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TEST 2
Cardiac drugs
Question | Answer |
---|---|
Stroke Volume (SV) | Amount of blood ejected with each contraction. Average stroke volume is about 70 mL per beat |
Cardiac Output (CO) | Amount of blood pumped by the ventricles in 1 minute. Cardiac output is calculated by multiplying the stroke volume (SV) times the heart rate (HR). Normal cardiac output is 4-8 L/min. SV X HR = CO |
SV X HR = CO | If cardiac output is poor, oxygen and nutrients do not reach cells as needed, impairing tissue perfusion. |
Right ventricle | pumps blood into the low-pressure, low-resistance pulmonary vascular system; therefore the pressures generated by the right ventricle are fairly low. |
Left ventricle | pumps blood into the higher-pressure systemic arterial system, generating much higher pressure and requires more work. |
Arterial Circulation | Moves blood from the heart to the tissues, maintaining a constant flow to the capillary beds. Pressure differences and resistance determine blood flow through the vessels. Blood always moves from higher pressure to lower pressure. |
Greater the difference between pressures... | the greater the blood flow. |
Blood Pressure | Force exerted on arterial walls by the blood flowing within the vessels. |
Peripheral Vascular Resistance (PVR) | Impedes or opposes blood flow to the tissues. PVR is determined by: Viscosity/thickness of the blood. Blood vessel length & diameter |
Mean Arterial Pressure | Maintains blood flow to the tissues throughout the cardiac cycle. It is a product of cardiac output times PVR. CO X PVR = MAP |
Blood | Transport medium within the cardiovascular system. Responsible for: Transporting oxygen, nutrients, hormones to the cells and metabolic wastes from the cells for elimination Regulating body temp, pH and fluid volume |
Heart failure | Develops when the heart is unable to keep up with the body's need for oxygen and nutrients to the tissues. |
Signs of heart failure include | Pulmonary congestion; adventitious breath sounds Shortness of breath Dyspnea on exertion (DOE) Increased heart rate S3 heart sound Increased respiratory rate Nocturia Orthopnea Distended neck veins |
Conditions that increase afterload: Conditions that affect myocardial function: " Myocardial infarction " Cardiomyopathy " Coronary artery disease | |
Conditions that increase preload: | Hypervolemia Valvular disorders such as mitral regurgitation Congenital defects such as patent ductus arteriosus |
Conditions that increase after load: | Hypertension Atherosclerosis |
Conditions that affect myocardial function | Myocardial infarction Cardiomyopathy Coronary artery disease |
Ischemia | Lack of blood supply-obstructed circulation. Partial obstruction in coronary arteries causes MI Full obstruction in coronary arteries causes a MI Partial/Full obstruction in cerebral vessels cause a TIA |
Promoting vascular circulation | Elevate leg to promote venous return to the heart Avoid pillows under knees or more than 15 degrees of knee flexion to improve blood flow. Encourage leg exercises for a client on bed rest and promote ambulation as soon as possible. |
Promoting cardiac circulation | Position the client in high-fowlers position to decrease preload and reduce pulmonary congestion Monitor intake and output. Fluid restriction may be required for those with severe heart failure |
Heparin | Heparin (anticoagulant) used in patients after surgeries. Also in patients at risk for thromboembolus due to prolonged bed rest from acute illness. |
Heparin administration | Given sub-q either once day or every 12 hours Client should be lying down for administration Do not massage site - bruises Avoid aspirins or NSAIDS |