hi Minh,

    This is a very contentious issue (as you know). We’ve done some work on BBs around this with one from the Southern Hemisphere http://www.bestbets.org/bets/bet.php?id=2280 and more recently the fabulous Dr Natalie May’s article in the EMJ on the same subject http://www.bestbets.org/bets/bet.php?id=2268

    Whenever we publish on this we always get lots of comments from our anaesthetic colleagues which is always great to see, but does demonstrate the passions that surround this.

    Good luck on the post, I’m sure there are a number of airway colleague who may choose to disagree. I understand that there are letters in the pipeline about Natalie’s review in the EMJ and I’d love to hear your opinions on the subject.

    What do you routinely use? Are a sux or roc chap? Or (like me) does it rather depend on the circumstances.

    vb

    S

  3. Hi Ben, you joining the Google Hangout in critical care in 50 minutes? Search for Dr Haney Mallemat on google plus..might talk to you then!
    I dont think the results would have been any different to be honest as they checked for TOF absent response with both sux and roc before testing the ventilation volumes with BVM.

    I have been doing roc only RSI for a while now with no issues. However many colleagues are nervous to abandon sux in RSI. This study suggests there is at least a ventilation benefit via airway patency improvement with Sux at a common RSI dose

    I still use Sux for RSI of neurologic patients like status epilepticus or those who need repeated neuro exam soon after intubation. And now if it looks like a tricky airway partic BVM, there is a benefit to revert to using Sux for your RSI.

  4. Minh

    This is a straw man paper, dosing roc at 0.6mg/kg was bound to produce no improvement. A larger study looking at roc 1.2mg/kg would have made better reading.

    Roc still rocks my world.

    Loving your work

    Dean

      • Read the paper carefully
        Roc was given then TOF tested till lost then measurements taken , not just at 60s . Sux given then after 60s , measurements taken . Their lit review cites similar past findings for roc vs sux and face mask ventilation .

  5. Ive been following this debate for some time now and it always strikes me how the superiority of one agent over another is argued. Objectivelly, the evidence for Roc is compelling and makes sense in the prehospital environment. Many of the quoted reasons why Sux should continue to be preferred over Roc do not spk adequatelly to the prehospital environment and are written by people from an in-hospital perspective (where clearly the bulk of their anaesthetic / emergency experience is). And most important of all: People are scared of change. The mere suggestion of anything that challenges convention sends people into a complete spin. In my experience, every time one scratches below the surface of convention, one is often pleasantly surprised at how poorly conventional argumets are supported and argued.

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