IV SEDATIVES AND HYPNOTICS (PP+Notes) Flashcards
Barbiturates
how fast?
rapid onset and rapid awakening
Short-acting: thiopental, methohexital, thiamylal
Barbituates Mechanism of action
Depress the Reticular Activating System (RAS)
Hypoproteinemia intensifies the response to barbiturates because the free fraction of drug is increased, causing more to diffuse from blood to brain
potentiating GABAa channel activity, functions allosterically to increase the affinity of gaba for its binding site increasing the duration of the gaba
Barbiturates PH? Lipid soluble?
High pH; drug dissolved in low pH solution should not be mixed with thiopental to avoid precipitation
Lipid soluble, 60% unionized in plasma—good entry into the brain; rapid onset
Methohexital has prominent excitatory effects—hiccups, seizures
Thiopental -vascular and intracranial effects? power point
good for seizures?
Anticonvulsant and amnestic actions
Increases cerebral vascular resistance; decreases cerebral blood flow and intracranial pressure; decreases cerebral metabolism
Drug of choice in head injury
Thiopental and pain control?(PP)
Poor analgesic; may be hyperalgesic
Thiopental and Histamine? (PP)
May cause histamine release (avoid in severe asthmatics)
Thiopental and contraindications (PP)
Contraindicated in patient with porphyria
Thiopental and Respiratory and cardiac system (pp)
Depresses respiratory system, myocardial contractility
Why is thiopental is mixed and stored in a solution with pH = 10-11? (PP)
To keep thiopental in ionized form. Ionized form is more water soluble. A precipitate will not from when thiopental is stored in a solution with a high pH
Thiopental (BOOK) induction dose requirements
vary with patient age, weight, and most importantly cardiac output.
the dose should decrease with age
dose needed for anesthesia in early pregnancy is decreased 18%
requirements are higher in children 1 year post thermal injury.
Methohexital (BOOK) and seizures?
effective in inducing seizures. useful during electroconvulsive therapy.
disadvantage is myoclonus.
Propofol (PP) MOA & recovery?
Acts on GABA and glycine receptors
Quicker, better recovery than with the barbiturates
Most important advantage—more rapid and complete awakening
Propofol cardiac changes
PP
Causes greater decrease in BP than thiopental (decrease in CO and SVR); HR often unchanged; may have sympatholytic or parasympathomimetic action
Propofol Respiratory (PP)
More profound ventilatory depressant than thiopental
Propofol antiemetics properties ?
pruritic?
analgesic effects?
anticonvulsant effect?
cerebral blood effects?
(PP)
Antiemetic properties— chemoreceptor trigger zone (CTZ) and vomiting center action
Antipruritic
No analgesic effects
Anticonvulsant
Decreases cerebral blood flow and metabolism
Propofol preparations considerations BOOK
increases triglyceride,
supports bacterial growth.
what is different about propofol and spinal motor neuron excitability? (book)
in contrast to volatile anesthetics, spinal motor neuron excitability is not altered by propofol suggesting that immobility during propofol anesthesia is not caused by drug induced spinal cord depression.
propofol metabolism (book)
metabolized by p450 and excreted by the kidneys. no evidence of delayed clearing in patients with cirrhosis.
propofol lungs uptake? (book)
pulmonary uptake of propofol is significant and influences the initial availability of propofol. most of the drug that undergoes pulmonary uptake during the first pass is released back into the circulation
Propofol induction children and elderly (BOOK)
children require higher doses elderly require lower induction dose
propofol conscious sedation dose?
25-100mcg/kg/min
propofol maintenance of anesthesia dose
100-300mcg/kg/min
propofol antiemetic dose?
10-15mg IV in pacu
Propofol cardiac dry old people. tell me about this.
exaggerated in hypovolemic patients, elderly patients and patient with compromised left ventricular function.
what does propofol block the stimulation of? (think airway)
stimulation produced by direct laryngoscopy and intubation of the trachea reverses the blood pressure effects of propofol.
also blunts the hypertensive response to placement of laryngeal mask airway.
propofol
hepatic and renal function,
eye pressure,
coags?
green urine
decreases intraocular pressure
no alter of coags
risk of brady cardia- give epinephrine
propofol lactic acidosis
propofol infusion syndrome metabolic acidosis. doses exceeding 75mcg/kg/min
Benzodiazepines moa (pp)
Enhance actions of GABA lead to increase entry of Cl- leads to hyperpolarization
Short-acting: diazepam, lorazapam, midazolam
Benzodiazepines used for?(pp)
Antianxiety, amnestic, sedative, hypnotic, anticonvulsant; muscle relaxation
Poor analgesics
benzodiazepines (pp) cardiac effects
Little effect on CV system unless patient is hypovolemic—profound hypotension
benzodiazepines (pp) cerebral effects
Cause cerebral vasoconstriction—lowers cerebral blood flow, metabolism and intracranial pressure
benzodiazepines (pp) soluability?
Diazepam is poorly water soluble; dissolved in organic solvent and pain may occur on injection
protein bound of diazepam %? (pp)
98-99%
Epidural placement considerations (in class discussion)
GIVE FLUIDS! some will not put in an epidural until they have had a liter of fluids
Benzodiazepines side effects BOOK
name the synergistic effects with various drugs?
fatigue and drowsiness are most common side effects antacids decrease absorption impairment of cognitive function. anterograde amnesia-especially if there is concomitant ingestion of ETOH. Synergistics effects with ETOH, inhaled and injected anesthetics opioids and alpha 2 agonists.
Ketamine (pp)
Produces amnesia and profound analgesia by interacting with NMDA-type glutamate receptor
Cerebral vasodilator— increases cerebral blood flow and metabolism and increases intracranial pressure
Contraindicated in head injury
Causes hypertonus and nystagmus
Stimulates SNS—CV enhancement (increased HR, CO, bp)
IV or IM
Ketamine in class discussion
Never give ketamine unless your on the way to the or
Give versed as it will relax the patient. Don’t give with dementia, ptsd, if they start having flashbacks give more versed
If you know the patient has ptsd or they are a young buck 18-19 year old kids- they get wild when they wake up. Move them over to the bed, put your rails up, then wake them up.
Deep extubate if they don’t have any contraindications.
Hypertonus- tense muscles, ridged, nystagmus- eyes are going twitchy.
Im- pediatric patients. Mentally retarded, psychiatric issues- im ketamine calms them down. If someone is already wild you need to IM them
Higher icp- infarct the brain. They can’t play the piano anymore
Severe dreams hallucinations nausea and vomiting
ketamine who is a poor candidate? (pp)
Poor risk patients are candidates for ketamine
Avoid in cardiac patient, glaucoma patient, patient with elevated ICP
Emergence is severe; dreams, hallucinations, N/V
Weak base; do not mix with alkaline solutions
Versed BOOK pharmacokinetics
rapid absorption from the GI tract and prompt passage across the blood brain barrier. extensively bound to plasma proteins
versed metabolism (book) what drugs will slow the metabolism of this drug
hepatic ally metabolized. metabolism is slowed in the presence of cimetidine, erythromycin calcium channel blockers an anti fungal drugs. that inhibit p450. really excreted and not altered by renal failure.
versed central nervous system (book)
potent anticonvulsant effects. produces decreases in CMRO2 and cerebral blood flow comparable to barbiturates and propofol.
versed ventilation (book)
dose dependent decreases in ventilation by decreasing hypoxic drive. COPD- even greater respiratory depression. transient apnea may occur after rapid injection of large doses of midazolam. decreases upper airway activity and swelling reflex
versed cardiovascular system (book)
induction dose create a decrease in systemic blood pressure and increase in heart rate. cardiac output not effected. decrease in bp is due to decrease in SVR.
versed sedation dose, onset, peak, and duration.
1-2.5mg iv onset 60 seconds peak 5 minutes duration 80 minutes.
versed induction of anesthesia
0.1-0.2mg/kg iv over 30-60 minutes synergistic interaction is facilitated when a small dose of opioid
flumazenil dose? onset? peak? duration?
0.2-1mg IV give additional doses up to 3mg in 1 hour. duration of action is 30-60 mimutes. RESEDATION MAY OCCUR!
flumazenil and antieliptics drugs
administration to patients being treated with anti epileptic drugs for control of seizure activity is not recommended as it could precipitate acute withdrawal seizures.
Scopolamine (Hyoscine) & indications
competitive ACH antagonist at muscarinic receptor. prevent and create N&V motion sickness amnesia sedation or vagolysis. greater antisialagogue and ocular effects that does atropine with lesser effects on the heart.
Scopolamine onset
apply one patch the evening before surgery or 1 hour before cesarean section. effects within 4 hours and last for 72 hours
scopolamine reversal
pyridostigmine 15-60mg/kg
scopolamine adverse effects
hallucinations, delirium, tachycardia drowsiness restlessness, confusion, anaphylaxis increased intraocular pressure decreased sweating.
scopalamine precautions
children and elderly more suspectable to adverse effects. contraindicated in acute angle glaucoma, patients unable to tolerate tachycardia.
scopolamine on the eye
produces mydriasis and cycloplegia
Etomidate dose
0.2-0.4mg/kg
onset 1 minute
duration 10min
Etomidate contraindications
adrenocortical suppression.
etomidate metabolism
metabolized by hydrolysis in the liver.
lorazepam
1-2mg max of 4mg
more potent sedative and amnesic than midazolam and diazepam. obesity prolongs the sedative effects of lorazepam duration 6-24hrs.
ketamine
dissociative anesthesia. resembles a cataleptic state in which the eyes remain open with a slow nystagmic gaze. non communicative though wakefulness may appear present. however frequency of emergence delirium limits the clinical usefulness of ketamine as a sole agent.
ketamine binding site
NMDA receptor possibly muscarinic receptors??
ketamine induction dose
1-2mg/kg IV
ketamine precautions
HTN, coronary heart disease. increased intracranial pressure, history of cerebrovascular accident increased intraocular pressure and psychiatric disorder, it is contraindicated for surgery or diagnostic procedures of the pharynx. use it cautionsly in patients with convulsive disorder.
VERSED CONTRAINDICATION
GLAUCOMA
risk factors for propofol infusion syndrome
propofol greater than 75mcg/kg/min infusion duration greater than 48hours children greater adults inadequate oxygen delivery sepsis significant cerebral injury
clinical presentation of propofol infusion syndrome
metabolic acidosis rhyabdomyolysis enlarged or fatty liver renal failure hyperlipidemia lipemia (cloudy plasma or blood)
