What Is Blood Pressure,How We Can Record And Measure Blood Pressure

What Is Blood pressure. It is the force of blood at walls of vessels at which the blood is pushed out of heart. In various diseases the blood pressure of patient increases or decreases and sometimes poses the alarming situation. It is a part of nursing job to record and note down the blood pressure of such patient.

Equipment Required

  1. Sphygmomanometer (Blood pressure instrument).
  2. stethoscope


  • Patient should be either sitting or lying down.
  • Intimate the procedure to the patient you are going to do.
  • Roll patient’s sleeve above or slip sleeve off conveniently.
  • The patient is instructed to extend his arm if conscious. Support the arm over the pillow or on the bed.
  • Apply the cuff sphygmomanometer smoothly and not too tightly.
  • The manometer is placed on the bed or bed side table in a position at the level of your eyes.
  • The base of sphygmomanometer and cuff attached to patient arm should be at the same level. If the patient is sitting the B.P. Instrument should be hold by an assistant to bring the level. Otherwise ft will not record the correct reading.
  • Locate the brachial artery pulsation at elbow where it bifur­cates into two branches.
  • Hold the stethoscope on arm at this point with left hand.
  • Close air valve screw with right hand, pump bulb to inflate cuff until artery cases to pulsate.
  • Watch mercury column closely and continue pumping air to inflate cuff about 10 to 15 mm higher than where the artery started stopping pulsation
  • With right hand release valve screw slightly and slowly. (The mercury column should not fall more than 5 mm per second).
  • Note carefully the exact reading of mercury column where the first sound (thumping or snaping) is heard. Record this as systolic blood pressure.
  • Allow the mercury to fall slowly until the sound heard suddenly gets softer and diminished gradually. This point where it gets softer is recorded as diastolic blood pressure.
  • Release the pressure completely and repeat the procedure for 2nd time for confirmation of your reading. Bring the mercury to zero and then again raise it.
  • Record the B.P. reading in chart or patient’s history sheet with time and date.

What Is Blood Pressure,Palpatory Method to Record Systolic Pressure

By this method only systolic blood pressure can be recorded. For this purpose now stethoscope is required. Inflate the armlets or cuff until radial pulse at wrist is not felt. First radial pulse is felt and while putting the finger above radial artery the cuff is inflated*. Through valve release air to allow fall of mercury column. Now concentrate feeling for return of pulse while the mercury is falling. Note the reading when you feel the return of pulse. This is the Systolic pressure. For mercury manometer always mention the reading in millimeter of mercury or as for example 120/80 mm of Hg. By palpatory method it is about 5 to 10 mm higher than auditory method. In common practice auditory method is advisable.

Aneroid Manometer

This is a sphygmomanometer having a dial system for reading in place of mercury column. This is convenient and handy for use and compact for handling. After binding the cuff or armlets the dial for reading is fixed with the armlets at its place. Then the procedure is same to record. This mechanism is liable to give false reading especially with longer of time. It is therefore important to correct it, from time to time against a mercury manometer to make sure that it is accurate.

Precautions while taking Blood Pressure

  • Never take blood pressure after meals, fear, excitement and exertion.
  • Change of posture causes variation in blood pressure.
  • The patient should be reassured and B.P. taken when be is quiet and relaxed.
  • In nervous patient the first reading is very high and should be rejected and 2nd reading is taken.
  • The procedure of taking blood pressure should be done as quick as possible, because the compression of vessels itself causes reflex rise of blood pressure.
  • To avoid this error the mercury should touch zero every time you want to take 2nd reading.
  • Some time sound becomes faint and in course of examination. In this case the armlets or cuff should be removed and placed it on other arm or on same arm after an interval.
  • If there is gross oedema (swelling) of arm or the muscles are contracted, the B.P. readings are incorrect.

Blood Pressure in Leg

Occasionally it becomes necessary to compare the systolic blood pressure in arm downward. The cuff is applied above the knee and auscultation is carried out over political artery at the back of knee. In health it is found that systolic B.P. in arm and leg is more or less same approximately in horizontal position. In aortic incompetence the systolic B.P. is higher in leg than arm. In disease like coarctation of aorta the systolic B.P. is low in leg.

Normal Blood Pressure

The average systolic blood pressure in healthy adult is 100- 140mm of Hg. The average diastolic varies 60-90 mm of Hg normal­ly. In children it is lower. In old age normally it can go higher than mentioned in adults. Some physician figure normal systolic B.P. as Age +100. If a person is 50 years, his systolic B.P. should be around 50+100=150 mm of Hg. The difference of systolic and diastolic pressure is known as ‘Pulse Pressure’ which is normally 30-50 mm of Hg.

Abnormal Blood Pressure

An increases in blood pressure is known as hypertension. If it is very high it is known as ‘Malignant Hypertension’. If it is mild to moderately high it is known as ‘Benign Hypertension. In chronic nephritis, pre-eclampsia and eclampsia, the B.P. is always high. There are causes of hypertension in which no specific cause is found, and is known as ‘Essential Hypertension.’

An abnormally low B.P. is known as hypotension. Temporarily it can be seen in haemorrhage or peripheral circulatory failure or in Addison’s disease. Sometimes low pressure persist throughout life without causing any significant problem.

by Abdullah Sam
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