In summary, patients who received dexmedetomidine:

Benefits in NNT

  • 17% lower risk of intubation requirement
  • 19% lower risk of delirium
  • 2.4 fewer ICU days
  • 17% lower risk of pneumonia
  • 1 in 6 were helped (lower risk of intubation)
  • 1 in 6 were helped (lower risk of delirium)
  • 1 in 6 were helped (lower risk of pneumonia)

Harms in NNT

  • 23% higher risk of bradycardia
  • 18% higher risk of hypotension
  • 1 in 4 were harmed (bradycardia)
  • 1 in 5 were harmed (hypotension)

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Source: Lewis K, Piticaru J, Chaudhuri D, Basmaji J, Fan E, Møller MH, et al. Safety and Efficacy of Dexmedetomidine in Acutely Ill Adults Requiring Noninvasive Ventilation: A Systematic Review and Meta-analysis of Randomized Trials. Chest. 2021 Jun;159(6):2274-2288.

Study Population: 738 critically ill patients requiring noninvasive ventilation

Efficacy Endpoints: Need for intubation, delirium, intensive care unit length of stay, pneumonia, mortality

Harm Endpoints: Bradycardia, hypotension

Narrative: Noninvasive ventilation (NIV) is an effective therapy for hypercapnic and hypoxemic respiratory failure and can reduce the need for intubation and mechanical ventilation.1 It may also reduce intensive care unit (ICU) length of stay, pneumonia, and mortality.2, 3, 4, 5, 6 However, NIV can be uncomfortable for patients due to the mask interface and respiratory pressures delivered, and over one-third of patients placed on NIV will experience agitation.7, 8 Intolerance to NIV typically requires intubation. A variety of interventions can be utilized to improve compliance with NIV, including medications such as dexmedetomidine, an α-2 agonist with sedative and analgesic effects.9 Current guidelines recommend the use of a non-benzodiazepine sedative such as propofol or dexmedetomidine in critically ill, mechanically ventilated adults, as these medications may improve delirium, ICU length of stay, and duration of mechanical ventilation.10

The systematic review summarized here included randomized trials (RCTs) of adults > 18 years admitted to the ICU with acute respiratory failure treated with NIV.11 Authors included studies in which the intervention group received dexmedetomidine in the ICU (any dose, initiation day, route, frequency, formulation, administration, and duration) and the control group received a different form of pharmacologic sedation or placebo. Studies of patients treated chronically at home with NIV who were admitted to the ICU, patients supported with NIV for post-extubation respiratory failure, and patients with alcohol withdrawal were excluded. Outcomes included need for intubation and mechanical ventilation, delirium, ICU length of stay, mortality, duration of NIV, pneumonia, bradycardia, and hypotension.

The authors of the meta-analysis identified 12 RCTs comprising 738 ICU patients.11 The mean age was 61.5 years and 36% of patients were women. Four trials included 200 patients with baseline agitation or delirium. Four trials provided an intravenous (IV) loading dose of dexmedetomidine, 2 trials did not report a loading dose, and 6 trials used IV infusion only. Most studies used a dosing range of 0.2-0.7 micrograms/kilogram/hour IV, though 3 trials used a wider range of dosing (0.2-2 micrograms/kilogram/hour). Six RCTs used placebo as the comparator, while 2 used haloperidol, 3 used midazolam, 1 used propofol, and 1 utilized sedation according to the ICU team.

Dexmedetomidine reduced the need for intubation and mechanical ventilation (Relative risk [RR]: 0.54; 95% confidence interval [CI]: 0.41-0.71; absolute risk difference [ARD]: 17%; number needed to treat [NNT]: 6; moderate certainty), delirium (RR: 0.34; 95% CI: 0.22-0.54; ARD: 19%; NNT: 6; moderate certainty), ICU length of stay (mean difference [MD]: 2.40 days fewer ICU days; 95% CI: 3.51-1.29, low certainty), and pneumonia (RR: 0.30; 95% CI: 0.17- 0.52; ARR: 16.7%; NNT: 6; moderate certainty). Dexmedetomidine did not impact survival (low certainty). However, it increased the risk of bradycardia (RR: 2.80; 95% CI: 1.92-4.07; ARD: 23%; number needed to harm [NNH]: 4; moderate certainty) and hypotension (RR: 1.98; 95% CI: 1.32-2.98; ARD: 18%; NNH: 5; moderate certainty).11

Caveats: While 12 RCTs were included, not all trials reported all the outcomes. In particular, the data pertaining to mortality were limited. The low number of patients who died in the ICU resulted in imprecision in reporting this outcome. Second, due to the relatively small population of 738 patients, results may be associated with a type I or type II error due to overestimation or underestimation of the statistical significance of the results, respectively. Third, authors were unable to complete analysis of several prespecified outcomes such as hypertension and subgroup analyses by age and dose of dexmedetomidine due to limited patient-level data. This also limited subgroup analyses including patients with and without agitation or delirium at the time of enrollment. Fourth, the systematic review was not able to generate a funnel plot for publication bias due to the small number of trials. Of note, dexmedetomidine was associated with an increased risk of bradycardia and hypotension. Overall, bradycardia occurred in 78 of 236 patients and hypotension in 75 of 232 patients receiving dexmedetomidine. However, treatment for bradycardia and hypotension varied significantly in the included studies, including decreased dexmedetomidine infusion, vasopressor or inotrope infusion, or no intervention, with not all studies reporting treatment for bradycardia and hypotension. Finally, there was significant statistical heterogeneity concerning ICU length of stay, as well as clinical heterogeneity concerning the other outcomes. While the other outcomes demonstrated little to no statistical heterogeneity, the underlying etiology requiring the use of NIV differed in the included studies, raising concerns of significant clinical heterogeneity and threatening the validity of the results.

Based on the presented evidence, we have assigned a color recommendation of Yellow (Data Inadequate) for use of dexmedetomidine in critically ill patients undergoing NIV. Further data from larger trials are needed to provide a more accurate effect size and to evaluate the ideal dosing, as well as studies comparing dexmedetomidine with other agents. Additional research is also needed to assess the effects on important subgroups such as patients with pre-existing delirium or agitation, elderly patients, and those separated by etiology of acute respiratory failure (e.g., hypoxemic, hypercarbic).

The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.

Author: Brit Long, MD; Michael Gottlieb, MD
Supervising Editors: Shahriar Zehtabchi, MD

Published/Updated: August 19, 2021

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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