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MAC - Exam 2 Flashcards

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1
Q

What is monitored anesthesia care (MAC)?

A

An anesthetic technique achieving goals similar to GA: sedation, amnesia, anxiolysis, analgesia, delivered along the continuum of sedation.

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2
Q

What types of anesthesia may supplement MAC for analgesia?

A

Local or regional anesthesia.

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3
Q

What is a general advantage of MAC compared with general anesthesia?

A

Less physiologic disturbance with faster recovery/discharge.

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4
Q

What does MAC require from the patient?

A

Acceptance and cooperation (often increases satisfaction).

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5
Q

Why are more procedures now done under MAC?

A

Use of drugs with favorable pharmacokinetic profiles.

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6
Q

Define MAC as a service.

A

A service where a qualified anesthesia provider is continually focused on sedation, comfort, vital signs, and safety before/during/after the procedure.

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7
Q

What determines indications for MAC?

A

Nature of procedure, patient clinical condition, and potential need to convert to GA or regional.

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8
Q

What aspects of anesthesia care are included in MAC?

A

Pre-procedure evaluation, intra-procedure care, and post-procedure anesthesia management.

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9
Q

What can MAC include in terms of sedation level?

A

Varying levels of sedation, analgesia, anxiolysis along the continuum.

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10
Q

What must you “know” regarding sedation levels in MAC?

A

ASA Definitions of General Anesthesia and Levels of Sedation/Analgesia.

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11
Q

What must you always be prepared to do during MAC?

A

Convert to general anesthesia.

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12
Q

During MAC, if the patient loses consciousness and cannot respond purposefully, what is it now considered?

A

General anesthesia, regardless of airway device/instrumentation.

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13
Q

What fasting guidelines are recommended for MAC cases?

A

Follow the same NPO guidelines as general anesthesia.

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14
Q

What may be used to reduce aspiration risk in MAC cases?

A

Appropriate pharmacologic treatment.

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15
Q

What is required before a MAC anesthetic?

A

A complete preoperative anesthetic evaluation.

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16
Q

What should the MAC preop evaluation include?

A

PMH, allergies, NPO status, prior anesthesia complications, physical exam (CV/resp/airway), labs, and relevant studies (EKG, CXR, ECHO).

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17
Q

Why is patient education/counseling critical for MAC success?

A

Patients must have realistic expectations about awareness/level of consciousness; education helps prevent “recall” dissatisfaction.

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18
Q

If a patient insists on guaranteed amnesia/hypnosis for MAC, what should be offered?

A

General anesthesia, if feasible.

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19
Q

MAC has no absolute contraindications, but may be unsuitable for which patients?

A

Pediatric patients; patients without full mental capacity; intoxicated patients; those unable to lie still; language barriers; psychotic/uncooperative patients.

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20
Q

What additional conditions/procedures may make MAC unsuitable?

A

Medically unstable patients; suspected/known difficult airway; uncomfortable positioning; expected large blood loss or cardiorespiratory instability; procedures where even minor movement is hazardous.

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21
Q

How should monitoring standards for MAC compare to GA/regional?

A

Identical standards.

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22
Q

Why does MAC require vigilance?

A

Elderly/ill patients can rapidly go from light sedation to obtunded.

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23
Q

What AANA Standard of Care elements are listed for monitoring?

A

-Oxygenation: continuous clinical observation + pulse oximetry;
-Ventilation: continuously; verify intubation (auscultation/chest excursion/expired CO₂); continuous ETCO₂ monitoring;
-Cardiovascular: continuous EKG; BP/HR at least every 5 min; - -Thermoregulation: monitor temperature to maintain normothermia;
-Neuromuscular: if NMBD used, monitor response/recovery;
-Positioning: monitor/assess positioning and protective measures.

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24
Q

What must be continuously monitored during MAC besides vitals?

A

Level of sedation.

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25
Name sedation scoring systems used in MAC.
OAA/S, MOAA/S, and Ramsay sedation scale.
26
Observer's Assessment of Altertness/Sedation Scale (OAA/S) scoring
Scored 1-5
27
Modified observer assessment of alertness and sedation (MOAA/S) scale scoring
Scored 0-5
28
Why use sedation scales?
They guide the anesthesia provider in assessing sedation depth.
29
What is BIS (Bispectral Index)?
An objective sedation measure using an algorithm producing a number 0–100 that decreases with anesthetic depth.
30
What BIS range is targeted during MAC?
60–80.
31
What BIS range is targeted during GA?
40–60.
32
BIS approaching 60 is associated with what?
Low probability of recall.
33
How do recall and response to command relate to BIS?
Recall is impaired at higher BIS than loss of response to command.
34
Is MAC necessarily simpler/safer than GA?
No—MAC is not necessarily simpler or safer.
35
Is MAC preferred if a patient is “too sick for anesthesia”?
No.
36
In ASA closed claims, what was the most common respiratory event in MAC?
Inadequate ventilation and oxygenation.
37
What is a common cause of respiratory events in MAC per closed claims?
Multimodal sedation (propofol + midazolam + fentanyl).
38
What case type is most common in MAC claims?
Head and neck cases (reduced airway access).
39
#1 cause of morbidity/mortality due to MAC per slide?
Cardiorespiratory compromise: hypoxia from hypoventilation → cardiorespiratory collapse.
40
How do MAC medications impact the airway/respiration?
Decrease respiratory drive, reduce upper airway patency, and blunt protective reflexes.
41
How do MAC meds lead to hypoxemia/hypoxia?
Meds → alveolar hypoventilation → hypoxemia/hypoxia.
42
In a patient with a normal A–a gradient, what fixes med-induced hypoxemia during MAC?
Increased FiO₂ and adequate ventilation.
43
What equation concept illustrates why both oxygenation and ventilation matter in MAC?
The alveolar gas equation.
44
What does the alveolar gas equation calculate?
PAO₂ (alveolar partial pressure of oxygen).
45
What is the A–a gradient?
Difference between PAO₂ and PaO₂.
46
Hypoxemia with normal A–a gradient suggests what cause?
Reduced FiO₂, hypoventilation, or both (healthy lungs).
47
Hypoxemia with increased A–a gradient suggests what cause?
V/Q mismatch, shunt, or diffusion impairment (unhealthy lungs).
48
In MAC, how does giving sedatives/hypnotics/analgesics affect oxygenation?
Causes hypoventilation → hypoxemia/hypoxia → decreased saturation.
49
If the patient is ventilating adequately, what may be enough?
Increasing FiO₂.
50
If the patient is hypoventilating, what is the danger of simply increasing FiO₂?
It can mask hypoventilation (hypercarbia).
51
What is the definitive treatment if PaCO₂ continues to rise?
Improve ventilation (oxygen alone won’t prevent respiratory failure).
52
What are practical interventions to improve ventilation during MAC?
Chin lift, jaw thrust, CPAP, positioning, decrease sedation, plus supplemental oxygen.
53
What is Patm at sea level?
760 mmHg.
54
What is PH₂O (water vapor pressure)?
47 mmHg.
55
What is normal PaCO₂ used in examples?
40 mmHg.
56
What is RespQ (respiratory quotient) used?
0.8.
57
PAO2 = (___x (___ - ___)) - (___/___)
(FiO2 x (Patmos - PH20)) - (PaCO2/RespQ)
58
Example 1: Room air FiO₂ 0.21 with PaCO₂ 40 — what is PAO₂?
~99.7 mmHg.
59
In Example 1, increasing FiO₂ from 21% to 50% changes PAO₂ how?
~100 → 306.5 mmHg.
60
Example 2: Room air FiO₂ 0.21 with PaCO₂ 60 — what is PAO₂?
74.7 mmHg.
61
Example 2: With FiO₂ 0.50 and PaCO₂ 60 — what is PAO₂?
281.5 mmHg.
62
What key concept do the PAO2 examples demonstrate?
Hypoventilation lowers PAO₂; supplemental oxygen can partially offset, but improving ventilation is definitive.
63
What are ideal sedative properties for MAC?
Easy titration; potent sedative/amnestic with analgesia; rapid onset & predictable PK/PD; rapid recovery/no residual; high safety with cardiorespiratory stability; painless injection.
64
Has the “ideal sedative” been discovered?
No—common sedatives have some, not all, properties.
65
Propofol indications in MAC?
Sedation, hypnosis, mild amnesia.
66
Propofol MOA (as listed)?
Enhances GABA activity.
67
Why is propofol preferred for sedation/hypnosis?
Rapid onset/offset and low PONV incidence.
68
Does propofol have an antagonist?
No.
69
What explains rapid awakening after propofol bolus?
Redistribution (not metabolism initially).
70
Typical reawakening time after propofol?
5–15 minutes (dose dependent).
71
Where is propofol metabolized?
Rapidly in the liver.
72
Propofol bolus dosing for MAC?
0.25–1.0 mg/kg IV.
73
Common propofol infusion range for MAC maintenance?
25–75 mcg/kg/min (up to 150 mcg/kg/min).
74
Induction approach with propofol infusion per slide?
Start 100–150 mcg/kg/min for 3–5 min, then titrate.
75
Intermittent bolus maintenance dosing for propofol?
10–20 mg titrated to effect.
76
How should dosing change in elderly/debilitated patients?
Reduce the dose.
77
Propofol pros listed?
Rapid onset, short recovery, easy titration, antiemetic.
78
Propofol respiratory cons listed?
Inhibits hypoxic ventilatory drive, depresses hypercarbic response, can cause apnea (higher doses), inhibits protective reflexes (higher doses).
79
Why does propofol cause pain on injection?
It’s an alkylphenol; phenols irritate endothelium.
80
Immediate vs delayed mechanisms of propofol injection pain?
Immediate: vein endothelium irritation; delayed: mediator release.
81
How to reduce propofol injection pain?
Give ≥2 drugs simultaneously (e.g., lidocaine).
82
What is propofol infusion syndrome (as described)?
Rare/serious ICU complication: metabolic acidosis, arrhythmias, acute renal failure, rhabdomyolysis, hyperkalemia, CV collapse.
83
Benzodiazepine indications in MAC?
Anxiolysis, amnesia, hypnosis.
84
Benzodiazepine MOA (as listed)?
Facilitate GABA receptor binding.
85
Are benzos reliable hypnotics at high doses compared to propofol/dexmedetomidine?
Less reliable and may cause psychomotor impairment after sedation.
86
Midazolam routes of administration?
Oral, intranasal, IM, IV.
87
Midazolam onset/ duration depend on what?
Route, dose, and concurrent meds; also patient factors.
88
Does midazolam provide analgesia?
No, so used with opioids.
89
Time to peak effect after single IV dose of Versed?
2–3 minutes.
90
IV incremental dosing for midazolam sedation?
0.5–2 mg increments to effect.
91
Adult oral midazolam dose listed?
5–15 mg.
92
Pediatric oral midazolam dose listed?
0.5–0.75 mg/kg.
93
Midazolam continuous infusion rate listed?
1–2 mcg/kg/min.
94
Benzodiazepine pros listed?
Less respiratory depression than other sedatives, reliable anxiolysis, reliable amnesia, may prevent N/V, elevates seizure threshold, theoretical increased safety of LAST.
95
Benzodiazepine cons listed?
Respiratory depression, prolonged sedation/drowsiness, cognitive impairment, hypoventilation/apnea, airway obstruction, hypotension/bradycardia.
96
Benzodiazepine antagonist?
Flumazenil.
97
Opioid indication in MAC?
Analgesia.
98
What receptors do opioids act on for analgesia?
Mu receptors.
99
Why combine opioids with benzodiazepines in MAC?
Creates blend of analgesia + anxiolysis + amnesia.
100
Where do opioids exert analgesic action?
Brain, spinal cord, and peripherally.
101
Opioid adverse effects listed?
Pruritus, N/V, respiratory depression (even small doses), chest wall rigidity (treat with naloxone or GA + MR).
102
Why is fentanyl commonly used in MAC?
Common MAC analgesic; bolus or infusion dosing.
103
Fentanyl bolus dosing range listed?
0.5–1 mcg/kg.
104
Common “real life” fentanyl bolus dose listed?
25–100 mcg.
105
Fentanyl infusion dosing listed?
0.01–0.05 mcg/kg/min.
106
Why may morphine be a poor MAC choice for titration?
Delayed onset and prolonged duration.
107
When might morphine be useful during MAC?
Small intraop doses for prolonged postop analgesia if significant pain expected.
108
Morphine bolus dosing listed?
20–80 mcg/kg.
109
Morphine infusion dosing listed?
0.01–0.05 mg/kg/hr.
110
Common “real life” morphine bolus dose listed?
1–5 mg.
111
Why are newer rapid-onset, short-acting synthetic opioids used in MAC?
Potent and easy titration; typically via continuous infusion ± bolus.
112
What was found when remifentanil was used as a sole procedural sedation agent?
Good satisfaction, but high recall (usually not unpleasant) and common respiratory depression.
113
How is remifentanil commonly used in MAC?
Combined with sedatives like propofol or midazolam.
114
Remifentanil bolus dose listed?
0.5–1 mcg/kg, repeatable.
115
Remifentanil infusion rate listed?
0.05–0.1 mcg/kg/min.
116
Ketamine indications in MAC?
Analgesia, sedation, amnesia.
117
Ketamine MOA (as listed)?
NMDA receptor blockade → powerful analgesia + dissociative sedation/amnesia.
118
Key physiologic advantages of ketamine listed?
Preserves spontaneous breathing, cardiovascular stability, airway reflexes; bronchodilation.
119
Why combine ketamine with benzodiazepines?
Reduce hallucinations/emergence phenomena.
120
Ketamine airway-related risk listed?
Increased oral secretions → consider glycopyrrolate.
121
Ketamine MAC dosing range listed?
0.2–0.8 mg/kg.
122
Common “real life” ketamine bolus listed?
10–25 mg IV.
123
Ketamine onset after IV dose?
30–60 seconds.
124
Ketamine peak effect?
~1 minute.
125
Ketamine duration of action listed?
15 minutes.
126
What benefit does low-dose ketamine provide?
Raises pain threshold (analgesia) and sedation; analgesia can extend into postprocedural period.
127
What common practice is mentioned regarding ketamine and propofol?
Many providers mix propofol and ketamine.
128
What are ketamine emergence phenomena and incidence?
10–20%: disorientation, sensory/perceptual illusions, vivid dreams.
129
How can ketamine emergence reactions be prevented/attenuated?
Co-administer benzodiazepine, barbiturate, or propofol.
130
What does ketamine increase (per slide)?
Salivation, ICP, IOP, myocardial oxygen consumption.
131
Dexmedetomidine indications in MAC?
Sedation, hypnosis, analgesia.
132
Dexmedetomidine MOA (as listed)?
Alpha-2 agonism → decreased sympathetic outflow + analgesia.
133
Pediatric benefit listed for dexmedetomidine?
Reduces emergence agitation.
134
Does dexmedetomidine alone provide amnesia?
No.
135
Dexmedetomidine infusion rate listed?
0.2–1 mcg/kg/hour.
136
Precedex optional loading dose listed?
0.5–1 mcg/kg over 10–20 minutes.
137
Dexmedetomidine onset after bolus?
5–10 minutes.
138
Dexmedetomidine peak effect?
15–30 minutes.
139
Dexmedetomidine duration of action listed?
60–120 minutes (dose-dependent).
140
Unique advantage of dexmedetomidine listed?
Maintains respiratory stability; patients are easily aroused and cooperative (e.g., airway instrumentation, awake FOI).
141
Other dexmedetomidine properties listed?
Moderate analgesic, limited amnestic, antisialagogue.
142
Cardiovascular cons listed for dexmedetomidine?
Bradycardia; biphasic BP response (brief HTN then longer hypotension); stronger effects in elderly (bolus/high rates).
143
How does dexmedetomidine recovery compare to propofol?
Slower onset and delayed recovery reported.
144
Why is PONV generally less with MAC than GA?
No inhalational anesthetics.
145
Why can nausea/vomiting still occur in MAC?
Procedure stress, the procedure itself (GI endoscopy/ophthalmic), or sedatives/analgesics (opioids).
146
Why does PONV matter post-MAC?
Dissatisfaction and delayed discharge.
147
When can antiemetics be administered in MAC cases?
Before, during, or after—based on risk.
148
What caution is noted about antiemetics in elderly?
Some have sedative properties—use care.
149
PONV incidence listed: general population vs high-risk?
20–30% general; 70–80% high-risk.
150
5-HT3 antagonist and dose listed?
Ondansetron (Zofran) 4–8 mg IV.
151
Butyrophenone and dose listed?
Droperidol 0.625–1.25 mg IV (black box warning).
152
Steroid and dose listed?
Dexamethasone 4 mg IV.
153
Scop patch timing listed?
Transdermal scopolamine 2–4 hours before end of surgery.
154
Antihistamine and dose listed?
Diphenhydramine 12.5–50 mg IV.
155
What antiemetic approach is recommended?
Consider multimodal.
156
Why plan pain control during MAC?
Provide analgesia during and after the procedure.
157
What local technique is common for postprocedure analgesia?
Wound infiltration with local anesthetics (know toxic doses).
158
What multimodal analgesic options are listed?
Local anesthetics + acetaminophen + NSAIDs + opioids when needed.
159
What should MAC anesthetics allow?
Rapid recovery.
160
How should MAC discharge criteria compare to GA/regional?
No different.
161
What objective discharge scoring system is listed?
Aldrete Score. Max score of 10. Based on activity, respiration, circulation, consciousness, and color
162
What must be documented for discharge?
Objective discharge criteria.
163
What patient counseling is required regarding discharge readiness?
Home readiness ≠ safe to drive or return to work.
164
What is the Aldrete score used for?
Objective assessment of recovery/discharge readiness (postanesthetic recovery score).
165
List complications of MAC from the slide.
Hypoxemia/hypercarbia (resp depression) or hypotension; arrhythmias; aspiration; laryngospasm; LAST (systemic absorption during nerve block).
166
What is the intermittent-bolus technique?
Provider gives intermittent meds titrated to effect.
167
Advantages of intermittent bolus technique?
Simple, patient-tailored, provider detects over/under sedation, best for short minor procedures.
168
Disadvantages of intermittent bolus technique?
Requires frequent monitoring; peaks/troughs; risk of underdosing.
169
Steps of intermittent bolus approach?
Initial dose → assess → repeat dosing.
170
What is the continuous-infusion technique?
Steady controlled infusion using a pump.
171
Advantages of continuous infusion technique?
Improved cardiopulmonary stability, predictable plasma levels, less rescue meds, faster recovery, lower total doses, reduced workload, customizable.
172
Disadvantages of continuous infusion technique?
Oversedation risk, drug accumulation, higher resource needs.
173
Steps of continuous infusion approach?
Optional loading dose → set infusion → titrate.
174
What does “guttae” mean?
Latin for “drops.”
175
Core concept: continuous infusion vs bolus?
Continuous infusion maintains therapeutic concentration; bolus causes fluctuations.
176
What is a target-controlled infusion (TCI)?
Computer-assisted infusion using PK models to maintain constant plasma or effect-site concentration.
177
TCI advantages listed?
Precise, easy for provider (computer-controlled), flexible, patient comfort (suggested).
178
TCI disadvantages listed?
Expensive, complex, oversedation risk, limited drug models.
179
Propofol target plasma concentration range listed for TCI?
1–5 mcg/mL.
180
Remifentanil target plasma concentration range listed for TCI?
2–8 ng/mL.
181
What patient covariates can be incorporated into TCI models?
Weight, age, hepatic function, cardiac output.
182
What are closed-loop sedation techniques?
Automated sedation guided by hypnotic state (BIS or responsiveness).
183
How does closed-loop sedation work (as described)?
Clinician sets desired sedation (e.g., BIS), system analyzes real-time data, computer-controlled pump delivers sedation.
184
Define pharmacokinetics.
“What the body does to the drug” — dose vs concentrations over time.
185
Define pharmacodynamics.
“What the drug does to the body” — concentration vs effects.
186
What is the “most important” concept noted on this slide?
Context-sensitive half-time (CSHT).
187
Define context-sensitive half-time (CSHT).
Time for central compartment concentration of an infused drug to fall to 50% after stopping the infusion.
188
Why does infusion duration affect CSHT?
Drug distributes to compartments; redistribution can maintain plasma levels after infusion (increases CSHT).
189
Is CSHT a single fixed number?
No—it's a function of infusion duration (“context”).
190
Why does CSHT matter clinically in MAC?
MAC often uses infusions; you want rapid offset for discharge/recovery.
191
What drugs are listed as having short, stable CSHT and wearing off quickly?
Propofol and remifentanil (remi).
192
What drugs are listed as having more prolonged CSHT?
Fentanyl and thiopental.
193
What does CSHT help the CRNA decide?
When to turn off the infusion.
194
What do the CSHT simulation slides highlight about sedatives?
Etomidate and propofol have short CSHT.
195
What do the CSHT simulation slides highlight about opioids?
Remifentanil has short CSHT.
196
Clinical reminder: After CSHT, how much drug remains in central compartment?
50% remains (only 50% reduction).
197
Why are drug interactions especially important in MAC?
No single drug provides all components; drugs act synergistically.
198
“Good news” synergy: opioids + hypnotics do what?
Potentiate → quicker recovery and improved stress response abolition; allow reduced doses.
199
“Bad news” synergy: opioids + hypnotics can cause what?
Synergistic cardiovascular and respiratory depression → vigilance required.
200
What is Cp50?
Concentration preventing movement in 50% (analogous to MAC for IV agents).
201
Why is MAC not relevant for IV agents (per slide)?
Instead use Cp50 as the analogous concept to MAC.
202
Define Cp50 clinically.
Steady plasma concentration that abolishes purposeful movement at incision in 50% of patients.
203
What lowers Cp50?
Combining opioids/benzos/alpha-2 agonists with IV anesthetics (potentiation), increased age, hypothermia, liver disease.
204
What else impacts Cp50?
Stimulus intensity.
205
not relevant for IV agents (per slide)?
Instead use Cp50 as the analogous concept.
206
List clinical uses/routes of local anesthetics from the slide.
Local dermal infiltration; regional anatomic approaches; IV limb administration (Bier block); direct peripheral nerve blocks; central deposition near nerve roots (spinal/intrathecal, epidural thoracic/lumbar/caudal); peripheral plexus injections.
207
What level of sedation is this? Responsiveness: normal response to verbal stimul. Airway: unaffected Spont. ventilation: unaffected CV function: unaffected
Minimal sedation (anxiolysis)
208
What level of sedation is this? Responsiveness: Purposeful response to verbal or tactile stim. Airway: No intervention required Spont. ventilation: Adequate CV function: Usually maintained
Moderate sedation/analgesia (conscious sedation)
209
What level of sedation is this? Responsiveness: Purposeful response after repeated or painful stimulation Airway: Intervention may be required Spont. ventilation: May be inadequate CV function: Usually maintained
Deep sedation/analgesia
210
What level of sedation is this? Responsiveness: Unarousable even to pain Airway: Intervention often required Spont. ventilation: Frequently inadequate CV function: May be impaired
General anesthesia
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