Original recordings of simultaneous pharyngeal manometry, nasal pressure, and nasal/oral airflow during spontaneous saliva swallows with the respiratory-phase patterns E-E, that is, inspiration-expiration-swallow apnea-expiration at baseline recordings (A), E-E at recordings 10 min after infusion of morphine (B), E-I, that is, the respiratory-phase pattern inspiration-expiration-swallow apnea-inspiration at recordings 10 min after infusion of morphine (C), and E-I at recordings 30 min after infusion of midazolam (D). Manometry recordings made at tongue base (TB), upper and lower pharyngeal transducer, and upper esophageal sphincter (UES) levels. “Swallow” indicates duration of pharyngeal swallowing. Apnea during pharyngeal swallowing, indicated “Swallow apnea,” was detected as an oscillating signal (zero airflow) from the gas flow discriminator indicated “Oral and nasal airflow.” In pharyngeal manometry, the dotted baseline represents pressure = 0 mmHg. E-E = the respiratory-phase pattern with inspiration-expiration-swallow apnea-expiration; E-I = the respiratory-phase pattern with inspiration-expiration-swallow apnea-inspiration; Mi = midazolam; Mo = morphine; Mo_10min/Mi_10min, Mo_30min/Mi_30min = recordings 10 and 30 min after infusion of morphine/midazolam was stopped; Ph Up and Ph Low = upper and lower pharyngeal transducer level; Ph Up-start and Ph Low-start = onset of pressure rise at the upper and lower pharyngeal transducer level; TB-start = onset of pressure rise at the tongue base; UES-start = onset of pressure rise at the UES; UES relaxation-start = onset of relaxation of the UES.