What is MAC (monitored anesthesia care)?

What aspects of anesthesia care does it include?

a specific anethesia service in which an anesthesia provider has been requested to participate in the care of a patient undergoing a diagnostic or therapeutic procedure

MAC includes all aspects of anesthesia care - preop visit, intraop care, postop care

Can the patient typically protect their own airway throughout a MAC case?

Can this become a GA?

yes, patient can typically protect their own airway

yes-if, for an extended period of time, the pt is unconscious and/or loses normal protective reflexes, the anesthetic is considered a general

(currently no clear definition of "extended period of time")

What is the purpose of MAC? (5)

Is MAC safer than GETA?

anxiolysis

amnesia

analgesia

comfort

safety 

yes it is in some populations

safety

decreased PACU time

decreased N/V

improved OR turnover

patient satisfaction

decreased operating costs; increased profits

patient (& surgeon) cooperation

physical status

sleep apnea/morbid obesity

(best if you can be close to the airway the whole time..may need to do occasional jaw thrusts etc)

COPD (coughing)

neurological disorders (Parkinson's, RLS)

chronic back pain (prop knees)

age**

CV function

verbal and auditory function

mental retardation

positioning

prone vs supine vs lateral

NPO status

MAC is safer with elderly pts d/t less manipulation of their airway etc T/F?

Can MAC be done with a mentally retarded pt?

Is there an NPO requirement before a MAC case?

True

Yes, but Richard sts he would never try...."just put them to sleep"

Yes...time frame varies but often about 4 hours or so per lec.

midazolam

fentanyl/sufenta/alfentanil

propofol

ketamine

remifentanil

doxapram (dopram)

narcan

flumazenil (romazicon)

Propofol

Why is this a good choice?

Infusion dose & duration?

When do they regain consciousness?

Advantages? (2)

Be aware?

its pharmacokinetic profile makes it easily titratable with an excellent recovery time

infusions of 50-70mcg/kg/min for 100 min.

regain consciousness in ~4 min

low incidence of N/V

clear-headed upon awakening

be aware: no analgesic properties or amnestic properties at sub hypnotic doses

What bolus dose of propofol will usually not cause apnea?

Is there quicker recovery with an infusion pump or int. bolus doses of propofol? why?

~30-70mg bolus for injection of local or painful stimulus usually will not cause apnea

infusion via pump will usually yield a lower accumulative dose than intermittent boluses and therefore quicker recovery

T/F: Midazolam is the most commonly used BZD

Midazolam

properties?

elderly dosage?

short elim. 1/2 life of ____ yet...?

true

anxiolytic, amnestic, & hypnotic properties

significantly reduced doses needed in the elderly - 1/3 to 1/4 normal dose 

short elimination half-life of 1-4hrs, yet prolonged psychomotor impairment when used as a large portion of your MAC

(give 1-2mg not 5mg as an adjunct to other meds like propofol)

Should midazolam be given alone or in combination with propofol? Why?

Reversal agent & dose? Max dose?

Effects of mdz may recur in ___ min

Disadvantage?

much more advantageous to use at small dose for amnestic properties along with propofol for hypnotic properties (doses of propofol given for MAC are usually sub-amnestic & thus a lil benzos is needed) 

Reverse w/ Flumazenil - 0.2mg q 60sec to max of 1mg

Effects of mdz may recur in 90 min

cost prohibitive ($60-70 per 5cc vial)

What do opioids provide in MAC?

Lack?

Limiting adverse effects? (4)

provide the analgesic portion of a balanced technique

Lack amnestic properties

Limiting adverse effects:

respiratory depression

mm rigidity

emesis

pruritus

Are opioid effects predictible?

How do we deal w/ the above?

reversal?

No, effects of opioids unpredictable from patient to patient

problem can be overcome in practice by giving small incremental doses

Narcan 40mcg boluses effective in reversing respiratory depression

Opioids + Benzos

Are they additive or synergistic?

Dose to produce hypnosis in 50% of patients?

What about complications?

significantly synergistic

~25% of ED50 dose of each needed in cobmination to produce hypnosis in 50% of patients

this synergism extends to their unwanted life-threatening complications of respiratory & cardiac depression

What med is used most commonly for opioid boluses?

Remi bolus dose & uses?

Remi infusion dose & uses?

Remi will provide a bit of post procedure pain relief as well T/F?

fentanyl most common 25-100mcg boluses

Remi boluses of 0.5-1mcg/kg over 60-90sec effective for brief painful stimulation such as retrobulbar blocks

remi infusions of 0.025-0.1mcg/kg/min to provide analgesic effect w midazolam for amnesia

False, need to cover post procedure pain with something else

Ketamine

A __________ derivative

Intense __________ agent

Bolus dose & use?

Is it assoc. w/ resp or cardiac depression?

Produces what kind of state?

phencyclidine derivative

intense analgesic

0.025-0.5mg/kg bolus for painful stimuli

Not usually assoc. w/ resp. or cardiac depression

Produces dissociative state; eyes remain open with nystagmic gaze

Ketamine

Why should you consider a bzd for amnesia when you give Ketamine?

What increases likelihood of laryngospasms with this drug? What attenuates this?

Ketamine also may increase ____ and ____?

intense hallucinations; consider bzd for amnesia, also will attenuate the excitatory effects of ketamine.

Increased oral secretions increasing likelihood of laryngospasms - Glycopyrrolate 0.2mg IV or 0.4mg IM

may increase IOP & ICP

Doxapram (Dopram)

Action?

At reg doses of _______ what 2 things increase?

SE (5)

Stimulates chemoreceptors in the carotid arteries - which then stimulates the respiratory centers of the brain stem = causes pt to breath!

20-40mg (1-2cc) = increase RR & Vt

SE:

increased BP

tachycardia

 sweating

 vomiting

tremors

What type of monitoring is used for MAC?

What must we be prepared for?

What is the most imp monitor?

What does most litigation pertain to w/ a MAC?

same for all anesthetics

always be prepared for GETA

you are the most important monitor, Vigilance!

most litigation pertaining to MAC are related to respiratory failure that then leads to cardiac failure

ABC's of MAC

Think ______of respirations.

Supplemental __.

______ head and neck.

Monitor______.

__ vs ___airway.

Communicate with _____.

Be aware of risk for _______ ______.

Think quality of respirations

Supplemental O2

Reposition head and neck

Monitor ETCO2

oral vs nasal airway

Communicate with patient

Be aware of risk for pulmonary embolism

Describe toxicity escalation with LA.

low, medium, high levels

low levels 

 tongue & circumoral tissue numbness

medium levels

restlessness

difficulty focusing

vertigo

tinnitus

higher levels 

 slurred speech

skeletal mm twitching

tonic-clonic seizures

Initial TX of LA toxicity (4)

1. airway mgmt

2. seizure suppression

and, if needed

3. CPR

4. alert the nearest facility having cardiopulmonary bypass capability

TX LA toxicity

Administer 20% ________

Describe 5 steps of administration of this

administer 20% lipid emulsion

(values in parenthesis are for 70kg):

1. bolus 1.5ml/kg IV over 1 min (~100ml)

2. continuous infusion 0.25ml/kg/min (~500ml over 30min)

3. repeat bolus q 5 min for persistent CV collapse

4. double infusion rate if BP returns but remains low

5. continue infusion for a minimum of 30 min