Physiological studies of transition

There are two thought provoking physiological studies from the group in Melbourne, Australia, led by Stuart Hooper. Both concern the physiology of transition in relation to whether or not the umbilical cord is clamped. In the first study, Aidan Kashyap et al studied physiologically based cord clamping in lambs with congenital diaphragmatic hernia. Compared with lambs in which the cord was clamped before the onset of ventilation, lambs who were ventilated with their cord intact had dramatically greater pulmonary blood flow and cerebral oxygenation. Pulmonary vascular resistance in lambs with physiologically based cord clamping was 3-fold lower 2 hours later, suggesting the potential to influence the natural history of pulmonary hypertension after transition. If these findings are replicated in human infants this approach could bring about a huge shift in the management of this condition. In the second study, Emma Brouwer et al measured umbilical blood flow in spontaneously breathing lambs with intact umbilical cords. Flow varied with respiration and, contrary to their prior hypothesis, it decreased during inspiration and increased during expiration. Vigorous inspiration caused flow to cease altogether and they consider these observations likely to reflect compression of the …