When maintaining light sedation in critically ill ICU patients, dexmedetomidine should be avoided in those predisposed to bradycardia and propofol in those predisposed to hypotension.
While propofol and dexmedetomidine are the preferred sedative agents to maintain light sedation in the ICU, both sedatives leave critically ill patients at risk for hemodynamic adverse events, said Amy West, PharmD, BCPS, a critical care pharmacy resident at Lee Memorial Health System in Fort Myers, who was the lead researcher of the study.
Numerous studies have compared the efficacy of dexmedetomidine with propofol and found no difference in maintaining light to moderate sedation in patients.
However, the researchers wanted to know their effects on the cardiovascular system.
“It is imperative to provide optimal sedation for patients in the intensive care unit, especially those requiring mechanical ventilation, to prevent agitation and anxiety,” Dr. West said. “The potential risks associated with these agents must always be weighed against the benefits prior to initiation.” Findings were presented at the Society of Critical Care Medicine’s 2016 Critical Care Congress (abstract 576).
Hemodynamic Effects Rather High
In a multicenter, retrospective study, the researchers looked at adult patients in the ICU who received continuous infusions of either dexmedetomidine (150 patients) or propofol (150 patients) for at least four hours.
Patients were excluded if they were allergic or hypersensitive to either drug studied; required vasopressor therapy, α-2 agonists or antagonists within 24 hours of initiating sedation; had a spinal cord injury; experienced excessive hemorrhaging or were pregnant; or had a pacemaker.
They also were excluded if they experienced a heart rate less than 60 beats per minute or mean arterial pressure (MAP) less than 65 mm Hg immediately before receiving sedation.
The study patients were a diverse group medically, coming from cardiac, trauma, medical and neurosurgical wards. The overall median stay in the ICU was four days, and the median hospital stay was 9.5 days. Eighty-three percent of the critically ill patients survived.
The researchers defined bradycardia as a heart rate less than 60 beats per minute and hypotension as MAP less than 65 mm Hg.
“Our definition of bradycardia and hypotension could have led to clinically insignificant events being classified as hemodynamic disturbances, as minimal or no intervention was required for the majority of adverse events,” the researchers noted.
The researchers found that dexmedetomidine was associated with significantly more bradycardia than propofol, and propofol was weakly associated with more hypotension than dexmedetomidine. Additionally, no significant difference in composite incidence, ICU length of stay, hospital length of stay or hospital survival was found between the two agents.
The researchers said the overall prevalence of hypotension and bradycardia seen in their study was relatively high, but still within the ranges previously reported in the literature.
The incidence of bradycardia in patients receiving dexmedetomidine has been reported as high as 42%, and the frequency of hypotension in ICU patients receiving propofol is typically between 26% and 30%, but up to 68% has been reported, the researchers said.
“This was a retrospective study, and further prospective studies should be conducted to confirm these findings,” Dr. West said.
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