Compare the use of propofol and dexmedetomidine when used for sedation in the mechanically ventilated patient with specific reference to
A) pharmacodynamics
B) indications
C) complications
for each of the drugs. (You may tabulate your answer).
Propofol
Pharamcodynamics
• GABA receptor action, though different from benzodiazepine receptor
• Hydrophobic with high lipid solubility that allows it to cross blood brain barrier rapidly. Lipid solubility allows rapid redistribution to tissues so duration of action is only a few minutes.
B) Indications
• Sedation in ICU for ventilation
• Sedation for procedures such as ETT, endoscopy, TOE etc
• Sedation for transport
• Effective anticonvulsant.
C) Complications
• Cardiovascular: hypotension from preload reduction due to dilation of venous capacitance vessels & mild myocardial depression.
• Hyperlipidaemia possible: monitor triglyceride levels. Adjust TPN accordingly
• Propofol infusion syndrome: dysrhythmias, heart failure, metabolic acidosis, hyperkalaemia, rhabdomyolysis. Beware of high doses ( > 80 microg/kg/min) and/or higher concentrations ( 2% vs 1% ).
Dexmedetomidine
A)
Selective alpha-2 agonist with both sedative and analgesic properties.
B) Indications
Patients are sedated when undisturbed but they arouse easily with minimal stimulation, allowing frequent neurologic examinations. Useful in the agitated, ventilated patient.
• Analgesic sparing in post operative patients.
• Results in less delirium compared to benzodiazepines.
C) Complications
• Cardiovascular: bradycardia & hypotension. ( Vasoconstriction & hypertension have been reported with higher doses )
• Not well studied for long term administration to critically ill, mechanically ventilated patients.Licensed for use in Australia for 24 hours only, though utilised in trials for up to 120 hours.
Agian, the college has effectively and concisely summarised everything in their answer.
But, they didn't tabulate it, even though they invited the candidates to do so.
I have tabulated it for them.
|
Feature |
Propofol |
Dexmedetomidine |
|
Pharmacodynamics |
GABA agonist; |
Centrally acting alpha-2 receptor agonist; |
|
Indications |
Sedation (rapid onset) |
Sedation (slower in onset) |
|
Complications |
Loss of airway reflexes |
Bradycardia More adverse effects than with benzodiazepines |
Arain, Shahbaz R., and Thomas J. Ebert. "The efficacy, side effects, and recovery characteristics of dexmedetomidine versus propofol when used for intraoperative sedation." Anesthesia & Analgesia 95.2 (2002): 461-466.
Venn, R. M., and R. M. Grounds. "Comparison between dexmedetomidine and propofol for sedation in the intensive care unit: patient and clinician perceptions†."British journal of anaesthesia 87.5 (2001): 684-690.
Jakob, Stephan M., et al. "Dexmedetomidine vs midazolam or propofol for sedation during prolonged mechanical ventilation: two randomized controlled trials." JAMA307.11 (2012): 1151-1160.