Inhalational Agents II Flashcards

Question

Factors affecting FA

Answer 1

Alveolar concentration Agent blood solubility Alveolar blood flow Partial pressure b/w alveoli & venous blood FA > ET - Venous admixture - Alveolar dead space - Non-uniform distribution

Answer 2

``` ??? NMDA receptors Tandem pore K+ channels VGNa+ Glycine receptors GABA Huff enough gas ya pass out ```

Answer 3

Altered transmission in the cerebral cortex ``` Brain stem arousal centers - amnesia Central thalamus (pain relay center) - analgesia Spinal cord (skeletal muscle relaxation) - areflexia ```

Answer 4

Lipophilicity = potency Accepted dogma BUT exceptions exist

Answer 5

``` ↓ CMRO2 ↑ CBF (dose dependent) Cerebral vascular responsiveness to CO2 - Vasodilate or constrict ICP concern → mild hyperventilation ↓ CO2 to compensate (vasoconstriction to prevent ↑ ICP) ``` EEG burst suppression Evoked potentials ↓ amplitude ↑ latency Spinal surgery w/ nerve monitoring consider TIVA

Answer 6

``` Combined effects Increased w/ Sevoflurane ↓ CMRO2 ↑ CBF Exception: Nitrous oxide Mild hyperventilation helps attenuate ↑ CBF Cerebral vasculature responsive to CO2 ```

Answer 7

``` No evidence to support in human studies PANDA study, GAS trial, & population-based cohort study ↓ anesthetic agent usage Consider TIVA or regional w/ local Multimodal approaches Utilize short-acting medications ```

Answer 8

Increased concern in elderly | No clinically significant association b/w major surgery & anesthesia w/ long-term cognitive dysfunction

Answer 9

``` Pediatrics More common w/ Sevo & Des Potential to cause injury & delay discharge Preventative measures - Quiet, stress-free environment - Medication adjuncts ```

Answer 10

All volatile inhalational agents ↓ CO ↓ MAP secondary to ↓ SVR (vasodilation) Utilize N2O ↑SVR in combination to decrease Heart rate changes via SA node antagonism, baroreflex activity modulation, & SNS activity

Answer 11

Steal blood flow from ischemic areas and divert to well-perfused Vasodilation ↓SVR in hypotensive patients *Isoflurane (dilates coronary arteries)

Answer 12

Exposure to mild intracellular events ↓HR ↓BP ↓CO that protect from ischemic injury & reperfusion insult Pre-conditioned to respond to severe event Develop "memory"

Answer 13

Volatile agents reduce catecholamines necessary to evoke arrhythmias Less common in ASA I & II classifications Safe epinephrine dosing 10mL 1:100,000 Epi Halothane

Answer 14

Nitrous oxide causes slight ↑ PVR Worse in pulmonary hypertension patients (avoid N2O) Volatile agents ↓ pulmonary artery pressure d/t vasodilation effects Hypoxic pulmonary vasoconstriction mildly depressed Isoflurane has greatest effect

Answer 15

Shallow breaths ↓ TV ↑ RR (not sufficient to offset) ↓ CO2 responsiveness ↑ apneic threshold Relaxes airway muscle & produces bronchodilation

Answer 16

↓ renal SVR ↓ GFR ↓ UOP Desflurane least impact on renal function Sevoflurane associated w/ risk in renal compromise patients leading to haloalkene Compound A (nephrotoxic) - Older absorbents CaOH or Lithium OH - Do not exceed 2 MAC hours at flow < 2L/min (another dogma) - Fresh gas flow < 1L/min not recommended

Answer 17

Halothane hepatitis Trifluoracetyl metabolites binding to proteins & forming anti-trifluoracetyl protein antibodies Repeat exposure antibodies mediate massive hepatic necrosis Potentially lethal No longer use Halothane d/t metabolism & potential to impair hepatic function Current volatile agents - significant liver damage extremely rare Molecular structure fluorination resists hepatic degradation No significant impact on hepatic flow *Sevoflurane 5-8% metabolism

Answer 18

All volatile agents produce dose-dependent skeletal muscle relaxation (areflexia) Additive effect w/ NMBDs - potentiation ↓ 25-50% dose when compared to TIVA Delay non-depolarizing NMBD recovery

Answer 19

1. Non-irritating 2. Rapid induction & emergence 3. Chemically stable (not flammable) 4. Produce amnesia, analgesia, & areflexia 5. Potent concentration 6. No metabolism - excreted by respiratory tract 7. Non-toxic & no allergic reactions 8. Minimal systemic changes 9. Uses standardized vaporizer 10. Affordable

Answer 20

Affect how agents work: Vapor pressure Boiling point Partial pressure Solubility

Answer 21

Minimum alveolar concentration when 50% population opens eyes to command Amnestic w/out analgesic or areflexic

Answer 22

Block adrenergic response Usually 1.3 MAC Reduce w/ administering narcotic prior Closer to ED95

Answer 23

Gender Anesthesia duration Comorbidities

Answer 24

``` Hyperthermia Drug-induced ↑ CNS activity Hypernatremia Chronic alcohol abuse Red-haired females ```

Answer 25

``` Hypothermia Increasing age 6% decline each decade after 40yo Alpha 2 agonists Acute alcohol ingestion Pregnancy Hyponatremia ```

Answer 26

Volatile agents delivery device Facilitate anesthetic movement from machine to the patient through fresh gas flow, pressure, & temperature Calibrated for specific agents

Answer 27

Halogenated methyl ethyl ether Most potent current volatile agents Slower onset & recovery - most soluble blood:gas Minimal cardiac depression & preserves carotid baroreceptors Dilates coronary arteries - reverse Robin Hood concern Pungent not used for inhalational induction Tachypnea less pronounced Most stable & consistent

Answer 28

Least potent volatile agent Rapid induction & emergence Boiling point close to room temperature Overpressurizing not recommended d/t ↑HR ↑BP Pungent - airway irritation, increased salivation, breath holding, coughing, laryngospasm, not used for inhalational induction Avoid in patients w/ reactive airway disease

Answer 29

Fluorinated methyl isopropyl ether Moderate potency - rapid induction & emergence Prolong QT interval CO less maintained than other volatile agents No heart rate increase/compensation Non-pungent preferred volatile for inhalational induction

Answer 30

CYP450 2E1 5-8% metabolism Increased inorganic fluoride ions Only volatile agent metabolized

Answer 31

Sevoflurane absorbent soda lime potential to degrade into Compound A Increased gas temperature, low flow anesthesia, high Sevo concentrations, & prolonged surgeries Nephrotoxic? Safety - utilize CaOh absorbent, flow 2L/min, avoid in patients w/ renal dysfunction Dogma*

Answer 32

``` Not volatile anesthetic Colorless & odorless Non-explosive & non-flammable NMDA receptor antagonist Lower chronic pain risk after surgery ```

Answer 33

``` Stimulates SNS Cardiovascular stability ↑ RR ↓ hypoxic drive ↑ CMRO2 ↑ CBF ↑ PONV risk ```

Answer 34

Absolute: Methionine synthase pathway deficiency Gas-filled space expansion ``` Relative: PONV risk ↑ ICP 1st trimester (teratogenic effects) Pulmonary hypertension >6hr surgery ```

Answer 35

``` Girl of the 21st century Ideal inhalational agent Nobel gas w/ known anesthetic properties Colorless & odorless Non-flammable Inert does not form chemical bonds MOA via NMDA & glycine receptor binding sites Minimal CV, hepatic, or renal effects Neuroprotective? No ozone layer effect Cost & limited availability ```

Answer 36

Pharmacogenetic disorder triggered by volatile anesthetics, succinylcholine, stress Ryanodine receptor gene mutation (chromosome 19) S/S: ↑CO2, muscle rigidity, tachycardia, tachypnea, metabolic acidosis, ↑temp (late sign)

Answer 37

Muscle relaxant 1mg/kg up to 10mg/kg 20mg per vial Admin until S/S subside

Answer 38

``` New IV formulation to prevent & treat Fewer vials & less reconstitution Shorter half-life Mannitol supplementation 2.5mg/kg ```