IV Sedation TRuelearn Flashcards
The only 2 BDZ metabolized undergoes through glucouridation are?
“OTL” OXAZEPAM, temazepam, Lorazepam
Midazolam by C-P450 hydroxylation
Diazepam by C-P450 oxidation
Sedation dosage of precedex
The sedative effect of dexmedetomidine is concentration dependent, with plasma concentrations between 0.2 and 0.3 ng/mL resulting in significant and rousable sedation. Unarousable deep sedation is thought to occur at plasma concentrations above 1.9 ng/mL
Respiratory effects is expected of midazolam?
Midazolam and all benzodiazepines cause a dose dependent decrease in minute ventilation. The decreased minute ventilation is mainly a result of decreased tidal volume. Benzodiazepines decrease the respiratory sensitivity to CO2 and act synergistically with opioids.
Myoclonus induced by induction agents likely results from …
inhibition of descending cortical inhibitory pathways. Myoclonus can resemble seizures but EEG evidence of seizures is lacking during these episodes. It may also be associated with jaw clenching, which can complicate airway management.
Etomidate, ketamine, and methohexital are associated with myoclonus. Propofol, although less common, is also associated with myoclonic movements. Midazolam has not been associated with myoclonus.
Why Patients on Primidone for essintial tremors may need double dose of versed?
Chronic administration of barbiturates decreases the duration of action of drugs metabolized by cytochrome p450, such as midazolam.
because primidone is a barbiturate that is active in itself and also due to its active metabolite phenobarbital.
What is the biphasic response induced by precedex? and why it happens?
A bolus dose (2mcg/kg) of dexmedetomidine has a biphasic hemodynamic response. Initially, dexmedetomidine stimulates peripheral alpha-2 receptors resulting in hypertension and subsequent decrease in heart rate and cardiac output.
The peak hypertensive response occurs around 3 minutes after the bolus dose is given and the blood pressure returns to baseline after around 10 minutes. Subsequently, there is a slow decline in blood pressure over the next hour.
The biphasic response occurs because alpha-2 receptors are located in two locations producing different responses. Initially, dexmedetomidine acts on peripheral alpha-2 receptors and causes vasoconstriction in the peripheral vasculature. Subsequently, the centrally located alpha-2 receptors are stimulated. The central receptors reduce the sympathetic tone and increase the parasympathetic outflow. It also acts to reset the baroreceptor system to a lower set blood pressure.
Hemodynamic effect of Dexmedetomidine given bolus vs infusion?
A bolus can produce transient hypertension while an infusion may cause a slight decrease in pressure that returns to baseline as the infusion continues.
Cardiac output and heart rate decrease to varying degrees with bolus and infusion dosing. (The cardiac output and heart rate are still reduced due to the decrease in sympathetic outflow)
The most effective methods to reduce pain are propofol injections using …
An antecubital vein.
The next most effective method is the use of a modified Bier block.
Mixing propofol with lidocaine has been shown to decrease the stability of the propofol emulsion and may cause pulmonary embolism. The FDA recommends against mixing propofol with any other therapeutic medications prior to administration. If lidocaine is mixed with propofol, it should be done immediately before injection and in a dose not exceeding 20 mg / 200 mg propofol.
propofol acts primarily at which receptors?
Propofol acts to potentiate GABAA receptors.
Benzodiazepines have some degree of muscle relaxation which is likely due to
the potentiation of GABA effects on the interneurons of the spinal cord; they can be used for muscle spasm and spasticity disorders.
Benzodiazepines exert their effects selectively at the
GABA receptors in the central nervous system.
GABA is an inhibitory neurotransmitter that controls the state of chloride ion channels. Activation of the chloride channel results in neuronal hyperpolarization which will act to drive the membrane potential away from threshold potential. In other words, hyperpolarization will decrease the ability for a membrane potential to occur.
The bioavailability of midazolam, from greatest to least is:
intravenous > intramuscular > intranasal > rectal > oral.
Intravenous administration of a drug will offer 100% bioavailability through avoidance of the “first pass” effect.
