Increased urinary flow without development of polyhydramnios in response to prolonged hypoxia in the ovine fetus

Larry C. Matsumoto, Cecilia Cheung, Robert A. Brace

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

OBJECTIVE: In the ovine fetus subjected to 24 hours of hypoxia, urinary flow is normal within a few hours from the onset of hypoxia and there is a maintained inhibition of swallowing. We hypothesized that 4 days of fetal hypoxia would lead to polyhydramnios. STUDY DESIGN: Five late-gestation fetal sheep were subjected to hypoxia for 4 days and 7 other late-gestation fetal sheep served as time control animals. Fetal hypoxia was produced on postsurgical days 5 through 9 by continuous intratracheal nitrogen insufflation to the ewe. On days 3, 5, 7, and 9 after surgery, amniotic fluid volume, fetal urinary flow rate, and the compositions of maternal and fetal blood, amniotic fluid, and fetal urine were, measured. A 3-factor analysis of variance was used for statistical analysis. RESULTS: During the period of experimental hypoxia the mean (±SE) fetal Pao2 was 16.0 ± 0.6 mm Hg, versus 21.2 ± 0.7 mm Hg in control sheep (P <.001). Fetal hypoxia was associated with increased urinary flow on days 7 and 9, averaging 1410 ± 310 and 2101 ± 345 mL/d, respectively, versus 585 ± 92 and 699 ± 78 mL/d, respectively, in control animals (P <.001). Amniotic fluid volume was unchanged with time and averaged 960 ± 159 mL in hypoxic fetuses on postsurgical days 7 through 9 and 851 ± 130 mL in control animals (P = .60). Fetal blood lactate increased in the hypoxic animals, averaging 3.4 ± 2.1 mmol/L versus 1.6 ± 0.3 mmol/L in control animals (P = .02). Fetal urinary excretions of sodium, potassium, chloride, and lactate increased significantly during hypoxia, by 170% to 400%. CONCLUSION: Four days of nitrogen-induced hypoxia in the ovine fetus resulted in excess fetal urinary flow approximating 1000 mL/d greater than normal without the development of polyhydramnios. Because amniotic fluid volume did not change and hypoxia is a known inhibitor of fetal swallowing, we speculate that intramembranous absorption of amniotic water, electrolytes, and lactate increased.

Original languageEnglish (US)
Pages (from-to)1008-1014
Number of pages7
JournalAmerican Journal of Obstetrics and Gynecology
Volume184
Issue number5
DOIs
StatePublished - 2001
Externally publishedYes

Fingerprint

Polyhydramnios
Sheep
Fetus
Fetal Hypoxia
Amniotic Fluid
Deglutition
Fetal Blood
Lactic Acid
Nitrogen
Sodium Lactate
Pregnancy
Insufflation
Potassium Chloride
Hypoxia
Sodium Chloride
Electrolytes
Statistical Factor Analysis
Analysis of Variance
Mothers
Urine

Keywords

  • Amniotic fluid
  • Hypoxia
  • Intramembranous absorption
  • Renal function
  • Sheep
  • Urinary flow

ASJC Scopus subject areas

  • Medicine(all)
  • Obstetrics and Gynecology

Cite this

Increased urinary flow without development of polyhydramnios in response to prolonged hypoxia in the ovine fetus. / Matsumoto, Larry C.; Cheung, Cecilia; Brace, Robert A.

In: American Journal of Obstetrics and Gynecology, Vol. 184, No. 5, 2001, p. 1008-1014.

Research output: Contribution to journalArticle

Matsumoto, Larry C. ; Cheung, Cecilia ; Brace, Robert A. / Increased urinary flow without development of polyhydramnios in response to prolonged hypoxia in the ovine fetus. In: American Journal of Obstetrics and Gynecology. 2001 ; Vol. 184, No. 5. pp. 1008-1014.
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N2 - OBJECTIVE: In the ovine fetus subjected to 24 hours of hypoxia, urinary flow is normal within a few hours from the onset of hypoxia and there is a maintained inhibition of swallowing. We hypothesized that 4 days of fetal hypoxia would lead to polyhydramnios. STUDY DESIGN: Five late-gestation fetal sheep were subjected to hypoxia for 4 days and 7 other late-gestation fetal sheep served as time control animals. Fetal hypoxia was produced on postsurgical days 5 through 9 by continuous intratracheal nitrogen insufflation to the ewe. On days 3, 5, 7, and 9 after surgery, amniotic fluid volume, fetal urinary flow rate, and the compositions of maternal and fetal blood, amniotic fluid, and fetal urine were, measured. A 3-factor analysis of variance was used for statistical analysis. RESULTS: During the period of experimental hypoxia the mean (±SE) fetal Pao2 was 16.0 ± 0.6 mm Hg, versus 21.2 ± 0.7 mm Hg in control sheep (P <.001). Fetal hypoxia was associated with increased urinary flow on days 7 and 9, averaging 1410 ± 310 and 2101 ± 345 mL/d, respectively, versus 585 ± 92 and 699 ± 78 mL/d, respectively, in control animals (P <.001). Amniotic fluid volume was unchanged with time and averaged 960 ± 159 mL in hypoxic fetuses on postsurgical days 7 through 9 and 851 ± 130 mL in control animals (P = .60). Fetal blood lactate increased in the hypoxic animals, averaging 3.4 ± 2.1 mmol/L versus 1.6 ± 0.3 mmol/L in control animals (P = .02). Fetal urinary excretions of sodium, potassium, chloride, and lactate increased significantly during hypoxia, by 170% to 400%. CONCLUSION: Four days of nitrogen-induced hypoxia in the ovine fetus resulted in excess fetal urinary flow approximating 1000 mL/d greater than normal without the development of polyhydramnios. Because amniotic fluid volume did not change and hypoxia is a known inhibitor of fetal swallowing, we speculate that intramembranous absorption of amniotic water, electrolytes, and lactate increased.

AB - OBJECTIVE: In the ovine fetus subjected to 24 hours of hypoxia, urinary flow is normal within a few hours from the onset of hypoxia and there is a maintained inhibition of swallowing. We hypothesized that 4 days of fetal hypoxia would lead to polyhydramnios. STUDY DESIGN: Five late-gestation fetal sheep were subjected to hypoxia for 4 days and 7 other late-gestation fetal sheep served as time control animals. Fetal hypoxia was produced on postsurgical days 5 through 9 by continuous intratracheal nitrogen insufflation to the ewe. On days 3, 5, 7, and 9 after surgery, amniotic fluid volume, fetal urinary flow rate, and the compositions of maternal and fetal blood, amniotic fluid, and fetal urine were, measured. A 3-factor analysis of variance was used for statistical analysis. RESULTS: During the period of experimental hypoxia the mean (±SE) fetal Pao2 was 16.0 ± 0.6 mm Hg, versus 21.2 ± 0.7 mm Hg in control sheep (P <.001). Fetal hypoxia was associated with increased urinary flow on days 7 and 9, averaging 1410 ± 310 and 2101 ± 345 mL/d, respectively, versus 585 ± 92 and 699 ± 78 mL/d, respectively, in control animals (P <.001). Amniotic fluid volume was unchanged with time and averaged 960 ± 159 mL in hypoxic fetuses on postsurgical days 7 through 9 and 851 ± 130 mL in control animals (P = .60). Fetal blood lactate increased in the hypoxic animals, averaging 3.4 ± 2.1 mmol/L versus 1.6 ± 0.3 mmol/L in control animals (P = .02). Fetal urinary excretions of sodium, potassium, chloride, and lactate increased significantly during hypoxia, by 170% to 400%. CONCLUSION: Four days of nitrogen-induced hypoxia in the ovine fetus resulted in excess fetal urinary flow approximating 1000 mL/d greater than normal without the development of polyhydramnios. Because amniotic fluid volume did not change and hypoxia is a known inhibitor of fetal swallowing, we speculate that intramembranous absorption of amniotic water, electrolytes, and lactate increased.

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