Step 1: General Anesthetics Flashcards
** Balanced anesthesia**
- Anesthesia produced by a combination of drugs, often including both inhaled and intravenous agents.
Inhalation anesthesia
Inhalation anesthesia
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Balanced anesthesia
Balanced anesthesia
Balanced anesthesia
Balanced anesthesia
Balanced anesthesia
A zxcasdfasdfasdfasdfasdfInhalation anesthesia
Anesthesia induced by inhalation of the drug
MAC (Minimal alveolar anesthetic concentration)
The alveolar concentration of an anesthetic that is required to prevent a response to a standardized painful stimulus in 50% of patients.
Analgesia
A state of decreased awareness of pain, sometimes with amnesia.
Stages of Anesthesia
- **Stage 1: ** Analgesia
- Stage 2: Disinhibition
- **Stage 3: ** Surgical Anesthesia
- Stage 4: Medullary Depression
** Inhaled Anesthetics (categories)tgorie( ca **
- Classification & Pharmacokintetics
- Elimination
- Miniminum alvelolar anesthetic concentration
- Effects of inhaled anesthetics
5.
Anestheisa protocols
Minor procedures: conscious sedation techniques that combine intravenous agents with local anesthetics are often used.
Extensive surfgical procedures: anesthesia protocols commonly include the use of IV drugs to induce the anesthetic state (inhaled anesthetics (with or without IV agents) to maintain an anesthetic staet and neuromuscular blocking agents to effect muscle relazation.
Inhaled Anesthesia
MOA
- Increase threshold fo rfiring of CNS neurons
- (potency of inhaled anesthetics is roughly proportionate to their lipid solubility.
- effects on ion channesl by interactions of anesthetic drugs with membrane lipies or proteins with subsequent effects on central neurotransmitter mechanism.
**Classification & Pharmacokinetics **
(inhaled anesthetics)
- Solubility (rapid equilibration with the blood, the more quickly the drug passes into the brain)
- Inspired gas partial pressure (high partial pressure of the gas, in the lungs –> more rapid achievement of anesthetic levels in the blood).
- Ventilation rate (greater the ventialtion, the more rapid is the rise in alveolar and blood partial pressure of the agent and the onset of anesthesia)
- Pulmonary blood flow (at high pulmonary blood flows, the gas parital pressure rises at a slower rate: thus the speed of the anesthetia is reduced)
- Arteriovenous concentration gradient (Uptake of soluble anesthetics into highly perfused tissues may decrease gas tension in mixed venous blood.)
Elimination
(Inhaled Anesthesia)
- Termination occurs by redistribution of the drug from the brain to the blood
- And elimination of the drug through the lungs.
MAC
(Minimum alveolar anesthetic concentration)
- Alveolar concentraiton required to eliminate the response to a standardize painful stimlus in 50% of patients.
- MAC values lower for adolescents and young adults vs. infants and elderly.
- Several anesthetic agents are used simultaneously, their MAC values are additive.
Effects of Inhaled Anesthetics
- CNS effects (decrease brain metabolitc rate, reduce vascular resistance and thus increase Cerebral blood flow–>increase in intracranial pressure).
- Cardiovascular effects (decrease arterial blood pressure moderately).
-
Respiratory effects (all inhaled anesthetics cause a dose-dependent decrease in tidal volume and minute ventilation, leading to an increase in arterial CO2 tension)
- malignant hyperthermia:
Malignant hyperthermia
- When anesthetics are used together with neuromuscular blockers (especially succinylcholine).
- This rare condition is thought in some cases to be due to mutations in teh gene loci corresponding to ryanodine receptor (RyR1).
- Treatment: Dantrolene w/supportive management.
IV Anesthetics
(BB POKE)
- Barbiturates
- Benzodiazepines
- Propofol
- Opioids
- Ketamine
- Etomidate
Barbiturates
Thiopental & methohexital
- Have lipid solubility (which promotes rapid entry into the brain and results in surgical anesthesia)
- Respiratory and circulatory depressants (b/c they depress cerebral blood flow, they can also decrease intracranial pressure).