Accurate Blood Pressure Measurement in Lateral Decubitus Position

Rationale for Arm Placement

The American College of Cardiology and Hypertension guidelines recommend that the cuff must be positioned at the level of the right atrium (mid-sternum) to avoid hydrostatic pressure errors, which can be achieved by placing the NIBP cuff on the left arm (non-dependent, upper arm) in a patient in the right lateral decubitus position 1, 2, 3, 4
The left arm (non-dependent/upper arm) can be properly supported and positioned at the level of the right atrium, allowing accurate measurements, as recommended by the American College of Cardiology and Hypertension 1, 2

The American Heart Association and European Heart Journal recommend that the arm must be supported at the exact level of the right atrium (mid-sternum/fourth intercostal space), not held by the patient or hanging unsupported, to avoid clinically significant measurement errors 1, 2, 3, 4
Arm position relative to heart level creates clinically significant measurement errors, with arm below heart level producing falsely high readings and arm above heart level producing falsely low readings, as reported in the European Heart Journal and Circulation 1, 2, 3, 4

The American College of Cardiology and Hypertension recommend positioning and supporting the left arm at mid-sternum level using an armboard or padded support, and ensuring the cuff bladder encircles at least 80% of the arm circumference for accurate readings 1, 2, 3, 4
The European Heart Journal and Circulation recommend using a validated oscillometric device appropriate for intraoperative monitoring, with the middle of the cuff overlying the brachial artery 1, 2, 3, 4, 5

The American Journal of Kidney Diseases and American College of Cardiology recommend that the core principle of accurate blood pressure measurement remains constant, with the measurement site must be at right atrial level, which can be achieved by placing the NIBP cuff on the non-dependent (upper) arm in lateral decubitus position 1, 2, 3, 4, 5, 6, 7
The American Journal of Kidney Diseases recommends considering lower extremity measurement if bilateral arm access is restricted, with recognition that lower limb pressures are typically 10-20 mmHg higher than brachial pressures 6, 7

The American Heart Association recommends that the arm must be positioned precisely at the level of the right atrium (mid-sternum or fourth intercostal space when sitting) to obtain accurate measurements 8, 9, 10
The arm must be supported at heart level, not elevated above or hanging below it, as deviations from heart level cause clinically significant errors due to hydrostatic pressure effects 8, 9, 10
Arm above heart level: Readings will be falsely LOW by approximately 2 mmHg for every inch above heart level, potentially 10 mmHg or more total 8, 9, 10
Arm below heart level: Readings will be falsely HIGH by the same magnitude 8, 9, 10

The American College of Cardiology recommends positioning the arm at the midpoint of the sternum or fourth intercostal space (right atrium level) when sitting 8, 9, 10
Support the arm on a desk or armrest at this level—do not have the patient hold their arm up 8, 9
Back must be supported against a chair (not an examination table) to avoid falsely elevated diastolic pressure by 6 mmHg 8, 9, 10
Feet flat on floor with legs uncrossed (crossing legs raises systolic BP by 2-8 mmHg) 8, 9, 10

The European Society of Cardiology recommends measuring BP in both arms at first visit, and if difference >10 mmHg, use the arm with higher readings for subsequent measurements 11
Supine systolic BP is approximately 8-10 mmHg HIGHER than sitting when arm position is meticulously controlled at right atrium level in both positions 8, 9
Supine diastolic BP is approximately 5 mmHg LOWER than sitting when arm position is meticulously controlled at right atrium level in both positions 8, 9

Never measure with the arm hanging down at the patient's side—this produces falsely elevated readings 8, 9, 10
Never elevate the arm above heart level—this produces falsely low readings 8, 9, 10
Never allow unsupported arm positioning—muscle tension from holding the arm up elevates BP 8, 9, 10