Fetal heart rate changes do not reflect cardiovascular deterioration during brief repeated umbilical cord occlusions in near-term fetal lambs


      OBJECTIVE: Brief repetitive total umbilical cord occlusions were used to induce fetal asphyxia and to evaluate the interrelationships with hypotension and fetal heart rate decelerations. STUDY DESIGN: In 21 chronically instrumented fetal lambs (gestational age 126.8 ± 0.6 days), repetitive total umbilical cord occlusion was performed 1 out of 2.5 minutes (n = 7), 2 out of 5 minutes (n = 9), or not at all (shams, n = 5). Occlusions proceeded until fetal blood pressure was <20 mm Hg or failed to recover to baseline before the next occlusion. RESULTS: At the nadir of asphyxia pH (mean ± SEM) was 6.84 ± 0.02, base excess 23.1 ± 1.0 mmol/L, and lactate 14.2 ± 0.4 mmol/L. Two fetuses died. The pattern of fetal heart rate decelerations remained relatively consistent throughout the experiments. In contrast, after an initial phase of sustained hypertension a progressive fall in trough blood pressure occurred after approximately 15 minutes of occlusion. The blood pressure recovery time in almost all fetuses lengthened abruptly near the end of the occlusion series, at a variable metabolic threshold. This was accompanied by a significant delay in fetal heart rate recovery in only five fetuses. CONCLUSIONS: Fetal compromise presented with the development of hypotension, without change in the pattern of fetal heart rate response. These data illustrate the limited diagnostic value of fetal heart rate monitoring to identify the development of cardiovascular compromise associated with severe decelerations in the previously healthy fetus. (Am J Obstet Gynecol 1997;176:8-17.)


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        • de Haan HH
        • Van Reempts JLH
        • Vles JSH
        • de Haan J
        • Hasaart THM.
        Effects of asphyxia on the fetal lamb brain.
        Am J Obstet Gynecol. 1993; 169: 1493-1501
        • Block BS
        • Schlafer DH
        • Wentworth RA
        • Kreitzer LA
        • Nathanielsz PW.
        Intrauterine asphyxia and the breakdown of physiologic circulatory compensation in fetal sheep.
        Am J Obstet Gynecol. 1990; 162: 1325-1331
        • Gunn AJ
        • Parer JT
        • Mallard EC
        • Williams CE
        • Gluckman PD.
        Cerebral histological and electrophysiological changes after asphyxia in fetal sheep.
        Pediatr Res. 1992; 31: 486-491
        • Rosen KG
        • Hrbek A
        • Karlsson K
        • Kjellmer I.
        Fetal cerebral, cardiovascular and metabolic reactions to intermittent occlusion of ovine maternal placental blood flow.
        Acta Physiol Scand. 1986; 126: 209-216
        • Gunn AJ
        • Cook CJ
        • Williams CE
        • Johnston BM
        • Gluckman PD.
        Electrophysiological responses of the fetus to hypoxia and asphyxia.
        J Dev Physiol. 1991; 16: 147-153
        • Ball RH
        • Parer JT
        • Caldwell LE
        • Johnson J.
        Regional blood flow and metabolism in ovine fetuses during severe cord occlusion.
        Am J Obstet Gynecol. 1994; 171: 1549-1555
        • Mallard EC
        • Gunn AJ
        • Williams CE
        • Johnston BM
        • Gluckman PD.
        Transient umbilical cord occlusion causes hippocampal damage in the fetal sheep.
        Am J Obstet Gynecol. 1992; 167: 1423-1430
        • Mallard EC
        • Williams CE
        • Johnston BM
        • Gunning MI
        • Davis SL
        • Gluckman PD.
        Repeated episodes of umbilical cord occlusion in fetal sheep lead to preferential damage to the striatum and sensitise the heart to further insults.
        Pediatr Res. 1995; 37: 707-713
        • Itskovitz J
        • LaGamma EF
        • Rudolph AM.
        Heart rate and blood pressure responses to umbilical cord compression in fetal lambs with special reference to the mechanism of variable deceleration.
        Am J Obstet Gynecol. 1983; 147: 451-457
        • Jensen A
        • Kunzel W
        • Kastendieck E.
        Fetal sympathetic activity, transcutaneous PO2, and skin blood flow during repeated asphyxia in sheep.
        J Dev Physiol. 1987; 9: 337-346
        • Clapp JF
        • Peress NS
        • Wesley M
        • Mann LI.
        Brain damage after intermittent partial cord occlusion in the chronically instrumented fetal lamb.
        Am J Obstet Gynecol. 1988; 159: 504-509
        • Murata Y
        • Quilligan EJ
        • Ninomiya Y
        • Wakatsuki A
        • Masaoka N
        • Fujimori K
        • et al.
        Variable fetal heart rate decelerations and electrocortical activities.
        Am J Obstet Gynecol. 1994; 170: 689-692
        • Akagi K
        • Okamura K
        • Endo C
        • Saito J
        • Tanigawara S
        • Shintaku Y
        • et al.
        The slope of fetal heart rate deceleration is predictive of fetal condition during repeated umbilical cord compression in sheep.
        Am J Obstet Gynecol. 1988; 159: 516-522
        • Thiringer K
        • Hrbek A
        • Karlsson K
        • Rosen K
        • Kjellmer I.
        Postasphyxial cerebral survival in newborn sheep after treatment with oxygen free radical scavengers and a calcium antagonist.
        Pediatr Res. 1987; 221: 62-66
        • Jensen A
        • Hohmann M
        • Kunzel W.
        Dynamic changes in organ blood flow and oxygen consumption during acute asphyxia in fetal sheep.
        J Dev Physiol. 1987; 9: 543-559
        • Lewinsky RM.
        Cardiac systolic time intervals and other parameters of myocardial contractility as indices of fetal acid-base status.
        Baillieres Clin Obstet Gynaecol. 1994; 8: 663-681
        • Hoerter J.
        Changes in the sensitivity to hypoxia and glucose deprivation in the isolated perfused rabbit heart during perinatal development.
        Pflugers Arch. 1976; 363: 1-6
        • Hokegard KH
        • Eriksson BO
        • Kjellmer I
        • Magno R
        • Rosen KG.
        Myocardial metabolism in relation to electrocardiographic changes and cardiac function during graded hypoxia in the fetal lamb.
        Acta Physiol Scand. 1981; 113: 1-7
        • Fisher DJ.
        Acidemia reduces cardiac output and left ventricular contractility in conscious lambs.
        J Dev Physiol. 1986; 8: 23-31
        • Pisarenko OI
        • Solomatina ES
        • Studneva IM
        • Kapelko VI.
        The relationship between the cardiac contractile function, adenine nucleotides and amino acids of cardiac tissue and mitochondria at acute respiratory hypoxia.
        Pflugers Arch. 1987; 409: 169-174
        • Hoffmeister HM
        • Storf R
        • Thiedemann KU
        • Seipel L.
        High-energy phosphates, myocardial contractile function and material properties after short periods of oxygen deficiency.
        Basic Res Cardiol. 1989; 84: 77-90
        • Giussani DA
        • Spencer JA
        • Moore PJ
        • Bennet L
        • Hanson MA.
        Afferent and efferent components of the cardiovascular reflex responses to acute hypoxia in term fetal sheep.
        J Physiol Lond. 1993; 461: 431-449
        • Bocking AD.
        The relationship between heart rate and asphyxia in the animal fetus.
        Clin Invest Med. 1993; 16: 166-175
        • Nelson KB
        • Dambrosia JM
        • Ting TY
        • Grether JK.
        Uncertain value of electronic fetal monitoring in predicting cerebral palsy.
        N Engl J Med. 1996; 334: 613-618