21 - Blood Pressure Patterns for Pediatric Cystic Fibrosis Patients in Outpatient and Inpatient Settings

Normative pediatric blood pressures are based on outpatient measurements, and it’s unclear how well these standards apply to inpatient settings.  Clinicians often assume that a host of factors (pain, stress, medications, kidney injury) may contribute to higher inpatient blood pressures, but there have been no studies comparing pediatric blood pressures between inpatient and outpatient settings.  This study attempts to address this knowledge gap by selecting a population in which potential factors affecting blood pressure are minimized due to the nature of their hospitalizations: cystic fibrosis patients with admissions for antibiotics and without hypertension or acute kidney injury.

Objective:

To compare inpatient and outpatient blood pressures in pediatric cystic fibrosis patients without hypertension or acute kidney injury.

Design/Methods:

Blood pressures for all cystic fibrosis patients at a tertiary care children’s hospital were examined.  Patients with a diagnosis of hypertension or on antihypertensive medications and patients without blood pressure measurements as inpatients and outpatients were excluded.  For included patients, blood pressures taken between 7 p.m. and 7 a.m. and blood pressures overlapping with an episode of KDIGO-defined AKI were excluded.  Average systolic and diastolic blood pressures were determined for each patient in both the inpatient and outpatient setting, and the difference between these values was calculated.  T-tests were used to determine whether the differences were statistically significant (p < 0.05).

Results:

9248 blood pressures from 109 cystic fibrosis patients aged 3 to 17 years were used for analysis.  Average systolic and diastolic blood pressures for each age are shown in Table 1.  Adolescents had significantly lower systolic and diastolic blood pressures in inpatient settings compared to outpatient settings.  This was not seen in younger patients.  Figures 1-2 show the distribution of systolic and diastolic blood pressures in each age group.

Conclusion(s):

Adolescent cystic fibrosis patients without a diagnosis of hypertension or AKI had significantly lower average systolic and diastolic blood pressures in inpatient settings compared to outpatient settings.  There were no significant differences for younger patients.  These are somewhat surprising results, but could be explained by differences in equipment between the two settings or possible decreases in activity level when patients are admitted.  These findings suggest caution is warranted when making assumptions about an admission’s effect on blood pressure, and they deserve further exploration.