IV induction agents Flashcards
Dose of propofol
2 mg/kg
150-200 mg IV
Propofol infusion rate
100-300mcg/kg/min
Etomidate disadvantages
Adrenal suppression
Myoclonus
Postop nausea and vomiting
Etomidate dose
0.2 mg/kg
20 standard
Ketamine advantages
Can be used IM
Analgesic
Bronchodilator
Ketamine disadvantages
Avoid in patients with increased ICP
Emergence delirium and hallucinations
Increases HR and BP
Ketamine dose
2 mg/kg IV
4 mg/kg IM
Thiopental half life
Barb coma
10 hrs
Suppress seizures in status, neuroprotection in focal ischemia
Which agent is used in ECT?
Which agent is used in seizure surgery?
Methohexital
Etomidate
Both activate epileptic foci
How does thiopental reduce BP?
3 ways
Dilation of capacitance vessels
Blunted baroreceptor response (not as much as prop)
Negative inotropy
Lower dose of thiopental in the elderly, why?
Pharmacokinetically, elderly patients have a smaller central compartment and clear drugs much more slowly
Which types of enzymes are induced by barbiturates?
CYP450
ALA synthetase (acute intermittent porphyria): increases porphyrin formation
Chronic administration of barbiturates has what effect on dosage of BZDs?
Opioid prodrug? (Codeine, -codones , tramadol)
Anticoagulants?phenytoin?
Their own metabolism?
Chronic barb exposure increases the expression of CYP450 enzymes, thus requiring a higher dose of BZDs because they are broken down more quickly
Pts will require LESS codeine and other opioid pro drugs because the active form will become more available
OACs and phenytoin will get broken down more
They also enhance their own metabolism causing tolerance
Propofol effects on the CNS
Decreases CBS, CMR 02, and I CP, may greatly decrease cerebral perfusion pressure as CPP = MAP - ICP, Also decreases IOP
Burst suppression flattened EEG
Not desirable with ECT
Cardiovascular effects of propofol
Most pronounced decrease in BP of induction agents
Arterial and venous vasodilation next line marked inhibition of baro receptor response to hypotension
Negative Inotropy
Propofol infusion syndrome
Population
Manifestation
Etiology
Critically ill children and adults receiving high dose infusions
Unexpected tachycardia metabolic acidosis heart failure and rhabdomyolysis
May be related to high lipid burden and mitochondrial failure
Etomidate CNS effects
Decreases cerebral metabolic activity, CBF and ICP
May maintain CPP because there is little drop in MAP (MAP-ICP)
Causes excitatory space on eeg, may activate seizure foci
Maye clonus occurs in more than 50%
Etomidate adrenal cortical suppression
Inhibits 11 B hydroxylase which converts cholesterol to cortisol
Lasts 4-8 hours
How does ketamine work
It blocks the NMDA receptor which does allow for some analgesia
It causes dissociation between the thalamus and the cortex
What are the cardiovascular effects of ketamine
Release of endogenous catecholamines
This increases HRBP and pulmonary artery pressure
Ketamine is a direct myocardial depressant, this affect is usually only seen in patients with autonomic nervous system dysfunction
Ketamine’s affects on the pulmonary system
Effects on BIS
Bronchodilation, increased secretions
No significant change in BIS; The cortex is not been affected, only the communication between the thalamus and the cortex
What is ketamine affect on cardiac work and myocardial oxygen consumption
Both are significantly increase due to catecholamine release
What is the concern of giving atropine alongside of ketamine
This significantly increases the rate of emergence delirium
In general, what is the effective anesthetic drugs on EEG
What are two exceptions?
Decreased frequency and increased amplitude, slowing toward Delta and theta wave from Alpha and beta
Opioids and ketamine
Which two anesthetic to activate seizure foci
Methohexital and etomidate
What do most anesthetic to do to SSEP
Which two are the exceptions?
Most increase the latency and decrease the amplitude of response to stimulus
etomidate and ketamine may increase amplitude
Which anesthetics confound the use of the BIS monitor
Opioids ketamine and nitrous oxide
The usual affect of anesthetics on VIS monitor is decreased frequency and increased amplitude similar to EEG
Does propofol or ketamine have a greater amount of analgesia
Ketamine
Which anesthetic increases your pulmonary vascular resistance
Ketamine
Does obesity affects the dosage of nondepolarizing NMB?
Not really, he does buy ideal body weight but you might add 20% to include the extra lean body mass
Obesity and succinylcholine
Those must be increased because of the increased pseudocholinesterase activity
