Using Muscle Relaxant with LMA

Have you ever used muscle relaxant with LMA? Is muscle relaxant contraindicated with the use of LMA? We all know what is the answer in the textbook: the use of muscle relaxant in LMA case would not be supported. But recent studies have shown that the use of muscle relaxant with LMA cases are beneficial for several reasons.  One is to facilitate the placement of LMA by suppressing the coughing, gagging reflex. In addition, it appeared that the use of low-dose muscle relaxant could reduce the ventilation leak for mechanical ventilation with FLMA.  Lastly, on a morbidly obese patient, low dose muscle relaxant makes it easier to ventilate the patient.

I have been using 20mg succinylcholine to facilitate my LMA placement on the big muscular guy and I found that it was a lot easier to place it correctly with ease compared to without it. Lately, I started to use small dose of rocuronium 10mg on morbidly obese patient in some of the LMA cases. One of the attendings have taught me this trick and it worked wonders. I didn’t have to worry about desaturation due to inadequate tidal volume with PSV mode.

Do you also use muscle relaxant in your practice with LMA cases? Please let me know your thoughts and comments.



Effect of low dose rocuronium in preventing ventilation leak for flexible laryngeal mask airwayduring radical mastectomy. Gong YH, Yi J, Zhang Q, Xu L. Int J Clin Exp Med. 2015 Aug 15;8(8):13616-21. eCollection 2015.

Muscle relaxant effects on insertion efficacy of the laryngeal mask ProSeal(®) in anesthetized patients: a prospective randomized controlled trial. Fujiwara A, Komasawa N, Nishihara I, Miyazaki S, Tatsumi S, Nishimura W, Minami T. J Anesth. 2015 Aug;29(4):580-4. doi: 10.1007/s00540-015-1982-3. Epub 2015 Feb 10.

3 Comments Add yours

  1. D says:

    Interesting topic. I rarely use a NMB (muscle relaxant) with an LMA. I don’t think I have ever read in a textbook that use of a NMB is contraindicated with an LMA but am happy to be proven wrong about that. A multitude of factors would come into play on the decision, however. If difficulty inserting and sealing the LMA is the problem I think there are other issues in play. First, you cited the suppression of coughing and gagging. Those are anesthetic depth issues and have an easy solution – more propofol or mask ventilate with a volatile anesthetic agent until the depth required is achieved. Next, you mentioned leak with a FLMA, which are notoriously difficult to place and keep in place and I have now switched to use an AirQ LMA in place of the FLMA and have had good success. The return of spontaneous breathing is a huge plus with the initiation of an LMA as your primary airway. Therefore, I typically do not administer narcotics before induction, which might also allow for the use of more propofol. The return of spontaneous respiration is almost immediate in most cases when using propofol. Patient selection for an LMA is extremely important. I would hesitate to use an LMA or a morbidly obese patient in the first place. Relative hypoventilation is almost always an issue for morbidly obese patients with an LMA. However, I do not consider morbid obesity an absolute contraindication to use of an LMA. In any case, if there is a problem with placement due to high muscle tone and the ability to achieve a greater depth of anesthesia is limited for fear of hypotension, then a NMB agent would absolutely be in my arsenal of choices.

    I know everyone has a technique for LMA insertion that they think is the best but that’s because they don’t know mine, haha. Placement technique is a huge issue though. I don’t use rigid LMAs like the Supreme for a couple of reasons. First, if you have concern about gastric contents then an LMA is not the right choice for routine use. Second, the rigidity of the Supreme LMA does not accommodate anatomic difference in airway length and creates problems with achieving a good seal as a result. The AirQ, although pre-formed, is not as rigid but can be difficult to place although not as difficult and apt to dislodge as the FLMA. The best LMA for routine use is, hands down, the Classic. I inflate the LMA with 20-30 mls of air and test the pilot balloon. I then place the 20 ml syringe on the pilot balloon and let the pressure equilibrate, often having to remove the syringe and expel excess air and then reattach the syringe for the larger sizes (of course air volumes are lower for smaller sizes). I lubricate the entire LMA except for the orifice. I place the LMA just past the teeth, extend the head and use my left index finger to insure that the tip is flipped past the oropharynx. Once that is done I advance until the glottis is met, which you can tell by feel and depth, and the seating and seal is almost always perfect. Insuring the tip is correctly positioned with the finger prevents folding and twisting. I think this is just a semi-inflated variation of the original Dr. Brain technique.

    Just my thoughts after 20 years of anesthesia practice. Thanks for reading and please offer your thoughts.


    1. Behind The Drape says:

      Thanks Dave for your comments. It is funny in the NCE exam, one of the practice text question is the use of NMB is contraindicated. I think it traces back to when the LMA was originally designed for. I don’t normally use NMB on a regular basis, I use it more for rescue technique. Last week, i had a patient whose BMI is 37. I didn’t consider him as morbidly obese, but he was hyperventilating after returning to spontaneous breathing and started to desaturate. It was ESWL, a short procedure, so I didn’t want to convert to ET. I used 10mg Roc and it worked great. I was able to ventilate late with adequate tide volume and rate, and didn’t have to give reservsal at the end. It worked great. I would say the NMB is more for rescue with LMA cases.


  2. Thanks for this
    I’m a GP Anaesthetist out in rural South Australia, but with only 1.5 years of anaesthesia experience.
    I had a middle aged fellow for exploration of a deep wrist laceration today that required a GA (or a great nerve block which I didn’t have equipment or expertise for).
    He smoked 25/day and drank 6-12 beers / day.
    I decided to use Roc electively to facilitate LMA placement (I felt he would be one to take 200 Fent and 600 Propofol and still require gassing down further) and reduce airway irritability and facilitate initial ventilation to achieve adequate depth

    Induction was with fentanyl 150, propofol 300 and roc 20
    I was surprised that by 20 minutes he was already spontaneously ventilating with adequate tidal volumes.

    Granted it was very minor surgery, so very limited stimulus from the surgery, but I felt the roc worked well.


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