TABLE 3.

Major sources of error during blood pressure measurement

Source	Range of mean error in SBP (mmHg)	Range of mean error in DBP (mmHg)
Patient-related
Acute meal ingestion	−6	−5 to −2
Acute caffeine use	+3 to +14	+2 to +13
Acute nicotine use	+3 to +25	+3 to +18
Bladder distension	+4 to +33	+3 to +19
White-coat effect	Up to +26	Up to +21
Procedure-related
Insufficient rest	+4 to +12	+2 to +4
Legs crossed at knees	+3 to +15	+1 to +11
Arm lower than heart level	+4 to +23	+3 to +12
Talking during measurement	+4 to +19	+5 to +14
Fast deflation rate	−9 to −3	+2 to +6
Equipment-related
Automated device variabilitya	−4 to +17	−8 to +10
Too small a cuff	+2 to +11	+2 to +7
Too large a cuff	−4 to −1	−5 to −1
Observer-related
Terminal digit preference for zero (rounding off during auscultatory measurements)	Up to 79% over-representation of terminal zero	Up to 79% over-representation of terminal zero
Reliance on a single measurement	+3 to +10	−2 to +1
Hearing deficit	−2 to −0.1	+1 to +4

Data from [24].

^aTo optimize automated device accuracy, use a validated device.