Background: Dexmedetomidine is a sedative promoted as having minimal impact on ventilatory drive or upper airway muscle activity. However, a trial recently demonstrated impaired ventilatory drive and induction of apneas in sedated volunteers. The present study measured upper airway collapsibility during dexmedetomidine sedation and related it to propofol. Methods: Twelve volunteers (seven female) entered this nonblinded, randomized crossover study. Upper airway collapsibility (pharyngeal critical pressure) was measured during low and moderate infusion rates of propofol or dexmedetomidine. A bolus dose was followed by low (0.5 μg · kg-1 · h-1 or 42 μg · kg-1 · min-1) and moderate (1.5 μg · kg-1 · h-1 or 83 μg · kg-1 · min-1) rates of infusion of dexmedetomidine and propofol, respectively. Results: Complete data sets were obtained from nine volunteers (median age [range], 46 [23 to 66] yr; body mass index, 25.4 [20.3 to 32.4] kg/m2). The Bispectral Index score at time of pharyngeal critical pressure measurements was 74 ± 10 and 65 ± 13 (mean difference, 9; 95% CI, 3 to 16; P = 0.011) during low infusion rates versus 57 ± 16 and 39 ± 12 (mean difference, 18; 95% CI, 8 to 28; P = 0.003) during moderate infusion rates of dexmedetomidine and propofol, respectively. A difference in pharyngeal critical pressure during sedation with dexmedetomidine or propofol could not be shown at either the low or moderate infusion rate. Median (interquartile range) pharyngeal critical pressure was-2.0 (less than-15 to 2.3) and 0.9 (less than-15 to 1.5) cm H2O (mean difference, 0.9; 95% CI,-4.7 to 3.1) during low infusion rates (P = 0. 595) versus-0.3 (-9.2 to 1.4) and-0.6 (-7.7 to 1.3) cm H2O (mean difference, 0.0; 95% CI,-2.1 to 2.1; P = 0.980) during moderate infusion of dexmedetomidine and propofol, respectively. A strong linear relationship between pharyngeal critical pressure during dexmedetomidine and propofol sedation was evident at low (r = 0.82; P = 0.007) and moderate (r = 0.90; P < 0.001) infusion rates. Conclusions: These observations suggest that dexmedetomidine sedation does not inherently protect against upper airway obstruction.
- sedation procedure
- upper respiratory tract