Week 6: Blood Pressure Flashcards
Determinants of blood Pressure
The pumping action of the heart
The peripheral vascular resistance
Blood Volume
Blood Viscosity
The pumping action of the heart
When the pumping action of the heart is weak, less blood is pumped into the arteries (lowering the cardiac output) and the blood pressure decreases. When the pumping action is strong and the blood pumped into the circulation increases (higher cardiac output), the blood pressure increases.
Blood Volume
When the blood volume decreases as a result of dehydration, the blood pressure decreases because of the decreased fluid in the arteries. When the volume increases as a result of rapid intravenous infusion, the blood pressure increases because of the greater fluid volume within the circulatory system.
Blood Viscosity
Blood pressure is higher when the blood is highly viscous(thick), when the ratio of red blood cells to blood plasma is high which is so known as haematocrit.
Hypertension:
- A blood pressure persistently above normal range
- When an adult has either a diastolic blood of 90 mm Hg or higher or a systolic blood pressure higher than 140 mm Hg
- Hypertension cannot be diagnosed unless an elevated blood pressure is found when measured twice at different times
Hypotension
- A blood pressure that is below normal range and a systolic reading consistently between 85-110 mm HG in an adult whose normal pressure is higher than this
Orthostatic Hypotension
The patient has orthostatic hypotension if there is:
1. A drop in systolic BP of 20mmHg or more (with or without
symptoms)
2. A drop to below 90mmHg on standing, even if the drop is less than 20mmHg
3. A drop in diastolic BP of 10mmHg with symptoms
Orthostatic Hypotension
– Dizziness
– Vagueness
– Visual disturbances
– Palpitations
- Light headedness
- Pallor
- Feelings of weakness
Causes of orthostatic hypotension
- Taking certain medications for blood pressure, heart, mood and Parkinson’s disease.
- Dehydration due to not drinking enough fluids, vomiting or diarrhoea.
- Prolonged bed rest.
- Certain conditions e.g. diabetes, heart problems, Parkinson’s disease and anaemia.
- Excessive amounts of alcohol.
Nursing Interventions Orthostatic Hypotension
– Get out of bed slowly
– First sit up, then sit on the side of the bed, then stand up.
– Take their time when changing position, such as when getting up from a chair.
– Have something steady to hold onto when they stand up.
– Take it steady when walking or get support if they feel dizzy.
– Exercise gently before getting up (move their feet up and down and clench and unclench their hands) or after standing (march in place).
– Avoid standing still over a long time.
– Avoid taking very hot baths or showers.
- Increase Fluid intake
– Try sleeping with extra pillows to raise their head.
Blood Pressure Normal ranges (newborn, 1 year, 6 years, 14-17years, middle adult)
- Newborn: 40 mean
- 1 year: 85/54
- 6 years: 95/65
- 14-17years: 120/75
- Middle adult: less than 120/80
Cardiac Output
- How much volume of blood per minute pimpled
- Cardiac output= Stroke Volume x Heart Rate
- Stroke volume + amount of blood out in 1 beat
- How many beats per minute
Systolic Pressure
The Pressure of the blood as a result of contraction of the ventricles. Height of Blood wave.
Discuss common errors in blood pressure assessment.
- Cuff/bladder too narrow–false high
- Cuff/bladder too wide–false low
- Cuff/bladder too loose or uneven–false high
- Above heart level–false low - Below heart level– false high - Unsupported– false high
- Deflating cuff too quickly = low systolic and high diastolic reading
- Deflating cuff too slowly = high diastolic reading
- Repeating assessment too quickly = high systolic or low diastolic reading
Diastolic Pressure
The pressure of the blood when the ventricles are at rest
