Rasvahapot valtimotaudin vaaran arvioinnissa Blood pressure measurement - EHES September 21, 2010 Antti Jula

2 Developed Countries Deaths in 2000 Attributable to Selected Leading Risk Factors Number of deaths (000s)

Antti Jula3 Hypertension as a cardiovascular risk factor

Antti Jula4 Systolic and diastolic blood pressure and mean arterial pressure in different parts of circulation

Antti Jula5 What is blood pressure? Systolic blood pressure, higher of the two values, 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 of the two values, represents the pressure when the heart relaxes between beats –Disappearance of the repetitive sounds (Phase V)

Factors affecting the accuracy of BP measurement Measurement circumstances Patient dependent factors Observer dependent factors Measurement technique –Auscultatory technique –Oscillometric technique Devices –Accuracy of the measurement device –Cuff size

Antti Jula7 Factors affecting BP variability Respiration – beat to beat oscillation Emotions – sympathetic stimulation – white coat effect Exercise Meals Tobacco Caffeine Alcohol Temperature Bladder distension Pain Diurnal variation –Sleep, posture, BP-lowering medication

Antti Jula8 Average effects on blood pressure of commonly occuring activites relative to BP while relaxing Meetings+20.2/+15.0 mmHg Work+16.0/+13.0 mmHg Walking+12.0/+9.2 mmHg Dressing+11.5/+9.5 mmHg Telephone+9.5/+7.2 mmHg Eating+8.8/+9.6 mmHg Talking+6.7/+6.7 mmHg Reading+1.9/+2.2 mmHg Sleeping-10.0/-7.6 mmHg Clark LA et al. J Chronic Dis 1987;40:671-9

Antti Jula9 Inter-room difference with sphygmomanometer 8.7/3.5 mmHg Kumpusalo et al. J Human Hypertens 2002;16:

Antti Jula10 Inter-room differences measured by patients with Omron IC device 5.9/2.8 mmHg 2.9/1.1 mmHg 3.0/1.7 mmHg Kumpusalo et al. J Human Hypertens 2002;16:

Antti Jula11 Watson et al, J Hypertens 1987, 5:207–11 Paired BP readings without careful preceding procedures and measurement techniques

Antti Jula12 Jula et al, Hypertension 1999, 34:261–6 Paired BP readings with careful preceding procedures and measurement techniques

Antti Jula13 Univariate correlates with the left ventricle and albuminuria Jula, Puukka, Karanko, Hypertension 1999;34:

Antti Jula14 Univariate correlates with the left ventricle and albuminuria Jula, Puukka, Karanko, Hypertension 1999;34:

Antti Jula15 Interarm differences BP measured from the right arm is 2.3/0.5 mmHg higher than that measured from the left arm (unpublished findings from 493 subjects aged years, The Finrisk 2007 study) If reproducible differences greater than 10 mmHg are observed, the measurements should be done from the arm with higher readings

Antti Jula16 Three categories of observer error Rose G et al. Lancet 1965; 1: Systematic error that leads to both intraobserver and interobserver 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

Antti Jula17 Mismatching of bladder and arm Maxwell ym. Lancet 1982;2:33-36

Antti Jula18 Use appropriate cuff size A too small cuff overestimates and a too large cuff underestimates BP Optimal size of the cuff: width >40% and length >80% of the arm circumference Finnish guidelines: –Cuff width 13 cm (arm circumference cm) –Cuff width 15 cm (arm circumference cm) –Cuff width 18 cm (arm circumference > 41 cm)

Antti Jula19 Different BP measurement devices

Antti Jula20 Oscillometric vs auscultatory measurement technique

Antti Jula21 Regression Equation for Converting Auscultatory to Automated Oscillometric (Omron M6) Systolic Blood Pressure Finriski 2007, unpublished findings, n=493

Antti Jula22 Regression Equation for Converting Auscultatory to Automated Oscillometric (Omron M6) Diastolic Blood Pressure Finriski 2007, unpublished findings, n=493

Antti Jula23 Corresponding oscillometric BP of five auscultory measured BP level Auscultatory BP 120/80 140/90 160/ / /120 Oscillometric BP 122.4/ / / / /118.7 Finrisk 2007, junpublished findings, n=493

Antti Jula24 Summary of the measurement I Participant conditions –Posture: the participant should sit queitly for 5 min with the cuff around the arm, arm baired and supported at the level of the heart and the back resting againts a chair Circumstances –The participant should avoid a heavy meal, smoking, heavy exercise and drinking caffeine containing beverages at least within 30 minutes preceding the reading –A quiet, warm setting

Antti Jula25 Summary of the measurement II Equipment –Appropriate cuff size –Either a mercury, a validated and recently calibrated aneroid or validated electronic device –The bell of the stetoscope should be used (avoid excess bell pressure!) Technique –At least two measurements (3) 1-2 minute apart of each other –Avoid observer error by training observers in the proper technique of auscultatory BP measurements (manuals, binaural stethoscope, audio-tape training methods, video-films etc.)