Have you ever wondered whether we should mask ventilate before giving muscle relaxant? I know we were taught that we should attempt to mask ventilate first. But is this evidence based? The answer is that this practice is really not evidence-based. There is a growing body of evidence suggesting that the NBD should be given first to facilitate mask ventilation. The old school of thoughts is that spontaneous ventilation may be possible if difficult mask ventilation is identified. However, it would be difficult for the patient to recover spontaneous ventilation before hypoxia develops.
The pros of giving muscle relaxant before attempting mask ventilation:
- Muscle relaxants improve face mask ventilation and facilitate tracheal intubation by reducing the muscle tone and airway reflexes. Good intubation conditions could be achieved earlier if NBD is given earlier (Sachdeva et. al, 2014).
- You don’t lose precious time to attempt to mask ventilate when you know mask ventilation would be difficult on the patient, e.g obese patient, patients with known OSA, patient with thick neck etc. By giving muscle relaxant early, it makes face mask ventilation easier. Therefore, it decreases the likelihood of developing hypoxia due to unable to mask ventilate (Calder et al 2008 and Lieutaud et al).
One may argue that you may have burnt the bridge if you run into “the cannot ventilate cannot intubate situation”. Again, returning of spontaneous ventilation is almost impossible when hypoxia occurs due to difficulty in mask ventilation. In addition, NBD facilitates mask ventilation and achieves good intubation condition. We do need airway carefully assess patient’s airway preoperatively. If difficult ventilation or intubation is expected, a backup plan should be chosen if you can’t ventilate and intubate. We know that there is no single airway technique that would work for every single airway that we encounter, muscle relaxant is often the solution than the problem itself. We don’t do things as we were told. We do things based on evidence-based practice.
Please leave a comment as I would like to know your thoughts on this topic.
1. Calder I, Yentis SM. Could ‘safe practice’ be compromising safe practice? Should anaesthetists have to demonstrate that face mask ventilation is possible before giving a neuromuscular blocker? Anaesthesia 2008; 63: 113–5.
2. Sachdeva R, Kannan TR, Mendoca C, Patteril M. Evaluation of changes of tidal volume during mask ventilation following administration of neuromuscular blocking drugs. Anaesthesia 2014; 69: 826–32
3. Lieutaud T, Billard V, Khalaf H, Debaene B. Muscle relaxation and increasing doses of propofol improve intubating conditions. Canadian Journal of Anesthesia 2003; 50: 121–6