Determinants of Changes in B-Type Natriuretic Peptide Levels in Hospitalized Patients

Journal of Clinical and Basic Cardiology 2006; 9 (1-4): 31-36

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Keywords: B-natriuretisches Peptid,  Betablocker,  Herzinsuffizienz,  beta-blocker,  BNP,  heart failure

Background: BNP trends in outpatients reflect use of cardiac medications and correlate with morbidity and mortality. However, their role in the inpatient setting is unclear. We hypothesized that (1) BNP measurements are more available and reliable than standard measures of volume status and (2) inpatient BNP trends are influenced by volume and neurohormonal status. Methods: We conducted a retrospective study of patients with multiple BNP measurements during their hospitalization. The comparative availability of weights and laboratory tests was assessed by examining the frequency of recorded weights and the frequency of recorded phlebotomy results. To evaluate a surrogate for weights, we examined the correlation between changes in weight and concomitant fluid balance. Contributors to BNP trends were determined by multivariate regression analysis. Results: The cohort consisted of 60 non-critically ill patients. BNP measurements were taken 54 ± 57 hours apart (initial: 939 ± 925 pg/ml; follow-up: 711 ± 726 pg/ml; p = 0.003). Laboratory tests were more often recorded than weights (94 ± 11 % vs. 50 ± 33 % of hospital-days; p < 0.0001). The correlation between changes in weight and fluid balance was poor. Time between measurements and inter-measurement doses of diuretic and beta-blocker were associated with a change in BNP of at least 24 % and 200 pg/ml. Conclusions: Inpatient BNP trends may reflect response to diuretics and neurohormonal agents, thus offering information beyond standard indicators of volume status, which are relatively unavailable and unreliable.