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Anticipate the need for physiological transition in extremely preterm babies
- David JR Hutchon (11 July 2009)
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Authors' response
- Christoph C Lees, Natalie K Yeaney, Edile M Murdoch (20 July 2009)
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David JR Hutchon, Consultant Obstetrician DL3 6HX
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Dear Sir,
Re: Clinical review. The extremely premature neonate: anticipating and managing care. Yeaney N K, Murcoch E M, Lees C C. BMJ 2009;338:b2325 Co-operation between obstetrician and neonatologist is probably never more important than with the delivery of the extremely preterm neonate. It is inevitable that evidence for the optimal management of these babies is limited but it is reasonable to extrapolate the evidence available for the less preterm. This clinical review is notable for the complete absence of any discussion about the timing of cord clamping and its impact on neonatal health. It can be reasonably argued that the physiology of pregnancy and labour has been disrupted and adhering to natural processes may not be beneficial to the neonate. On the other hand the pathological event of preterm labour is not a licence to abandon all of nature’s processes. Abruptly interfering with the transition from fetal to adult pattern circulation at birth is generally tolerated well by the healthy term neonate. However it may not be tolerated so well by the preterm baby and there is likley to be a lot more to good care at preterm birth than just “sweetness and warmth.” (1) The Cochrane review shows the evidence that allowing time for transition of the circulation results in better neonatal outcomes for the preterm baby. (2) A randomised controlled trial showed similar benefits for the very preterm neonate. (3) In this study there was a reduced incidence of necrotising enterocolitis and late onset sepsis, conditions which the authors point out have not changed in incidence over the last 15 years. Long before the evidence base for antenatal corticosteroids was available the search for obstetric solutions for respiratory distress syndrome was sought. Moss working in California (4) and Dunn in Bristol (5) both showed improved outcomes of preterm babies when a more physiological transition of the circulation was allowed to occur at birth. It is a lot easier to simply give an injection of steroid so the preliminary evidence was never followed up. However the subsequent studies included in the Cochrane review show that the two approaches of antenatal steroids and delayed cord clamping are likely to be complimentary. Immediate cord clamping is not a necessary element of the active management of the third stage of labour (6,7,8) so the benefits for the baby can be fully appreciated. As the authors point out it is events in the first hours after birth that affect the neonatal mortality and morbidity. Cord clamping is an event which cannot be any closer to the moment of birth but its importance is largely ignored. Other issues which impinge on this can be overcome with a little lateral thinking, (9) however, for some inexplicable reason, suddenly clamping off a functioning placental circulation is undertaken without any consideration of the consequences. In the extremely preterm neonate there may not be a great deal of RCT evidence to support one or another approach to the timing of cord clamping but logical and ethical standards requires us to support any intervention with evidence. Until the evidence is available we should do everything possible to support a physiological transition. The authors describe a whole range of reasons “why survival has improved for these infants” describing less invasive care etc without quoting any RCT evidence to support these changes. It may have seemed logical to provide non-physiological concentrations of oxygen until the risk of oxygen toxicity was recognised. Although they quote the value of caffeine they do not mention the common need for neonatal transfusion in these infants and anaemia is a risk factor for apnoea in these babies. (9a) We are anxious to try to measure placental and cerebral blood flow in the fetus to determine fetal health but at birth make no effort to allow the transition from fetal pattern to adult pattern circulation to occur physiologically, usually within a few minutes. Delaying clamping of the cord at birth should not be considered an intervention. There may be some who fear consequences of over transfusion, polycythemia or kernicterus from jaundice. None of their fears have been supported by what evidence there is. The balance of evidence strongly favours a physiological transition. One problem is that it is the obstetrician who must clamp the cord they will not have to care for the neonate. Co-operation between the obstetrician and paediatrician with preparation for the optimal management of the delivery are essential. Practice throughout the UK is variable but generally it is considered too awkward to delay clamping! (10) The practice throughout the rest of Europe is also variable (11) but late cord clamping (3 minutes) in very preterm infants is carried out at the Hvidovre University Hospital, Denmark. (Personnal communication Dr. Pernille Pedersen), and more recently in many parts of Sweden. There has also been increasing recognition of importance of the so called “placental transfusion” which occurs during a physiological transition.(12) We have to reach the disturbing conclusion that the department of neonatology and the department of feto-maternal medicine in one of the world’s centres of excellence do not know of or do not wish to discuss the role of the timing of cord clamping in the outcome for the preterm or extremely preterm neonate. No single element in the care of these infants can prove to be a panacea, but each element in the care can contribute to the outcome. It is a valid opinion to consider that delayed cord clamping does not warrant whole hearted endorsement but it is quite inappropriate, in my view, to exclude it entirely from such a clinical review. I am not questioning the dedication of the neonatologists, the neonatal nurses nor the obstetricians, however for some inexplicable reason the mainstream of neonatology and obstetrics is reluctant to openly discuss the current evidence available and pursue more research on the timing of cord clamping. Nature does nothing uselessly – Aristotle.
David J R Hutchon FRCOG Competing interests: None declared |
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Christoph C Lees, Consultant, Obstetrics and Fetal-Maternal Medicine CB2 2QQ, Natalie K Yeaney, Edile M Murdoch
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We thank Dr Hutchon for his comments. There may be benefits to delayed cord camping in premature infants, though as he observes these are not proven. We consider in this review extremely premature neonates, born at 23-26 weeks gestation and can find no evidence to suggest that delayed cord clamping is beneficial in this context. Moreover, some babies at these very preterm gestations will be born with little or no respiratory or cardiac effort. Immediate cardio- respiratory resuscitation with the baby detached from the placenta and mother's body must be the main priority. This would, we believe, take precedence over waiting up to several minutes prior to clamping the cord and only then commencing active resuscitation. Competing interests: Author's Response |
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