Blood pressure measurement by

mercury sphygmomanometer

- background information

EHES Training Material

Hypertension as a cardiovascular risk factor

What is blood pressure?

• Systolic blood pressure (higher value), represents the pressure while the heart contracts to pump blood to the body• First appearance of a clear

repetitive sounds (Phase I)

• Diastolic blood pressure (lower value), represents the pressure when the heart relaxes between beats• Disappearance of the

repetitive sounds (Phase V)

Risk factors of elevated blood pressure

• Salt intake• Obesity• Alcohol use• Sedentary lifestyle• Smoking• Fat contents of the food

Factors affecting blood pressure levels

• Measurement environment• Noise, temperature

• Factors related to the participant• Factors related to the measurer• Measurement device

• Cuff size

Factors related to the participant

• Emotions – white coat hypertension• Exercise• Eating before measurement• Smoking• Use of caffeine containing drinks• Alcohol use• Full bladder• Pain• Daily variation• Medication

Average magnitude of the effects (1/3)

Effect Systolic bp (mmHg) Diastolic bp (mmHg)

Full bladder 10-15 mmHg, even up to 50 mmHg if bladder uncomfortably distended

10 mmHg, even up to 40 mmHg if bladder uncomfortably distended

Not resting 3 to 5 minutes before measurement

10-20 mmHg 14 mmHg

Back / feet unsupported

5-15 mmHg 6 mmHg

Supine posture instead of sitting posture

3-10 mmHg 1-5 mmHg

Average magnitude of the effects (2/3)

Effect Systolic bp (mmHg) Diastolic bp (mmHg)

Legs crossed 5-8 mmHg 3-5 mmHg

Participant talks during the measurement

10-15 mmHg 6-10 mmHg

Arm below heart level

10 mmHg 10 mmHg

Physical exercise before measurement

22 mmHg 7-8 mmHg

Left arm instead of right arm

1-3 mmHg 1 mmHg

Arm unsupported during the measurement

1-7 mmHg 5-11 mmHg

Average magnitude of the effects (3/3)

Effect Systolic bp (mmHg) Diastolic bp (mmHg)

Diaphragm of the stethoscope instead of bell

2 mmHg 0-2 mmHg

Cuff too small 3-12 mmHg 2-8 mmHg

Cuff too large 10-30 mmHg 10-30 mmHg

Cuff over clothing up to 5 mmHg

Three categories of observer error

1. Systematic error that leads to both intra-observer and inter-observer error

2. Terminal digit preference, which results in the observer rounding of the pressure reading to a digit of his or her choosing, most often to zero

3. Observer prejudice or bias, whereby the observer adjust the pressure to meet his or her preconceived notion of what the pressure should be

Rose G et al. Lancet 1965; 1: 673-4

Acknowledgements

• Slides• Hanna Tolonen