Intact Cord Resuscitation
Physiological transition with an intact umbilical cord
Terminology around this subject varies from bedside stabilisation with an intact cord (my favourite when discussing this with families as it feels less scary) to resuscitation with the cord intact and intact cord resuscitation (ICR), the latter being a regular abbreviation.
Care of the newborn with optimal cord clamping – which has recently been termed ‘optimal cord management’ by the British Association of Perinatal Medicine (BAPM, 2020) is slightly different again. This refers to waiting at least 60 seconds before clamping the umbilical cord for preterm babies less than 34 weeks. A recent meta-analysis comparing delayed cord clamping (DCC) with immediate cord clamping (ICC) in preterm infants showed fewer blood transfusions, a reduction in intraventricular haemorrhage and a reduction mortality by up to one third (Fogarty, 2018).
I suspect the term ‘optimal cord management’ (OCM) will become more widely used in the future and will eventually incorporate a physiological ‘baby led’ approach where the timing of cord clamping is determined by neonatal behaviour and onset of spontaneous respiration as well as waiting for cord pulsations to cease.
We are at a pivotal moment in science, where the evidence is beginning to indicate that change is needed to the way neonates are stabilised after birth – especially those in need of resuscitation.
What are the physiological considerations at birth when the neonate needs support?
In 2014, Mercer and Erickson-Owens discussed the role of neonatal hypovolaemia at birth. Hypovolemia, often associated with nuchal cord or shoulder dystocia, may lead to an inflammatory cascade and ischemic injury. Other potential labour induced hypovolaemia, degrees of which occur more often than we'd like, may be due to cord compression, occult cord and/or uterine tachysystole of a medically induced labour (these examples are not exhaustive). The result is a non vigorous 'floppy' baby at risk of ischemic injury and who requires resuscitation. In practice you will see variations of neonatal wellbeing at birth but a sudden unexpected neonatal asystole (cardiac arrest) may occur from severe hypovolemia.
Normal birth physiology provides some protective factors. During birth the tight compressive squeeze of the vaginal wall forces neonates’ blood towards the central circulation, to protect the brain, heart and lungs and reduces the impact of harm (Mercer et al., 2009).
When the baby is born, the peripheral circulation opens, this sudden release of pressure on the infant's body results in hypoperfusion resulting in low central circulation and blood pressure (Mercer et al., 2009).
When caring for a newborn who may require resusciatation, the midwife following recommendations by the World Health Organisation (2012) and National Institute for Health and Care Excellence (2014) should firstly facilitate delayed cord clamping for at least 60 seconds, whilst ensuring tactile stimulation, drying and adequate thermoregulation.
During transition from the umbilical circulation to extra-uterine life, lung aeration is pivotal for the major physiological changes in respiratory and cardiovascular function that are required for survival after birth (Morton & Brodsky, 2016). So at this stage, given that the practitioner wants to support the baby's airway and inflate the lungs, current practice recommends that the neonate is separated from the placenta so it can be transfered to a resuscitaire as per national and international guidelines (Wyllie et al., 2015).
It’s worth noting that this recommendation is not based on scientific or clinical evidence (Roher et al, 2011) but rather a culture of practice.
If there is a significant delay between cord clamping and onset of ventilation, the newborn is exposed to a prolonged period of low cardiac output, placing the infant at risk of a hypoxic/ischemic insult. Practitioner experts in newborn life support are acutely aware of these harms which can make this process all the more stressful and open to problems relating to human factors and overly vigorous resuscitation.
The practice of immediate cord clamping can cause significant bradycardia after birth due vagal stimuli, especially if the cord is cut before the infant has taken a breath (Hooper et al., 2016). Further, any initial hypovolaemia is compounded by immediate cord clamping which causes blood volume depletion. Approximately one third of the newborn’s circulating blood remains in the placenta at birth (Farrar et al., 2010). Decreased volume reduces perfusion of the lungs, heart and brain - the brainstem contains vital respiratory centers which provide the neural drive for breathing. Lack of blood supply to the medulla oblongata causes impaired autoresuscitation capacity (Stojanovska et al., 2018). The medulla oblongata requires continuous respiratory neural output to control breathing as well as blood pressure, heart rate, and basic muscle tone (Zillmer et al., 2008). So it's vital the neonate has it's blood from the placenta to boost pulmonary blood flow.
Intact cord resuscitation
If the cord is clamped prior to inflation of the lungs, the heart rate will drop and cardiac output decreases by up to 50% in 60 seconds, thereby reducing the supply of vital oxygen to the baby’s organs, especially the brain.
If the cord is clamped after the onset of breathing the left atrium will be supplied with sufficient blood, to restore cardiac output. Blood is re-distributed to the baby’s organs, delivering oxygen and important nutrients like iron.
Please visit the Concord website for further detailed explanation of the physiological mechanism of intact cord stabilisation.
There is however another option where the neonate can receive the benefit of its own blood to increase circulatory volume via an intact umbilical cord whilst also be able to receive mechanical ventilation if necessary! Blood volume is key, optimal cord clamping allows time for a transfer of the fetal blood in the placenta to the neonate at the time of birth.
Deferring cord clamping until the onset of breathing can help to mitigate the decrease in cardiac output with benefits in terms of preventing low blood pressure with associated reduction in intraventricular haemorrhage, less inotropes and less iron deficiency anaemia (Hooper et al., 2016).
This gentle placental transfusion can provide the infant with an additional 30% more blood volume (Farrar, 2010). Cardiac output remains normal and stable throughout the transition sequence, avoiding a reduction in output and large fluctuations in pressure and flow (Bhatt, 2013). If the neonate has suffered a degree of hypoxia in utero, intact cord resusciation can reduce the severity of ischaemia, inflammatory responses, and injury from hypoxia (Mercer & Erickson-Owens, 2014).
Video's explaining physiology and bedside stabilisation options