Assessment of Cardiovascular Function Part 4

Dopamine (Intropin) Naturally occurring catecholamine nT Potent dopaminergic as well as beta1- and alpha1-adrenergic receptor activity Low dosages: can dilate blood vessels in the brain, heart, kidneys, and mesentery, which increases blood flow to these areas (dopaminergic receptor activity) Higher infusion rates: improve cardiac contractility and output (beta1-adrenergic receptor activity). Highest doses: vasoconstriction (alpha1-adrenergic receptor activity). Contraindication: pts who have a catecholamine-secreting tumor of the adrenal gland (pheochromocytoma) ** Only available IV; given by continuous infusion epinephrine (Adrenalin) Endogenous vasoactive catecholamine Acts directly on both the alpha- and betaadrenergic receptors of tissues innervated by the SNS Prototypical nonselective adrenergic agonist Administered in emergency situations One of the primary vasoactive drugs used in many advanced cardiac life support protocols Additional assessments o Vital signs o Breath sounds o ABGs (if ordered) o ECG/EKG findings Physiologic response is dose related: o Low dosages à stimulates mostly beta-1 receptors, increasing force of contraction and HR. it is also used to TX acute asthma and anaphylactic shock at these dosages b/c it has significant bronchodilatory effects via the beta-2 receptors in the lungs o High dosages à (ex. IV drip) it stimulates mostly alpha-adrenergic receptors, causing vasoconstriction, which elevates the BP Available in 2 strengths for IV use: 1:1000 (1 mg/mL) and also 1:10,000 (0.1 mg/mL) à Read label carefully for patient safety! norepinephrine (Levophed) • Stimulates alpha-adrenergic receptors • Causes vasoconstriction • Direct-stimulating betaadrenergic effects on the heart (beta1-adrenergic receptors) • No stimulation to beta2adrenergic receptors of the lung • TX of hypotension and shock • Administered only by continuous infusion phenylephrine (Neo-Synephrine) • Works almost exclusively on the alpha-adrenergic receptors • Used primarily for: • short-term TX to raise BP in patients in shock • Controls supraventricular tachycardias (dysrhythmias) • Produces vasoconstriction in regional anesthesia • Topical ophthalmic drug • Nasal decongestant IMPLEMENTATION: • Intravenous administration – Check IV site often for infiltration (may lead to tissue necrosis from excessive vasoconstriction around the IV site) à phentolamine = often used for TX of infiltration – Use only clear IV solutions – Always use an infusion device pump – Infuse agent slowly to avoid dangerous cardiovascular effects – Closely monitor cardiac rhythm (V/S, heart sounds, and/or ECG monitoring) – What treatment is necessary for infiltration of an adrenergic drug? What is the drug of choice in treating shock? Dopamine (b/c in specific dose ranges it helps TX shock-related syndrome through its ability to produce vasoconstriction of peripheral blood vessels and increase blood pressure, but without vasoconstriction of the renal vasculature). NOT epinephrine b/c it leads to vasoconstriction of the renal vessels and subsequent renal damage or shutdown. EVALUATION: • Monitor for therapeutic effects (cardiovascular uses) – vasoactive drugs – Improved CO – Decreased edema – Increased urinary output – Return to normal vital signs – Improved skin color (pallor to pink) and temperature (cool to warm) in the extremities – Improved peripheral pulses – Increased LOC PATIENT TEACHING: • Take medications as prescribed. • Inform prescriber of any over-the-counter or herbal supplements before taking • Report worsening of symptoms CH. 19 ADRENERGIC-BLOCKING DRUGS Adrenergic antagonists – (Sympatholytics) à opposite effects of adrenergic drugs; inhibit the stimulation of the SNS by acting on different receptor types Alpha-2 receptors = INHIBITORY in nature; it is actually stimulation of alpha-2 receptors that causes the inhibitory effects of the SNS ALPHA BLOCKERS – interrupt stimulation of the SNS at the alpha-1 adrenergic receptors Alpha blockers work either by direct competition with norepinephrine or by a noncompetitive process Alpha blockers have a greater affinity for the alpha-adrenergic receptor than norepinephrine does and therefore can chemically displace NE molecules from the receptor Drug Effects: adrenergic blockade of these alpha-1 receptors leads to effects such as: o Vasodilation (both arterial and venous) o Reduced BP o Miosis (pupillary constriction) o Reduced smooth muscle tone in organs like bladder + prostate o Increased GI tract motility Indications: o Used to TX hypertension o Effect receptors on prostate gland and bladder à decreased resistance to urinary outflow à reducing urinary obstruction and relieving effects of BPH o Used to control and prevent HTN in patients with pheochromocytoma (adrenal gland tumor would be secreting norepinephrine and stimulating the SNS) ** o Raynaud’s disease, acrocyanosis, and frostbite à increased endogenous alpha-adrenergic agonist activity, which results in vasoconstriction o Phentolamine = alpha blocker that is effective at counteracting the effects of injected EPI and norepi. They do this by causing peripheral vasodilation and reducing peripheral resistance by blocking catecholamine-stimulated à used to prevent skin necrosis after extravasation (leak vasoconstriction out of blood vessel into the surrounding tissue) which could cause tissue death (necrosis) and even loss of limb Adverse Effects: primary adverse effects are those related to their effects on vasculature First-dose phenomenon* = severe and sudden drop in BP after admin. of the first dose of an alpha-adrenergic blocker, can cause pts to fall or pass out o Warn pts about this before they take their first dose of an alpha blocker ** Orthostatic hypotension can happen with any dose of an alpha blocker o Warn pts to get up slowly from a supine position Dizziness, headache, and constipation = common adverse effects Contraindications: Allergy peripheral vascular disease Caution in: o hepatic and renal disease o coronary artery disease o peptic ulcer disease o sepsis Interactions: Other alpha blockers Beta blockers Erectile dysfunction drugs Warfarin Antihypertensives Alcohol Toxicity Management: Supportive measures Administration of fluids*, volume expanders, and vasopressor drugs to support BP Anticonvulsants for control of seizures (ex. diazepam) ALPHA BLOCKERS – are commonly used to TX HTN and/or BPH Phenoxybenzamine HCl Phentolamine Prazosin Terazosin - treats BPH and HTN Alfuzosin Tamsulosin - tell dentist of this medication for pts with BPH ** Doxazosin - treats BPH and HTN phentolamine (Regitine) ** Alpha blocker that reduces peripheral vascular resistance + also used to treat HTN Used to TX the high BP associated w/ pheochromocytoma (like phenoxybenzamine), but also used to establish a DX of pheochromocytoma o A single IV dose of phentolamine is given to the hypertensive pt – if the blood pressure declines rapidly, it is highly likely that the pt has a pheochromocytoma Most commonly used to treat the extravasation of vasoconstricting drugs such as norepinephrine, epinephrine, and dopamine ** o When injected SC in a circular fashion around the extravasation site, causes alpha-adrenergic receptor blockade and vasodilation, which in turn increases blood flow to the ischemic tissue and prevents permanent damage Contraindication: allergy, myocardial infarction (MI), & coronary artery disease Adverse effects = tachycardia, dizziness, GI upset Drug interactions: o beta blockers, alcohol, erectile dysfunction drugs = additive effects resulting in profound hypotension o epinephrine = antagonistic effect; results in reduced phentolamine effect tamsulosin (Flomax) ** Alpha blocker used primarily to treat BPH; is exclusively indicated for male patients o Blocks alpha-adrenergic receptors on smooth muscle within the prostate + bladder; results in relaxation of these smooth muscle fibers and improved urinary flow Contraindications: allergy + concurrent use of erectile dysfunction drugs such as sildenafil. Adverse effects: headache, abnormal ejaculation, rhinitis, and others *** PO ONLY Interactions: o Warfarin à competition for plasma protein-binding sites; risk for bleeding o Antihypertensives, erectile dysfunction drugs, alcohol à additive effects; risk for hypotension must be taken as directed and with caution in pts with BP problems (e.g. hypotension) must also be used with caution by OLDER ADULT PTS and while driving b/c adverse effects include blurred vision, dizziness, and drowsiness BETA BLOCKERS Block stimulation of beta-receptors in the SNS Compete with norepinephrine and epinephrine Selective (cardioselective) beta-blockers o Block beta1 only Non-selective (nonspecific) betablockers o Block both beta1 and beta2 receptors Cardioselective beta blockers MOA (block beta-1 receptors) Reduces SNS stimulation of the heart Decreases HR Prolongs SA node recovery – blocking the conduction in the SA node = low HR, low BP Slows conduction rate through AV node Decreases myocardial contractility, thus decreasing myocardial oxygen demand Nonselective beta blockers MOA (block beta-1 and beta-2 receptors) Cause same effects on the heart as cardioselective beta blockers Constrict bronchioles, resulting in narrowing of airways and shortness of breath Produce vasoconstriction of blood vessels nonselective beta blockers can cause either hypoglycemia or hyperglycemia ** o Beta-2 receptors promote glycogenolysis in response to hypoglycemia -nonselective beta blockers block glycogenolysis and can delay recovery from à tachycardia, hypoglycemia and mask the symptoms associated with it tremor, or nervousness. They can also impede insulin secretion from the pancreas, which results in elevated blood glucose levels (hyperglycemia). Beta blockers cause release of fatty acids from adipose tissue à result = elevated triglyceride levels and reduced HDL levels (good cholesterol) Intrinsic sympathomimetic activity – drugs with intrinsic sympathomimetic activity not only block beta-adrenergic receptors but also partially stimulate them (ex. acebutolol, penbutolol, pindolol) Carvedilol and labetalol à two beta blockers that also have alpha-receptor blocking activity; especially at higher dosages INDICATIONS: Anti-angina o Decreases demand for myocardial oxygen demand – (allows more O2 to get to the heart muscle, relieving the pain in heart muscle caused by lack of O2) MI o MI causes catecholamines to be released o Beta blockers are “cardioprotective” = they protect the heart from being stimulated by these catecholamines by binding at the receptor sites à beta blockers commonly given to patients after they have experienced an MI to protect the heart Dysrhythmias o Beta blockers slow the conduction from the SA to AV node, resulting in a decreased heart rate o Class II antidysrhythmic Migraine headache o Lipophilicity (attraction to lipid or fat) allows some beta blockers (ex. propranolol) to enter the CNS Anti-hypertensive à b/c of ability to reduce SNS stim. of the heart (reducing HR and force of contraction) Heart failure – carvedilol and metropolol – useful in HF Glaucoma (topical use) à timolol CONTRAINDICATIONS: Drug allergies Uncompensated heart failure Cardiogenic shock Heart block or bradycardia Pregnancy Severe pulmonary disease Raynaud’s disease srekcobl atbe lAl w ksee21- revoderpeat rudne fooni tbarecxae INTERACTIONS: Other beta blockers Antacids Anticholinergics Digoxin Diuretics Neuromuscular blocking drugs Oral hypoglycemic drugs Insulin os la srekcolb aBte m nanterofVI nevgi ebmyT aneOopiX rC T tIaàIY Nonselective beta blockers – Adverse effects: May interfere with normal responses to hypoglycemia (tremor, tachycardia, nervousness) o May mask signs and symptoms of hypoglycemia o Use with caution in patients with diabetes mellitus olm pgyhrf aidracyhcat hetm ksyasrekocbl atbeoevi t*N celenos dencnahe ebmynai ulnsi of ff tecem eccyilpgyoh het BETA BLOCKERS Cardioselective (beta-1 blocking drugs) • • • • • • Acebutolol Atenolol Betaxolol Esmolol Nebivolol Metoprolol Nonselective (both beta-1 & beta-2 blocking drugs) orm t oinrekcobl aB “te rofbB ePhet kchecwsyala b2l gthwieniaguoy • • • • • • • • carvedilol Labetalol Nadolol Penbutolol Pindolol Propranolol Sotalol Timolol atenolol (Tenormin) • • • • • Cardioselective beta blocker Commonly used to prevent future heart attacks in patients who have had one TX Hypertension + angina Management of thyrotoxicosis to help block the symptoms of excessive thyroid activity Atenolol is available for oral use carvedilol (Coreg) • • • • Nonselective beta blocker, alpha1-blocker, Ca+ channel blocker, & possibly an antioxidant Uses: heart failure*, hypertension, and angina Shown to slow the progression of heart failure & to decrease the frequency of hospitalization in patients with mild to moderate (class II or III) heart failure Most commonly added to digoxin, furosemide, and angiotensin-converting enzyme inhibitors when used to treat heart failure esmolol (Brevibloc) • • • Very strong short-acting beta1-blocker. Primary use = acute situations to provide rapid temporary control of the ventricular rate in patients with supraventricular tachydysrhythmias ONLY Administered IV metropolol (Lopressor)= most commonly used beta-1 blocker Increased survival in pts given the drug after they have experienced an MI PO and IV (when given IV à considered high-alert drug and patient should be monitored) propranolol (Inderal) = prototypical nonselective beta-1 and beta-2 blocking drug Same indications as metropolol TX of pheochromocytoma, thyrotoxicosis, migraine headache Same contraindications as cardioselective beta blockers CONTRAINDICATION = ASTHMA PO and IV use NURSING PROCESS ASSESSMENT Assess for allergies and history of COPD, hypotension, cardiac dysrhythmias, bradycardia, HF, or other cardiovascular problems o Any preexisting condition that might be exacerbated by the use of these agents might be a contraindication to their use Remember alpha blockers may precipitate hypotension Remember that some beta blockers may precipitate bradycardia, hypotension, heart block, heart failure, and bronchoconstriction oni tam cdieht retsSV dm aniN m Ti-rola raulcir tnevaurps m syxolarap xie-erphtwis ntei tapCA kcoNblNOT tT A raehKE B hE B tw TL A 1iO -CKE*RS asaHofX a htwis ntei tapCA onN iN tcOiTT A r KE tB osnhcoocnE BrbTL A 2O-CKER *S EVALUATION Monitor for adverse effects o Bradycardia, depression, fatigue, and hypotension Monitor for therapeutic effects o Decreased chest pain in patients with angina o Return to normal BP and heart rate o Other specific effects, depending on the use Encourage intake of water, frequent rinsing/spraying of mouth w/ OTC dental products, sugarless gum/candy to help dry mouth If any of the meds are given IV à ECG monitoring recommended PATIENT TEACHING Encourage to take medications as prescribed Should never stop these drugs abruptly Alpha blockers à Change positions slowly to prevent or minimize postural hypotension Avoid caffeine (excessive irritability) Avoid alcohol ingestion and hazardous activities until blood levels become stable o Alcohol causes vasodilation which increases risk for hypotension and postural bp changes Notify or report to healthcare provider: o Constipation or the development of any urinary hesitancy or bladder distention o Palpitations, dyspnea, nausea, or vomiting occurs o increase fluids and fiber to help prevent CONSTIPATION ** Patients taking tamsulosin (newer alpha blocker) for BPH must inform all HCPs, including dentists, that they are taking this drug – especially before any type of surgery *** in addition, anything leading to vasodilation (e.g. AVOID alcohol intake, excessive exercise, exposure to hot climates, use of saunas, hot tubs, and heated showers or baths) must be avoided to prevent postural hypotension, dizziness, syncope NURSING IMPLICATIONS for BETA-BLOCKERS Rebound hypertension or chest pain may occur if this medication is D/C abruptly Notify healthcare provider if become ill and unable to take medication; if decrease in activity tolerance or dizziness and fainting with increase activity occurs Notify or report any of the following: o Weight gain of 2 lbs or more in 24 hours OR 5 lbs or more within 1 week (1 kg) o Edema of the feet or ankles o Shortness of breath o Excessive fatigue or weakness o Syncope or dizziness revnedw odn,erpaet bemu tsrkeocbl atbe lAl ki het romo tndanioni ntet ta ypa mtsu i euswyhnda noi tam cdieht ndatsrneud rekcobl aO tbeRrekcolb pahla na rhetWh ie ne gi oltsys f i rebircsepr tcaCotn om t noiorf ntam tiàopr sghtwieyl idadR orce