MAC - Exam 3 Flashcards
Leading cause of death and severe nervous system injury during MAC
hypoxia from suppression of spont respiration from sedatives
Risk factors for burns around head and neck from MAC
-electrocautery
-O2
-alcohol prep
-flammable drapes
Which of the following anesthetic agents provide amnesia, analgesia, anxiolysis and hypnosis with an acceptable margin of safety and ease of titratability for MAC?
none
T/F MAC defines the continuum of depth of sedation
false
“Nonanesthesia sedation practitioner” =
physician, dentist, podiatrist who have training and licensure to give MODERATE sedation
Nonanesthesia providers should not intend to attain a level of sedation in which a pt is _
unresponsive
T/F If pt loses consciousness and ability to respond purposefully, it is then considered GA regardless of whether airway instrumentation is required
PER BARASH: true
-Holly gave us a similar question that was dicey, pt needed airway help but didnt mentions ability to respond and answer was “deep”; she also said to forget about it tho…
Unlike MAC, “moderate sedation/analgesia” is a service directed by _ who are preoccupied in focusing on successfully completing procedure
proceduralist
T/F MAC should be subject to same lvel of payment as GA or regional
true
Per ASA, MAC should be requested by the _ _ and be made known to the pt in accordance with accepted procedures of the institution
attending physician
Per ASA, MAC services include:
-performing preanesthetic eval
-prescription of anesthetic care
-participation in entire plan of care
-continuous physical presence of anesthetist
-proximate presence of anesthesiologist for emergencies
-usual noninvasive cardiocirculatory and resp monitoring
-O2 administration PRN
-admin of necessary pharm therapies by the judgment of anesthetist
Conditions that make pt a poor MAC candidate (lots of gray areas, remember!)
-CV disease (pulm HTN)
-ANXIETY (claustrophobia, etc; NEED AIRWAY PLAN)
-Chronic pain (narcotic use)
-OSA (NEED AIRWAY PLAN)
-Morbid obesity (NEED AIRWAY PLAN)
-Chronic renal/ hepatic failure
-Adv. chronic lung disease
-Elderly (>70y)
-ASA III or IV
-Use of opioids, sedatives, or rec drugs
-pt doesn’t want MAC
-pt cant lay flat/still
-dementia or cognitive dysfunction
-tremors
NO MAC ; not a gray area
-Asp risk (NPO status, obese, esoph conditions, symptomatic GERD)
-Diff airway(hx neck radiation, limited mouth opening/neck extension, oropharyngeal issues)
-poor pt access for CRNA (head/neck cases, prone, etc)
Risk factors for difficult mask vent:
-beard
-mallampati III or IV
-hx of snoring
-limited mandib protrusion
-etc (y’all know the rest)
T/F MAC pts don’t need to fast
false!
should follow GA guidelines for fasting
-high asp risk = poor MAC candidate
3 reasons verbal communication is vital during MAC
-helps monitor cardiorespiratory function (also if sedation needs titration)
-explain to/reassure pt
-talk when pt is needed to cooperate
General things to consider for MAC
-depth of sedation needed (paralysis?)
-case length (tourniquet time)
-fire risk
-ease of airway accessibility
Factors that will halt procedure/ risk pt safety and require switch from MAC to GA
-combative pt/ not staying still/ AMS
-resp depression causing hypoxia or CV compromise (hypercarbia, coughing)
-aspiration
-loss of IV access
-increased sedation needs
-regional anesthesia failure
-procedure complications (prolonged time, surgeon request)
Things to tell pts about possible MAC procedure:
-they can say yes or no to this
-may be awake, slightly sedated, AWARE, responsive, have memories, have to participate
-we CANNOT promise amnesia and hypnosis
-possibility of conversion to GA for their safety
Define MAC
an anesthesia service in which and anesthesia provider continuously monitors and supports the patient’s vital functions, diagnoses and treats clinical problems that occur, administers sedative, anxiolytic, amnestic, or analgesic medications, and coverts to GA PRN
Is a primarily regional case considered MAC?
NO
-principles of sedation for MAC will apply to regional tho
When non anesthetist gives moderate sedation it is moderate sedation and when an anesthetist gives moderate sedation it is _
MAC
PAUSE. Stop for a sec and imagine 3 doors in your head. Behind each door is a version of you, 3 years in the future, happy, thriving. What are you doing behind those doors?
Know that this career you’re busting your ass for will open those and many other doors you can’t even imagine yet. You didn’t make it this far to only make it THIS far. YOU GOT THIS! Now go give NA 1 some hell. <3
Continuous visual, tactile, and auditory assessment of physiologic function during MAC involves
-observing rate, depth, pattern of respiration
-palpation of arterial pulse
-assessment of peripheral perfusion via temp, cap refill, diaphoresis, pallor, cyanosis, shiver, AMS
T/F Use of only qualitative measurement of oxygenation is mandated by ASA standards for intraoperative monitoring
false, BOTH qualitative and quantitative
_ usually precedes cardiac arrest in MAC cases
cyanosis
Risk factors for arterial desaturation during MAC:
obesity
pre-existing upper airway obstruction
pre-existing resp disease
increased metabolic rate
GA
age extremes
surgical site
pt positioning
sedatives/opioids
protective airway reflexes
_ events constitute the single largest source of adverse outcomes in MAC cases
respiratory
Which main airway monitoring tools are crucial for preventing respiratory events in MAC cases?
pulse ox and capnography!
-all MAC cases should have both
Desaturation signs could be delayed with supp O2, what would help you catch these signs early during a MAC case?
Capnography!
-in most if not all cases really
-resp depression is 17.6 x more likely to be caught while using cap
-catches obstructions, apnea, other events quicker than you can
T/F You can’t monitor capnography during MAC cases
false
-should absolutely do this!
-sidestream capnography exist that works w NC, face masks, and nasal airways FOR MAC
EKG must be displayed _ and BP measured/recorded Q _ min at a minimum for MAC cases
continuously
5min
Pulse should be monitored in MAC cases in at least one of 3 ways:
-ascultation
-palpation
-pulse ox
T/F It is an ASA standard for any pt receiving anesthesia to have temp monitored when clinically significant changes in body temp are intended, expected, or suspected.
true
T/F Hypothermia is less of a risk with MAC cases
false, just as prevalent
-shivering, behavior changes and vasoconstriction can still happen
Without reliable temp monitoring, possible first indication of hypothermia could be _
shivering
-late sign
Sensation of _ could be a first indicator of hypoxia, hypercarbia, cerebral ischemia, LAST, and myocardial ischemia in MAC cases
hyperthermia
Minimal sedation =
-normal response to verbal stim
-airway, spont vent and CV function are unaffected
Moderate sedation(AKA conscious sedation) =
-purposeful response to verbal or light tough stim
-airway, spont vent
-CV function are preserved
Deep sedation =
-purposeful response to REPEATED or painful stim but may lose response to verbal or light touch stim
-COULD need help with airway patency
-CV function maintained usually
GA=
-pt is unarousable to painful stim
-airway support is REQUIRED and spont ventilation is usually inadequate, needing PPV
-CV function could be altered
Ramsay Sedation Scale (RSS)
-what inspired the creation of the RASS scale
-observed sedated ICU pts
-6 levels; 3 w pt awake, 3 w pt asleep
Richard Agitation Sedation Scale (RASS)
-assesses LOC and agitated behavior in ICU pts
-10 levels, 3 steps:
observation
response to auditory stim
response to physical stim
-high interrater reliability
-not used much in procedural sedation
Modified Observer’s Assessment of Alertness/Sedation Scale (OAA/S scale)
4 areas of observation:
-responsiveness, speech, facial expression, eyes
score 1= deep sleep, score 5= alert
-USED FOR PROCEDURAL SEDATION(mods by ASA)
BIS and EEG have limited ability to evaluate pt response to anesthesia/sedation when pt has neuro deficits such as:
-aphasia
-deafness
-paralysis
BIS has been shown to correlate with _ scale during propofol induced sedation for regional anesthesia
OAA/S
Typically, lower BIS number, more _ pt is.
sedated
-typically absence of recall assoc w BIS <80 (BARASH) or <60 (Anesthesiology?)
-BIS can vary depending on meds given so not perfect
BIS target for MAC=
60-80
BIS target for GA=
40-60
T/F Isolated hypoventilation requires large increases in supp O2 to restore O2 sat to adequate levels
false, MODEST, not significant
-only in isolated hypoventilation, not pt w resp disease/complication
T/F A pt may have significant underlying alveolar hypoventilation despite acceptable O2 sat and minimal O2
true
-hence why we like capnography
A normal A-a gradient is _ which is low. If it becomes higher, this could indicate a _.
10mmHg
shunt
T/F My patient is not requiring supp O2 in MAC case so I don’t need to monitor capnography
false!!!
Most common equipment related problem in MAC cases:
cautery fires around head and neck
Fire risk score components=
-heat
-fuel
-O2
Key risks for fire in OR (1 point each, 3pts = high fire risk)
-surg site/ incision above xiphoid
-open O2 source (supp O2)
-ignition source (electrosurg unit, laser, FIS, cautery)
-score 3= all 3 present
-score 2= procedure is in the thoracic cavity, the ignition source is remote from an open oxygen source, the ignition source is close to a closed oxygen source, or no supplemental oxygen is used.
-score 1= just supp O2
2nd most common cause of injury in MAC cases:
cautery fires
-really?!
Factors contributing to fire risk
-supp O2
-cautery
-alcohol prep
-flammable drapes
-drapes tenting with O2 inside
Fire risk prevention:
-avoid tenting drapes, open face draping
-lowest acceptable supp O2
-using compressed air instead of O2 to prevent CO2 accumulation
-stop O2 flow for 60sec before cautery
-avoid alcohol prep solutions
-awareness of fire causes
Venturi masks and fire risk:
-causes entrainment of O2 rich gas if under drapes
-just avoid this mask if cautery will be happening near face
Pain agitation may be the result of:
-pain
-anxiety
-hypoxia
-hypercarbia
-impending LAST
-cerebral hypoperfusion
-noxious stim like temp extremes, itch, full bladder, IV infiltration, prolonged pneumatic tourniquet
Continuous infusions are generally _ to intermittent bolus dosing. Why?
superior
-They produce less fluctuation in drug concentration, reducing number of episodes of inadequate or oversedation and prompts sooner recovery
After IV admin of drugs, distribution occurs simultaneously to the vessel-rich groups and tissues like _ and _
muscle and skin
-fat and bone is later and accumulate there if lipophilic; could cause delayed recovery if takes a while to redistribute back to central compartment
Elimination half life is only reliable in _ -compartment pharmacokinetic models because only factor changing drug concentration in these models is elimination
single
T/F In multi-compartmental pharmacokinetic models useful parameters include: elimination half life, distribution half life, distribution volume, intercompartmental rate constants etc.
false, these are not reliable, play a minor role
-context sensitive half time is more useful
During early parts of infusion of lipophilic drugs, distributive factors _ plasma concentrations as drug is sent to unsaturated peripheral tissues, then _ infusion is discontinued, drug will return from peripheral tissues and re-enter central circulation.
decrease
after
Context sensitive half time (CSHT) =
time needed for plasma drug concentration to decline by 50% AFTER stopping infusion of particular duration
-a function of the LENGTH of infusion too
Context sensitive half time reflects the combined effects of _ and _ on drug disposition
distribution and metabolism
T/F The context sensitive half times of all drugs bear constant relationship with their elimination half times
false
-ex) fentanyl has shorter elimination half life than sufentanil but its context-sensitive half time is much longer than sufentanil after 2 hr, lasts in system longer
T/F Context sensitive half time is significantly increases in propofol and thiopental
FENTANYL and thiopental
- not propofol; despite lipophilic nature and slow return from peripheral tissue, context sensitive half time is short due to its rapid metabolic clearance
T/F context sensitive half time helps determine how long it will take for pt to recover from MAC
false; partly
-effect site (brain) concentration decay describes this
-CSHT only describes how long it will take for plasma concentration of drug to drop by 50%
-pt still has 50% of drug left in plasma
Awakening from MAC anesthesia is usually a function of:
effect site (brain) concentration decay
AKA when drug leaves effector site!
-CSHT , length of infusion, and cardiac output can play a role
-can show a variable time lag behind changes in plasma drug concentration
The delay in onset of drug effects upon IV injection is the result of
distribution