Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Anesthesia > IV Anesthetics > Flashcards

IV Anesthetics Flashcards

(82 cards)

Start Studying
1
Q

Name the 3 benzos commonly used and how are they different?

A

Differ in duration of action from short to long (half-lives):

Midazolam (2hrs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name the mechanism of action of benzodiazepines and its effects

A

α1 and α2 subunits of the GABAA receptor –> conformational change to allow GABA to bind and open channel for hyperpolarization (ceiling effect)

α1 subunit –> sedation, anticonvulsant activity, and anterograde amnesia

α2 subunit —> anxiolysis and muscle relaxation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name the two pathways of benzodiazepine biotransformation in the liver.

A

microsomal oxidation
- impaired by advanced age, cirrhosis, and enzyme induction

glucuronide conjugation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the two benzodiazepines with active metabolites.

A

Diazepam - oxazepam and desmethyldiazepam
- enterohepatic circulation prolongs its effect with a secondary peak in concentration 6-12 hours later

Midazolam - hydroxymidazolam, which may lead to prolonged sedation in renal failure

Metabolites are excreted in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

For sedation, which benzodiazepine is most potent (greatest receptor affinity)?

A

Lorazepam 1mg = midazolam 2.5mg = diazepam 5-10mg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the effect of benzodiazepines on respiration?

A

reduction in resting ventilation (but lower than barbiturates)

reduction in the ventilatory response to hypoxia and hypercarbia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Compare the effects of different benzos on respiration.

A

Midazolam has significantly more respiratory depressant effects than diazepam or lorazepam at equipotent doses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the effect of benzodiazepines on the carbon-dioxide response curve?

A

downward shift of the carbon-dioxide response curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the effect of benzodiazepines on circulation and BP?

A

modest effects
- decrease in systemic vascular resistance and ventilation –> slight decrease in arterial blood pressure

  • no effect on contractility or HR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the effect of benzodiazepines on cerebral metabolic rate (CMRO2)?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the induction dose of midazolam?

A

0.15-0.25 mg/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some contraindications to using benzos?

A

Acute intermittent porphyria

HIV medications
- Midazolam and efavirenz compete for CYP3A4 –> midazolam toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the side effects of benzos?

A

Resp depression
Delayed emergence
Delirium in elderly

Lorazepam has propylene glycol –> metabolic acidosis
Long term –> tolerance and dependence
Withdrawal –> Insomnia, anxiety, restlessness, seizures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are two good options for providing anxiolysis without respiratory depression?

A

Ketamine or dexmedetomidine (requires 10min to load)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the effects of benzos based on receptor occupancy % - 20%, 30-50%, 60%

A 
(20%) = amnesia and anxiolysis
(30-50%) = sedation
60% = unconsciousness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which benzo is water soluble but becomes lipid soluble at physiologic pH?

A

Midazolam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What subunit is responsible for benzos sedative, amnestic, and anticonvulsant effects?

A

alpha-1 subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What subunit is responsible for benzos anxiolysis and muscle relaxation effects?

A

alpha-2 subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the common additives and formula of propofol?

A

Propofol + 10% soybean oil + 2.25% glycerol + 1.2% egg lecithin

Diprivan - disodium edentate and sodium hydroxide (pH 7-8.5)
Generic - sodium metabisulfite (pH 4.5-6.4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the mech of action of propofol?

A

Activating GABA-A –> keeps Cl- channels open –> hyper polarization and inhibition of post-synaptic neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What properties of propofol explain its fast onset and recovery?

A

High lipid solubility

Rapid distribution from brain (highly perfused) to less well perfused tissues (muscle, fat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where is propofol metabolized?

A

Liver –> water soluble sulphate and glucuronic acid –> eliminated by kidneys

May have some 30% metabolized by lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why do children require a higher induction dose and elderly a lower induction dose?

A

Kids - larger central distribution and higher clearance rate

Elderly - opposite

Hypothermia dec metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do you explain rapid awakening following a long propofol infusion?

A

Diffuses slowly from periphery to central –> rapidly metabolized so it’s half life is less than 40 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How does propofol affect blood pressure?
Dec systemic blood pressure - myocardial depression - dec systemic vascular resistance + venodilation --> red preload Dec baroreflex --> smaller inc in HR for given dec in BP
26
What is the effect of propofol on the ventilatory response to hypoxia and hypercarbia?
Dose dependent respiratory depression More likely to induce apnea than other induction agents - etomidate, ketamine Blunts the ventilatory response to hypoxia and hypercarbia Decreases tidal volume and respiratory rate
27
What is the effect of propofol on cerebral blood flow and intracranial pressure?
decreases cerebral blood flow decreases CMRO2 decreases ICP does NOT affect monitoring of somatosensory and motor evoked potentials.
28
What is propofol infusion syndrome?
Rare often fatal o Critically ill, high doses and long-term infusion o Acute refractory bradycardia → asystole o Rhabdo, tachycardia with metabolic acidosis, cardiomyopathy with failure and lipemia o ? mitochondrial toxicity
29
How can you minimize the pain with injection of propofol?
Larger vein | Prior administration of lidocaine or potent opioids like fentanyl or remi
30
What is the relationship between propofol and egg allergy?
``` Allergy = egg white (albumin) Propofol = lecithin (yolk) ```
31
What is the induction dose of propofol?
2. 0 - 2.5 mg/kg adult | 1. 0 - 2.0 mg/kg elderly
32
What is the GA maintenance dose of propofol?
100-300mcg/kg/min
33
What is the induction dose of propofol for kids?
2.5-3.5mg/kg IV
34
How does Forpropofol differ from propofol?
Water soluble = no pain, HLD, PE or sepsis risks Onset and recovery prolonged
35
How does methohexital differ in onset and recovery than thiopental?
Cleared more rapidly, faster, more complete recovery Also more stimulating --hiccups
36
With what disease must you avoid barbiturates?
Acute intermittent porphyria | - aminolevulinic acid synthase inc porphyrins
37
What happens when you mix NMBs with barbiturates?
pH 10 = precipitates when mixed with acidic drugs like NMBs → irreversibly block IV lines
38
Describe barbiturates effects on CMRO, CBF and ICP
Decreases • Possible neuroprotection from focal cerebral ischemia • Methohexital – activates epileptic foci = used in ECT
39
Describe barbiturates effects on HR, MAP
Baroreceptor reflex blunting but inc in HR → transient dec in MAP
40
Describe barbiturates effects on ventilation
Dec TV, RR --> dec MV Dec response to hypercapnia, hypoxia
41
What are the side effects of barbiturates?
Intra-arterial injection = excruciating pain, vasoconstriction → gangrene Garlic or onion taste with induction
42
What barbiturate is used for ECT and why?
Methohexital - produces longer seizure duration
43
What is the mechanisms of action of ketamine?
1. Non-competitive NMDA antagonist 2. Mu-opioid agonist 3. Antagonize muscarinic acetylcholine receptors 4. Inhibits Na channels (modest local anesthetic effect) 5. Inhibits Ca channels (cerebral vasodilation) May also have effects on cholinergic, nicotinic
44
Describe the onset of ketamine and its unique properties
Profound analgesia Stim symp nervous system Bronchodilation MINIMAL resp depression
45
What is the induction dose of ketamine?
1.0 - 2.5 mg/kg IV 5 - 10 mg/kg IM
46
What is the dose of ketamine for infusion with and without nitrous oxide?
15-45 ug/kg/min infusion w/ NO 30-90 ug/kg/min infusion alone
47
What are some of the side effects of ketamine?
Dissociative amnesia - eyes open, nystagmic gaze - some reflexes intact but may not be protective Inc lacrimation and salivation Emergence reactions - hallucinations, vivid dreams, fear, disorientation, euphoria - reduced w/ midazolam 5min b4 - inc w/ droperidol and atropine NOT recommended in pregnancy
48
Describe the effects of ketamine on CBF and ICP and EEG waves
Cerebrovasodilator = INC CBF > CMRO2 --> inc ICP These effects can be blunted by maintaining normocapnia excitatory CNS effects --> EEG theta waves
49
Describe the effects of ketamine on cardiac function
Inc MAP, HR, CO Inc CNS SNS stimulation Direct myocardial depressant Can be blunted with co-admin of opioids, benzos, gases
50
Describe the effects of ketamine respiratory system
Little respiratory depression Bronchial smooth muscle relaxation INCREASES PAP (avoid in pul HTN) Inc secretions --> airway obstruction
51
What are risk factors for developing emergence reactions with ketamine?
``` Risk greater when >15yrs female >2mg/kg dose IV psychiatric hx atropine use ```
52
What is the mechanism of action of etomidate?
Potentiates GABA-A
53
Describe etomidate's uniques properties regarding hemodynamics, N/V, and side effects
Hypnotic but NOT analgesia Minimal hemodynamic effects * More PONV* * Adrenocortical suppression* – limits infusion ability
54
What is the induction dose of etomidate?
0.2-0.3 mg/kg IV
55
Describe etomidate's effects on the CNS
Potent cerebral vasoconstrictor → dec CBF, ICP No neuroprotection May activate seizure foci (like methohexital) Myoclonic activity in 50% of patients
56
Describe etomidate's effects on the cardiovascular system
MAP, HR, CO minimal change
57
What is the mechanism of action of Dexmedetomidine?
Alpha-2 adrenergic agonist
58
What is the induction dose of Dexmedetomidine?
0.5-1 ug/kg over 10-15min
59
What is the maintenance dose of Dexmedetomidine?
0.2 - 1.5 ug/kg/hr infusion
60
What are the effects of Dexmedetomidine on the CNS?
Hypnosis – locus ceruleus Analgesic – spinal cord Sedation – more closely resembles physiologic sleep Decreases CBF without much change in ICP, CMRO
61
What are the effects of Dexmedetomidine on cardiovascular system?
Mod dec HR, SVR, MAP, CO Bradycardia may --> arrest
62
What are the effects of Dexmedetomidine on ventilation?
Small dec in Tv Little change in rate
63
What are Dexmedetomidine's effects pre and post-synaptically?
Presynaptic – inhibits NE → sedation (dec MAC) Postsynaptic → dec symp, BP, HR, need for morphine
64
What is the active metabolite of Ketamine?
N-demethylation by CYP450 system --> Nor-ketamine 1/3 the potency of ketamine Coadministration w/ drugs that require hepatic metabolism --> prolong the action of ketamine up to 30%.
65
What are some of the common indications for using ketamine?
respiratory and cardiovascular compromise (except ischemic heart disease) reactive airway disease hemodynamic compromise - hypovolemia or cardiomyopathy (not coronary artery disease with active ischemia) trauma patients septic shock congenital heart disease patients, especially w/ propensity for R-->L heart shunting
66
What are contraindications to using ketamine?
1. poorly controlled hypertension 2. active ischemic heart disease 3. preeclampsia 4. elevated intracranial pressure 5. open eye injuries and procedures.
67
What is the binding site of etomidate?
GABA-A potentiator --> enhances ability of GABA to bind --> hyperpolarization
68
What property of etomidate is responsible for its rapid onset of action?
lipopilicity Onset 30-60sec Duration 3-5min
69
How is etomidate excreted?
urine (85%)
70
What is the induction dose of etomidate?
0.2-0.4mg/kg 35% propylene glycol
71
How is etomidate metabolized?
plasma esterases + hepatic microsomal enzymes
72
What are the common indications for using etomidate?
hemodynamic instability - trauma or critical care retrobulbar block Cardioversion ECT - prolongs seizures
73
What are the effects of etomidate on circulation?
MAP - stable SVR - dec 10-15% HR, PAP, PSOP, CO - minimal changes
74
How does etomidate affect ventilation in comparison to propofol and barbiturates?
Minimal rest depression compared to propofol or barbiturates Dec ventilatory response to CO2 Typically no apnea or only brief Slight dec Vt but inc RR Lasts 3-5min
75
How does etomidate affect the CNS and the eyes?
``` ICP - dec CBF - dec CMRO2 - dec CPP - maintained IOP - dec for 5 min ```
76
How does etomidate affect EEG and SSEPs?
SSEPs: Inc amplitude EEG: activation at [low]; inhibition at [high]
77
Describe 4 side effects of etomidate administration
1. Adrenocortical suppression - for 5-8hrs, inhibited 11-b-OH 2. Myoclonus 3. Pain on injection - propylene glycol 4. Greater PONV
78
Describe 2 common contraindications for using etomidate
1. Patient's that require intact stress response - septic shock or hemorrhage 2. Epilepsy/seizure prone patients - Inc excitatory spike frequency
79
What might be the cause of nephrotoxicity from an etomidate infusion?
Propylene glycol
80
What are the side effects of flumazenil?
N/V = #1 Seizures in chronic bento users or epileptic patients Shorter 1/2 life than midaz Poor oral absorption
81
Which benzo can cause phlebitis, thrombosis on injection?
Diazepam
82
What is the onset and peak of Dex?
Onset 5min --> peak 15min

Anesthesia (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions