Flashcards in Pharm - Inhalation Anesthesia Deck (27):
What is analgesia?
relief of pain w/o intentional production of altered mental state
What is anxiolysis?
decreased apprehension w/ no change in level of awareness
What defines a conscious sedation?
- Protective reflexes maintained
- Independent maintenance of airway/O2 sat/ventilation
- Response to physical or verbal stimulation
What defines deep or unconscious sedation?
- Profound effects & loss of 1 or more of the 2 components listed:
1. Protective reflexes maintained
2. Independent maintenance of airway/O2 sat/ventilation
3. Response to physical or verbal stimulation
What is general anesthesia?
- Sensory, Mental, Reflex & Motor Blockade
- Concurrent loss of all protective reflexes
What is the difference in rate between inhalation and IV agents?
Inhalation agents accumulate in the body w/ each successive breath--goes up from zero & then reaches a plateau over a period of time.
IV dosing has an instantaneous effect.
Would you want a more lipid soluble drug to be an anesthetic?
Yes, the more lipid soluble a drug, the better it is as an anesthetic -- bc must reach the CNS. This means you would need a lower concentration of the anesthetic to have an effect, and thus a more lipid soluble drug has a higher potency.
Would a more potent anesthetic have a small MAC or a large MAC?
MAC is the degree of potency and is usu expressed as % of gas in mixture required to achieve an anesthetic effect. So if you need less to get an effect (more potent drug), that means a lower/smaller minimum alveolar concentration (MAC.)
*Main point: Potency is an inverse of MAC.
What are the planes of Guedel-Stages of Anesthesia, and what plane(s) would dental work fall under?
1. ***Analgesia: dental surgery
2. Delerium: no surgery
3. ***Plane 1: dental & thoracic surgery
4. Plane 2: abdominal surgery
5. Plane 3: deep abdominal surgery
6. Plane 4:
7. Medullary Paralysis/death
*** = for dentistry
What are the general features of the structures of volatile agents? What are some examples?
- simple, diverse, usu containing halogens
- asymmetric carbon atom-racemic mixtures
- ex. isoflurane, desflurane, sevoflurane
* Note how all of the above cpds have fluoride in them, which can cause renal toxicity.
- We use fluoride bc it stabilizes the cpds.
How would you get partial pressure (tension) of a drug?
PP (tension) of drug: percentage of drug in mixture multiplied by atmospheric pressure
If have a lipophilic compound, dissolved in the lipid environment of the blood, is it free to move?
No, until the lipid environment is saturated (they are not free, but dissolved in lipid solution)
*This causes a lag time, how fast it takes from the drug to reach saturation
Would more rapid effects of anesthesia have a lower or higher blood-gas partition ratio?
- The lower the blood gas partition = the more rapid the unconsciousness
- For example, DESFLURANE & SEVOFLURANE move more quickly to the blood and brain due to their low B/G ratio. Thus, they have higher speeds of onset and higher speeds of recovery.
What effect does cardiac output have on the inhalation of anesthetic drugs?
A higher CO removes more volatile anesthetic from the alveoli and lowers therefore the alveolar partial pressure of the gas. The agent might be faster distributed within the body but the partial pressure in the arterial blood is lower. It will take longer for the gas to reach an equilibrium between the alveoli and the brain. Therefore, a high cardiac output prolongs induction time.
What inhalation agent/drug has no significant cardiovascular effect?
What does direct depression have on the CV system?
Direct depression > sympathetic outflow > peripheral ganglion blockade > adrenal catecholamine release > baroreceptor attenuation > Ca2+ reflux > vagal stimulation > dec in BP > inc in unconciousness
The only inhalation agent with pain relief is...?
N2O is an inhibitor of what...?
vit B12 synthetase
With increasing depth of unconsciousness, you can see a progressive reduction in ____ and decrease in ___
inhalation rate; normal physiological response of rising levels of CO2
Regardless of muscle relaxation or pain relieving qualities, it is customary to administer ___ and an ___.
neuromuscular blocking drugs; analgesic (N2O or opiod)
What disease is Halothane associated w/?
Hepatic toxicity (halothane hepatitis)—covalent binding of metabolite to liver tissue and the immunologic response to foreign antigen damages liver
Which inhalation agent is a teratogen?
- N2O; teratogen = an agent or factor that causes malformation of an embryo
What is the second gas effect?
- when N2O can concentrate halogenated anesthetics in alveoli when they are administered together bc of N2O's fast uptake from alveolar gas.
Main pt: presence of volatile drug conc rises faster in presence of N2O.
What is a major problem with N2O?
- considered a teratogen bc it causes demyelination in infants upon chronic exposure.
What is diffusional hypoxia?
- N2O can retard O2 uptake during delivery--this can be overcome by administering significant concentrations of inspired O2 during recovery.
- Main pt: Diffusional hypoxia = when one administers O2 to maintain oxygenation in immediate post-anesthetic phase.
What is N2O solubility?
- 34 x that of nitrogen - potential problem with air spaces-bowel surgery, pneumothorax, middle ear
- start to replace N in body--some air spaces are compliant while others are not--due to change in pressure betw two.