Fig. 3. Upper airway critical closing pressure (Pcrit) in awake healthy volunteers at baseline before neuromuscular blockade, with impaired neuromuscular transmission and a target train-of-four (TOF) ratio of 0.5, after spontaneous recovery of the TOF ratio to unity, and after injection of neostigmine/glycopyrrolate. Upper airway closing pressure significantly increased during partial neuromuscular blockade and was still abnormal even with recovery of the TOF ratio to unity (i.e., before injection of neostigmine/glycopyrrolate) (P = 0.01 vs . baseline). However, upper airway closing pressure significantly increased after injection of neostigmine/glycopyrrolate. Data are mean ± SD from 10 awake volunteers. *P = 0.002 versus baseline; # P = 0.02 versus recovery.