Measuring Blood Pressure

Diagnostic Criteria for HTN Two or more separate occasions – BP > 140/90 –Average of Seated Standing for > 2 min Seated with back support - arm at heart level After five minutes of rest If readings differ by more than 5 mm Hg additional readings should be taken and averaged Additional readings if suspect "white coat" hypertension

Sources of Error in BP Measurement Wrong size of sphygmomanometer (cuff) Hearing, concentration, skill of tester Placement on arm Anxiety or stress (white coat) Bladder distention Caffeine Exercise

Steps for Accurate Blood Pressure Quiet environment Rest for 5 minutes No smoke, food, exercise, or caffeine within 30 minutes prior Cuff size: –Bladder width at least 40% of arm circumference –length at least 80% of circumference. Lannec stethoscope

Blood Pressure (cont) Use mercury, or calibrated aneroid sphygmomanometer and a good stethoscope Center and wrap cuff around brachial artery on bare arm Rapidly inflate cuff to 30 mmHg above level where radial pulse is unpalpable. Deflate cuff at a rate of 2 to 3 mm per second.

Measuring BP

Korotkoff sounds Sounds: sounds/content/blood-pressure-korotkoff-sounds-2 sounds/content/blood-pressure-korotkoff-sounds-2

Blood Pressure (cont) Note systolic pressure at onset of at least two consecutive beats (Phase I). Record in even numbers read to nearest 2 mmHg. Note diastolic pressure at muffling (Phase IV) for children and cessation of sound (Phase V) for adults. Rapidly deflate cuff after measuring diastole Record arm (L or R) and systolic/diastolic pressure

Blood Pressure (cont) Wait 1 to 2 minutes before repeating the reading and average the two readings. If differ by more than 5 mmHg, then repeat. Use table to classify and provide follow-up recommendations. Measure both arms – if BP > 15 mmHg – higher mortality Thigh BP – Mid thigh cuff listen over popliteal artery