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2 results

  • Chapter 11.2 - Twin-to-twin transfusion syndrome

  • from Section 2 - Fetal disease
  • Edited by Mark D. Kilby, Anthony Johnson, Baylor College of Medicine, Texas, Dick Oepkes
  • Book:
    Fetal Therapy
    Published online:
    05 February 2013
    Print publication:
    13 December 2012, pp 156-165

  • Summary

    Monochorionic (MC) twin and triplet pregnancies pose complex clinical problems and high risks of types that are not seen in dichorionic (DC) twin pregnancies. Fetal growth discordance (FGD) and twin-to-twin transfusion syndrome (TTTS) are the most common problems. The MC twin placenta is usually a truly single, not fused, placenta that is produced by a single zygote and intended for the metabolic support of a singleton fetus. There are three vascular consequences of the insertion of two or more umbilical cords into an MC placenta: cord insertions, single umbilical artery, and interfetal vascular connections. TTTS is usually caused by a relatively low number of small diameter arteriovenous connections (AVCs) in combinations that result in net chronic blood seepage into the recipient twin. All types of vascular connections are involved in major complications in MC twins, including TTTS, donor/recipient role reversal after treatment, and neurological damage of a single surviving fetus.

  • Nitrous oxide concentrations in maternal and fetal blood during Caesarean section

  • F. Karasawa, A. Takita, I. Fukuda, Y. Kawatani
  • Journal:
    European Journal of Anaesthesiology / Volume 20 / Issue 7 / September 2003
    Published online by Cambridge University Press:
    11 July 2005, pp. 555-559
    Print publication:
    September 2003

  • Summary

    Background and objective: There are little data on nitrous oxide (N2O) concentrations in neonatal blood at delivery. We investigated the effects of the time elapsing between the induction of anaesthesia and delivery (the I–D interval) on umbilical blood N2O concentrations.

    Methods: Maternal and neonatal blood N2O concentrations were measured in 27 patients undergoing Caesarean section under N2O 67% anaesthesia. The duration of N2O administration (range 2–50 min) was arbitrarily divided into three groups (each n = 9): short (2–9 min), medium (9.1–14 min) and long duration (14.1–50 min).

    Results: Compared with a rapid increase in the maternal arterial N2O concentration (48.9 ± 4.7%), the umbilical venous N2O concentration (17.9 ± 8.3%) rose slowly in the short duration group, whereas the N2O concentrations became more similar (61.6 ± 4.3 and 43.2 ± 10.0%, respectively) in the long duration group. The ratio of umbilical vein to maternal artery N2O concentrations correlated with the duration of N2O anaesthesia (r = 0.739), resulting in ratios of 0.37 ± 0.18, 0.61 ± 012 and 0.70 ± 0.13 for the short, medium and long duration groups, respectively. The Apgar score at 1 min correlated inversely with the duration of anaesthesia and with the umbilical vein N2O concentration (r = −0.457 and −0.423, respectively).

    Conclusions: The data suggest that placental N2O transfer during Caesarean section is time-dependent and slower compared with maternal N2O uptake. They also suggest that the Apgar score is less affected by N2O administration when the I–D interval is shorter.