Sedation During Noninvasive Mechanical Ventilation With Dexmedetomidine or Midazolam: A Randomized, Double-Blind, Prospective Study

BACKGROUND: Effective noninvasive mechanical ventilation (NIV) requires a patient to be comfortable and in synch with the ventilator, for which sedation is usually needed. Choice of the proper drug for sedation can lead to improved clinical outcomes. OBJECTIVE: The aim of this study was to compare the effectiveness of dexmedetomidine and midazolam on sedation and their effects on hemodynamics and gas exchange. METHODS: In this randomized, double-blind study, intensive care unit patients with acute respiratory failure due to acute exacerbations of chronic obstructive pulmonary disease undergoing NIV were equally randomized to receive a loading dose of 1 mu g/kg IV dexmedetomidine or 0.05 mg/kg midazolam over 10 minutes followed by a maintenance infusion of 0.5 mu g/kg/h dexmedetomidine (group D) or 0.1 mg/kg/h midazolam (group M). The following parameters were measured by a blinded clinician at baseline and 1, 2, 4, 6, 8, 12, and 24 hours after the loading dose was administered: Ramsay Sedation Score (RSS), Riker Sedation-Agitation Scale (RSAS), Bispectral Index (BIS), arterial blood gases, and vital signs. A second blinded investigator determined dosing changes according to the outcome of maintaining a target sedation level of RSS 2 to 3, RSAS 3 to 4, and BIS >85. RESULTS: A total of 45 patients were assessed for enrollment in the study; 4 did not meet the inclusion criteria and 1 refused to participate (men/women 19/21; mean age 58/60; all patients were receiving bronchodilators, steroids, antibiotics, and mucolytics). In both groups (n = 20), RSS significantly increased and RSAS levels and BIS values significantly decreased after the loading dose, compared with baseline (P < 0.05). RSS levels were significantly lower beginning at 4 hours in group D compared with group M (P < 0.05). RSAS levels were not significantly different between the 2 groups in the first 8 hours. However, RSAS levels were significantly higher at 8 hours after the loading dose was administered in group D compared with group M (P < 0.01). BIS was significantly higher in group D throughout the study period (P < 0.05). Respiratory rates and gas exchange values were not significantly different between the 2 groups. The number of times a change in infusion dose was needed was significantly lower in group D (2 patients with 1 change each) than in group M (3 patients with 1 change, 1 patient with 2 changes, and 3 patients with 3 changes each) (P < 0.01). CONCLUSIONS: Dexmedetomidine and midazolam are both effective sedatives for patients with NIV. Dexmedetomidine required fewer adjustments in dosing compared with midazolam to maintain adequate sedation. (Curr Ther Res Clin Exp. 2010; 71:141-153) (C) 2010 Excerpta Medica Inc.