Autonomic Nervous System Chapter 17,18, 19, 20

Central Nervous System or CNS Brain and spinal cord: receives and processes incoming sensory information and responds by sending out signals that initiate or modify a process.

Peripheral Nervous System Includes all the neurons and ganglia found outside the CNS Includes the  Sympathetic receptors (adrenergic)  Parasympathetic receptors (cholinergic)

Sympathetic Nervous System Helps the body cope with external stimuli and functions during stress (triggers the flight or fight response)  Vasoconstriction – increase in blood pressure  Increased heart rate  Increased respiratory rate  Cold, sweaty palms  Pupil dilation

Sympathetic Nervous System

Parasympathetic Nervous System Works to save energy, aids in digestion, and supports restorative, resting body functions.  Decrease in heart rate  Increased gastro intestinal tract tone and peristalsis  Urinary sphincter relaxation  Vasodilation – decrease in blood pressure

The Race Horse and the Cow Sympathetic Nervous System

Norepinephrine and epinephrine Both always present in the blood. Norepinephrine varies according to the amount of stress present and will cause transient changes in heart rate and systemic arteries and veins. Epinephrine is a constant in regulating heart rate, vasoconstriction in systemic arteries and veins and vasodilation of muscles and liver.

Adrenergic Receptors Norepinephrine produces its effects by combining with adrenergic receptors  Alpha  Beta

Adrenergic Receptors Found in:  Cardiovascular  Endocrine  Gastrointestinal  Genitourinary  Respiratory  Ocular

Alpha Receptors Alpha 1: adrenergic receptors located on postsynaptic effector cells.  Smooth muscles of blood vessels: Constriction  Bladder sphincter  Penis  Uterus  Pupillary muscles of iris

Adrenergic Receptor Alpha 1 Therapeutic Uses  Control topical superficial bleeding  Treat nasal congestion  Elevate blood pressure  Delay absorption of local anesthesia  Decrease intraocular pressure (pressure in eye)

Alpha 2 Same as the Alpha 1 but are located in the presynaptic nerve terminals.

Adrenergic Receptor Beta 1 Cardiovascular  Cardiac muscle: increased contractility  Atrioventricular node (AV): increased heart rate  Sinoatrial node: increase (SA) in heart rate Endocrine  Pancreas (insulin)

Cardiac Conduction System

Beta 1 Drugs Predominately works on vascular smooth muscle of the heart.

Adrenergic Receptor Beta 2 Cardiovascular  Dilation of blood vessels Endocrine Uterine relaxation Respiratory: dilation of bronchial muscles

Beta 2 Drugs Used in Asthma to relieve bronchocontriction. Used to delay pre-term labor by relaxing the uterus.

Dopamine Adrenergic neurotransmitter – essential for normal brain function.  Studies focus on connection between dopamine malfunction in schizophrenia and Parkinson’s Disease.  Role of dopamine: stimulants and depressants.

Body Responses – “fight or flight” Increase in blood pressure and cardiac output. Increase blood flow to brain, heart and skeletal muscles. Decrease blood flow to skin and organs not needed for “fight”. Increase in glycogen for energy, mental activity, muscle strength, blood coagulation, respiratory rate, pupil dilation to aid vision, and increase in sweating.

Fight of Flight Response Can be a problem if the body stay in the “fight or flight” mode. Type A personalities? High stress environment? Medications may be needed reduce the physiologic body responses.

Parasympathetic Nervous System Rest and Digest Save energy Decreased heart rate

Sympathetic Nervous System Protective mechanisms designed to help person cope with the stress or get away from it.

Body Responses – “rest and digest” Dilation of blood vessels in skin Decrease heart rate Increase secretion of digestive enzymes Constriction of smooth muscle of bronchi Increase in sweat glands - cooling Contraction of smooth muscles of urinary bladder Contraction of smooth muscle of skeletal system

Adrenergic Drugs What do they do? Stimulation of the sympathetic nervous system.

Indications Respiratory conditions Topical nasal congestion Ophthalmic conditions Cardiovascular

Lungs Asthma and COPD (Chronic Obstructive Pulmonary Disease): Beta 2 drugs or bronchodilators are used to relieve broncho- constriction and broncho-spasm. Action: dilation of bronchioles

Asthma

OTC Adrenergic Drugs Common cold: anti-histamines Allergy: nasal or oral to relieve nasal congestion

Heart Direct stimulation of receptors  Alpha 1 – Vasoconstriction of blood vessels which increases blood pressure Pressor or vasopressor effect to maintain blood pressure  Beta 1 Increased force of myocardial contraction Increased speed of electrical conduction in the heart.

Heart: SA Node

Ophthalmic Conditions Used to reduce intraocular pressure in treatment of glaucoma.

Glaucoma

Contraindications Only contraindications to use of adrenergic drugs are:  Drug allergy  Severe hypertension

Adrenergic Drugs Epinephrine Pseudoephedrine – Sudafed Isoproterenol (Isuprel) Phenylephrine (Neo-Synephrine) Clonidine (antihypertensive)

pseudoephedrine Trade names: Sudafed, Afrin nose spray Functional Classification: Adrenergic Therapeutic classification: allergy, cold and cough remedies, nasal drying agents / decongestants Action: stimulates alpha and beta adrenergic receptors

Forms and Dosage How supplied: tabs, chew tabs, extended release tabs, liquid or drops Dosing: 30 to 60 mg / dose q 6-8 hours PO Maximum dose 240 mg/24 hours Sustained release: 120 mg PO q 12 hours

Contraindications Severe Hypertension Severe coronary artery disease (CAD) Use with caution in pregnancy, breast feeding and renal failure

Side Effects Dizziness, nervousness, restlessness, insomnia and arrhythmias Seizures Cardiovascular collapse

Additional Information Primarily excreted renally – adjust in patients with renal impairment May cause false-positive for amphetamines – athletes Currently need to ask pharmacist for Sudafed – OTC has been limited due to abuse

Nursing Implications Assess for congestion Monitor pulse and blood pressure before beginning therapy Assess lung sound for signs of bronchial secretions

Allergies

Anaphylactic Shock

Epinephrine Epinephrine would be the drug of choice Classification: Adrenergic Action: affects both the beta 1 (cardiac) and beta 2 (pulmonary) receptors  produces bronchodilation  inhibits hypersensitivity reaction of mast cells.

Epinephrine Therapeutic Effects:  Bronchodilation  Maintenance of heart rate and blood pressure Adverse Side Effects:  Nervousness, restlessness, tremors, angina, arrhythmias, hypertension, tachycardia

How it is given? Sub-Q or IV or inhaled Epi-pen is given to clients with severe allergy reactions Not given by mouth because drug is inactivated by gastric juices Can be inhaled in asthma attack

CAUTION! Check dose, concentration, and route of administration  fatalities have occurred from medication errors  use TB syringe for subcutaneous administration Inhaled provided as metered dose inhaler 160 to 250 mcg – can have 3 treatments 5 minutes apart. IV would be 0.1 to 0.25 mg (cardiopulmonary resuscitation)

Calculation The order is for 0.25 mg of epinephrine. How much would you need to draw up from the vial:  Epinephrine 1 mg / 1 ml

Precautions with Use Tachyarrhythmia's (fast irregular heart rate), headache, nausea, and palpitations Short acting so more definitive treatment needs to be initiated Need cardio-respiratory monitoring  Pulse oximetry  Cardiac monitor

Vasopressive Drugs Pressor drugs or “pressors” or inotropes Used to support the cardiovascular system during cardiac failure or shock. Common vasopressors:  Dobutamine #1  Dopamine # 2  Nor-epinephrine (in addition to 1 & 2)

Dobutamine Functional classification: Adrenergic direct acting B1 agonist, cardiac stimulant Uses: management of heart failure caused by depressed contractibility of the heart Action: stimulates beta 1 (myocardial) adrenergic receptors with relatively minor effect on heart rate or peripheral blood vessels.

Dopomine Functional Classification: adrenergic Uses: to improve blood pressure, cardiac output, urine output – treatment of shock Action: stimulates Dopomine receptors and beta 1 adrenergic receptors Effect: increase BP, cardiac output and renal blood flow

Adrenergic-blocking Drugs Chapter 18

Antiadrenergic Drugs Blocks the effects of the sympathetic nerve stimulation, endogenous catecholamine and adrenergic drugs.

Mechanism of Action Act on alpha or beta receptors Receptors are blocked by adrenergic antagonists or pre-synaptic alpha 2 receptors are stimulated.

When Used? To manage hypertension and a number of cardiovascular disorders.  Beta 1 blocking drugs: acute myocardial infarction (heart attack) MI, angina (chest pain), hypertension  Alpha1 blocking drugs: heart failure, angina, hypertension

When Used? Urinary retention – to reduce smooth muscle contraction of the bladder neck Migraine headaches: ergotamines to dilate blood vessels of the brain and carotid arteries. Uterine contractions: ocytocics used to control post-partum bleeding

Patient Teaching Teach about therapeutic and adverse effects. Take medications as prescribed and do not abruptly stop do not take more or less. Avoid caffeine and other CNS stimulants. Change positions slowly to avoid dizziness or syncope  Hypotension  Postural hypotension or orthostatic hypotension

Patient Education Avoid alcohol Hot tubs and saunas Report constipation and urinary retention Report to health care providers:  Confusion  Depression  Hallucinations  Nightmares  Palpitations  Dizziness

Orthostatic Hypotension Abnormally low blood pressure that occurs when a person assumes a standing position from a sitting or lying position.

Cholinergic Drugs: Chapter 19 Cholinergic drugs stimulate the parasympathetic nervous system.

Mechanism of Action Direct acting cholinergic drugs are synthetic derivative of choline. Effects of drug  Decrease heart rate, vasodilation, and changes in BP  Increase tone and contractibility of smooth muscle  Increase tone and contractibility of bronchial smooth muscles  Increased respiratory secretions

Indications for Use Urinary retention without obstruction Postoperative abdominal distention due to paralytic ileus Myasthenia gravis – muscle weakness During surgery to reverse the effects of muscle relaxants used during surgery

bethanechol Trade name: Urecholine Functional classification: urinary tract stimulant Chemical classification: cholinergic Uses: postoperative urinary retention Action: stimulates cholinergic receptors

Nursing Assessment: urine retention Urinary retention  Bladder distention  Difficulty voiding How do you know drug is working?  Fluid intake equal to urine output  Patient has voided within the last 8 hours

Nursing Assessment: paralytic ileus Paralytic ileus  Hypo-peristalsis  Decreased bowel sounds  No gas or bowel movement How do you know drug is working?  Bowel sounds heart in all four quadrants  Client states has passes gas  Client states has had a bowel movement

Myasthenia Gravis Signs and symptoms: muscle weakness, ptosis (droopy eye lid), diplopia (double vision), difficulty chewing and swallowing, decreased activity intolerance. Ho

pyridostigmine Trade name: Mestinon and Antillrium Functional classification: antimyasthemics Chemical classification: cholinergics Indications: used to increase muscle strength in the symptomatic treatment of myasthenia gravis

Evaluation of drug effectiveness How do you know medication is working?  Increased muscle tone  No droopy eye lid or double vision  Increased activity tolerance.

Alzheimer Signs and symptoms: loss of memory, cognitive function and decreased self-care Clinical trials with Razadyne (drug is in test stage and there is not enough evidence to show that is works) Evaluation of medication effectiveness:  Increase memory and cognitive function  Increase interest in activities of daily living.

Cholinergic-Blocking Drugs Chapter 20

Colinergic-Blocking Drugs Anticholinergics are a class of medications that inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells.

Mechanism of Action Drugs act by occupying receptor sites on target organs innervated by parasympathetic nervous system leaving fewer receptor sites free to respond to acetylcholine. Parasympathetic response is absent or decreased depending on number of receptors blocked.

Effects of Anticholinergic Drugs CNS stimulation followed by depression Decreased cardiovascular response to parasympathetic (vagal) stimulation that slows heart rate. Bronchodilation and decrease respiratory secretions Antispasmodic effects in GI system Change in intra-ocular pressure in patients with glaucoma

Uses GI disorders – peptic ulcer disease, gastritis, increased gastric acid secretion – relax gastric smooth muscle (replaced by newer drugs) Genitourinary – anti-spasmodic – urgency Excessive secretions Ophthalmology – relax eye for exam Respiratory disorder – asthma or bronchitis – inhaled form only Cardiac disorders – bradycardia or heart block Parkinson’s disease

Side Effects Hyperthermia, hot, dry flushed skin, dry mouth, tachycardia, delirium, paralytic ileus and urinary retention

Atropine Chemical classification: anticholinergic Functional classification: antiarrhythmic Action: Inhibits the action of acetylcholine at postganglionic sites located in the smooth muscle, secretory glands, CNS. Low doses decrease: sweating, salivation and respiratory secretions.

Atropine Therapeutic effects:  Increased heart rate  Decreased GI and respiratory secretions  May have spasmodic action on the biliary and genitourinary tracts.

Atropine Side effects:  Drowsiness  Blurred vision  Tachycardia  Dry mouth  Urinary hesitancy