a) Precautions
It is a common observation that BP recordings are variable when taken by different individuals.To decrease this variability it is important that certain precautions are taken while BP is recorded.
b)Posture
The patient can be seated or lying, but must be comfortable and relaxed. This is important since the systolic pressure elevation due to anxiety (“white coat hypertension”) can go up by 17 to 27mmHg. In pregnant women BP must not be recorded lying down because of the possibility of the pressure on the Inferior Vena Cava diminishing the venous return.
c)Equipment
The standard mercury sphygmomanometer is still considered to be the best equipment.Instruments like the aneroid and electronic ones may show variations in readings and need to be calibrated (compared) with the mercury sphygmomanometer. When using the mercury sphygmomanometer, the following points must be adhered to the:
• cuff should snugly fit around the arm.
It is a common observation that BP recordings are variable when taken by different individuals.To decrease this variability it is important that certain precautions are taken while BP is recorded.
b)Posture
The patient can be seated or lying, but must be comfortable and relaxed. This is important since the systolic pressure elevation due to anxiety (“white coat hypertension”) can go up by 17 to 27mmHg. In pregnant women BP must not be recorded lying down because of the possibility of the pressure on the Inferior Vena Cava diminishing the venous return.
c)Equipment
The standard mercury sphygmomanometer is still considered to be the best equipment.Instruments like the aneroid and electronic ones may show variations in readings and need to be calibrated (compared) with the mercury sphygmomanometer. When using the mercury sphygmomanometer, the following points must be adhered to the:
• cuff should snugly fit around the arm.
• lower edge of the cuff should be 2.5 cms above the antecubital fossa.
• stethoscope diaphragm must be just below the cuff edge.
• width of the cuff must be 40 per cent of the circumference of the arm (usually 12.5 cms in normal adults, 17 cms in obese adults, 7.5 cms in young children, 3.5 cms in infants).
• length of the rubber bag (usually 25 cms), must be enough to cover more than 80 per cent of the circumference of the limb.
d)Technique
Palpate the radial or brachial artery pulsation while inflating the cuff to a level of 30 mm Hg above the point at which the brachial or radial artery pulsation disappears. Reinflate the cuff to this pressure and release the pressure (deflate) slowly and steadily at a rate of 2 mmHg/sec. The cuff is deflated fast after the diastolic pressure is recorded. A gap of at least one minute must be given in case the pressure is rerecorded.
What one listens to with the stethoscope are the Korotkoff sounds:
Phase 1 : The first appearance of clear tapping sound. This represents the systolic pressure
Phase 2 : Soft murmurs
Phase 3 : Louder murmurs
Phase 4 : Muffled sounds
Phase 5 : Disappearance of sounds
At what point is the diastolic pressure recorded? Comparative studies with intra arterial measurement shows that it corresponds to Phase 4. However, the diastolic is taken just before disappearance of Phase 5.
What are the conditions where Korotkoff sounds are difficult to hear? In slow rising pulse of aortic stenosis, shock and in heart failure, it might be difficult to hear these sounds. It helps to ask the patient to clench and unclench the fist 5 or 6 times and listen again.What is the auscultatory gap? This occurs when after the first appearance of the Kortkoff sound,it disappears, then reappears at a lower pressure. For this reason, it is better that the systolic pressure is noted by the palpation of the disappearance of the radial pulse. The cuff pressure must be raised to a point above this before one starts listening to the Korotkoff sounds.
When BP is recorded for the first time, it should be done in both arms. A difference of more than 10 mmHg should raise the suspicion of obstructive lesions in the arterial supply to the upper limb.
d)Technique
Palpate the radial or brachial artery pulsation while inflating the cuff to a level of 30 mm Hg above the point at which the brachial or radial artery pulsation disappears. Reinflate the cuff to this pressure and release the pressure (deflate) slowly and steadily at a rate of 2 mmHg/sec. The cuff is deflated fast after the diastolic pressure is recorded. A gap of at least one minute must be given in case the pressure is rerecorded.
What one listens to with the stethoscope are the Korotkoff sounds:
Phase 1 : The first appearance of clear tapping sound. This represents the systolic pressure
Phase 2 : Soft murmurs
Phase 3 : Louder murmurs
Phase 4 : Muffled sounds
Phase 5 : Disappearance of sounds
At what point is the diastolic pressure recorded? Comparative studies with intra arterial measurement shows that it corresponds to Phase 4. However, the diastolic is taken just before disappearance of Phase 5.
What are the conditions where Korotkoff sounds are difficult to hear? In slow rising pulse of aortic stenosis, shock and in heart failure, it might be difficult to hear these sounds. It helps to ask the patient to clench and unclench the fist 5 or 6 times and listen again.What is the auscultatory gap? This occurs when after the first appearance of the Kortkoff sound,it disappears, then reappears at a lower pressure. For this reason, it is better that the systolic pressure is noted by the palpation of the disappearance of the radial pulse. The cuff pressure must be raised to a point above this before one starts listening to the Korotkoff sounds.
When BP is recorded for the first time, it should be done in both arms. A difference of more than 10 mmHg should raise the suspicion of obstructive lesions in the arterial supply to the upper limb.
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