Dexmedetomidine for sedation in the medical ICU

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Introduction

The highly selective alpha-2 agonist, dexmedetomidine, has been shown to be an effective and safe agent for the sedation of postoperative patients requiring mechanical ventilation on the ICU [1]. It possesses analgesic and sympatholytic properties and its ability to sedate without significant respiratory depression may benefit other patient groups requiring ICU sedation. This study reports our experience of dexmedetomidine for the sedation of critically ill medical patients.

Methods

Twelve critically ill medical patients (mean APACHE II score 21) requiring artificial ventilation, received dexmedetomidine for up to seven days with rescue sedation and analgesia provided by propofol and morphine, respectively, if clinically indicated. Dexmedetomidine infusion was commenced with a loading infusion of 1 µg.kg^-1 over 10 min followed by a maintenance infusion of 0.2-0.7 µg/kg/h to maintain a Ramsay sedation score = 3. Following experience with the first four patients, the maintenance rate of infusion could be increased to a maximum of 2.5 µg.kg^-1h^-1. Heart rate, systolic and diastolic arterial pressures, central venous pressure and, where possible, cardiac output by thermodilution were monitored continuously and recorded at 10 min intervals for the first 30 min and then hourly.

Results

The mean duration of dexmedetomidine infusion for all patients was 33 (SD=19.7) h, and mean dexmedetomidine infusion rate in the latter eight patients was 1.0 (SD=0.7) µg.kg^-1h^-1. Only one out of the eight patients proved difficult to sedate with dexmedetomidine and required an additional propofol infusion of up to 100 mg.h^-1. Arterial pressure, heart rate and cardiac output were well-maintained during dexmedetomidine infusion. Patients requiring vasoactive drugs prior to commencement of dexmedetomidine showed diminishing requirements during the course of the study. Following discontinuation of dexmedetomidine infusion there was no clinically important rebound phenomenon in haemodynamic measurements. Adverse cardiovascular events (hypotension±bradycardia) were nearly all confined to the initial loading infusion of dexmedetomidine.

Summary

Dexmedetomidine provides safe, titratable sedation with cardiovascular stability for critically ill medical patients requiring artificial ventilation.