The slope of fetal heart rate deceleration is predictive of fetal condition during repeated umbilical cord compression in sheep

Akagi, Kozo; Okamura, Koji; Endo, Chikara; Saito, Junya; Tanigawara, Shingo; Shintaku, Yuichi; Watanabe, Takanori; Sato, Akira; Yajima, Akira

doi:10.1016/s0002-9378(88)80120-0

Cited by 23 publications

(23 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our finding of a faster bradycardic response in hypoxemic animals following cord occlusion is consistent with reports indicating an increased chemoreflex response in hypoxemic or otherwise compromised animals (1,3,13). The enhanced chemoreflex response to asphyxia may also be mediated by the increase in binding sites for angiotensin peptides.…”

Section: Discussionsupporting

confidence: 92%

“…Power of RRI spectra in the LF (LF RRI) and HF (HFRRI) range were calculated in normalized units, and the ratio of LFRRI/HFRRI was used as an estimation of sympathovagal balance (31). 1 antagonist losartan (3 M), AT2 antagonist PD-123319 (3 M), and ANG-(1-7) antagonist D-Ala (3 M)] were used as competitors as described (8). After exposure to films, images were quantified using a computerized densitometric system (MCID; InterFocus Imaging, Cambridge, UK).…”

Section: Animal Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep

Pulgar¹,

Hong²,

Jessup³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

The effects of chronic mild hypoxemia on the binding of angiotensin receptors in selected brain stem nuclei and reflex responses were studied in fetal sheep. Fetal and maternal catheters were placed at 120 days' gestation, and animals received intratracheal maternal administration of nitrogen (n ϭ 16) or compressed air in controls (n ϭ 19). Nitrogen infusion was adjusted to reduce fetal brachial artery PO2 by 25% during 5 days. Spontaneous baroreflex sensitivity and spectral analysis of the pulse interval were analyzed during the 5 days hypoxemia period using 90 min of daily recording. Brains of control and hypoxemic animals were collected, and brain stem angiotensin receptor binding was studied by in vitro autoradiography at 130 days of gestation. After 5 days of hypoxemia, some animals in each group were submitted to one complete umbilical cord occlusion during 5 min. [125 I]sarthran binding showed that chronic mild hypoxemia significantly increases angiotensin type 1 receptor, angiotensin type 2 receptor, and ANG-(1-7) angiotensin receptor binding sites in the nucleus tractus solitarius and dorsal motor nucleus of the vagus (P Ͻ 0.05). Hypoxemia induced lower baroreflex sensitivity and a higher low frequency-to-high frequency ratio in the fetus, consistent with a shift from vagal to sympathetic autonomic cardiac regulation. Cord occlusion to elicit a chemoreflex response induced a greater bradycardic response in hypoxemic fetuses (slope of the initial fall in heart rate; 11.3 Ϯ 1.9 vs. 6.4 Ϯ 1.2 beats ⅐ min Ϫ1 ⅐ s Ϫ1 , P Ͻ 0.05). In summary, chronic mild hypoxemia increased binding of angiotensin receptors in brain stem nuclei, decreased spontaneous baroreflex gain, and increased chemoreflex responses to asphyxia in the fetus. These results suggest hypoxemia-induced alterations in brain stem mechanisms for cardiovascular control.fetus; hypoxemia; baroreflex OXYGEN DEPRIVATION IMPOSES diverse challenges to fetal development, with changes in the autonomic cardiovascular control via baroreflex and chemoreflex pathways playing a major role as a survival strategy (16). In fetal sheep, acute episodes of hypoxemia induce a redistribution of cardiac output to maintain blood flow and oxygen delivery to the heart and brain (14). This response is initiated by stimulation of peripheral chemoreceptors and maintained by endocrine mechanisms involving secretion of hormones such as catecholamines, neuropeptide Y, arginine vasopressin, and cortisol (11). During acute severe hypoxia, i.e., complete occlusion of the umbilical cord, fetuses respond with a fall in heart rate (FHR) and an increase in blood pressure. This acute FHR during hypoxia represents a key fetal adaptation, believed to help reduce myocardial work and oxygen requirements (11). This initial bradycardia, which is mediated by chemoreflex vagal pathways (5, 17, 23), occurs before the increase in blood pressure and is an indication of the severity of the hypoxic insult (5). Recently, it was reported that the slope of the initial bradycardia increases during short ...

show abstract

Section: Discussionsupporting

confidence: 92%

Section: Animal Studiesmentioning

confidence: 99%

Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep

Pulgar¹,

Hong²,

Jessup³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…Although the details of FHR change in progress of acidemia have been previously reported [2], typical patterns observed in the experiment are shown in figure 1. The condition of the maternal ewe remained good during the PET study as evaluated by periodic blood gas analysis while respiration was maintained in the fashion described above.…”

Section: Resultsmentioning

confidence: 70%

Alteration of FHR pattern and cerebral metabolic rate of glucose of the fetus measured by positron emission tomography during progress of acidemia. The significance of overshoot acceleration in FHR

Okamura

Tanigawara²,

Shintaku³

et al. 1989

Jpme

Self Cite

View full text Add to dashboard Cite

“…We showed in our experimental system of fetal acidemia caused by repetitive cord compression that during progression of fetal acidemia, fetal heart rate pattern characteristically changes (Akagi et al 1988), the T wave in the fetal ECG is augmented , and blood flow in various vessels changes . These parameters could be helpful in clinically identifying fetal acidemia leading to irreversible central nervous system damage.…”

Section: Discussionmentioning

confidence: 86%

“…We recognized the characteristic spikes in the ECoG during cord compression in the status of muscle paralysis and concluded that the spikes were not elicited subsequent to fetal movement. In our model of fetal acidemia caused by repetitive cord compression, catecholamines are released even in the early stage of stress prior to development of acidemia (Akagi et al 1988). In the period of MD in fetal heart rate, the fetal brain should have been able to compensate for the hypoxic insult during cord compression so that brain damage was avoided.…”

Section: Discussionmentioning

confidence: 99%

Appearance of Abnormal Electrocorticogram Patterns during Umbilical Cord Compression in Sheep Fetus

Takahashi

Sugawara

Chisaka

et al. 2006

Tohoku J. Exp. Med.

Self Cite

View full text Add to dashboard Cite

A frequent cause of fetal acidemia, which sometimes results in hypoxic-ischemic encephalopathy, is umbilical cord compression associated with uterine contraction. Using a sheep model of fetal acidemia, we examined the changes in electrocorticogram (ECoG), carotid artery blood flow, arterial blood pressure and fetal heart rate during cord compression. A characteristic burst of ECoG spikes emerged during cord compression at fetal arterial pH 7.18 even before the pH went down to severe fetal acidemia (less than 7.10). The administration of a neuromuscular blocking agent to the fetus did not abolish the appearance of the spikes. These results suggest that cord compression may cause abnormal brain excitement even in the absence of severe fetal acidemia and that this abnormal excitement can lead to fetal brain dysfunction, if cord compression is repeated or prolonged.fetal heart rate; cord compression; fetal electrocorticogram; fetal acidemia

show abstract

The slope of fetal heart rate deceleration is predictive of fetal condition during repeated umbilical cord compression in sheep

Cited by 23 publications

References 16 publications

Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep

Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep

Alteration of FHR pattern and cerebral metabolic rate of glucose of the fetus measured by positron emission tomography during progress of acidemia. The significance of overshoot acceleration in FHR

Appearance of Abnormal Electrocorticogram Patterns during Umbilical Cord Compression in Sheep Fetus

Contact Info

Product

Resources

About