The investigators are aiming to show that administration of a neuromuscular blocking agent is "safe" with respect to mask ventilation. In other words, that the average exhaled tidal volume per breath over one minute after the administration of a NMBD will be non-inferior to that measured before their administration. At the time of the planning of this study, no studies had reported a mean±SD for tidal volumes before and after NMBDs. However, based upon a prior comparative trial of two different mask-hold techniques, the standard deviation (SD) of the average exhaled tidal volume after induction of anesthesia, using the anesthesia ventilator and a two-hand jaw-thrust mask hold technique was 130 mL. With the equivalence limit, d, set as 50 mL per breath, with a significance level (α) of 2.5% and a power (1-β) of 95%, a total sample size of 208 patients per group (before and after NMBD for a total sample of 416 study periods) were required. In other words, if there is truly no difference between the mask ventilation before and after NMBD, then 208 patients, each as their own control, are required to be 95% sure that the limits of a 2-sided 95% confidence interval will exclude a difference in means of >50 mL.