General Anesthetics Flashcards
Why are general anesthetics useful in surgery?
Amnesia
Analgesia (reflexes cant be initiated by noxious stimuli)
Muscle relaxation
Loss of autonomic responses to noxious stimuli
Loss of conciousness
Why is it important quickly induce anesthesia?
Want to get to level III (surgery plane) because level II has resp reflex suppression and possible hyperexcitability
What is N2O potency and why?
Low potency because it has a low oil:gas coefficient (direct correlation)
Are autonomic responses easier or harder to suppress than movements with inhalation anesthetics?
Harder - requires higher dosing
What determine the length of time required to induce anesthesia?
Solubility of the drug in blood because it has difficult moving from blood into the tissue.
Which inhalation anesthetics are effected more by increased ventilation?
Those with higher blood solubility because N2O is moving into the tissue regardless
At what MAC is anesthesia typically maintained?
1.3-1.4x
How is it possible to keep maintenance MAC at such a narrow range?
There is little inter-patient variability in dose-effect relationship
What determines the rate of recovery from an inhalation anesthetic?
Recovery (like induction) is determined by the drugs blood:gas solubility (lower the solubility the faster)
What are unique adverse effects of N2O?
It can become trapped in air spaces -> increasing pressure
Pneumothorax, middle ear, loops of intestine
Why do you need to terminate N2O use with 100% O2?
N2O will flood the alveoli as it moves out of the body pushing O2 and other gases out
What gas has second gas effect?
N2O only because it has both a high blood:tissue solubility and it has low potency so needs a high volume of administration
What inhalation anesthetic decreases CO?
Sevoflurane
What inhalation anesthetic has no CV effects?
N2O
Why does blood pressure decrease in high potency inhalation anesthetics?
Decrease in SVR
Why must you monitor spontaneously breathing patients on inhalation anesthetics?
Decrease response to CO2 at chemoreceptors will cause dose dependent depression of respiration
What should you be aware of when combining NMJ blockers with inhalation anesthetics?
Anesthetics have some muscle relaxing activity-can lower the dose of blockers
You used too much succinylcholine! What do you do?
Patient enters malignant hyperthermia. Treat with dantrolene
Why would a patient have bone marrow suppression on an inhalation anesthetic?
N2O causes B12 deficiency as it oxidizes cobalt
What is propofol’s main use and why? Does it help with pain?
Anesthesia induction because of 1 min effect. Not an analgesic.
What is two compartment kinetics?
Propofol quickly distributes to poorly diffused tissue. It is slowly eliminated by the liver.
Why is etomidate better than propofol?
It has minimal decreases in BP, HR, and CO
Reduced myocardial O2 consumption - GREAT FOR CV PATIENTS
What do you need to simultaneously inject when you inject etomidate or propofol?
Local anesthetic - shit is painful!
How does ketamine differ from etomidate and propofol in use?
It is an analgesic
Why is ketamine desirable for intubation?
Sympathetic affects increase bronchoconstriction
Adverse effects of etomidate?
Nausea and vomiting
Adverse effects of ketamine?
Dissociative - hallucinations
Patient appears unresponsive, eyes are open, and slow nystagmus. What are they on?
Ketamine - cataleptic state
