Acceleration and Deceleration Capacity of Fetal Heart Rate in an In-Vivo Sheep Model

作者：Rivolta Massimo W; Stampalija Tamara^*; Casati Daniela; Richardson Bryan S; Ross Michael G; Frasch Martin G; Bauer Axel; Ferrazzi Enrico; Sassi Roberto

来源：PLos One, 2014, 9(8): e104193.

DOI：10.1371/journal.pone.0104193

Background: Fetal heart rate (FHR) variability is an indirect index of fetal autonomic nervous system (ANS) integrity. FHR variability analysis in labor fails to detect early hypoxia and acidemia. Phase-rectified signal averaging (PRSA) is a new method of complex biological signals analysis that is more resistant to non-stationarities, signal loss and artifacts. It quantifies the average cardiac acceleration and deceleration (AC/DC) capacity.
Objective: The aims of the study were: (1) to investigate AC/DC in ovine fetuses exposed to acute hypoxic-acidemic insult; (2) to explore the relation between AC/DC and acid-base balance; and (3) to evaluate the influence of FHR decelerations and specific PRSA parameters on AC/DC computation.
Methods: Repetitive umbilical cord occlusions (UCOs) were applied in 9 pregnant near-term sheep to obtain three phases of MILD, MODERATE, and SEVERE hypoxic-acidemic insult. Acid-base balance was sampled and fetal ECGs continuously recorded. AC/DC were calculated: (1) for a spectrum of T values (T= 1 divided by 50 beats; the parameter limits the range of oscillations detected by PRSA); (2) on entire series of fetal RR intervals or on "stable'' series that excluded FHR decelerations caused by UCOs.
Results: AC and DC progressively increased with UCOs phases (MILD vs. MODERATE and MODERATE vs. SEVERE, p < 0.05 for DC T = 2-5, and AC T = 1-3). The time evolution of AC/DC correlated to acid-base balance (0.4 <vertical bar rho vertical bar <0.9, p < 0.05) with the highest D r D for 2 <= T <= 7. PRSA was not independent from FHR decelerations caused by UCOs.
Conclusions: This is the first in-vivo evaluation of PRSA on FHR analysis. In the presence of acute hypoxic-acidemia we found increasing values of AC/DC suggesting an activation of ANS. This correlation was strongest on time scale dominated by parasympathetic modulations. We identified the best performing T parameters (3 <= T <= 5), and found that AC/DC computation is not independent from FHR decelerations. These findings establish the basis for future clinical studies.

• 出版日期2014-8-20