Week 4 ANS Drugs Flashcards
3 Components of Cushing’s Triad
Increased ICP
Bradycardia
HTN
Describe Autonomic HYPERreflexia
Systemic HTN due to intense vasoconstriction, reflecting an inability of vasodilating inhibitory impulses from the CNS to pass beyond a spinal cord transection site
There is a loss if inhibitory impulses resulting in pure SNS stimulation
Spine injury generally at T5 or higher
Describe Baroreceptor Reflex
Stretch Receptors in Aorta & Carotid Arteries sense Increased BP–>
Signal sent via Vagus nerve–>
HR Decreased
Describe Central & Peripheral Chemoreceptor Reflexes
Central Chemoreceptor: Senses Increased arterial CO2 and/or Decreased arterial pH–>Causes increased TV and RR (aka Increased Minute Ventilation)
Peripheral Chemoreceptor: Senses Decreased O2 in Carotid Bodies–>Causes increased TV and RR (aka Increased Minute Ventilation)
Describe Bainbridge Reflex
Increase HR d/t Increase in CVP sensed by Atrial Stretch Receptors (aka Atrial Reflex)
Describe the Bezold-Jarisch Reflex
Vagally mediated reflex of the heart causing Hypotension, Bradycardia, & Coronary Dilation–> Cardioprotective
Describe OculoCardiac (Five & Dime) Reflex
Decreased HR d/t pressure on eye via CNs 5 and 10
Norepinephrine is the _______ POST-ganglionic neurotransmitter.
Norepinephrine is the Sympathetic Nervous System POST-ganglionic neurotransmitter.
Acetylcholine is a neurotransmitter of which nervous system? Sympathetic or Parasympathetic? Explain.
ACh is the Sympathetic and Parasympathetic PRE-ganglionic neurotransmitter AND the Parasympathetic POST-ganglionic neurotransmitter
Epinephrine
Where is it synthesized?
Infusion Doses and Receptors Activated
Synthesized in the Adrenal Medulla
2-10mcg/min (Beta 1, Beta 2)
>10mcg/min (Alpha 1)
MAX 20mcg/min
Norepinephrine
Infusion Doses and Receptors Activated
4-12mcg/min
Lower Doses activate Beta 1
Higher Doses activate Alpha 1
MAX 16mcg/min
Dopamine
Infusion Doses and Receptors Activated
1-3mcg/kg/min (D1, D2)
3-10mcg/kg/min (Beta 1)
>10mcg/kg/min (Alpha 1)
MAX 20mcg/kg/min
Fenoldopam
Infusion Doses and Receptors Activated
0.1-0.8mcg/kg/min (D1 Renal Receptors)
Phenylephrine
Bolus/Infusion Doses and Receptors Activated
Bolus Dose: 50-100mcg
Infusion Dose: 20-50 mcg/min
(Alpha 1 venous>Alpha 1 arterial)
Phentolamine
Use
Mechanism of Action
Phenylephrine OverDose, NE Infiltration
Non-Selective Alpha Antagonist
Midodrine
Use
Mechanism of Action
Dialysis Induced Hypotension
Oral Alpha 1 Agonist
Ephedrine
Mechanism of Action
Direct and Indirect-Acting Sympathomimetic: acts directly on Alpha and Beta receptors, acts indirectly by competing with NE for re-uptake in vesicles so that NE can stay at receptor sites longer
Does Ephedrine Increase or Decrease MAC required?
Any other Sympathomimetics that affect MAC dose?
Increases MAC d/t CNS Stimulation
Yes, Epinephrine and Isoproterenol
Clonidine
Use
Mechanism of Action
Resistant HTN, Prolong Spinals
Partial Alpha 2 Agonist
*Black Box for Pregnant Women
Isoproterenol
Use
Mechanism of Action
As “Chemical Pacemaker” til Permanent Pacemaker can be placed
Non-selective Beta 1, Beta 2 Agonist
Dobutamine
Use
Mechanism of Action
Improve Cardiac Output in CHF patients
Racemic Mixture: Beta 1 Agonist, Alpha 1 Agonist, and Alpha 1 Antagonist (Positive Inotropic agent)
*Has Ceiling Effect (Peak Effect) with respect to vasodilation @ Doses >5mcg/kg/min
Albuterol and Metaproterenol
Use
Mechanism of Action
Asthma, COPD
Beta 2 Agonists: bronchodilation
Terbutaline
Use
Mechanism of Action
Asthma, Tocolysis (Stop pre-mature contractions)
Beta 2 Agonist: bronchodilation and uterine smooth muscle relaxation
Vasopressin
Use
Mechanism of Action
Dosages
Codes, Refractory Hypotension (d/t ACEIs or ARBs)
Stimulation of V1 receptors on vascular smooth muscle- causes vasoconstriction
Code Dose: 40 unit Bolus
Intraoperative Dose: 1-8 units IV
Phenoxybenzamine
Use
Mechanism of Action
HTN in Pheochromocytoma patients
Non-Selective Alpha Antagonist (Alpha1>Alpha2)
Prazosin
Use
Mechanism of Action
HTN
Selective Alpha 1 Antagonist
Doxazosin and Tamsulosin
Use
Mechanism of Action
BPH
Selective Alpha 1 Antagonist
Metoprolol
Use
Mechanism of Action
Dose
Control HR when BP reduction NOT needed
Selective Beta 1 Antagonist
Dose: 2-5mg IV q2-5mins (Total dose 15mg)
Esmolol Use Mechanism of Action Metabolism Onset of Action Bolus and Infusion Dose
Fast BP control for Short Duration Selective Beta 1 Antagonist Metabolized by Non-specific Red Cell Esterase Onset: 90 secs Bolus Dose: 10-80mg IV Infusion Dose: 50-300mcg/kg/min
Labetalol Use Mechanism of Action Dose Onset of Action Duration of Action
Continued BP Control Beta 1, Beta 2 Antagonist>Alpha 1 Antagonist Dose: 5-10mg Bolus q10 mins Onset: 5-15mins DOA: 4-6 hours (long duration)
Propranolol
Mechanism of Action
Non-Selective Beta Antagonist
Atropine
Mechanism of Action
Dose
Anticholinergic Muscarinic Blockers
Dose: 0.5-1mg IV
*Tertiary Amine–>Crosses BBB
(Shorter DOA than Glycopyrrolate)
Glycopyrrolate
Mechanism of Action
Anticholinergic Muscarinic Blocker
*Quartenary Amine–>does NOT cross BBB
(Longer DOA than Atropine)
Reserpine and alpha-Methyldopa
Mechanism of Action
Adrenergic Blockers: Blocks the synthesis and storage of NE
