Egar Video #15 : Clinical Application of Inhaled Anesthetics Flashcards
What are the 3 C’s that make inhaled anesthetics the mainstay in the practice of anesthesia?
-They supply “CONTROL”
-Supply a “COMPLETE package”
-and are relatively “low COST”
What are the 3 primary anesthetics that we deal with?
Sevoflurane
Isoflurane
Desflurane
What does CONTROL in the 3 C’s of inhaled anesthetics refer to?
It refers to the better control of inhaled anesthetics during maintenance of anesthesia
-Ex: Study comparing Propofol vs Desflurane
Only 5% of anesthetized by Des moved, 40% anesthetized by Prop moved
What does the “COMPLETE package” in the 3 C’s of inhaled anesthetics refer to?
It provides immobility, amnesia, relaxation, suppression of autonomic reflexes, and (“although imperfect) supplies an element of analgesia
What does COST in the 3 C’s of inhaled anesthetics refer to?
Inhaled anesthetics are “relatively LOW cost” 🤑
What are the advantages of Sevo?
~Non-pungent
~Low solubility
~Minimal cardiovascular stimulation (No arrhythmogenic effects)
~Minimal effects on ozone layer (No chlorine)
What are the disadvantages of Sevo?
~Not the least soluble
~Agitation during recovery
~High acquisition cost
~Greatest degradation
Advantages of Isoflurane?
~Low cost (the CHEAPEST gas)
~Limited cardiovascular stimulation
~Intermediate resistance to degradation
(Both resistant to degradation by metabolism and absorbent)
Disadvantages of Isoflurane?
~Highest solubility
~Intermediate pungency
~Degradation by dry absorbents (turns to carbon monoxide)
~Minor effect on ozone layer (d/t Cl atom)
Advantages of Des?
~Least soluble
~Fastest recovery of all functions
~Greatest resistance to degradation (least degraded)
~Used @ low inflow rates
~Minimal effect on ozone layer (No Cl)
Disadvantages of Des?
~Pungent at concentrations >MAC
~Produces CV stimulation at >MAC
~High acquisition cost
~Degradation to dry absorbent (turns to carbon monoxide)
~Agitation during recovery (particularly in young patients)
General considerations when anesthetizing a 3 yo pt?
~MAC is higher (concentration must be higher)
~Neonates metabolism may be altered d/t reduced hepatic enzymes and hepatic shunts that increase DUA with drugs *not an issue w/ 3yo)
~Apprehension/separation anxiety (pre medicate w/ anxiolytic)
What was the proposed anesthetic plan for a 3 yo?
“Inhalation technique”:
-premedicate with 0.5 mg/kg of midazolam
-8% Sevo w/ 6L of nitrous and 3L oxygen
-once child is asleep THEN place IV and intubate (no IV placed prior d/t child resistance and having to hold child down for IV considered “barbaric”
-NO halothane d/t bradycardia in children
Why use Sevoflurane rather than halothane? What are the disadvantages of Sevo?
~ Quicker induction-recovery
~Smoother
~Less PONV
~Safer (better for bp, hr, and decreased hepatotoxicity)
BUT it is more expensive, and can have post-op agitation
How to avoid post-op agitation in a 3 yo?
~Administer opioid (Morphine d/t longer effects, but slower peak OR Fentanyl prior to emergence)
What are the concerns administering inhaled anesthetics to the elderly?
~They have more comorbidities so more of their drugs affect our anesthetic technique
~ they’re sensitive to depressants/anesthesia: opioids, benzos – need to decrease dose
~they awaken confused (use anesthetics that don’t linger AKA use the poorly soluble anesthetics)
Does minutes to PACU increase or decrease when administering a standard 2mg of Midazolam to an elderly pt?
INCREASES *w/ elderly pts
How does administering a standard 2mg in elderly pts affect their saturations post-operatively?
Based on the research: desaturations less than 94% increases significantly from 50% to close to 85%
How will the duration of the anesthesia influence the choice of anesthetic?
If the case is longer, the choose a less soluble agent so they patient will awaken faster (a poorly soluble agent)
Recovery is ___ rapid with less soluble anesthetic and __ influenced by the duration of anesthesia
-more rapid;
-less influenced
Desflurane takes __ time to recover than from Sevo
Less time
Obese Patient Disadvantages:
-Large fat stores (both depo fat and fat adjacent to highly perfused tissue).
-Enzyme induction (caution w/ highly metabolized anesthetics; can lead to toxicitiy)
-Decreased respiratory reserve (↓ FRC & chest wall compliance)
-limited mobility (difficult transfers)
What did the study on Post op movement to gurney of 130Kg patients show?
Those given the less soluble anesthetic had a greater ability to move from the operating table to the gurney (Des)
In an obese patient, referring to their decreased FRC -> ensure what two things to prevent desaturation
-At induction, make sure the lungs are full of 02 and that
-you have the capability of applying Positive pressure
