Assessment of splanchnic hemodynamics in neonates at risk of necrotizing enterocolitis

ABSTRACT

It has been suggested that either acute or chronic intestinal ischemia may play a primary role in the initiation of mucosol injury and subsequently the development of necrotizing enterocolitis [NEC]. Hence, this study aimed at assessment of gut blood flow in neonates at risk of developing NEC and to determine whether a disturbance in splanchnic perfusion could provide not only a pathophysiological basis for the development of NEC but also a mechanism linking a variety of seemingly disparate risk factors. Addingly, changes in splanchnic circulation with increasing postnatal age were evaluated. Duplex pulsed Doppler ultrasound was used to study changes in gut blood flow velocities during the first week of life in neonates at risk of developing NEC admitted to NICU of Obsteric and Gynecology Department, Ain Shams University Hospitals. This case-control study comprised 127 neonates [61 males and 66 females], their mean gestational age was 35.0 +/- 4.3 weeks and their mean birth weight was 2.35 +/- 0.63 kg. They were classified into 4 groups 2 control groups [preterms [n=21] and fullterms [n=41]] and 2 patient groups recognized as being at risk of developing NEC [at risk preterms [n=30] and at risk fullterms [n=35]]. They were subjected to history taking, clinical examination, laboratory investigations relevant to the diagonosis on admission, radiological evaluation including chest and abdominal x-rays and echocardiography. Duplex pulsed Doppler ultrasound was used to determine blood flow velocities in coeliac axis [CA] and superior mesentric aretry [SMA] in all studied groups. Subjects were studied on the first, second, third, and seventh days of life. The results of the current study showed that the mean peak systolic velocities [PSVs] in the SMA were lower in the at risk groups than in the control groups on all 4 days of measurements [p<0.001]. In contrast to the SMA, PSVs of CA increased significantly in the at risk groups compared to their controls [p<0.001]. The ratio of PSV in the CA to that in the SMA, an index of relative downstream resistance in the SMA, was significantly greater in the at risk groups than in the control groups on days 1, 2 and 3 [p< 0.001]. PSVs of SMA tended to increase over the first week of life in control groups. On the other hand, the increase in PSVs of SMA was delayed in the at risk groups In conclusion, these data demonstrate that neonates at risk of developing NEC have abnormal gut blood flow velocities and splanchnic perfusion is severely compromised. Hence, alteration in the splanchnic circulation may be an important factor in the final common pathway of different risk factors of NEC and the liver could be considered as the fourth preferential organ for arterial blood supply in the compromised neonate, besides heart, brain and adrenals. Therefore, serial Doppler measurements are mandatory for early detection and prediction of NEC