Measuring Blood Pressure
Blood pressure readings are performed as part of the vital signs skill set. Blood pressure can be described as the force of blood pushing against the walls of the blood vessels as the heart contracts and relaxes (Koutoukidis, Stainton & Hughson 2017). Measuring blood pressure (BP) comprises of two readings because the blood moves in waves; systolic pressure and diastolic pressure.
Systolic pressure is the greatest force exerted on the walls of the arteries by the heart as the ventricles contract. The range of a normal systolic pressure is between 100 and 120 millimetres of mercury (mm Hg). An elevated systolic pressure is considered to be above 140 mm Hg (Koutoukidis et al. 2017).
Diastolic pressure is the least force exerted on the walls of the arteries by the heart as it relaxes between ventricular contractions. The range of a normal diastolic pressure is between 60 and 80 mmHg. An elevated diastolic pressure is considered to be above 90 mm Hg (Koutoukidis et al. 2017).
It is important to note that blood pressure measurements are not performed on the affected arm of a person:
- who has had a mastectomy or an arteriovenous (AV) shunt or fistula
- with intravenous therapy (IVT) in situ
- with a plaster cast
- where trauma, burns or paralysis are present.
In addition, blood pressure measurement should be performed at least 30 minutes after exercise, caffeine or nicotine to avoid inaccurate readings being recorded.