Introduction:
Heart rate (HR) is an easily and quickly detectable parameter and modifies on the basis of volemia. We hypothesized that the estimated HR variation in acute compared with basal conditions (EHR%) could be a good clinical marker of both dehydration and acute kidney injury (AKI).
Material and methods:
Two independent cohorts, one prospective comprehending children at type 1 diabetes mellitus onset (derivation) and one retrospective comprehending children with acute gastroenteritis and pneumonia (validation) were used to develop and externally validate EHR% as predictor of dehydration and AKI. EHR% was calculated as [(HR at admission–50thpercentile of HR)/HR at admission]*100. Dehydration was classified on the basis of weight loss and AKI according to the KDIGO criteria. EHR% was evaluated as predictor of≥5%dehydration and AKI by receiver-operating characteristic (ROC) curves analysis in the derivation cohort. The best cut-offs were identified and their diagnostic performance was tested both in derivation and validation cohort
Results:
The prevalence of≥5%dehydration and AKI were 61.1% and 43.8% in the derivation cohort and 34.4% and 24.5% in the validation cohort. The area under ROC curve (AUROC) of the EHR% was 0.64(95%CI,0.56-0.71,p=0.001) for ≥5%dehydration and 0.67(95%CI,0.59-0.73,p<0.001) for AKI in the derivation cohort and 0.84(95%CI,0.77-0.90,p<0.001) for≥5%dehydration and 0.86(95%CI,0.79-0.93,p<0.001) for AKI in the validation cohort. The best EHR% cut-offs identified in the derivation cohort were>23.2% for≥5%dehydration and>24.5% for AKI. In the validation cohort, EHR%>23.2% showed specificity=99.1%(95%CI,95.2-99.9%), positive likelihood ratio (PLH)=24.6(95%CI,3.2-190.6), positive predictive value (PPV)=88.9%(95%CI,50.8-98.1%), negative predictive value (NPV)=79.6%(95%CI,76.7-82.2%), odds ratio (OR)=20.5(2.5-167.0) for ≥5%dehydration and specificity=99.0%(95%CI,94.5-99.9%), PLR=17.1(95%CI,2.2-131.6), PPV=90.0%(95%CI,54.0-98.6%), NPV=69.5%(95%CI,66.8-72.1), OR=31.2(95%CI,3.7-259.3) for AKI.
Conclusions:
EHR% could predict ≥5%dehydration if >23.2% and AKI if >24.5%. In case of ERH>24.5%, blood tests to detect AKI could be considered. While waiting for biochemical exams reports, a short-course of intravenous rehydration with 0.9%NaCl could be warranted to counteract the progression of prerenal AKI toward acute tubular necrosis.
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