What is the ONLY inorganic IA?
Nitrous (means it does NOT contain carbon)
When did IV inductions begin (approximately)
Just before WWII.
Dr Lundy first used thiopental as induction agent? (LM)
1850-1930 Diethyl ether - used for what?
Inhalation inductions - historically took a LONG time to induce. This is where the PLANE or STAGE of anesthesia came from.
(was the Queen of anesthesia)
Analgesia or disorientation - from the beginning of induction of GA to loss of conciousness
Excitement or delirium
from loss of conciousness to onset of automatic breathing. Eyelash reflex disappears. Coughing, vomitting & struggling may occur; respiration irregular with breath-holding.
(Almost skipped with current IV induction agents, could last 5 minutes with Diethyl ether!)
Stage of SURGICAL anesthesia
-from onset of automatic respiration to respiratory paralysis, divided into four planes:
(THIS IS WHERE IV INDUCTION PUTS PATIENTS VERY QUICKLY)
Stage III - PLANE 1
onset of automatic respiration to cessation of eyeball movements. Eyelid reflex lost, swallowing reflexes disappears, marked eyeball movement may occur, conjunctival reflex is lost at the bottom of the plane.
Stage III - PLANE 2
cessation of eyeball movements to beginning paralysis of intercostal muscles. Laryngeal reflex lost, corneal reflex disappears, secretion of tears increases (a good sign of LIGHT anesthesia), respiration automatic and regular, movement & deep breathing as response to skin stimulation disappears.
Stage III - PLANE 3
Beginning to completion of intercostal muscle paralysis. Diaphragmatic respiration persists, progressive intercostal paralysis, pupils dilated & light reflex abolished.
- desired plane when muscle relaxants were not used. Typically try to avoid now-a-days
Stage III - PLANE 4
Complete intercostal paralysis to diaphragmatic paralysis
(usually occurs around MAC of 2)
Stopping of respiration to death.
-Medullary paralysis with respiratory arrest and vasomotor collapse
-Pupils widely dilated and profound muscle relaxation.
MEET BART DURHAM!
-big problem in the 1930's, as there were no ETTs!
Desflurane was introduced when?
1992 (2 years before sevo)
Can be described as LIGHTSWITCH anesthesia.... (by des reps :)
still need to turn up gas flows at the end of a case however to help blow the gas off.
Getting rid of all halogens except for fluorine results in an anesthesitc with??
-Poor lipid solubility
-Extremely resistant to metabolsim
Insolubility Advantages are what?
- Precise control of anesthetic concentrations (can make very quick changes)
-Prompt recovery independent of length of anesthesia
Disadvantages of Des
- Airway irritation (not suitable for inhalation induction)
-SNS stimulation (if you increase levels too quickly)
-CO production (carbon monoxide)
-Requires New vaporizer technology (can fill des vaporizer while in use)
Vaporizer is warm while in use (like a little campfire in the OR! )
Des has a high bottle pricetag.
HOWEVER - more than just the pricetag should be a factor.
- factor in the cost savings of rapid induction and early wake-ups? - could save getting patients out of OR and home sooner.
- can use lower flow rates
Could be argued that DES might actually be the cheapest way to go.
What is the Vapor pressure of Des?
(close to atmospheric pressure! Ball-spring that pushes ball back and lets vapor out... )
Is why new technology was required...
For every cc you would get into a REGULAR vaporizer, 20 cc would get into the atmosphere...
What is the Odor of Des?
Etheral or monkey perfume (but goes away VERY quickly).... but LM said he doesn't think he has smelled it..
Which is more insoluble, Des or Nitrous?
What is the preservative in Des?
There is none!
What is the Blood gas partition of Des?
What is the typical MAC of Des (37 C, 40yo, sea level, 100% 02, blah blah blah)
Desflurane is Isoflurance with what chemical difference?
Clorine atom replaced witha fluorine atom.
Properties of DES
Is a Fluorinated methyl ethyl ether
- Substitution of flourine for chlorine on the ethyl component of the methy-ethyl ether
-Enhanced molecular STABILITY
-3 X Greater vapor pressure than ISO
5 X LESS potent than ISO
Is there a correlation between between anesthetic potency and blood gas partition coefficient?
What is the only measurable metabolite in Desflurane?
Airway properties of Des
Airway Irritant (especially if inspired concentrations are increased rapidly - avoided by incremental increases of inspired concentrations 2% every 2-3 breaths. )
Occurs mainly @ concentrations greater than 6% (NOT THE MAC, but the %)
Not for inhilation induction
May be used for LMAs
The FI quickly approximates WHAT?
-Rapid achievement of alveolar partial pressures necessary for anesthesia
Des patients usually wake up quickly or slowly (assuming sufficient gas flows)
(Lower blood gas solubility)
Will Desflurane impair the mental function of OR personnel via inhaling trace gases?