General Anesthesia Flashcards
Primary MOA for anesthetics
Facilitate inhibitory GABAergic neurotransmission
GABA potentiators
MOA for NO
NMDA glutamate receptor inhibitor
Inhibits kainate receptors too
MOA for ketamine
NMDA glutamate receptor inhibitor
Blood:gas partition coefficient
measures solubility of the drug getting from lungs into blood
Low value means less molecules needed to rise partial pressure therefore faster induction
Fat:blood coefficient
Higher value means that its more soluble in fat - be aware in obese patients
Halothane
2.3 - slow induction, soluble in fat
Disad: halothane hepatitis (necrosis, fever, rash, N/V)
Enflurane
Blood:gas 1.8 slow induction
Disad: CV depression d/t dec contractility
Seizures, uterine muscle relaxant
Isoflurane
1.4 somewhat fast induction
Most commonly used inhalant
Adv: maintain CO, dilation of systemic and coronary vessels
Disad:pungent, progressive respiratory depression w/ prolonged use
Sevoflurane
0.69 - fast induction
Can be used in outpatient d/t fast recovery
Disad: reports of toxicity
Desflurane
0.42 - very fast induction Good for outpatient, not very fat soluble Disad: irritating to airway Need special vaporizer (low volatility) Tachycardia
Methoxyflurane
Not really used anymore, blood gas 12, highly metabolized in body can produce renal failure and nephrotoxicity
Nitrous oxide
0.47, rapid induction Analgesic, not anesthetic Adv: little toxicity Disad: weak, hypoxia, cold air expansion Avoid in pts w/ pneumo, middle ear obstruction, air embolus, obstruction of bowel o intracranial air
Tx for malignant hyperthermia
Dantrolene to reduce intracellular Ca release
Barbiturates: sodium thiopental
Adv: little post n/v, water soluble
Disadv: resp/CV depression, no antagonist, slow recovery, no analgesia
Propofol
Adv: rapid recovery, little accum, “milk of amnesia”
Disad: not water soluble, no antag, no analgesia, cardioresp depression, can elicit pain on injection
Ketamine
Adv: analgesia, no resp depression, hypnotic state
Disad: inc muscle tone, invol mvmts, halluc
AE less common in children
Etomidate
Adv: antag available, anterograde amnesia, CV stability
Disad: accumulates which slows recovery, no analgesia, pain on injection
Benzodiazepines
Midazolam and diazepam
Reduces anxiety and induces amnesia
Antihistamines
Diphenhydramine
Prevention of allergic rxns, some sedation
Antiemetics
Ondansetron
Prevents vomiting and post surg n/v
Opioids
Fentanyl, morphine
Provides analgesia
Antimuscarinics
Scopolamine, atropine
Amnesia
Prevent bradycardia
Prevent fluid secretion in trachea
Muscle relaxants
Pancuronium
Facilitation of intubation
How do barbiturates act?
Increase length of time that Cl channels are open
How do benzodiazepines act?
Increase GABA efficacy by increasing GABA’s affinity for its binding site
What is MAC?
Minimum alveolar concentration
1 MAC renders 50% of subjects exposed to noxious stimuli as immobile
0.3 MAC = mild anesthesia
0.5 MAC = amnesia
Equilibrium rates for tissues
Lung/blood
Brain, heart, kidney
Muscle
Fat
Low blood:gas partition coefficient drugs
NO
Desflurane
Sevoflurane
High:blood gas partition coefficient agents
Isoflurane
Enflurane
Halothane
Methoxyflurane
What is the most commonly used inhalant anesthetic?
Isoflurane
Malignant hyperthermia
Heritable d/o triggered by anesthetics and neuromuscular blockers SR cannot sequester Ca Muscle contractions Lactate production Inc body temp
Which patients should you avoid giving NO to?
Pneumothorax Middle ear obstruction Air embolus SBO Intracranial/ocular air
Which IV should be used for patients at risk for hypotension?
Etomidate
Which IV agent is the only one to provide analgesia?
Ketamine
