Hypertension, Blood Pressure Variability, and Acute Kidney Injury in Hospitalized Children

Figures

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  Figure 1. Distribution of blood pressure percentile readings in 5425 hospitalizations for children aged 1 to 17 years. A, Among all the BP measurements, 32.7% were ≥95th percentile and 18.9% of readings were ≥99th percentile. B, For measurements in the ICU, 39.9% were ≥95th percentile and 24.8% of readings were ≥99th percentile. C, Mean BP calculated from all measurements during an entire admission was ≥95th percentile in 18.1% of encounters and ≥99th percentile in 6.7% of encounters. D, For each definition shown, the incidence rate of inpatient hypertension, in cases per 100 patient‐days, was 21.3 (95% CI, 20.5–22.1) (blue); 10.1 (95% CI, 9.6–10.6) (red); 11.1 (95% CI, 10.6–11.6) (green); and 5.4 (95% CI, 5.1–5.7) (orange). BP indicates blood pressure; and ICU, intensive care unit.

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  Figure 2. Nonlinear relationship between mean BP in the preceding 72 hours and AKI. Fitted second‐degree fractional polynomials adjusted for age and sex are shown for the log relative hazard of incident AKI and mean systolic blood pressure (powers [−1, −0.5], P=0.001 compared with simple linear model) (A); mean diastolic blood pressure (powers [0, 0], P=0.001) (B); and mean MAP (powers [−0.5, 0], P<0.001) (C). The fractional polynomial models fit the data significantly better than the simple linear models. In each case, the best‐fitting second‐degree fractional polynomial was chosen among each possible combination of power transformations of the mean BP from the following set of candidate powers (−2, −1, −0.5, 0, 0.5, 1, 2, 3). AKI indicates acute kidney injury; BP, blood pressure; HR, hazard ratio; and MAP, mean arterial pressure.

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  Figure 3. Survival curves for time to AKI by time‐varying hypertension status. Unadjusted survival curves are shown for time to acute kidney injury based on selected time‐varying thresholds for hypertension measured over the previous 72 hours. (A, Hypertension ≥3 BP readings ≥95th percentile in a 24‐hour period. B, Hypertension ≥3 BP readings ≥95th percentile plus 12 mmHg in a 24‐hour period. C, Hypertension ≥3 BP readings ≥130/80 mm Hg in a 24‐hour period for adolescent patients. D, Hypertension ≥3 BP readings ≥140/90 mm Hg in a 24‐hour period for adolescent patients). AKI indicates acute kidney injury; BP, blood pressure; and HTN, hypertension.