Generalized Anesthesia Flashcards
(41 cards)
1
Q
Inhaled Anesthetics (6)
A
- Isoflurane
- Desflurane
- Sevoflurane
- Halothane
- Nitrous Oxide
NEW: Halogenation increases potency and is non-flammable
OLD NOTES: All but Nitrous Oxide are halogenated, which adds stability, increases solubility and potency [TQ]
(DISH N)
2
Q
IV Anesthetics (6)
A
- Benzodiazepines (Midazolam)
- Opioids
- Ketamine
- Propofol
- Etomidate
- Dexmedetomidine
(BOP-KED)
3
Q
Sedatives (5)
A
- Benzodiazepines (Anxiolytics and Hypnotics)
- Propofol
- Dexmedetomidine
4
Q
Isoflurane (6)
A
- Flourine + Chlorine
- Lowest MAC at 1.15%
- (most potent, good)
- Highest Blood:Gas Partition Coefficient
- (lower affinity of blood or anesthetic, bad)
5
Q
Desflurane
A
- Flourine
- Highest halogenated MAC (6.3%)
- Lowest Blood:Gas Partition Coefficient
- Good!
- Lower Blood Solubility
- More rapid anesthetic effect and recovery
- Not used for induction (high pungency, high RI)
6
Q
Sevoflurane
A
- Flourine
- Between Desflurane and Isoflurane for both MAC and Blood:Gas Partition Coefficient
- Causes seizures and agitation
- Used for induction, low pungency and low RI
- OLD: Useful in patients with myocardial ischemia [TQ]
7
Q
Nitrous Oxide
A
- Produces anesthesia without decreasing BP or CO
- Can cause myocardial depression, offset by gas-associated sympathetic stimulation
- Amnestic and analgesic properties
- Decreases requirements of inhaled and IV anesthetics
- 25-40%: CNS depression (safely used clinically)
- 25%: produces maximum analgesic effects
- Unconscious at inspired levels of 60-80%
8
Q
Benzodiazepines: as IV anesthetics
A
- Midazolam
- Bind close to GABAa receptor and trigger opening of Cl channel, Cl ion influx (hyperpolarization) inhibits AP formation
- Preferred agent for balanced anesthesia
- Active metabolie – accumulation (caution with multiple doses)
- Uses: sedation, hypnotic (high doses), anticonvulsant, muscle relaxant, anxiolytic, anterograde amnesia [TQ], preserves hemodynamic stability
- Antidote: Flumazenil
- ADRs: respiratory depression
9
Q
Midazolam
A
- Preferred agent for balanced anesthesia
- Synergistic other agents (propofol), opioids:
- decreased dose requirements
- potentiation with opioids
- respiratory depression is enhanced though
- Rapid onset (30-60 sec), peak 60 min
- ADRs: dose-dependent respiratory depression, active metabolite accumulation
10
Q
Flumazenil (4)
A
- Antidote for Benzo overdose
- Binds to same receptor without enhancing GABA binding
- Onset (1-2 min), peak (10 min), dose-dependent DOA
- High safety margin
11
Q
Opioids
A
- Interact at Mu receptors in CNS and GI tract
- Uses: analgesia and sedation (no amnesia)
- ADRs: respiratory depression, post-operative nausea/vomiting, bradycardia, hypotension
- Risk factors: co-administration with sedatives, old people, high doses
12
Q
Remifentanil
A
- First Mu-opioid receptor agonist
- No histamine release
- Rapid onset and recovery
- Uses: ED, ICU, procedures in SDS or endoscopy, combo therapy for induction
- Disadvantages: sudden onset of pain or withdrawal
13
Q
Naloxone
A
- Competitive opioid antagonist, strong mu affinity
- No analgesic effects
- Narcotic reversal in 1-3 min (IV)
- Ventilation can be restored without losing pain benefit of narcotic
14
Q
Ketamine
A
- PCP analog, slow onset
- Enhanced response to glutamate at NMDA receptor
- Interacts with CNS opiate receptors for pain relief
- Low dose: analgesia/anxiolysis for debridement/dressing changes
- Moderate dose: analgesia/anxiolysis plus sedation and amnesia
- High dose: used in prolonged surgical procedures (impairs airway reflexes)
- ADRs: dissociative anesthesia [TQ] (patient appears awake but unconscious and doesn’t feel pain)
- give with benzos to alleviate side effects
15
Q
Propofol: as IV anesthetic
A
- GABA mechanism
- Rapid onset (90 seconds), DOA (5-10 min), very apid recovery, hepatic elimination, easily titrated
- High lipid concentration, careful for bacterial growth
- Uses: long or short procedures, good for induction in ambulatory procedures, sedative hypnotic
- No analgesia and no amnesia
- ADRs: nausea/vomiting, residual drowsiness, pain on injection (give with lido), apnea, hypotension, respiratory depression, allergic reactions (egg whites)
16
Q
Etomidate (6)
A
- Depresses RAS and mimics effects of GABA
- Onset (30-60 seconds), DOA (3-5 min)
- Uses: IV induction, procedural sedation
- Advantage: hemodynamic stability
- ADRs: adrenal suppression [TQ]
17
Q
Dexmedetomidine: as IV anesthetic
A
- a2-Receptor agonist (like clonidine)
- Don’t use alone, useful for decreasing amount of opioid required and therefore decreasing side effects (sparing effect)
- Hepatic metabolism, T1/2: 2 hours
- Ability to awaken patients more easily
- Uses: anesthetic, sedative, minimal analgesia
18
Q
Benzodiazepines: as sedatives
A
- Not the preferred method (propofol/dex are)
- Cons:
- associated with worse clinical outcome
- slow onset, metabolism and excretion
- Pros:
- alcohol/sedative withdrawal
- intractable seizures
- sedation when paralyzed
- calming effect of intermittent dosing
19
Q
Propofol: as a sedative
A
- Rapid onset/offset, shorter ICU length of stay
- Titratable
- Uses: deep sedation (ventilator, deep hypothermia),
- frequent neurologic checks
- status epilepticus,
- open wounds
- Add analgesia
- Watch BP and triglycerides
20
Q
Dexmedetomidine: as a sedative
A
- Very expensive, limited FDA approval
- Reduces narcotics requirements
- Light sedation (don’t use with paralytics)
- Can use in extubated patients (doesn’t depress respiratory drive)
- Causes hemodynamic changes and shivering
21
Q
Which has the best analgesic effects?
- Opioids
- Benzos
- Propofol
- Haloperidol
A
- OPIOIDS: ****
- Propofol: *
- Haloperidol: *
22
Q
Which has the best anxiolytic effects?
- Opioids
- Benzos
- Propofol
- Haloperidol
A
- BENZOS: ****
- HALOPERIDOL: ****
- Propofol: ***
- Opioids: **
23
Q
Which causes respiratory depression?
- Opioids
- Benzos
- Propofol
- Haloperidol
A
-OPIOIDS: ****
24
Q
Which has the best amnesia effects?
- Opioids
- Benzos
- Propofol
- Haloperidol
A
-Benzos: ** -Propofol: **
25
4 Stages of Anesthesia
1. Induction
2. Excitement
3. Surgical Anesthesia
4. Overdose
26
3 Drugs used for IV induction
1. Propofol
2. Etomidate
3. Ketamine
(PEK you with a needle)
27
7 Perianesthetic Agents
1. Antihypertensives: for low BP
2. Beta agonists: treat asthma/laryngospasm
3. Anticholinergics: prevent bradycardia and excess fluid secretion
4. Antihistamines: prevent allergic reactions and reduce gastric acidity
5. Antiemetics: treat nausea/vomiting
6. Benzodiazepines: amnesia, sedation
7. Opioids: analgesia
28
TIVA (6)
* Total IV Anesthesia
* Propofol
* Target controlled infusions
* Less post-operative nausea and vomiting
* More costly, short cases
* Indications: history of malignant hyperthermia, needle phobia
29
Potency of Inhaled Anesthetic MAC (8)
* Minimum Alveolar concentration
* Reflects the dosage required to produce desired anesthesia
* Alveolar concentration of inhaled agent at 1 atmosphere of pressure that prevents movement in 50% of patients
* Nitrous Oxide: 105% MAC
* Desflurane: 6.3% MAC
* Sevoflurane: 2% MAC
* Isoflurane: 1.15% MAC
* _MAC decreases with age and pregnancy [TQ]_
* _High MAC = Decreased Potency [TQ]_
30
Partial Pressure (4)
* The pressure exerted by that gas alone
* Normal gas transport - passive (driven by concentration gradient)
* Gases in body may bind (oxygen to hemoglobin) or transform (CO2 to HCO3)
* Controlling partial pressure manages anesthetic gas concentration in brain
31
4 stages of equilibrium during anesthesia
1. Anesthesia machine
2. Alveolar spaces
3. Arterial blood
4. Brain tissues
32
Blood:Gas Partition Coefficient (4)
* Ratio of [anesthetic in blood phase] to [anesthetic in gas phase]
* Partition coefficient: 0.5 if arterial concentration is 3% or lung concentration is 6%
* Low= low affinity of blood for anesthetic (this is good, more precise control and rapid recovery)
* Desflurane has lowest Blood:Gas Partition Coefficient (on chart) at just over 0.4
33
Malignant Hyperthermia
* Muscle rigidity, rhabdomyolysis, fever, tachycardia, acidosis
* Family history
* When confirmed: discontinue inhalation agent, hyperventilate, use non-triggering agents to finish, intubate, _dantrolene [TQ]_
34
5 Causes of Agitation
1. Physiologic: pain, constipation, nausea, thirst
2. Chemical: hypoglycemia, electrolyte imbalance
3. Pharm: steroids, sedatives, anticholinergics
4. Emotional: anxiety, confinement, restraints
5. Environment: noise, altered circadian rhythms, no sleep
35
PAD Guidelines (7)
* Consensus document
* P: Pain (pain scores)
* A: Agitation/Sedation (RASS)
* D: Delirium (CAM-ICU)
* Representative of best practice
* Base decisions on: patient condition, local practice norms and resource availability
* First address: withdrawal, psychiatric drug resumption
36
Analgo-Sedation (5)
* Analgesia then sedation
* Short acting IV opioid (alleviate need for sedative, control pain, improve outcomes, earlier mobilization, reduce delirium, facilitate ICU discharge)
* Practice routine evaluation with valid/reliable scales
* Pain indicators should evaluate pain at rest and before potentially painful procedures
* Titrate
37
Agitation and Sedation (2)
* Prior to sedation: provide analgesia, reorient to surroundings, maintain normal sleep-wake cycle
* Options: benzos, propofol, dexmedetomidine
38
Titrate/Balance Sedation in ICU (2)
* Reduce over/under sedation
* Advantages: optimize comfort/safety, minimize time in ICU, Communicate with other caregivers, titrate to pre-specified goals/ranges
39
RASS (4)
* Richmond Agitation Sedation Scale
* 0: alert/calm
* +4: combative, violent
* -5: unarousable, no response to voice or physical stimulation
40
What level is surgical anesthia?
3
41
T/F: you want to administer pre-anesthetics before surgery to stimulate patient
False
