The trial was stopped prematurely because of slow recruitment.

Delirium is common in septic patients, especially those receiving mechanical ventilation in the intensive care unit (ICU). Dexmedetomidine is a highly selective α2 adrenoreceptor agonist with anxiolytic, sedative, analgesic, and anti-inflammatory effects. Use of dexmedetomidine in mechanically ventilated ICU patients is associated with less delirium and improved outcomes. However, dexmedetomidine infusion produces dose-dependent bradycardia and hypotension; these limited the use of dexmedetomidine in ICU patients. This study is designed to test the hypothesis that low-dose dexmedetomidine infusion can also reduce delirium in mechanically ventilated ICU patients with sepsis.

Delirium is an acutely occurred and fluctuating disorder of consciousness, attention, and cognition. The occurrence of delirium is associated with worse outcomes including prolonged mechanical ventilation, prolonged length of stay in ICU and hospital, increased complications, higher in-hospital mortality, and evaluated medical expenses. It is also associated with worse long-term outcomes including cognitive decline, worse quality of life, and shortened long-term survival.

Dexmedetomidine is a highly selective α2 adrenoreceptor agonist with anxiolytic, sedative, analgesic, and anti-inflammatory effects. Studies showed that use of dexmedetomidine is associated with less delirium in ICU patients. Potential mechanisms may include better sleep quality, less consumption of opioids and benzodiazepines, and suppressed inflammatory response.

The incidence of sepsis in ICU patients is as high as 47.2%; 93% of septic patients relying on mechanical ventilation. Delirium is common in septic patients; the reported incidences varies from 20% to 50%. The incidence of delirium in critically ill patients with mechanical ventilation is up to 60-84%. However, the majority of mechanically ventilated ICU patients are sedated with propofol; only 10% of them are given dexmedetomidine. A main reason is that dexmedetomidine infusion is associated with dose-related bradycardia and hypotension.

In a previous study, might-time low-dose dexmedetomidine infusion (0.1 μg/kg/h) improved subjective sleep quality and reduced delirium in elderly patients admitted to ICU after surgery. In another study of ICU patients receiving mechanical ventilation, low-dose dexmedetomidine infusion (0-0.5 μg/kg/h) based on protocol sedation also reduced delirium and shortened mechanical ventilation without increasing adverse events. We hypothesized that, in ICU septic patients with mechanical ventilation, low-dose dexmedetomidine infusion (0.1-0.2 μg/kg/h) might also reduce delirium.

The purpose of this study is to investigate the effect of low-dose dexmedetomidine infusion on incidence of delirium in ICU septic patients with mechanical ventilation.

Inclusion Criteria:

1. Aged 18 years or older;
2. Admitted to the ICU;
3. With expected mechanical ventilation duration ≥12 hours;
4. Meet the diagnostic criteria of sepsis (sepsis 3.0; patient with infection and a sequential organ failure assessment score ≥2).

Exclusion Criteria:

1. Refuse to participate in;
2. Pregnancy;
3. History of schizophrenia, epilepsy, parkinsonism, or myasthenia gravis;
4. Inability to communicate (coma, profound dementia, or language barrier);
5. Brain injury or neurosurgery;
6. Left ventricular ejection fraction (LVEF) less than 30%, sick sinus syndrome, severe sinus bradycardia (<50 beats per min [bpm]), or second degree or greater atrioventricular block without pacemaker;
7. Serious hepatic dysfunction (Child-Pugh class C);
8. Serious renal dysfunction (undergoing dialysis);
9. With expected survival for no more than 24 hours;
10. Allergic to dexmedetomidine;
11. Other conditions that were considered unsuitable for study participation.