ACUTE MYOCARDIAL INFARCTION.pdf

nursingcaremngt112: oxygenation&perfusion mpesinable lecturer  nursingcaremngt112: respiratorysystem 4: Acute Myocardial 2 Infarction ACUTE MYOCARDIAL INFARCTION - The death of myocardial cells from inadequate ox...

nursingcaremngt112: oxygenation&perfusion mpesinable lecturer  nursingcaremngt112: respiratorysystem 4: Acute Myocardial 2 Infarction ACUTE MYOCARDIAL INFARCTION - The death of myocardial cells from inadequate oxygenation - often caused by a sudden complete blockage of a coronary artery.  ACS and MI Spectrum includes: a. Unstable Angina b. NSTEMI - partial occlusion of coronary artery, or conditions like; 1.increased metabolic demand ( extreme physical exertion, hypertension) 2. severe aortic valve stenosis 3. low cardiac output c. STEMI - total occlusion of coronary artery - carries a great risk of death and disability MYOCARDIAL INFARCTION  Causes Coronary artery spasm atherosclerosis  Causes Decreased Increased demand for oxygen supply oxygen ( acute blood ( rapid HR, ingestion of loss, anemia, cocaine) low blood pressure)  Risk Factors 1. Cigarette smoking 2. Hyperlipidemia 3. Diabetes 4. Obesity 5. Sedentary lifestyle 6. Stress 7. Sex : men – older than 50 yrs. Old women – postmenopausal 8. Family history Assessment findings: 1. Pain - accumulation of metabolites within the ischemic part - same as in angina - crushing with sudden onset - UNRELIEVED by rest or nitrates 2. nausea/vomiting, dyspnea 3. skin: cool, clammy, ashen 4. elevated temperature CHEST PAIN ADEQUATE O2  5. initial increase in BP and pulse, with gradual drop in BP 6. Restlessness 7. Occasional findings: rales or crackles  Diagnostic tests: 1. 12- LEAD ECG 2. Creatine kinase (CK and CKMB) 3. Troponin – T 4. Troponin I 5. Myoglobin 6. Elevated WBC 7. Echocardiogram NORMAL ECG 3 I’s of MI ST elevation T wave Q wave inversion T WAVE DEPRESSION SIGNIFICANT Q WAVE  Pathophysiology… Atherosclerotic plaque & thrombi Occlusion Absence of blood supply and O2 Anaerobic metabolism dec. ATP and increase lactic acid  Increase lactic acid acidosis Decrease myocardial contractility Conductivity disorder decrease CO Dysrythmia develops decrease tissue perfusion  Acute care management 1. Salvage myocardium/limit infarction size a. thrombolytic therapy - dissolve/break up blood clots b. intra-aortic balloon pump - ↑ myocardial O2 perfusion  c. PTCA – percutaneous transluminal coronary angiography 1. angioplasty - opens the narrowed arteries 2. Stenting - stops the vessel from collapsing d. CABG – coronary artery bypass graft 2. Improve myocardial oxygen supply a. supplemental oxygen b. aspirin - prevent platelet adherence on coronary artery c. heparin - dissolves blood clot 3. Decrease myocardial oxygen demand a. mechanical assist devices b. bedrest c. NPO, liquid or soft diet d. beta-adrenergic blocking agents - interferes w/ the binding to the receptors of epinephrine and other stress hormones 4. Decrease preload (except RV infarction) a. morphine sulfate – relief of moderate to severe pain b. Nitroglycerin – widens or dilates the arteries c. diuretic agents – leaves less water to be reabsorbed into the blood Preload - the amount of ventricular stretch at the end of diastole - known as “ left ventricular end- diastolic pressure ( LVEDP)”  5. decrease afterload a. morphine sulfate b. NTG ( nitroglycerine) - widens or dilates the arteries c. Calcium channel blocking agent (CCB) - reduce coronary vasospasm - ↓ BP by relaxing the smooth muscle d. ACE inhibitors - reduce tension of blood vessels and reduce blood volume 6. increase contractility a. positive inotropics (dobutamine, dopamine) - increases contractility and CO INOTROPICS - increase renal perfusion at lower doses - increase in Cardiac Output, Heart Rate, and Systemic Arterial Pressure which increases the pumping action of the heart (positive inotropy). Rate Calculation: DOPAMINE: =weight (mcg / kg) Single Dose 13.3 (200mg/250ml) = weight (mcg / kg) 26.6 Double dose (400mg/250ml) Rex is 50kg and will be started with DOPAMINE 200mg/250ml at 5mcg/kg Compute for the rate =weight (mcg / kg) 13.3 50kg x 5mcg/kg = 250mcg = 18.79cc/h 13.3 13.3 DOBUTAMINE: = weight (mcg / kg) Single dose 16.6 (250mg/250ml) = weight (mcg / kg) 33.2 Double dose (5oomg/250ml) INOTROPICS Titration Dosing: Renal Dose = 1-5 mcg / kilo Inotropic Dose = 6-10 mcg / kilo Vasoconstriction = 11-20 mcg / kilo 7. maintain electrophysiologic stability a. lidocaine - antiarrythmic - Na channel blocker b. amiodarone - slows intracardiac conduction - K+ channel blocker c. beta-adrenergic blocking agents d. calcium channel blocking agents e. magnesium sulfate / potassium chloride 8. maintain hemodynamic stability a. volume loading to provide adequate pressure loading e.g. IVF b. vaso-active medications (dopamine, norepinephrine) Priority nursing diagnosis: 1. Acute Pain 2. Decreased cardiac output 3. Ineffective tissue perfusion Nursing interventions: 1. establish a patent IV line. 2. provide pain relief; morphine sulfate IV. 3. Administer O2 as ordered. 4. Provide bed rest. 5. Monitor ECG and hemodynamic procedures 6. Administer anti-arrhythmics 7. Monitor I & O, report if UO