Perfusion Flashcards
What is perfusion?
the flow of blood through arteries and capillaries delivering nutrients and oxygen to cells
What does perfusion require?
Perfusion requires the heart to generate sufficient cardiac output to transport blood through patent blood vessels for distribution in tissues throughout the body
What is the scope of perfusion?
Perfusion ranges from optimal perfusion to no perfusion
Changes in perfusion can be…
temporary, long-term, or permanent
Type of disorder that leads to changes in perfusion include:
acute conditions (MI, stroke, or shock) and chronic disorders (hypertension, heart failure, sickle cell, or hemophilia)
Conditions that specifically involve perfusion include:
neurologic (affecting vessels in the brain)
pulmonary (impaired blood flow to and from the lungs)
cardiovascular (interfering blood flow in the heart, arteries, and veins)
What are the causes of disorders related to perfusion?
congenital defects, genetic disorders, injury, inflammation, and infections
What does central perfusion require?
adequate cardiac function, blood pressure, and blood volume
What is cardiac output?
the amount of blood pumped by the heart each minute
What is systole?
phase of the cardiac where the ventricles contract
Central perfusion propels blood to all organs & tissues from patent _____ through ____ and returns the blood to the heart through patents ____
Central perfusion propels blood to all organs & tissues from patent arteries through capillaries and returns the blood to the heart through patent veins
When does central perfusion begin?
heart is stimulated by an electrical impulse that originates in the sinoatrial (SA) node and travels to the atrioventricular (AV) node
What is diastole?
the phase of the cardiac cycle when ventricles fill with blood
What is the normal cardiac output range?
4 to 6 L/min in the adult
What are two variables that influence cardiac output?
stroke volume and heart rate influence cardiac output
What is stroke volume?
the amount of blood ejected from each ventricle during contraction
What affects stroke volume?
preload and contractility affect stroke volume
What is preload?
amount of blood in the ventricles at the end of diastole aka diastolic pressure
What is contractility?
strength of myocardial contraction; greater the volume of blood in the ventricles (preload), greater the stretch of the myocardium & stronger the myocardial contraction
Cardiac output (CO) formula =
stroke volume x heart rate; normal range is 4-6L/ per minute in the adult
What is after load?
force the ventricles must exert to open the semilunar valves (aortic and pulmonic); influenced by systemic vascular resistance (SVR)
What is systemic vascular resistance?
resistance to the ejected blood created by the diameter of blood vessels receiving the blood
The smaller or more constricted the blood vessels, the …..
greater the pressure required to open the semilunar valves to eject the blood, increasing the heart’s workload (e.g. hypertension)
The larger or more dilated blood vessels, the…
less pressure required to eject the blood; reducing the workload on the heart