Autonomic Nervous System F07

Autonomic Nervous System Chapter 16, 17, 18, 19, 20 Clinical Drug Therapy Nervous System  Two main divisions   Central Nervous System or CNS Peripheral Nervous System or PNS 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 or PNS  Includes all the neurons and ganglia found outside the CNS   Afferent (sensory): modify motor output Efferent: Afferent Neurons  Afferent neurons carry sensory input from the periphery to the CNS and modify motor output through the reflex arc. Efferent Neurons  Efferent neurons carry motor signals from the CNS to the peripheral areas of the body. ANS / SNS   Autonomic nervous system controls involuntary activities of smooth muscle, secretory glands and the visceral organs of the body such as the heart (involuntary activities of smooth muscle) Somatic nervous system innervates the skeletal muscles and controls voluntary movement Autonomic Nervous System    Sympathetic Nervous System Para sympathetic System Enteric System The Race Horse and the Cow Sympathetic Nervous System Sympathetic System  Fight or Flight – stimulated by physical or emotional stress (exercise or work), pain, hemorrhage, intense emotions, temperature extremes Sympathetic Nervous System  Protective mechanisms designed to help person cope with the stress or get away from it. Neurotransmitters  Neurotransmitters   Acetylcholine: skeletal muscle Norepinepherine: stress response 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. Dopamine  Adrenergic neurotransmitter – essential for normal brain function.   Studies focus on connection between dopamine malfunction in schizophrenia and Parkinson’s Disease. Role of dopamine in drug addition to drugs: stimulants and depressants. Protective Mechanisms   Intensity of response depends on Norepinephrine and epinephrine Fight or flight Body Responses     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 “flight”. 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 Adrenergic Receptors  Norepinephrine and epinephrine interact with two adrenergic receptors  Alpha and beta     Alpha 1 Alpha 2 Beta 1 Beta 2 Alpha 1  Alpha 1 receptors allows calcium ions to move into the cell and produce muscle contraction. Alpha 1 Location  Blood vessels  Kidney  Intestinal smooth muscles  Genitourinary  Eyes = blinking  Pregnant uterus = contractions  Male sexual organs = sexual function Effects of stimulation  Vasoconstriction  Release of renin (kidney)  Relaxation Alpha 2 Location  Nerve endings  Vascular smooth muscles  Pancreatic beta cells  Platelets Effects of stimulation  Inhibits release of Norepinephrine  Vasoconstriction  Inhibit insulin secretion  Aggregation or clotting Beta 1 Location  Heart Effects of stimulation  Increase heart rate, force of contraction, automaticity and rate of atrial-ventricular function  Increased renin release  Kidneys Beta 2 Location  Bronchioles  Blood vessels  Gastrointestinal tract  Liver  Urinary bladder  Pregnant uterus Effects of stimulation  Vasodilation  Decreased motility and tone  Glycogenolysis  Relaxed detrusor muscle (bladder muscle)  Relaxation of uterus Parasympathetic Nervous System Functions stimulated by PNS: Resting, reparative, or vegetative function Body Responses        Dilation of blood vessels in skin Decrease heart rate (bradycardia) Increase secretion of digestive enzymes Constriction of smooth muscle of bronchi Increase in sweat glands Contraction of smooth muscles of urinary bladder Contraction of smooth muscle of skeletal system Autonomic Drugs  Drugs used due to their ability to stimulate or block activity of the sympathetic or parasympathetic nervous system. Effect of Drugs   Drugs that act of ANS usually affect the entire body. Effects depend on whether you are trying to stimulate or inhibit function. Receptor Activity    Drugs are developed to stimulate or inhibit particular subtypes of receptors. More selective on particular body tissues. Decrease adverse effects on other body tissues – side effects. Classifications: SNS  Sympathetic nervous system drug classifications   Adrenergic - stimulating Antiadrenergic - blocking Classifications: PNS  Parasympathetic nervous system drugs   Cholinergic Anticholinergic Adrenergic Drugs Chapter 17 Adrenergic Drugs   What do they do? Stimulation of the sympathetic nervous system. Mechanism of Action  Three mechanisms:    Directly with alpha 1 or beta-adrenergic receptors on surface membrane. Indirect effects of postsynaptic adrenergic receptors. Mixed action – combination of action on direct and indirect receptor. Heart  Direct stimulation of receptors   Alpha 1 - Vasoconstriction of blood vessels which increases blood pressure – pressor or vasopressor effect. Beta 1 - increased force of myocardial contraction - Increased speed of electrical conduction in the heart. Lungs Asthma and COPD (Chronic Obstructive Pulmonary Disease): Beta 2 drugs or bronchodilators are used to relieve bronchoconstriction and broncho-spasm. Pregnancy  Adrenergic drugs used to relax uterine muscles in preterm labor. OTC Adrenergic Drugs   Common cold: anti-histamines Allergy: nasal or oral to relieve nasal congestion Adrenergic Drugs      Epinephrine Pseudoephedrine – Sudafed Isoproterenol (Isuprel) Phenylephrine (Neo-Synephrine) Clonidine (antihypertensive) How does one choose a drug?   How emergent is the situation PO or IM or IV Allergic Response    Runny nose, itchy eyes, cough Asthma: Cough with bronchospasms, difficulty breathing or SOB (shortness of breath) Anaphylactic shock – edema of airway Allergy Response    Nasal congestion, itchy eyes, non-productive cough Seasonal response to environmental causes Commonly mixed with other drugs in cold medications Pseudoephedrine     Therapeutic classification: allergy, cold, and cough remedies, nasal drying, and decongestants. Indications: symptomatic management of nasal congestion associated with acute viral upper respiratory tract infection. Most often used in combination with other drugs. Action: stimulates Alpha and beta-adrenergic receptors – vasoconstriction in respiratory tract mucosa – possible bronchodilation Therapeutic effects: reduction of nasal congestion, and swelling of nasal passages. 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 CAD / coronary artery disease Use with caution in pregnancy, breast feeding and renal failure Use with caution!  Mild or moderate hypertension, hyperglycemia, hyperthyroidism, and cardiac disease. Side Effects    Dizziness, nervousness, restlessness, insomnia and arrhythmias Seizures Cardiovascular collapse Additional Information     OTC used in combination with antihistamines 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 Severe Anaphylactic Shock     Usually involving the airways Some thing as simple as food allergy can trigger it Peanuts, shell fish, legumes, bee sting, medications Symptoms usually starts with numbness and tingling of lips and leads to swelling of the glottis or epiglottis – this can result in closure of the airway. How Do You Treat It?    Epinephrine would be the drug of choice Classification: adrenergic Action: affects both the beta (cardiac) and beta (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 The subcutaneous or intramuscular administration will help it to get into the blood stream quicker – 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 – us TB syringe for subcutaneous administration Inhaled provided as metered dose inhaler 160 to 250 mcg – broncho-constriction is asthma IV would be 0.1 to 0.25 mg (cardiopulmonary resuscitation) 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 Cardiac Arrest Epinephrine is the best studied and most widely administered adrenergic agonist used for the treatment of cardiac arrest. Used to jump start the heart.  Vasopressor / Inotropic Drugs   Used extensively along with Dopamine to maintain myocardial and cerebral perfusion post cardiac arrest. Administered in small, consistent amounts intravenous. Antiadrenergic Drugs Chapter 18 Clinical Drug Therapy 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. Cholinergic Drugs Chapter 19 Clinical Drug Therapy Cholinergic Drugs  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 Nursing Assessment: urine retention  Urinary retention    Bladder distention Fluid intake Time of last void  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 Nursing Assessment: Myasthenia Gravis   Signs and symptoms: muscle weakness, ptosis (droopy eye lid), diplopia (double vision), difficulty chewing and swallowing, decreased activity intolerance. How do you know medication is working? Increased muscle tone, no droopy eye lid or double vision, increased activity tolerance. Nursing Assessment: Alzheimer   Signs and symptoms: loss of memory, cognitive function and decreased self-care Signs medication is working: increase memory and cognitive function and increase interest in activities of daily living Use in Older Adults  May be used in myasthenia gravis or Alzheimer’s disease Contraindications   Renal obstruction Liver disease Anticholinergic Drugs Chapter 20 Clinical Drug Therapy Anticholinergic 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    Pharmacological classification: anticholinergic Therapeutic 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 Reversal of muscarinic effects May have spasmodic action on the biliary and genitourinary tracts. Atropine  Side effects: drowsiness, blurred vision, tachycardia, dry mouth, urinary hesitancy. Atropine Prototype of anticholineric drugs – atropine sulfate Therapeutic Previously used in preoperative patients to reduce secretions – other newer drugs have replaced