All About Precedex in the ICU for Sedating Patients
Channel: Nurse Howie
Date: 2021-09-03

LET'S DISCUSS PRECEDEX's MECHANISM OF ACTION 

Precedex (since dexmedetomidine is too hard to say and spell) is an alpha2-adrenergic agonist (it boosts the receptor). 

- Not effective in producing deep sedation (very important!!!). It's like propofol lite?
 - I remember having someone on precedes that was found down after an opioid overdose. They gave him narcan and he came to me under precedex sedation. The instant I went to go put a sheet over him he woke up swinging and fighting he almost strangled me! Thank goodness the restraints were on. It just goes to show that your patients aren't really that sedated. So be careful.
- As a selective alpha2 agonist, [Precedex] also inhibits sympathetic nervous system (boo-hoo), resulting in an overall reduction in circulating plasma of norepinephrine and epinephrine. 
 - The effect is dose dependent. Patients receiving low doses or prolonged infusions of dexmedetomidine have a drop in systemic blood pressure. 
  - this is believed to be due to occurrence of peripheral vasodilation once inhibition of sympathetic nervous response has been achieved 
   - self note: does this make Precedex a poor choice for septic shock, where SVR is already too low? 
 - Patients on Precedex have heart rates that are dose dependent!!
  - That means too much dosing can potentially slow down their heart rate (bradycardia)
  - Propofol, it's meaner cousin, is also dose dependent towards blood pressure (hypotension)
  - However, please also keep in mind that a recent study in 2018 showed that despite Precedex's effect causing Bradycardia and hypertension (systolic BP), it was not associated with significant changes in CI, PAP, or CVP
   - in fact, it may actually be a benefit for pt's with hypertension
 - Precedex has a half-life of 9 minutes
  - that means that if you stop giving it, the remaining propofol in the body will reduce to half within 9 minutes, and then half of that and that half of that...
 - Precedex makes metabolites in the urine
  - so make sure that your patients' kidneys aren't too damaged such as from AKI, CKD, or ESRD
  - however post op AKI was reduced in pt's that received precedex than nothing else for sedation (Ji et al, N = 1133)
 - Precedex may help circulation
  - Lieu et al (2016) found differences in microvascular circulation positing that precedex was superior to propofol in improving micro circulation in cardiac surgery pt's during the postoperative period
   - however no optimum dosing is recommended yet
 - Precedex's other main advantage to other forms of sedation is that there seems to be a reduced incidence of delirium (which is a big problem in the ICU) vs remifentanil (though I don't see remifentanil often d/t it's cost)
  - The precise mechanism of why precedex is so effective at combating delirium is not fully understood
   - also it may be d/t the fact that benzodiazepines aren't being used (benzos, except for midazolam and fentanyl, are a big no no in the ICU). We will go over these in another video
   - it's no surprise that precedex also reduces the use of benzos just because it is largely replacing them for pain 
    -  but not completely! Remember, sedation is NOT pain control. You HAVE TO HAVE BOTH in the ICU if you're sedating them! Never forget that! 
  -  Another blow to Propofol, but precedex seems to allow post op cardiac surgery pt's an earlier extubation time (57% vs 16.7%) 
 -  In our sensitive elderly pt's, Cheng et al found that there were significant (P=.004) reduction in hospital mortality (0.9% vs 2.83%). This is HUGE! Because we are always looking to decrease mortality (death)
 -  Cost of precedex is higher than propofol, unfortunately (in the author's institution), ($0.367 per microgram for dexme- detomidine vs $0.0113 per milligram for propofol at their institution), but found that a shorter length of stay and avoidance of adverse events setoff the price (this may be a biased opinion)
  -  shorter duration of mechanical ventilation and shorter ICU stays saved $2600 which offset the cost of the medication




Reference
Dexmedetomidine: A Review of Its Use for Sedation in the Intensive Care Setting
Gillian M. Keating
Drugs. 2015 vol. 75 (10) pp. 1119-1130

Video by Ivan Samkov from Pexels