Exam

Blood Pressure

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Blood Pressure, BP Examination, Korotkoff Sound

  • Precautions
  1. Blood Pressures are frequently inaccurate due to improper cuff size, technique, or inadequate rest before measurement
  2. Recent nicotine in last 30-60 minutes can raise systolic Blood Pressure as much as 25 mmHg
  3. Avoid finger Blood Pressure monitors (and aside from morbidly obese patients, avoid wrist monitors)
  4. Automated Blood Pressure measurements are inaccurate, overestimating both systolic and diastolic Blood Pressure
    1. Confirm elevated automated Blood Pressure with 2 manual, auscultated Blood Pressures
    2. Flynn (2012) J Pediatr 160(3): 434-40 [PubMed]
    3. Mansoor (2016) Open Access Maced J Med Sci 4(3): 404–9 [PubMed]
      1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042623/
  • Equipment
  • Blood Pressure cuff size
  1. Poor cuff fit results in inaccurate Blood Pressure
    1. Undersized cuff artificially raises Blood Pressure
    2. Oversized cuff artificially lowers Blood Pressure
  2. Pediatric Cuff size
    1. Based on arm circumference measured at point midway between acromion and olecranon
    2. Minimum Cuff Width
      1. Width >2/3 length of upper arm
      2. Width >40% of arm circumference
    3. Minimum Cuff length
      1. Bladder nearly encircles arm
      2. Bladder length 80-100% of circumference
  3. Adult Cuff size
    1. Cuff Width: 40% of limb's circumference
    2. Cuff Length: Bladder at 80% of limb's circumference
    3. Indications for large cuff or thigh cuff
      1. Upper arm circumference >34 cm
    4. Indications for Forearm cuff (with radial palpation)
      1. Upper arm circumference >50 cm
  • Preparation
  • Positioning of Blood Pressure Cuff
  1. Cuff applied directly over skin (not through clothes)
    1. Clothes artificially raises Blood Pressure
  2. Center inflatable Bladder over brachial artery
  3. Position lower cuff border 2.5 cm above antecubital
  4. Patient's arm slightly flexed at elbow
  5. Position stethoscope bell over brachial artery
  • Technique
  • BP measurement
  1. Patient should be comfortable, with empty Bladder
  2. Legs uncrossed and feet flat on the floor
  3. Patient should not speaking during measurement
  4. Wait 5 minutes of rest before checking Blood Pressure
  5. Check Blood Pressure while seated, in right arm (Aortic Coarctation may falsely lower BP measurement)
  6. Take Blood Pressure with arm supported at heart level
  7. Inflate cuff rapidly to level above suspected SBP
  8. Deflate cuff slowly at a rate of 2-3 mmHg per second
  9. Listen for auditory vibrations from artery (Korotkoff)
    1. Systolic Blood Pressure: Onset of consecutive sounds
    2. Diastolic Blood Pressure: Disappearance of sounds
  • Technique
  • Obtain Multiple Blood Pressure measurements
  1. Validation of abnormal readings
    1. Recheck Blood Pressure twice more at same visit
    2. Blood Pressure improves to <160/89 after 30 minutes rest in >30% with Severe Hypertension
      1. Grassi (2008) J Clin Hypertens 10(9): 662-7 [PubMed]
  2. Aortic Coarctation
    1. Left and right arm, and one lower extremity
  3. Orthostatic Hypotension
    1. Most common chronically in the elderly (fall risk)
    2. Check Blood Pressure and Pulse, Supine and Standing (Postural Blood Pressure)
  • Interpretation
  • Interpretation
  • Children
  1. See Pediatric Vital Signs
  2. Formulas for Systolic Blood Pressure estimate (for over age 1 year)
    1. Median SBP = 90 mmHg + (2 x Age in years)
    2. Minimum SBP = 70 mmHg + (2 x Age in years)
  3. Rough estimate for Systolic Blood Pressure (SBP)
    1. Typical systolic Blood Pressure
      1. Infant: 80
      2. Preschool: 90
      3. Adolescent: 100
    2. Minimal systolic Blood Pressure
      1. Infant: >60
      2. Toddler >70
      3. Preschool >75
      4. School-age: >80
      5. Teen >90
  4. Term Newborn (3 kg)
    1. Age 12 hours: 50-70 / 25-45
    2. Age 96 hours: 60-90 / 20-60
    3. Age 7 days: 74 +/- 22 mmHg (Systolic BP)
    4. Age 42 days: 96 +/- 20 mmHg (Systolic BP)
  5. Infant (6 months old)
    1. Blood Pressure: 87-105 / 53-66
  6. Toddler (2 years old)
    1. Blood Pressure: 95-105/53-66
  7. School age (7 years old)
    1. Blood Pressure: 97-112 / 57-71
  8. Adolescent (15 years old)
    1. Blood Pressure: 112-128 / 66-80