Transcript Dexmedetomidine - ISAKanyakumari

Dexmeditomidine
Dr.G.K.Kumar
What is dexmedetomidine ?
• Dexmedetomidine
-An intravenous anesthetic agent
• Provides
-Sedation
-Anxiolysis
-Analgesia
• No respiratory depression.
• Mild antihypertensive effects.
What is dexmedetomidine ?
• Dexmedetomidine
- selective α2 adreno receptor agonist.
- for sedation in the intensive care unit
setting.
- decrease the need for other analgesic
medications such as opioids
What is the mechanism of action
of dexmedetomidine?
• A selective α2-adrenoceptor agonist.
• It’s action is unique and different.
• Alpha2-adrenoceptors are located in
the CNS, vascular smooth muscle,
and a variety of other organs.
What is the mechanism of action of
dexmedetomidine?
• Presynaptic activation of alpha2-adrenoceptors
inhibits the release of norepinephrine.
• Postsynaptic activation of alpha2-adrenoceptors in
the central nervous system inhibits sympathetic
activity and can decrease blood pressure and heart
rate,so sedation and anxiolysis can result from this
activity.
• Analgesia is provided through binding of
dexmedetomidine to alpha2-adrenoceptors in the
spinal cord.
What is the mechanism of action of
dexmedetomidine?
What is the pharmacological profile
of dexmedetomidine?
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Rapid redistribution: 6 min
Elimination half-life: 2 h
Protein binding: 94%
Metabolism: biotransformation in liver to
inactive metabolites + excreted in urine
• No accumulation after infusions 12-24 h
• Pharmacokinetics similar in young adults +
elderly
What is the difference between
clonidine and dexmedetomidine?
Clonidine
Dexmedetomidine
• Selectivity: 2:1
200:1
• t1/2  8 hrs1
• PO, patch, epidural
• Antihypertensive
• Analgesic adjunct
• Selectivity: 2:1
1620:1
• t1/2  2 hrs
• Intravenous
• Sedative-analgesic
• Primary sedative
How does it differ from other
sedatives?
• This unique sedative quality - someone be clinically
sedated yet arousable.
• This has not been seen previously with other
sedative agents in the intensive care unit.
• Patients sedated, remaining so when unstimulated.
But, when stimulated, they are arousable, alert, and
able to respond without becoming uncomfortable.
• It ‘s also observed that they would quickly return to
their sleep-like state.
In what types of patients
dexmedetomidine should not be used?
• Infusion over 24 hours.
• In obstetric procedures , cesarean section deliveries,
as the safety has not been studied.
• Patients with pre-existent severe bradycardia and
related bradydysrhythmias (e.g., advanced heart
block).
• Patients with impaired ventricular functions (ejection
fraction <30%).
• Patients who are hypovolemic or hypotensive.
What are hemodynamic effects of
dexmedetomidine?
• Reduces sympathetic activity, resulting in
lower blood pressure and reduced heart
rate.
• When dexmedetomidine is discontinued,
these hemodynamic parameters return
to baseline with no rebound effects.
What are the respiratory effects
of dexmedetomidine?
• There is no evidence of respiratory
depression associated with the use
of dexmedetomidine.
Are there any special considerations
when using dexmedetomidine?
• Prevention of hypotension and bradycardia
• Patients who are hypovolemic may become
hypotensive - fluid supplementation should be
administered prior to and during the administration
of dexmedetomidine.
• Where other vasodilators or negative chronotropic
agents are administered, dexmedetomidine could
have an additive pharmacodynamic effect and should
be administered with caution and careful titration.
How is dexmedetomidine given?
• Dexmedetomidine is supplied in a 2-mL
ampoule, 100 mcg/ml as the base.
• Dexmedetomidine must be diluted in 0.9%
sodium chloride to achieve the required
concentrations prior to administration.
• To prepare the infusion, withdraw 2 ml of
dexmedetomidine and add to 48 ml of 0.9%
sodium chloride injection to a total of 50 ml.
How is dexmedetomidine given?
• The target concentration is 4 mcg/ml. So 2 ml
of dexmedetomidine needs to be diluted to 50
ml in 0.9% sodium chloride, 4 ml of
dexmedetomidine to 100 ml in 0.9% sodium
chloride, 6 ml to 150 ml, etc.
• Loading dose -0.5µg-1µg/kg [6-12ml]over 10
min
• Maintenance -0.3µg-0.7µg/kg/hr[4-9ml/hr]
• Titration ±0.1µg/kg/hr.
Is dosing affected by renal or hepatic
impairment?
• Although dexmedetomidine is dosed to effect,
metabolites may accumulate with long-term
infusions with renal or hepatic impairment,
and dose reductions may be necessary.
Clinical Uses of Dexmeditomidine
• Bariatric surgery
• Sleep apnea patients
• Craniotomy: aneurysm,
AVM [hypothermia]
• Cervical spine surgery
• Off-pump CABG
• Vascular surgery
• Thoracic surgery
• Conventional CABG
• Spine surgery, evoked
potentials
• Head injury
• Burn
• Trauma
• Alcohol withdrawal
• Awake intubation
Uses of dexmeditomidine
• ICU sedation.
• Procedural sedation
-gynecological
-urological
-burns patients
-pediatric patients
• Sedation during RA
• OBESE,OSA Patients
Uses of dexmeditomidine
• Loading dose 1µg/kg
0.5ml[50µg] diluted as10ml ×10min.
• Maintenance 0.3-0.6µg/kg/hr
1.5ml[150µg] diluted in 500ml NS
solution conc-0.3µg/ml
infusion-16 to32drops/min
• Recovery 10-12mins after cessation.
What measures were used to determine sedation in
clinical studies with dexmedetomidine?
• The Ramsay scoring system (Ramsay MA et al: Br Med J
1974:2; 656-659) was used throughout the clinical trials.
• It is a 6-point scale as follows: 1 represents anxiety, agitation,
or restlessness; 2 denotes cooperative, oriented, and tranquil;
• 3 is the patient responds to commands; 4 denotes asleep but
with brisk response to light glabellar tap or loud auditory
stimulus;
• 5 is asleep, sluggish response to light glabellar tap or loud
auditory stimulus; and 6 represents deep sedation (asleep, no
response)