Background: It is assumed that BP decreases with repeat measurements and multiple readings are recommended. There is limited information about within-visit BP variability (BPV) in healthy children. Methods: We used NHANES data (2013-2020) to measure BPV in subjects 8-17 years old with three BP readings. During 2013 to 2016, auscultatory BP was obtained (manual protocol, MP). Subsequently, oscillometric BP was measured (automated protocol, AP). We excluded subjects with diastolic BP 'zero'. Results: We included a total 5656 subjects with 3365 (59.5%) in the MP and 2291 (40.5%) in the AP group. A ΔBP (individual-level difference between the highest and lowest of three BP readings) ≥5 mmHg was noted in 49.1% and 60.7% subjects for systolic BP (SBP) and diastolic BP (DBP) respectively. A ΔDBP ≥10 mmHg and DBP average real variability ≥10 mmHg was twice as common in the MP than AP group. A ΔBP ≥20 mmHg was noted in 1.3% and 4.4% subjects for SBP and DBP respectively. The first SBP and DBP reading was ?5 mmHg higher or lower than the averaged second and third SBP and DBP readings in 24.9% and 34.5% of subjects respectively. The first SBP and DBP reading was the highest of three BP readings in 44.2% and 42.4% subjects respectively. Conclusions: There is significant BPV in children and adolescents. Diastolic BPV is more common in MP than AP groups. Initial BP is not always the highest and inclusion of second and third BP reading may be more representative of patient's actual BP.

SKR has stocks. AMS has received consulting fee (Conjupro).

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