In this episode, I’ll discuss predicting the chance of successful sedation and the development of hypotension with dexmedetomidine.
Have you ever noticed that dexmedetomidine seems to be a “hit or a miss” type of sedative? It seems to me to work great for some patients and poorly for others, with little in between. A few studies point to measures of the severity of illness like SOFA and APACHE II score, which may help identify which patients are likely to have success with dexmedetomidine and which are not.
Researchers published in Pharmacotherapy a single-center, retrospective, cohort study of 158 critically ill adult patients receiving dexmedetomidine to identify factors associated with clinical success.
Success was defined as having a mean time within goal RASS score of 60% or greater in the first 48 hours of mechanical ventilation after intubation. The goal RASS score was defined as 0 to -2. Patients on benzodiazepine or propofol infusions for greater than 12 hours were excluded.
Almost two-thirds of the patients achieved clinical success. Success was associated with a significantly increased mechanical ventilator-free duration at 14 days.
The authors performed a multivariate analysis looking at 9 factors in regards to the chance of clinical success:
- RASS prior to dexmedetomidine
- Initiation of dexmedetomidine with fentanyl
- SOFA score at dexmedetomidine initiation
- Medical or cardiac ICU
- Alcohol, opioid, or other substance abuse disorder
- Age
- Liver disease
- Anxiety or depression
- Sleep disorder
Of the 9 possible factors, only SOFA score at initiation predicted response to dexmedetomidine. The odds of success were decreased by 9% for every point increase in sequential organ failure assessment score. While this finding was statistically significant, the 95% confidence interval was 0.82‐0.99.
At least two retrospective studies have looked at factors that might predict hypotension from dexmedetomidine. The first was published in International Journal of Critical Illness & Injury Science September 2016 and the 2nd was published as an abstract in Critical Care Medicine in 2018.
The 2016 study was a retrospective study covering 4 ICUs within a single center. Patients who were hypotensive at baseline were excluded. 283 patients were analyzed. The primary endpoint was the finding of hypotension (MAP < 60 mmHg).
The 2018 study was a retrospective cohort study of patients with a primary cardiac diagnosis who received dexmedetomidine in a single CVICU. 276 patients were analyzed. The primary endpoint was the finding of hypotension (MAP < 60 mmHg).
In both studies, hypotension occurred in about 40% of patients.
In the CVICU study, univariate analysis showed that patients with a ST-elevation myocardial infarction, longer duration of dexmedetomidine infusion, or an increased number of rate changes were significantly more likely to develop hypotension.
In the ICU study after multi-variate analysis, the risk factors associated with dexmedetomidine-related hypotension were:
1. Baseline MAP
2. APACHE II score
3. History of coronary artery disease
Despite the ICU study being a single-center study, several elements suggest the results may apply to other ICUs.
- No patient received a bolus of dexmedetomidine. The one mcg/kg over 10-minute bolus of dexmedetomidine is still listed in prescribing information as a potential treatment option. However, it is not commonly used in clinical practice due to excessive side effects.
- The dose range for dexmedetomidine was up to 1.4 mcg/kg/hour which is a commonly used maximum dose range. However, only one-third of the patients in the study received a dose >1 mcg/kg/hour.
- Excessive titration (dose adjustment more frequent than every 30 minutes) was similar in both the hypotensive and non-hypotensive group (15.4% vs. 19.8%).
Because the CVICU study was only published as an abstract, similar detail on the external validity is unknown.
The topic in this episode is inspired by an in-depth training available to members of my Hospital Pharmacy Academy. The Hospital Pharmacy Academy is my online membership site that will teach you practical critical care and hospital pharmacy skills you can apply at the bedside so that you can become confident in your ability to save lives and improve patient outcomes. To get immediate access to this and many other resources to help in your practice, go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
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