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D&T II Exam 2 > Anesthetics > Flashcards

Anesthetics Flashcards

1
Q

Halogenated anesthetics

A

Halothane, Isoflurane, Enflurane, Sevoflurane, Deslfurane

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2
Q

Non-Halogenated anesthetics

A

Nitrous Oxide

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3
Q

Ideal “Balanced” Anesthesia properties

A

Amnesia, Analgesia, produced state of consciousness or unresponsiveness, block sensory and autonomic reflexes, skeletal muscle relaxation, rapid induction and emergence, wide window of safety

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4
Q

MAC

A

potency is expressed as minimum alveolar concentration:

inspired concentration of anesthetic required to produce anesthesia in 1/2 of subjects (equivalent to ED50) expressed as % of inhaled gas

Affected by: Age, Health Status, Drug interactions, and red hair

Not affected by: type of noxious stimulus, sex, height, weight, and duration of exposure

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5
Q

Examples of MAC changes

A

Age: increased MAC in infancy/childhood; decreased in elderly
Health Status: increased in hyperthyroidism; decreased in hypothyroidism
Drug Interactions: increased in amphetamines, decreased in sedatives
Red Hair increases MAC

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6
Q

Determining Rate of Induction

A

Increasing Concentration - Increase Rate

Increase Alveolar ventilation - Increase Rate

Increase solubility (blood:gas partition coefficient) - Decrease rate

Increase Cardiac Output - Decrease Rate (because higher CO removes more volatile anesthetic from alveoli and lowers partial pressure of the gas, prolonging induction time)

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7
Q

Concentration of Agent is __________ proportional to Partial Pressure.

A

Directly

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8
Q

Anesthetic induction occurs faster with agent which are more or less soluble in blood?

A

Less

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9
Q

Meyer-Overton Theory

A

Anesthetic dissolves in the membrane and “affects” the function of membrane proteins

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10
Q

Mechanism of Action of Anesthetics

A

Meyer-Overton Theory
Interaction with hydrophobic regions of embedded proteins
May impede breakdown of GABA
Potentiate GABA increased Cl- influx
Increase K+ efflux, Reduce Na+ and Ca2+ influx

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11
Q

Halothane

A 
Potent anesthetic
Weak analgesic
Blood:Gas - 2.3
Coadminister with nitrous oxide, opioids, or local anesthetics
pleasant odor
do not repeat within 2-3 weeks

Effects: sensitizes heart to catecholamines (increase risk of arrhythmias), decrease BP, decrease CO, depress baroreceptor reflex, rapid/shallow breathing, decrease response to CO2

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12
Q

Halothane + Succinylcholine

A

increased risk of malignant hyperthermia, sustained contraction of skeletal muscles, dramatic increase in O2 consumption, increase body temp

effects due to inability of SR to sequester Ca2+

Tx: Dantrolene

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13
Q

Enflurane

A

less potent than halothane, rapid induction/recovery, pleasant odor

Effects: less sensitization of heart to catecholamines, decreased BP, decreased myocardial contractility,
respiratory depression, greater potentiation of muscle relaxants, possibly lead to seizures

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14
Q

Isoflurane

A

smooth/rapid induction and recovery, PUNGENT ODOR, isomer of enflurane

Effects: DOES NOT induce arrhythmia, does not sensitize heart to catecholamines, does not decrease CO
Dose dependent decrease B P and respiration
Relaxes skeletal muscle directly and via CNS depression

Low toxicity

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15
Q

Desflurane

A

Newer drug, very rapid

Effects: dose dependent decrease of BP and respiration, respiratory irritant, relaxes skeletal muscle directly and via CNS depression

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16
Q

Sevoflurane

A

new drug, rapid induction and recovery, low pungency, similar to desflurance

Reacts with soda lime in breathing apparatus at low flow rates, uses special equipment
Leads to production of toxic compound, Compound A

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17
Q

Nitrous Oxide

A

Potent analgesic
Weak anesthetic
Balanced Anesthesia
Rapid induction and recovery

Effects: enhances respiratory depression of other agents, AT LEAST 30% O2 should be used with N2O
chronic exposure can lead to megaloblastic anemia

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18
Q

Second Gas Effect

A

Rapidly absorbed gas INCREASES rate of uptake of a 2nd gas, concentration of gas 1 is high and then rate of uptake of gas 2 is higher

Nitric Oxide commonly used

19
Q

Elimination of Inhalation Anesthetics

A

Major Route: Lungs
Metab in liver causing release of halide ions that can cause toxicity
Low blood solubility are eliminated at a faster rate

20
Q

IV Anesthetic Agents

A

rapid induction of anesthesia then maintained with inhalation
preanesthetic sedation, induction, perioperative anesthesia, minor procedures
Agents: Barbiturates, Benzos, Opioids, Others

21
Q

Propofol

A 
For induction and maintenance (2-8 min distribution and 30-60 min elimination)
Less hangover, more rapid recovery
CV and Respiratory depression
Not analgesic
Amnesia "milk of amnesia"
same day procedures

Mechanisms: potentiate GABA signaling
Effects: hypotension (more pronounced in elderly) bradycardia, arrhythmias, respiratory depressant, respiratory acidosis, decreases CBF and ICP, antiemetic

Abused by anesthesiologists

22
Q

Propofol Related Infusion Syndrome

A

serious, high mortality, dysarrhythmia, heart failure, hyperkalemia, lipemia, metabolic acidosis, rhabdomyolysis, myoglobinuria

23
Q

Propofol + Opiates

A

increased sedative or anesthetic effects, decreases in systolic, diastolic, and mean arterial pressure and CO, lower the dose of propofol
Fentanyl may cause serious bradycardia with propofol in pads
Alfentanil with propofol cause seizures

24
Q

Etomidate

A

Non-Barbiturate for induction, minimal CV effects, decreased cerebrovascular blood flow, advantage for brain/neural type surgeries, not analgesic, post-op nausea and vomiting

25
Q

Barbiturates

A

Thiopental, Methohexital, Thiamyl

Ultra-short acting, used for induction, used for sedation, can depress respiration

Recovery from thiopental is due to redistribution for brain into less vascular regions
No antagonist in case of overdose

may cause a transient rise in BP
Thiopental may result in hypotension, circulatory collapse, and cardiac arrest in cases of hypovolemia, circulatory instability, sepsis, toxemia, or shock

Contraindicated: variegate porphyria and acute intermittent porphyria

26
Q

Benzodiazepines

A

CNS depressants
Diazepam, Lorazepam, Midazolam
Anxiolytic, Amnesiac, Sedative, Antiepileptic

May depress respiration
Increase frequency of channel opening

BDZ Antagonist: Flumazenil

27
Q

Opioids

A

Fentanyl, Morphine, Sulfentanil
induce analgesia, used in Cardiac Surgery as CO and myocardial contractility are preserved
Effects: Hypotension, Respiratory depression, muscle rigidity, post anesthetic nausea and vomiting

Can interact with propofol!

Antagonist: Naloxone

28
Q

Anticholinergics

A

used to combat secretions, prevent vagal effects

Atropine, Scopolamine, Gycopyrrolate

Scopolamine more effective at preventing salivation than atropine but less effective at preventing reflex bradycardia

29
Q

Glycopyrrolate

A

Long acting, less sedation, better antisialogogue, produces less tachycardia, more effective in preventing bradycardia, does not cross BBB, causes peripheral effects

30
Q

Dissociate Anesthesia

A

mental state where individual appears to be dissociated from environment without complete loss of consciousness

Use Ketamine: related to PCP, blocks NMDA receptor, induction agent and profound analgesia

Recovery: delirium, hallucinations, irrational behavior, reduces utility (more likely in adults, not children)

31
Q

Stages of Anesthesia

A

I: Analgesia- conscious and conversational
II: Excitement- Experiences delirium and violent, combative behavior, increase in BP, HR, Respiration, and skeletal muscle tone, mydriasis (GOAL: keep duration and intensity of this stage to a minimum, give a short acting barbiturate IV before inhalation anesthesia to avoid)
III: Surgical Anesthesia- regular respiration, eye movements cease, relaxation of skeletal muscle
IV: Medullary Paralysis- severe depression of respiratory and vasomotor centers, death

As it proceeds to Stage IV there is increased CNS depression and accumulation of anesthetic in the brain

32
Q

Local Anesthetic

A

Create loss of sensation without loss of consciousness or impairment of central control

Ester Type: Benzocaine, Chloroprocaine, Cocaine, Procaine

Amide Type: Bupivacaine, Etidocaine, Lidocaine, Mepivacaine, Prilocaine, Ropivacaine

Ester i, Amide ii

33
Q

Local Anesthetic Mechanism

A

reversible inhibition of axonal nerve conduction by binding to Na+ channel, binds on internal site, ionized anesthetic has more affinity, prolongs inactivation of channel, restrict conformational change

Small, unmyelinated fibers are more easily anesthetized (autonomic and sensory nerve blocks are easier than motor)

Duration: determined by rate of diffusion and absorption

Metabolism: ester type - plasma cholinesterase’s
Amide type - amidases, liver
Urinary Excretion

Prolonged by vasoconstrictors (epinephrine or phenylephrine) slow the rate of absorption, decrease drug plasma concentration, less likelihood of side effects

DO NOT USE with END ARTERIES (may lead to Gangrene)

34
Q

Local Anesthetic Effects and Uses

A

Adverse effects: CNS stimulation (tremor, euphoria, convulsions) followed by CNS inhibition, headache, paresthesias, nausea, seizures, coma, death (via respiratory failure) hypotension, cardiac depression, allergic dermatitis, asthmatic attack (usually due to esters)

Uses: Topical (use with epinephrine)
Skin - Benzocaine
Mucous membranes - Tetracaine, Lidocaine, Cocaine
Mixtures
LET - Lidocaine, Epinephrine, Tetracaine
EMLA - Eutectic mixture of lidocaine and others

Infiltration anesthesia: directly injected into tissues, dental procedures, epinephrine doubles duration, have to use a large amount of drug for a small area though
Iontophoresis: small electrical current forces anesthetic into a tissue

35
Q

Field Block Anesthesia

A

series of injections to form a wall of anesthesia in operative field

Less drug for greater area of anesthesia than infiltration

36
Q

Nerve Block Anesthesia

A

injected into or adjacent to a nerve or nerve plexus

produces large area of anesthesia with small amount of drug, better than field block

37
Q

Spinal Anesthesia

A

injection into lumbar subarachnoid space below level of cord termination
spread of anesthetic in CSF controlled by horizontal tilt of patient and specific gravity

Can be used for people who cannot use general anesthesia for a lower body surgery

38
Q

Epidural Anesthesia

A

Injection into lumbar or caudal epidural space

Bupivacaine: labor/delivery

absorbed into systemic circulation, monitored closely to prevent cardiac depression and neurotoxicity in mother or neonate

39
Q

Cocaine

A

ester, only local anesthetic that causes vasoconstriction
controlled because subject to abuse
topically to anesthetize internal structures of nose, ear, throat

40
Q

Procaine

A

1st synthetic local anesthetic, ester, short duration, parenteral, metabolized to PABA

41
Q

Benzocaine

A

Ester, pruritus, ear drops, teething/gum pain, lozenges for pharyngitis, treatment of sunburn

42
Q

Lidocaine

A

amide, metal in liver to monoethylglcinexylidide and glycinexylidine

topical or parenteral, infiltration, nerve block, epidural, or spinal

intermediate duration (60-120 mins)

43
Q

Prilocaine

A

Lidocaine congener, metal to O-toluidine, can cause Methemoglobinemia
limited to topical and infiltration anesthesia, half life > lidocaine

44
Q

Bupivacaine

A

obstetrical anesthesia, cardiotoxic, decreases threshold for tachycardia, half life = 300 mins

D&T II Exam 2 (7 decks)

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