General Anesthetics (8-26-15) Flashcards
Nitrous Oxide (N20)
- Indication: used in conjunction w/ other drugs in anesthesia
- MOA: INHALED GENERAL ANESTHETIC
- PK: not blood soluble, fast induction
- Cardiovascular effects: no CV depression
- Respiratory Effect: respiratory depressant (like all inhaled anesthetics)
- What kind of patients this is for: okay for ASTHMATICS b/c will powerfully dilate constricted bronchioles
*Notes/Reminder: NOT soluble in blood; FAST to steady state & induction
Halothane
- Indication: also see isoflurane, desflurane
- MOA: INHALED GENERAL ANESTHETIC
- PK: very blood-soluble, slow induction
- Respiratory Effect: respiratory depressant (like all inhaled anesthetics)
- What kind of patients this is for: okay for ASTHMATICS b/c will powerfully dilate constricted bronchioles
*Notes/Reminder: REALLY soluble in blood, SLOW to steady state & induction; can speed up induction by increasing pt’s ventilation rate
Propofol
- Indication: for hypnosis/amnesia, increased ICP (selection note: has less cardio effects than thiopental)
- MOA: GENERAL IV ANESTHETIC, #1 used today
- Drug action: enhance GABA-ergic actions, works on B subunit of GABA-A, peak effect is in 60-90 seconds, duration is 8-10 minutes
- PK: very fat soluble, is stored in fat emulsion (which could grow bacteria…)
- Cardiovascular effects: Little change in heart rate, DON’T GET REFLEX TACHY w/ propofol; does cause some HYPOtension b/c baroreflex is blocked
- CBF, ICP, IOP, CMRO2: all four decrease
- Respiratory Effect: respiratory DEPRESSANT
- What kind of patients this is for: NOT for pediatrics (metabolic acidosis risk); no asthmatics (respiratory depressant effect); NOT for volume-contracted pts; pts can have pain on injection or myoclonus
*Notes/Reminder: elimination is by multiple routes which is good (lung/liver/kidney); anti-emetic activity, well-being on emergence, pts ambulate sooner
Thiopental
- Indication: increased ICP, or FOCAL ischemic injury
- MOA: GENERAL IV ANESTHETIC, is a barbituate
- Drug action: enhances GABA-ergic actions; has rapid onset (15-30 seconds)
- PK: is fat soluble and very basic (can precipitate out other drugs like antibiotics…)
- Cardiovascular effects: venodilation causes reflex tachycardia which combined w/ myocardial depression effect–>”Pearl Harbor effect”=MI in some pts; does cause some HYPOtension
- CBF, ICP, IOP, CMRO2: all four decrease
- Respiratory Effect: respiratory DEPRESSANT
- What kind of patients this is for: NOT for global ischemic injury or asthmatics; see some ALLERGIC or ANAPHYLACTIC rxns; TISSUE irritation or NECROSIS
*Notes/Reminder: note that elimination is not as good as propofol (which has multiple routes); levels fall due to redistribution to other tissues and then eliminated via the liver
Etomidate
- Indication: IS good for VERY SICK patients w/ CV disease, including ICP, trauma, aneurysm; good if CARDIAC PSYCH patient
- MOA: GENERAL IV ANESTHETIC
- Drug action: enhances GABA-ergic actions; produces hypnosis w/o analgesia
- PK: ENDOCRINE effects here, so no Addison’s dx pts or steroid therapy pts!
- Cardiovascular effects: minimal heart effects AND minimal effects on blood pressure (normotension!)
- CBF, ICP, IOP, CMRO2: all four decrease; note this drug does show stimulation on EEG, so it is NOT for SEIZURE patients!
- Respiratory Effect: minimal
- What kind of patients this is for: better than propofol or thiopental in volume-contracted pts b/c no hypotension effects!!; OKAY for asthmatics
*Notes/Reminder: patients get very nauseous, causes emesis or myoclonus; note endocrine suppression effects that could cause special concerns!
Ketamine
- Indication: profound analgesia; is a treatment for opioid induced hyperalgesia (OIH) if treatment w/ opioids makes pain worse
- MOA: GENERAL IV ANESTHETIC, dissociative (patients may appear awake)
- Drug action: has more of a CENTRAL mechanism of action; depresses cortical function; stimulates limbic system, including hippocampus
- PK: highly lipid soluable
- Cardiovascular effects: major cardiac stimulation (increased HR, BP & CO)
- CBF, ICP, IOP, CMRO2: WATCH OUT HERE–all four INCREASE–> increased ICP, increased cerebral oxygen needs; see CNS excitation here as well so no psych, seizure pts
- Respiratory Effect: minimal
- What kind of patients this is for: prevent emergence delirium in patients w/ midazolam (a benzo); is OKAY for asthmatics
*Notes/Reminder: NOT for psych patients (emergence delirium); NOT for ischemic heart dx (cardiac stimulant); NOT for INCREASED ICP (increases it!); no open eye injuries or aneurysms!
