Meds: autonomic

Question 1

Ephedrine: common uses?

Answer 1

Intra-op hypotension (temporizing tx) without tachycardia

Question 2

Ephedrine: significant properties & effects?

Answer 2

• Sympathomimetic effects
• ↑ HR, ↑ SV, ↑ CO, ↑ peripheral vasoconstriction
• ↑ myocardial demand

Question 3

Ephedrine: mechanism?

Answer 3

• Stimulates release of granules of norepinephrine at sympa- thetic nerve endingsindirect α/β adrenergic stimulation
• May have small amount of direct adrenergic effect
• Tachyphylaxis may occur with repeat doses (catecholamine
depletion)

Question 4

Ephedrine: adverse drug effects?

Answer 4

CNS: Dizziness, tremor
CVS: ↑↑ BP, palpitations, tachyarrhythmias

Question 5

Ephedrine: onset, duration?

Answer 5

<1min

10min

Question 6

Ephedrine: dosing?

Answer 6

Intra-op hypotension (bolus): 5-10mg IV prn to maximum 50mg

Question 7

Phenylephrine: common uses?

Answer 7

✔ Intra-op hypotension (temporizing tx)

✔ Hypotension from spinal/epidural (often used in L&D due to better effects than ephedrine on fetal acid-based status)

Question 8

Phenylephrine: significant properties & effects?

Answer 8

• Pure α drug (i.e. essentially no β-adrenergic activity unless very high doses)
• ↑↑ venous and arterial vasoconstriction = ↑ SVR
• May induce reflex bradycardia (2o to vagal response,
baroreceptor-mediated)
• Variable effect on CO (depends on preload/afterload as it has no chronotropic/inotropic effects)

Question 9

Phenylephrine: mechanism?

Answer 9

• Direct α1-adrenergic receptor agonist

Question 10

Phenylephrine: adverse drug effects?

Answer 10

CVS: Arrhythmia, ↓ CO, ↑↑ BP, R/L ventricular failure, myo- cardial demand ischemia, peripheral ischemia
RESP: Pulmonary edema

Question 11

Phenylephrine: onset, duration?

Answer 11

<1min

10-15min

Question 12

Phenylephrine: dosing?

Answer 12

Intra-op hypotension (bolus): 50-200mcg IV q10-15min prn Intra-op hypotension (infusion): 0.1-1mcg/kg/min IV titrated to BP

Question 13

Epinephrine: common uses?

Answer 13

✔ Cardiac arrest/resuscitation
✔ Anaphylaxis/bronchospasm, status asthmaticus
✔ Unstable/severe bradycardia
✔ Severe hypotension/shock (norepinephrine more com- monly used since less arrhythmogenic)
✔ Adjunct when using local anesthetics (vasoconstriction slows systemic absorption of anesthetic)

Question 14

Epinephrine: significant properties & effects?

Answer 14

• ↑ HR, ↑ SV, ↑ vasoconstriction
• ↑ bronchodilation, ↓ mucosal edema
• ↓ mast cell/basophil inflammatory mediator release

Question 15

Epinephrine: mechanism?

Answer 15

• Direct α1 and non-selective β adrenergic agonist

Question 16

Epinephrine: adverse drug effects?

Answer 16

CNS: Cerebral hemorrhage
CVS: Palpitations, arrhythmias, ↑↑ BP RESP: Pulmonary edema
OTHER: Infusion site necrosis

Question 17

Epinephrine: onset, duration?

Answer 17

<1min

5-10min

Question 18

Epinephrine: dosing?

Answer 18

• Anaphylaxis (bolus): 0.3-0.5mg q5-10min IM or 0.05-1mg IV/IO.
• Cardiac arrest/resus (bolus): 1mg IV/IO q3-5min until ROSC
• Status asthmaticus (bolus): 0.3-0.5mg q20min SQ to maxi- mum 3 doses
• Hypotension/shock (infusion): 0.05-2mcg/kg/min, titrate to desired MAP q10-15min

Question 19

Norepinephrine: common uses?

Answer 19

✔ Hypotension from undifferentiated/refractory shock (1st line especially for septic/distributive shock)
✔ Cardiac arrest/resuscitation

Question 20

Norepinephrine: significant properties & effects?

Answer 20

• At low dose, β1 effect predominant = ↑ HR, positive inotro- pe and chronotrope
• At higher dose, α1 effect predominant = ↑ peripheral vasoconstriction = ↑ SVR
• ↑ myocardial demand

Question 21

Norepinephrine: mechanism?

Answer 21

• Direct α1 and β1 adrenergic receptor agonist

Question 22

Norepinephrine: adverse drug effects?

Answer 22

CVS: ↓ HR (reflex, β1 effects don’t fully compensate), arrhythmia, ↑↑ BP, peripheral ischemia
GI/GU: Urinary retention
OTHER: Infusion site necrosis (from extravasation)

Question 23

Norepinephrine: onset, duration?

Answer 23

1-2min

1-2min

Question 24

Norepinephrine: dosing?

Answer 24

Hypotension, septic shock (infusion): 0.01-3mcg/kg/min IV Cardiac arrest/resus (infusion): initial 8-12mcg/min IV, main- tenance 2-4mcg/min IV

Question 25

Norepinephrine: alternate name?

Answer 25

Levophed

Question 26

Vasopressin: common uses?

Answer 26

✔ Hypotension from septic/distributive shock (2nd line added to norepinephrine for refractory shock)
✔ Cardiac arrest (refractory pulseless VTach/VFib, PEA/ asystole)
✔ GI variceal hemorrhage

Question 27

Vasopressin: significant properties & effects?

Answer 27

• Positive inotrope
• Vasoconstriction = ↑ SVR, ↑ MAP
• ↑ water retention

Question 28

Vasopressin: mechanism?

Answer 28

• Synthetic arginine vasopressin receptor agonist
• V1 receptor contracts vascular smooth muscle
• V2 receptor increases water resorption in renal tubules

Question 29

Vasopressin: adverse drug effects?

Answer 29

CVS: ↓ CO, arrhythmias, coronary artery vasoconstriction RESP: Pulmonary edema, bronchoconstriction
OTHER: Water intoxication syndrome (HypoNa+), infusion site necrosis (from extravasation)

Question 30

Vasopressin: onset, duration?

Answer 30

15min

duration: w/in 20min of infusion discontinuation

Question 31

Vasopressin: dosing?

Answer 31

Hypotension, septic/distributive shock (infusion): 0.04units/ min IV; maximum 0.07units/min
Cardiac arrest (bolus): 40units in 40mL