Analgesia
relief of pain w/out intentional production of altered mental state
Anxiolysis
decreased apprehension w/ no change in awareness
Conscious-sedation
dose dependent, protective reflexes are maintained, can still breathe independently, responds to stimulation
Deep sedation
profound effects w/ loss of one more functions maintained in conscious-sedation
General Anesthesia
sensory/mental/reflex/motor blockade
- concurrent loss of all protective reflexes
General anesthetics
drugs that produce reversible depression of neuronal fucntion w/ loss of ability to perceive pain/sensation
- must maintain airways
- offer more immediate minute to minute control over depth and duration of unconsciousness
what is MAC
min concentration required to anesthetize 50% of pts
- the more lipophilic a drug is the lower the MAC (Meyer Overton Hypothesis)
What all areas do anesthetics affect?
- decrease cortical interactions
- modulate ascending pathways to CNS and descending pathways to peripheral tissues
What are Guedel’s stage of anesthesia?
- initial admin = period of delirium, exaggerated respiration, increased BP/muscle tone, pupil dilation, vomiting
Plane 1 - dental and thoracic surgery - decreasing vitals, constriction
Plane 2 - abdominal surgery = decreasing vitals and tone, pupils constricted less
Plane 3 - deep abdominal surgery = decreasing vitals, loss of light reflex, dilated eye
Plane 4 - no surgery -
Medullary paralysis/death
What is the order of neuronal function loss w/ anesthesia?
Memory then awareness then movement in response to pain, and finally autonomics
- important to give anlagesia to ensure pt is pain free
What is the normal structure of inhalational anesthetics?
volatile structure that is mediated by adding halogens. Racemic mixture may alter potency.
What components are the inhalational anesthetics given?
- as gases w/ partial pressres
- usually give N20 at 70%, O2 at 25%, and the agent at 5%
How are the inhalational anesthetics distributed?
they must diffuse through the lung and get dissolved in the blood
- drug is equilibrated when the PP is the same in the alveoli and the blood
- but the mass of the drug may differ btw the blood and gas in different tissues
- GOAL: PP is the same but drug concentration is different.
What inhalational drugs will have a faster onset of action?
- those w/ low blood:gas partition will have a faster onset
- they also decrease action quicker b/c they get redistributed out of the high flow organs and into the skeletal muscle and fat
Which anesthetics have a high blood:gas partition?
low?
High Halothane > isoflurane > enflurane
Low: Xenon < Desflurane < N20 < Sevoflurane
- —> these also have very low metabolites as well!
What are all the factors that affect uptake of inhalational drugs?
concentration of inspired gas -- this is the only thinged that can be altered by doctors RR Solubility rate of blood flow to lungs CO tissue distribution
What are the respiratory effects of inhalational agents?
increased RR w/ decreased Tidal volume
- results in regular rhythmic shallow breathing
- reflex response to PaCO2 blocked by all except N20 - very good benefit of N20
What effects does N20 have on the heart?
- no effects on CV
- depression if used w/ opioid suggests a sympathomimetic action
What are some potential ways that anesthetics affect CV depression?
- decrease sympathetic outflow
-peripheral ganglion blockade - decreased adrenal catecholamine release
- baroreceptor attenuation
- decrease Ca flux
Vagal stimuation
What inhalational agent has irritating odor?
enflurane, isoflurane, desflurane
What inhalational agent has pain relief?
N20
What inhalational agent has muscle relaxation?
Enflurance and isoflurance
What inhalational agent has loss of reflexes?
all except N20
What inhalational agent has arrhythmia?
Halothane
