General Anesthetics Flashcards
What is anesthesia?
drug-induced reversible depression of the CNS resulting in the loss of response to, and perception of, all external stimuli
which type of general anesthetic are usually administered to children? adults?
- children = inhalant
- adult = IV
what are the 3 stages of general anesthesia? Which is usually IV or inhalational?
1) induction (usually IV)
2) maintenance (usually inhalational)
3) emergence / reversal / recovery
During which level of sedation is a patient not rousable, airway reflexes not protected, and apnea?
general anesthesia
List the inhalation anesthetic agents.
- sevoflurane
- desflurane
- isoflurane
- N2O
List the IV aesthetic agents.
- propofol
- ketamine
- etomidate
- methohexital
List the adjuvant agents.
- opioids
- midazolam
- lidocaine
- dexmedetomidine
List the neuromuscular blockade drugs.
- succinylcholine
- rocuronium
- atracurium
- cisatracurium
- NEOSTIGMINE
how is anesthesia measured?
minimum alveolar concentration (MAC)
What is minimum alveolar concentration (MAC)?
alveolar partial pressure of gas at which 50% of humans do not respond to a surgical incision
What are some factors that increase MAC?
- chronic alcohol use
- infancy (highest MAC at 6 months)
- hypernatremia
- hyperthermia
- amphetamines
- cocaine
- ephedrine
What are some factors that decrease MAC?
- acute alcohol use
- older age
- hyponatremia
- hypothermia
- anemia
- pregnancy
- NO
- opioids
- propofol
- Alpha2 agonists
- IV lidocaine
Why are more anesthetics required for younger patients?
MAC is very high in infancy
What are the protein receptor targets of general anesthetics?
- GABA(A) receptor
- voltage-gated ion channels (Na, K, Ca)
What is the mechanism of intravenous anesthetics?
- 1) potentiate movement of Cl- ions through GABA(A) receptor
- 2) GABA is inhibitory
- 3) decreased neuronal activity
What is the mechanism of inhalational anesthetics?
- 1) activate thalamic ‘extrasynaptic’ GABA(A) receptors
- 2) hyperpolarization
What is the Meyer-Overton Rule?
greater oil/gas partition coefficient = more potent
What does blood:gas partition coefficient determine about a drug? How does a high B:G relate to solubility and speed of onset?
- determines speed of onset
- high B:G = greater solubility, lower speed of onset
What is the function (mechanistically) of anesthetic agents?
- alter intrinsic firing rate of individual neurons
- alter communication between neurons via synaptic transmission
What are the effects of taking inhalational anesthetics on the CNS? What is the main effect to take note of?
- decreased cerebral metabolic rate
- increased cerebral blood flow
- increase intracerebral pressure (ICP)
- postoperative cognitive dysfunction
MAIN: flow-metabolism uncoupling (see first 2 points)
What are the effects of taking inhalational anesthetics on the circulatory system?
- decrease in SVR –> decreased BP and CO
- dose-dependent reductions in myocardial contractility
- coronary steal
- decreased sympathetic output
What are the effects of taking inhalational anesthetics on the pulmonary system? What is the main effect to take note of?
- decrease in tidal volume, increase respiratory rate
- dose-dependent decrease in ventilatory response to CO2
- bronchodilation
- attenuate hypoxic pulmonary vasoconstriction
MAIN: respiratory depression
Why is it important to note that inhalational anesthetics may be beneficial for patients with COPD?
inhalational anesthetics cause respiratory depression but also BRONCHODILATION
Which inhalational anesthetic is sweet smelling?
sevoflurane
