Highlights
The 4D trial provides robust evidence for the use of dexmedetomidine in managing hyperactive delirium among non-intubated patients. Key takeaways include:
- Dexmedetomidine significantly improved a joint primary endpoint encompassing agitation duration, delirium duration, and the risk of intubation.
- The median duration of agitation was reduced by approximately 50%, falling from 2 hours in the placebo group to 1 hour in the dexmedetomidine group.
- The study was terminated early due to clear evidence of efficacy at the preplanned interim analysis.
- Safety profiles regarding bradycardia and hypotension were comparable between the dexmedetomidine and placebo groups in this specific cohort.
The Clinical Challenge of Hyperactive Delirium in Non-Intubated Patients
Hyperactive delirium in the intensive care unit (ICU) represents a critical challenge for clinicians. Characterized by agitation, hallucinations, and often combative behavior, it poses immediate risks to patient safety, including accidental self-extubation, removal of invasive lines, and physical injury to both the patient and healthcare staff. In non-intubated patients, the management is particularly nuanced; clinicians must balance the need for sedation to control agitation with the imperative to avoid respiratory depression that could necessitate invasive mechanical ventilation.
Traditionally, antipsychotics like haloperidol or benzodiazepines have been used, but these often carry risks of over-sedation, QT prolongation, or paradoxical worsening of delirium. Dexmedetomidine, a selective alpha-2 adrenoceptor agonist, offers a unique pharmacological profile by providing ‘cooperative sedation’—where patients remain rousable—and lack of respiratory depression. While its benefits in intubated patients are well-documented, its efficacy in non-intubated patients with hyperactive delirium remained an area of clinical uncertainty until the publication of the 4D trial.
The 4D Trial: Methodology and Study Design
The 4D trial (Dexmedetomidine for treatment of hyperactive delirium in non-intubated ICU patients) was a multicenter, double-blind, placebo-controlled, randomized clinical trial conducted across nine ICUs. The study aimed to determine whether dexmedetomidine could improve the control of hyperactive delirium compared to a placebo in patients not requiring mechanical ventilation at the time of enrollment.
Screening, Randomization, and Follow-up of Patients. Non-intubated adults with agitated delirium who had been admitted to an intensive care unit (ICU) for an acute condition underwent screening. A total of 17 patients were withdrawn after randomization because they withdrew consent by a surrogate decision maker or once competent and able to give decision, even after receipt of study medications, as stated by French law. Four participants did not meet inclusion criteria, and 2 presented with exclusion criteria and were not included in per-protocol analysis. No data on the primary outcome was missing, but data on vital status at 30 days were not available for 5 patients (3 in dexmedetomidine group and 2 in placebo group). CAM-ICU denotes confusion assessment method for the ICU, ICU intensive care unit, ITT intention-to-treat, PP per-protocol and RASS Richmond agitation sedation scale
Study Population and Intervention
The trial included adults admitted to the ICU who exhibited hyperactive delirium, defined by clinical assessment and a Richmond Agitation-Sedation Scale (RASS) score of +1 or higher. A total of 151 patients were included in the final analysis. Participants were randomized to receive either a continuous intravenous infusion of dexmedetomidine or an equivalent volume of placebo for a minimum of 36 hours. Dose adjustments were permitted to achieve clinical stability while monitoring for adverse hemodynamic effects.
Endpoints and Statistical Approach
The primary outcome utilized a sophisticated joint modelling approach. This combined multiple clinically relevant variables: the duration of agitation (RASS +1 or higher), the duration of delirium, and the requirement for intubation or deep sedation. This methodology allowed the researchers to capture the multifaceted nature of delirium recovery rather than relying on a single, potentially narrow metric. Secondary outcomes included the incidence of complications (hypotension, bradycardia), ICU length of stay, and mortality.
Key Findings: Efficacy and Speed of Agitation Control
The results of the 4D trial were sufficiently compelling that the independent data monitoring committee recommended stopping the trial early for efficacy during the preplanned interim analysis. This decision underscores the strength of the signal observed in the dexmedetomidine group.
Primary Outcome Results
The joint modelling analysis revealed a statistically significant difference favoring dexmedetomidine. The median difference in the composite score was -30 points (95% CI, -49 to -12, p = 0.001). This indicates a substantial clinical benefit across the combined metrics of agitation, delirium duration, and avoidance of more invasive interventions.
Fig. Frequency Distribution of Primary Outcome and Items of the Primary Outcome. The bars represent the frequency distribution of z-scores of each item of primary outcome and of primary outcome. The higher the frequency at low values, the lower the delay to normalize RASS (in hours) and CAM-ICU (in days) (panel A and B, respectively), and the more favorable primary composite endpoint in each group (panel D). Panel C represents percentages of intubation during study (2 (2.6%) and 3 (4.1%), in dexmedetomidine and placebo groups, respectively). The primary endpoint was defined as a composite score of duration of agitation (in hours), defined by a RASS ≥ + 1, duration of delirium (in days), defined by the time to reach a negative score on the CAM-ICU), or the use of intubation with deep sedation and mechanical ventilation. As aforementioned, the primary endpoint was calculated as suggested by O’Brien: weighted summation of single endpoints with standard procedures leads to asymptotically normal statistics. Continuous (RASS delay and CAM-ICU delay) and dichotomous (intubation) variables were converted to z-scores by subtracting an individual’s value from the overall mean and dividing by the standard-deviation of the pooled group. The z-scores were then aligned to the same direction so that worse outcomes have smaller scores. The z-scores were then averaged across endpoints for each patient. Treatment groups were compared with respect to this average z-score. The higher the value of the primary endpoint, the more unfavorable it was. CAM-ICU denotes confusion assessment method for the ICU, ICU intensive care unit and RASS Richmond agitation sedation scale
Reduction in Agitation Duration
When looking specifically at agitation, dexmedetomidine demonstrated a clear advantage. The duration of agitation was significantly shorter in the dexmedetomidine group, with a median of 1.0 hour (IQR 1.0–2.0) compared to 2.0 hours (IQR 1.0–7.0) in the placebo group. The absolute difference was statistically significant (p = 0.001), with an effect size of -0.60. While a one-hour reduction may seem modest in absolute terms, in the context of acute ICU agitation, it represents a 50% reduction in the window of time where patients are at high risk for self-harm or clinical instability.
Safety and Secondary Metrics
One of the primary concerns with dexmedetomidine use is the risk of hemodynamic instability, specifically bradycardia and hypotension. Interestingly, in the 4D trial, the occurrence of these complications was similar between the dexmedetomidine and placebo groups. This suggests that when titrated carefully in an ICU setting, dexmedetomidine is safe for non-intubated patients. Other secondary outcomes, including mortality and ICU length of stay, did not show significant differences, which is often expected in trials of this size focusing on symptom management rather than long-term survival.
Expert Commentary: Redefining the Management Paradigm
The 4D trial fills a significant gap in the literature regarding the ‘difficult-to-manage’ non-intubated delirious patient. The biological plausibility of dexmedetomidine in this context is strong; by acting on the locus coeruleus to induce a state similar to non-REM sleep, it avoids the GABAergic pathways that are often implicated in the development or worsening of delirium.
Clinical Implications
For the clinician, these findings suggest that dexmedetomidine should be considered early in the course of hyperactive delirium for non-intubated patients. By rapidly controlling agitation, it may prevent the ‘downward spiral’ where increasing agitation leads to higher doses of conventional sedatives, which in turn leads to respiratory depression and the need for intubation.
Study Limitations
Despite its strengths, the trial has limitations. The early termination, while justified by efficacy, can sometimes lead to an overestimation of treatment effects. Additionally, while the joint modelling approach is statistically robust, it can be more difficult to interpret for bedside clinicians than simple individual endpoints. Finally, the study was conducted in specialized ICUs, and results might differ in settings with different nurse-to-patient ratios or monitoring capabilities.
Conclusion: A Valuable Tool for ICU Clinicians
In conclusion, the 4D randomized clinical trial establishes dexmedetomidine as a valuable and effective alternative to placebo for treating hyperactive delirium in non-intubated ICU patients. By significantly reducing the duration of agitation and improving the overall clinical trajectory without increasing the risk of adverse events, dexmedetomidine offers a pathway toward safer, more controlled management of this complex condition. Future research should focus on comparing dexmedetomidine directly with other active agents, such as atypical antipsychotics, to further refine the optimal pharmacological hierarchy for delirium management.
Funding and Trial Registration
This study was an investigator-initiated trial. It is registered at ClinicalTrials.gov with the identifier NCT03317067 (Registered October 17, 2017).
References
Godet T, Louis C, Rieu B, De Jong A, Couhault P, Pradel G, Tête H, Bourguignon N, Borao L, Jabaudon M, Futier E, Jaber S, Pereira B, Chanques G, Constantin JM; 4D study group. Dexmedetomidine for treatment of hyperactive delirium in non-intubated ICU patients: the 4D randomized clinical trial. Intensive Care Med. 2025 Dec;51(12):2305-2317. doi: 10.1007/s00134-025-08135-1 IF: 21.2 Q1 . Epub 2025 Oct 29. PMID: 41160116 IF: 21.2 Q1 .
