Profound hypotension and associated electrocardiographic changes during prolonged cord occlusion in the near term fetal sheep

Wibbens, Bert; Westgate, Jenny A.; Roelfsema, Vincent; Haan, Harmen H. de; Hunter, Christian J.; Gunn, Alistair J.

doi:10.1016/j.ajog.2005.01.058

Cited by 31 publications

(35 citation statements)

References 19 publications

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“…For example, chronically hypoxic fetal sheep exposed to acute hypoxia exhibited more pronounced centralization of circulation (6), with enhanced femoral vasoconstriction associated with greater increases in plasma norepinephrine and vasopressin (12). In contrast, when hypoxic twin or triplet fetuses were exposed to repeated umbilical cord occlusion, they developed severe hypotension and metabolic acidosis much more rapidly (44). It is highly likely that these differences reflect the observation that fetal compromise is not a single entity; it may be relatively pure fetal hypoxia, or varying degrees of substrate limitation or acidosis (12).…”

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confidence: 88%

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep

Wibbens

Westgate²,

Haan³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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There is limited information about whether preexisting fetal hypoxia alters hemodynamic responses and changes in T/QRS ratio and ST waveform shape during subsequent severe asphyxia. Chronically instrumented near-term sheep fetuses (124 +/- 1 days) were identified as either normoxic Pa(O(2)) > 17 mmHg (n = 9) or hypoxic Pa(O(2)) < or = 17 mmHg (n = 5); then they received complete occlusion of the umbilical cord for 15 min. Umbilical cord occlusion led to sustained bradycardia, severe acidosis, and transient hypertension followed by profound hypotension in both groups. Preexisting hypoxia did not affect changes in mean arterial blood pressure but was associated with a more rapid initial fall in femoral blood flow and vascular conductance and with transiently higher fetal heart rate at 2 min and from 9 to 11 min of occlusion compared with previously normoxic fetuses. Occlusion was associated with a significant but transient rise in T/QRS ratio; preexisting hypoxia was associated with a significant delay in this rise (maxima 3.7 +/- 0.4 vs. 6.2 +/- 0.5 min), but a slower rate of fall. There was a similar elevation in troponin-T levels 6 h after occlusion in the two groups [median (range) 0.43 (0.08, 1.32) vs. 0.55 (0.16, 2.32) microg/l, not significant]. In conclusion, mild preexisting hypoxia in normally grown singleton fetal sheep is associated with more rapid centralization of circulation after umbilical cord occlusion and delayed elevation of the ST waveform and slower fall, suggesting that chronic hypoxia alters myocardial dynamics during asphyxia.

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confidence: 88%

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep

Wibbens

Westgate²,

Haan³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…All fetuses had normal biochemical variables for their gestational ages. 24,25 Experimental Protocols At 128 ± 1 days gestation, ischemia was induced by reversible inflation of the carotid occluder cuffs with sterile saline for 30 minutes. Successful occlusion was confirmed by the onset of an isoelectric EEG signal within 30 seconds of inflation.…”

Section: Data Recordingmentioning

confidence: 99%

Non-Additive Effects of Delayed Connexin Hemichannel Blockade and Hypothermia after Cerebral Ischemia in Near-Term Fetal Sheep

Davidson

Rout

Wassink

et al. 2015

J Cereb Blood Flow Metab

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Hypothermia is partially neuroprotective after neonatal hypoxic-ischemic encephalopathy. Blockade of connexin hemichannels can improve recovery of brain activity and cell survival after ischemia in near-term fetal sheep. In this study, we investigated whether combining delayed hypothermia with connexin hemichannel blockade with intracerebroventricular infusion of a mimetic peptide can further improve outcomes after cerebral ischemia. Fetal sheep (0.85 gestation) received 30 minutes of cerebral ischemia followed by a 3-hour recovery period before treatment was started. Fetuses were randomized to one of the following treatment groups: normothermia (n=8), hypothermia for 3 days (n=8), connexin hemichannel blockade (50 μmol/L intracerebroventricular over 1 hour followed by 50 μmol/L over 24 hours, n=8) or hypothermia plus hemichannel blockade (n=7). After 7 days recovery, hypothermia was associated with reduced seizure burden, improved electroencephalographic (EEG) power, and a significant increase in neuronal and oligodendrocyte survival and reduced induction of Iba1-positive microglia. In contrast, although hemichannel blockade reduced seizure burden, there was no effect on EEG power or histology (P<0.05). There was no further improvement in outcomes with combined hypothermia plus hemichannel blockade. In conclusion, these data show that there is no additive neuroprotection with combined hypothermia and hemichannel blockade after cerebral ischemia in near-term fetal sheep.

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“…HRV provides noninvasive assessment of both the parasympathetic and sympathetic control of heart rate (HR) (7,8). Evidence of alterations in heart rate following hypoxia has long been observed in animal research (9) and adult human studies have also documented altered HRV following traumatic brain injury (10). The ability of HRV to grade HIE severity in neonates has also been explored in a small number of studies, and has been shown to change in encephalopathic neonates (11,12); however, the relationship with neurological outcome is unknown.…”

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Heart rate variability in hypoxic ischemic encephalopathy: correlation with EEG grade and 2-y neurodevelopmental outcome

et al. 2015

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Background:The study aims to describe heart rate variability (HRV) in neonatal hypoxic ischemic encephalopathy (HIE) and correlate HRV with electroencephalographic (EEG) grade of HIE and neurodevelopmental outcome. Methods: Multichannel EEG and electrocardiography (ECG) were assessed at 12-48 h after birth in healthy and encephalopathic full-term neonates. EEGs were graded (normal, mild, moderate, and severe). Neurodevelopmental outcome was assessed at 2 y of age. Seven HRV features were calculated using normalized-RR (NN) interval. The correlation of these features with EEG grade and outcome were measured using Spearman's correlation coefficient. results: HRV was significantly associated with HIE severity (P < 0.05): standard deviation of NN interval (SDNN) (r = −0.62), triangular interpolation of NN interval histogram (TINN) (r = −0.65), mean NN interval (r = −0.48), and the very low frequency (VLF) (r = −0.60), low frequency (LF) (r = −0.67) and high frequency (HF) components of the NN interval (r = −0.60). SDNN at 24 and 48 h were significantly associated (P < 0.05) with neurodevelopmental outcome (r = −0.41 and −0.54, respectively). conclusion: HRV is associated with EEG grade of HIE and neurodevelopmental outcome. HRV has potential as a prognostic tool to complement EEG.

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Profound hypotension and associated electrocardiographic changes during prolonged cord occlusion in the near term fetal sheep

Cited by 31 publications

References 19 publications

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep

Non-Additive Effects of Delayed Connexin Hemichannel Blockade and Hypothermia after Cerebral Ischemia in Near-Term Fetal Sheep

Heart rate variability in hypoxic ischemic encephalopathy: correlation with EEG grade and 2-y neurodevelopmental outcome

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