A very important aspect of inducing a patient under general anaesthesia is securing an airway for intraoperative ventilation. Expert airway management is an essential skill in anaesthetic practice for allowing oxygenation, ventilation and anaesthetic gas delivery.[1] Tracheal intubation remains the most common approach to airway management.

The general sequence of induction of anaesthesia is administration of an analgesic and IV anaesthetic agent after which facemask ventilation is tested and lastly a neuromuscular blocking agent is administered. Because of possible development of airway catastrophes, muscle relaxants have long been recommended to be administered after confirming adequate face mask ventilation, without any scientific validation of this principal.

The rationale for delaying administration of muscle relaxant is the belief that if face mask ventilation in an anaesthetised non-paralysed patient is ineffective, the patient can be reversed and an alternative airway management can be considered. Life threatening hypoxemia can therefore, theoretically, be averted.[2]

 In 2008, Calder and Yentis argued against the practice of checking facemask ventilation. They questioned the validity and safety of this practice. The argument against the practice was that if neuromuscular blocking agent is delayed on the pretext of assessing facemask ventilation, the anaesthetist has already lightened the plane of anaesthesia for the said patient and caused difficult ventilation. [4]

If facemask ventilation is difficult or impossible in an anaesthetised non-paralysed patient there are two courses of action that may be followed. First course could be to withhold all anaesthetic agents and allow the plane of anaesthesia to become superficial causing the spontaneous return of respiration. The second approach is to administer a neuromuscular blocking agent (Suxamethonium or rocuronium) to facilitate intubation and ventilate the patient, but, if even intubation fails, patient can be reversed and spontaneous respiration awaited. Both approaches seem logical as long as spontaneous respiration is achieved before severe hypoxemia develops. The limitation here, however, is that the pre-existing anatomic problems which were causing difficult facemask ventilation in the first place have been worsened with administration of anaesthetic agents which led to collapse of the upper airways. Therefore, the chances of achieving spontaneous respiration in an apnoeic, anaesthetised patient before severe hypoxemia develops is minute. [4]

At this crossroads the rationale of the practice of delayed administration of neuromuscular blocking agent becomes questionable.

Investigators have reported either no effect or improvements in mask ventilation difficulty scores and exhaled volumes after neuromuscular blocking drugs have been administered. 

This study uses cis-atracurium as the non-depolarising neuromuscular blocking agent. It is four to five times as potent as atracurium and does not cause histamine release. It provides intubating conditions in a dose of 0.10 - 0.15mg/kg within 2 minutes and results in blockade of intermediate duration.