Accurate Blood Pressure Measurement

How to measure Blood Pressure accurately by Automated Electronic Devices

Modern automated BP recording devices are now widely available through Online shopping sites. The following points need to be kept in mind while using these devices for BP recording.

Position of person:

Sitting upright, back supported, feet flat on ground, arm supported on a table horizontally at approximately the middle of the chest.


For persons on BP medications, the best time for recording is when the next dose of medicine is due.

Don’t measure BP within ½ an hour of smoking, coffee, tea or meals.

Don’t measure BP if the bladder is full, you are anxious, or having a headache or disturbing pain anywhere in the body. The results are likely to be higher.

Cuff size:

Bladder length should be ideally >80% of the circumference of the arm.

Cuff width should be >1/2 of the length of the arm (elbow to shoulder).

Small sized cuff tends to overestimate BP. Large size does not matter too much.

Other pointers:

The person should be sitting quietly for 5 mins before measurement.

Measure 3 or 4 times in case of high readings at an interval of 3-5 mins till last 2 readings are similar. The lowest readings are usually the most accurate!

Blood Pressure

How to measure BP: The correct way

BP measured at home and clinics of doctors vary with the time of day or night, physical activity and methods of measuring. To reach a diagnosis of hypertension, various precautions are required. The following should be kept in mind while measuring BP.

Methods used for measuring BP.

  1. Mercury sphygmomanometers: Traditional and accurate. Requires correct training. Now not used due to a ban on the use of mercury due to environmental pollution.
  2. Aneroid sphygmomanometers: The cuff may be inflated manually. With a stethoscope, sounds are heard over the brachial artery.
  3. Automated oscillometric BP measurement: The most popular method nowadays. It has a battery operated system for inflating the cuff. The cuff deflates on its own and BP is displayed digitally.
  4. Ambulatory BP monitoring(ABPM): Measures BP every 15 mins in the day and every 30 to 60 mins at night. The readings can be recorded and later displayed digitally via a computer.

ABPM is the best and close to the ideal way of measuring BP. Not used often as the instrument is not widely available, is costly and not many people including health personnel are aware of it. An average ABPM recording is usually lower than other methods of measurement and hypertension is diagnosed when average readings are > 135/85 mm Hg.

Cuff size: The length of bladder cuff should be 80% of arm circumference and its width 50%. Smaller size cuffs overestimate BP and bigger ones underestimate.

Cuff position: The centre of the cuff (may be marked with an arrow) should be over the middle of arm artery(brachial). It should be 2-3 cms above the elbow crease in auscultatory methods.

The position of the person whose BP is being measured:

It should in most cases be sitting without crossing the legs and back should be supported. The arm should be at the level of the heart, relaxed and supported on the table etc. It should not be hanging on the side of the chest or raised higher.

The timing of BP measurement: BP should be measured thrice over a week in clinics before a diagnosis of hypertension unless it is very high and targets organ damage or other evidence is clear. It should be measured at different times of the day, morning and evening etc.

It should not be measured within ½ hour of coffee, smoking, exercise or food intake.

Both the health personnel and the person whose BP is being measured should be sitting quietly without talking or moving.

BP is measured repeatedly with a gap of about 2 mins till the readings are almost similar or difference is < 5 mm. The lower readings are usually closer to truer BP as compared with ABPM.

White Coat Hypertension: About 20 to 25% of the population may have higher recordings of BP when measured by doctors. The repeated measurement may record lower BP readings. Nurses BP recording may be lower. With time in some cases, this effect disappears.

In follow up cases

In clinics, it should be measured at the same time of day during subsequent visits. It is best measured just before the BP medicines are due so that BP is recorded when the medicine concentration in the body is lowest.

Hypertension in Dialysis Patients

Hypertension in Dialysis Patients I

About ½ of dialysis patients have high BP while on regular dialysis. A pre-dialysis BP > 140/90 mm Hg is required for the diagnosis of hypertension in this group.

Mortality, cardiovascular events including heart attacks, congestive heart failure, strokes are more common in hypertensive dialysis patients.

Systolic BP < 110 mm Hg Or >160 mm Hg is also associated with poor outcome in dialysis patients. Hence the BP has to be optimised and kept somewhere between these two limits.

Causes of high BP in dialysis population:

Expansion of body water and blood volume

Reduced blood supply to kidneys

Salt accumulation

High Calcium level

Thickened arteries

Preexisting essential hypertension

Increased sympathetic nervous activity

Poor water compliance

Poor drug compliance.

BP is measured before and after dialysis. For better overall BP, 24-hour ambulatory recordings are made.

Coming up Treatment of hypertension in the dialysis population.

Obesity II

Obesity II

Obesity is evaluated by screening for confirmation and assessment of risk factors. Once the BMI confirms obesity severity is divided into

Grade I BMI >30 but < 35 Grade II BMI >35 but < 40 Grade III BMI > 40 Waist circumference is measured at the highest level of the hip bone by a tape placing it horizontally.

In woman a waist circumference of > 88 cm or 35 inches and in Man >102 cm or 40 inches signifies central obesity.

Persons with central obesity are more at risk for heart disease, diabetes, Obstructive sleep apnoea and hyperlipidemia (excess lipids in blood). Coexistence of coronary artery disease, atherosclerosis elsewhere, Sleep apnoea, high BP, h/o premature heart attacks in other close relatives, smoking and lack of exercise : all these act togather to increase mortality.

Treatment of Hypertension

Treatment of Hypertension

Why should hypertension be treated ?

The following are the benefits of treating hypertension:-

  • 50 % reduction in risk of heart failure
  • 30-40% reduction of risk of strokes of brain
  • 20-30 % reduction in risk of heart attacks.

The benefit occurs in all age groups including elderly. If a cause has been found (as happens in very few cases) treatment of underlying cause is useful e.g. treating kidney disease, removing adrenal tumours, stopping steroids, analgesics, contraceptive pills, certain anti depressants etc.

In the majority of cases, no cause is found. In these, we suggest non-pharmacologic ways as well as medicines to lower blood pressure.

Non-pharmacological methods may reduce blood pressure by 5- 10 mm on their own. These include

Reduction of weight if overweight

Reduction of salt in diet (avoid pickles, salted foods, preserved foods). Do not take salt substitutes if there is associated kidney disease.

Dash diet ( dietary approaches to stop hypertension diet ). Increase vegetables, whole grain cereals, low fat, low sugar and sweets, more fruits, fish and chicken if you are a non vegetarian

Increase physical activity, both physical aerobic activity and relaxation exercises may help

Stop or cut down on alcohol and smoking

Learn about Hypertension.

Pharmacological methods may reduce blood pressure

2 or more drugs are required if BP is >20/10 above the normal range. More medicines and higher doses are needed if blood pressure is due to kidney disease. These drugs may cause side effects and hence prescriptions are tailor made to suit particular requirements of the patient.

The drugs include

Diuretics : – which increase salt and water excretion in the body. These work only if salt is cut down in the diet.

ACE- inhibitors and ARB’s : -These are a class of medicines which protects against ill effects of high BP on kidneys, heart and brain. However, treatment is complicated and always should be under the guidance of a competent physician. These drugs are known to cause fetal malformations. Inform your doctor if you are pregnant or are planning to have a child,

Calcium Channel Blockers :- Very useful and often used class of drugs. Some times these may cause feet to swell otherwise these are well tolerated.

Betablockers:- These reduce heart rate and blood pressure. This is useful in reducing stress on the heart. However, these may cause serious worsening in asthma and may aggravate prostate symptoms, and may cause impotence.

Centrally acting and alfa blockers:- These are also useful in controlling BP. Some of these may cause or worsen depression.