Change in heart rate variability in relation to a significant ST‐event associates with newborn metabolic acidosis

• Published in: BJOG : an international journal of obstetrics and gynaecology 2007-07, Vol.114 (7), p.819-823
• Main Authors: Siira, S, Ojala, T, Ekholm, E, Vahlberg, T, Blad, S, Rosén, KG
• Format: Article
• Language: English
• Subjects: Acidosis - diagnosis; Acidosis - physiopathology; Arrhythmias, Cardiac - diagnosis; Arrhythmias, Cardiac - physiopathology; Babies; Biological and medical sciences; Cardiotocography; Case-Control Studies; Childbirth & labor; ecg; Electrocardiography; Fetal Diseases - diagnosis; Fetal Diseases - physiopathology; Fetal electrocardiography; fetal heart rate variability; fetal lamb electrocardiogram; Gestational Age; Gynecology. Andrology. Obstetrics; Heart rate; Heart Rate, Fetal - physiology; Humans; hypoxemia; hypoxia; Infant, Newborn; labour; Medical sciences; metabolic acidosis; Metabolic disorders; Obstetrics; Obstetrics, Gynecology and Reproductive Medicine; power spectra; power spectrum; Reproduktionsmedicin och gynekologi; sheep; spectral-analysis; ST‐event; waveform
• ISSN: 1470-0328; 1471-0528
• DOI: 10.1111/j.1471-0528.2007.01369.x

Objective  To find whether low‐to‐high frequency (LF/HF) ratio of fetal heart rate (FHR) variability changes in relation to a significant ST‐event during delivery, and if the change is predictive of metabolic acidosis of the newborn. Design  A case–control study. Setting  Data from a multicentre project. Subjects  Acidotic and control fetuses with abnormal cardiotocography together with a ST‐event in fetal electrocardiogram (ECG). Methods  We studied intrapartum FHR variability with spectral analysis from 34 fetuses with a significant ST‐event in the fetal ECG. LF/HF ratio of FHR variability was measured within a period of 1 hour before and 1 hour after a significant ST‐event. Sensitivity and specificity of the change in LF/HF ratio of FHR variability in prediction of metabolic acidosis (pH ≤ 7.05 and base deficit value > 12.0 mmol/l) of the newborn were described by means of the receiver operating characteristic curve. Main outcome measures  Change in LF/HF ratio of FHR in relation to a significant ST‐event. Results  We found that a relative change in LF/HF ratio greater than 30% in relation to a significant ST‐event predicted cord arterial metabolic acidosis with a sensitivity of 89% (95% CI 68–100%) and specificity of 80% (95% CI 64–96%). Conclusions  Relative changes in LF/HF ratio of FHR variability in relation to a significant ST‐event are more pronounced in fetuses born with metabolic acidosis.