It is a measure of the pressure exerted by blood on the artery walls in its drive through the arteries. Because the blood moves in waves, two types of measures of pressure:
Systolic pressure is the blood due to contraction of the ventricles, ie the maximum pressure and the diastolic pressure is the pressure that remains when the ventricles relax, this is the minimum pressure.

The mean arterial pressure (MAP) was calculated using the following formula: systolic pressure – diastolic pressure / 3 + diastolic pressure. The PA is determined by cardiac output and peripheral vascular resistance, hence the PA reflects both the stroke volume of blood as the elasticity of arterial walls.


  • The arm and forearm should be naked, or at least the clothes should not exert improper compression.
  • The cuff size should be chosen according to the diameter of the arm. The relative disparity between the size of the arm and the cuff may be cause of error, in very obese arms usually falsely elevated values are obtained very thin arms and obtained values below normal.

Normal blood pressures
Age / systolic pressure (mmHg) / diastolic blood pressure (mmHg)
Infant / 60 – 90 / 30 to 62
2 years / 78 – 112 / 48 to 78
8 years / 85 to 114 / 52 to 85
12 years / 95 to 135 / 58 to 88
Adults 100 to 140 / 60 – 90

Age Width (cm) / Length (cm)
Newborn 2.5 to 4.0 / 5.0 to 10.0
Infant 6.0 to 8.0 / 12.0 to 13.5
Children from 9.0 to 10, 0 / 17.0 to 22.5
Adult standard from 12.0 to 13.0 / 22.0 to 23.5
Adult, big arm 15.5 / 30.0
Adult thigh 18.0 / 36.0

  • The stethoscope is placed without too much pressure on the site of the brachial artery is palpated avoiding contacts the sleeve to remove adventitious sounds.
  • The application makes cuff too loose figures obtained above normal.
  • The patient must be left to stand long enough (10 to 15 min) prior to taking blood pressure to eliminate the influence of the previous exercise or emotional state.
  • Factors that affect blood pressure: age, the elderly are increased numbers, exercise, stress, and race. Black males over 35 years managing high blood pressure control more than whites of similar age.
  • Although the PA is measured routinely in the arm, should be measured in both arms, to determine differences. BP is 10 mmHg higher in the dominant arm. If necessary (diastolic pressure>90 mmHg, coarctation or aortic insufficiency) can be measured in the thigh, ideally with the patient prone, placing the popliteal pulse.

Hypertension: transient increases may occur in blood pressure, a result of various circumstances such as physical activity and pain and anxiety states. Hypertension is defined, usually based on diastolic pressure, since it is more stable than the systolic pressure, which responds to a variety of stimuli. The diagnosis of hypertension should be done after finding high blood pressure control (diastolic> 90 mmHg) Repeated examinations in the patient. Low blood pressure: the systolic blood pressure control range between 90 and 110 mmHg, is considered decreased cardiac output in patients with hypovolemia, malnutrition and some neurological diseases. Some signs and symptoms include fatigue, dizziness and fainting.
Postural hypotension: decrease in systolic blood pressure> 15 mmHg and diastolic pressure drop. It is characterized by dizziness and syncope. It was first diagnosed by measuring blood pressure supine and repeating measurement with the patient standing. The normal result is slight or no decrease in systolic pressure and slight increase in diastolic pressure.

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