Perfusion - Study guide 3 Flashcards
Four determinants of cardiac output
- Heart rate
- Preload
- Afterload
- Contractability
The number of cardiac contractions per minute. Can be affected by many variables depending on pressure.
Heart rate
increases HR by releasing norepinephrine
Positive chronotropic effect
decreases HR by releasing acetylcholine
Negative chronotropic effect
- Directly related to stroke volume.
- The amount of blood in the ventricles at the end of diastole.
- Also refers to the amount of stretch of the muscle tissue at the end of filling.
Preload
- Inversely correlated to stroke volume.
- The resistance to flow the ventricle must overcome to open the semilunar valves and eject its contents.
- This is related to bp, vessel lumen diameter and or vessel compliance.
Afterload
- The force of the mechanical contraction.
- Contractile force can be increased with sympathetic stimulation or calcium release.
- It can be decreased in the face of hypoxia or acidosis
Contractability
Effects of an increased afterload
Decreases stroke volume and decreased cardiac output
Effects of a decreased afterload
increases stroke volume, increases cardiac output
Formula for calculating cardiac output
Heart Rate X Stroke Volume = Cardiac Output
Normal cardiac output in a healthy adult
4-7L/min
HR increases depending on what?
Pressure
Conditions that cause alterations in perfusion
7 - CCCDEHM
- Clotting disorders
- Congenital cardiac defects
- CAD
- Dysrhythmias
- Early menopause
- Heart Failure
- MI
Parameters that for someone to be dx with pre-eclampsia
- BP >140>90 on two occasions at least 4 hrs apart with Proteinuria.
- Occurs after 20 wks.
- Protein creatinine ration (PCR) >0.3 MG/DL
Nursing Interventions for Pre-eclampsia
12
- Monitor BP
- Monitor weight
- Frequent provider visits
- Fetal kick counts
- Frequent rest/bedrest
- Adequate intake
- Monitor I and O
- Neuro status checks
- Evaluate renal function
- Evaluate Deep tendon reflexes and clonus
- Administer magnesium sulfate infusion as ordered
- Administer HTN medications