title: Determination of fetal heart rate reactivity from a single 20-min window of non-stress testing in compromised fetuses.
abstract: OBJECTIVE
  To shorten the analysis time needed for non-stress testing (NST) without decreasing efficacy in compromised fetuses.
  
  
  METHODS
  We selected 80 cases with a 5-min Apgar score <7 as a study group and 259 cases with a 5-min Apgar score >/=9 as a control group. We applied four different criteria (A, B, C, and D) to each study and control group for the first 20-min window of NST data to evaluate reactivity. Criteria A, B, and C consisted of conventional reactivity criteria according to amplitude (15 or 10 beats per minute), duration (15 or 10 s) and weeks of gestation (</=31, >/=32), and criteria D combined criteria C with approximate entropy (ApEn).
  
  
  RESULTS
  The sensitivity of criteria D (91.25%) was greater than the other three criteria (P<0.0001). The specificities of criteria C (96.14%) and D (99.23%) were also higher than criteria A and B (P<0.0001). The positive and negative predictive value of criteria D were better than that of criteria C (97.33 vs. 83.87, P=0.0066) and (97.35 vs. 89.89, P=0.0004), respectively.
  
  
  CONCLUSIONS
  Adding ApEn to the conventional criteria for reactivity shortened NST analysis time without decreasing efficacy, facilitating a decision of reactivity within a single 20-min NST window.
authors.affiliation: Department of Mathematics, College of Natural Sciences, Hanyang University, Sungdong-gu, Seoul, Korea.
authors.forename: Young-Sun
authors.initials: YS
authors.lastname: Park
authors.forename: Jeong-Kyu
authors.initials: JK
authors.lastname: Hoh
authors.forename: Seung-Kwon
authors.initials: SK
authors.lastname: Koh
authors.forename: Nam-Su
authors.initials: NS
authors.lastname: Kim
authors.forename: Moon-Il
authors.initials: MI
authors.lastname: Park
mesh_terms: D001034:Apgar Score; D019277:Entropy; D005260:Female; D005323:Fetal Monitoring / Q000592:standards*; D006340:Heart Rate, Fetal; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D012189:Retrospective Studies; D013997:Time Factors