General Anesthesia Flashcards
What is general anesthesia?
A pharmacologically induced state of amnesia, unconsciousness, skeletal muscle relaxation, and reduction of autonomic responses
What is altered with medically induced loss of consciousness?
Medically induced loss of consciousness (mLOC) causes a breakdown in the signaling between brain regions (macro scale) and altered signaling between neurons (microscale)
What are the five phases of an anesthesia?
Preoperative: eval, H&P, anxiolysis Induction Maintenance: during procedure Emergence: reverse or let medications wear off Postoperative: PACU
What is the goal preoperatively? What types of meds are used for this?
Anxiolysis; Benzodiazepines
Diazepam
- Use
- Mechanism of action
- Half life
- Sedation, anxiolysis, muscle relaxation, ANTEROgrade amnesia **No analgesic properties
- facilitates the action of GABA at the a subunit –> enhanced opening of Cl- channels causing hyper polarization of the membrane–> resistant to excitation
- 21-37 hrs
* *least potent
Midazolam
- Use
- Mechanism of action
- Half life
- Sedation, anxiolysis, muscle relaxation, ANTEROgrade amnesia **No analgesic properties
- facilitates the action of GABA at the a subunit –> enhanced opening of Cl- channels causing hyper polarization of the membrane–> resistant to excitation
- 1-4 hrs
* *medium potent
Lorazepam
- Use
- Mechanism of action
- Half life
- Sedation, anxiolysis, muscle relaxation, ANTEROgrade amnesia **No analgesic properties
- facilitates the action of GABA at the a subunit –> enhanced opening of Cl- channels causing hyper polarization of the membrane–> resistant to excitation
- 10-20 hrs
* *most potent
Propofol
- Use
- Mechanism of action
- Termination of action
- Induction of anesthesia and general anesthesia
- Presumed interaction with GABA; delays the dissociation of GABA from receptors –> hyperpolarization of cell membranes
- Tissue uptake and redistribution causes termination of action, not metabolism
Propofol
- CV effects
- Pulmonary effects
- CNS effects
- Decreased SBP, MAP, SVR (no change HR)
- RR depression is dose dependent
- Decreased CBF, ICP and CMRO2
Etomidate
- Use
- Mechanism of action
- Induction of anesthesia
- Rapid onset of sleep and awakening from assumed enhanced GABA effects
**Myoclonus and adrenal suppression; increased PONV
Etomidate
- CV effects
- Pulmonary effects
- CNS effects
- If low volume or pain/anxiety causing higher blood pressure or HR, can caused decreased BP and HR, otherwise no change. No change or decreased SVR
- Minimal respiratory depression
- Decreased CBF, ICP, CMRO2
Ketamine
- Use
- Mechanism of action
- Induction of anesthesia, adjunct analgesic
- NMDA, interaction with opiod, monoaminergic, muscarinic receptors and voltage gated Ca++ channels
**Emergence delirium
Ketamine
- CV effects
- Pulmonary effects
- CNS effects
- Increased BP, HR and SVR
- No respiratory depression
- Increased CBF, ICP, CMRO2 **don’t give for neuro surgery
Barbiturates
- Use
- Mechanism of action
- Induction of anesthesia
- Interacts with GABAa receptor
**contraindicated in patients with Acute Intermittent Porphyria
Barbiturates
- CV effects
- Pulmonary effects
- CNS effects
- Decreased BP, Increased HR, Decreased SVR
- Rapid and profound respiratory depression, apnea
- Decreased CBF, ICP, CMRO2