Patent Ductus Arteriosus and Splanchnic Oxygenation at First Feed
Condition: Patent Ductus Arteriosus
MeSH terms: Ductus Arteriosus, Patent
Study type: Observational

Summary: 
      Patent ductus arteriosus (PDA) is common in preterm infants. In the presence of a large PDA,
      significant systemic to pulmonary shunting occurs, which may results in pulmonary
      hyperperfusion and systemic hypoperfusion. As consequence of splanchnic hypoperfusion ensuing
      from left-to-right PDA shunting, a possible association between hemodynamically significant
      PDA and adverse gastrointestinal outcomes has been reported.

      An impaired blood flow velocity in superior mesenteric artery, evaluated by Doppler
      ultrasound, has been previously reported before and after feeds in infants with large PDA,
      whereas evidence on PDA effect on splanchnic tissue oxygenation, measured by Near Infrared
      Spectroscopy, is scarce and controversial.

      This study aims to evaluate whether splanchnic oxygenation patterns in response to enteral
      feeding introduction in preterm infants may be affected by PDA status.
    

Detailed description: 
      Patent ductus arteriosus (PDA) is a common condition among preterm infants. In the presence
      of a large PDA, significant systemic to pulmonary shunting occurs, possibly resulting in
      pulmonary blood flow overload and systemic hypoperfusion. A possible association with
      hemodynamically significant PDA and the occurrence of adverse gastrointestinal outcomes has
      been reported as a possible consequence of mesenteric hypoperfusion ensuing from
      left-to-right shunt through the PDA.

      Previous attempts to assess by Doppler ultrasound the effect of PDA on blood flow velocity in
      superior mesenteric artery (SMA BFV) showed a decreased SMA BFV before and after feedings and
      attenuated postprandial increases in infants with large PDA. Near-infrared spectroscopy
      (NIRS) provides a non-invasive measurement of regional tissue oxygen saturation and has been
      previously applied in neonatal settings for the monitoring of cerebral (CrSO2) or splanchnic
      (SrSO2) oxygen saturation. Current evidence on the effect of PDA on SrSO2 is scarce and
      controversial; moreover, a possible effect of PDA on SrSO2 patterns in response to enteral
      feeding introduction has not been evaluated yet.

      This study aims to evaluate whether SrSO2 patterns in response to enteral feeding
      introduction in preterm infants may be affected by the ductal status. The development of
      intestinal complications in relation to PDA are also evaluated.

      Preterm infants <32 weeks admitted to the Neonatal Intensive Care Unit (NICU) are
      consecutively enrolled in the study if younger than 3 days and if no enteral feeding has been
      administered prior to the enrollment.

      Written, informed consent to participate in the study is obtained from the parents/legal
      guardians of each infant before introducing enteral feeding.

      At the time of enteral feeding introduction, the enrolled infants undergo a continuous
      monitoring of CrSO2 and SrSO2 by means of INVOS 5100 oximeter. NIRS recording is performed
      from 30 minutes before to 3 hours after feeding administration. CrSO2 and SrSO2 are recorded
      every 5 seconds. Values recorded before, during and after feeding administration are
      clustered into 5-minute intervals and considered for statistical analysis.
      Splanchnic-cerebral oxygen ratio (SCOR), which derives by the ratio between SrSO2 and CrSO2
      and has been previously proposed as a valid marker for gut hypoxia-ischemia, is also
      calculated.

      As per normal routine, an echocardiographic evaluation is performed before enteral feeding
      introduction, in order to evaluate hemodynamics and PDA status of the infant. In relation to
      the PDA status, enrolled infants are divided into the following groups: PDA
      (echocardiographic evidence of patent ductus arteriosus at the time of first feed) and noPDA
      (echocardiographic evidence of closed ductus arterious at the time of first feed).

      Neonatal characteristics, including gestational age, birth weight, antenatal Doppler status,
      and echocardiographic PDA characteristics at the introduction of enteral feeding and the
      occurrence of intestinal complications during hospital stay, defined as the development of
      feeding intolerance (enteral feeding withholding for at least 24 hours because of
      gastrointestinal symptoms), necrotizing enterocolitis and spontaneous intestinal perforation,
      are recorded in a specific case report form.

      SrSO2, CrSO2 and SCOR patterns in response to first feed are evaluated and compared between
      PDA and noPDA infants and adjusted for possible influencing clinical variables using a
      multivariate model. Moreover, the rate of intestinal complications is compared between the
      two study groups by chi-square test. Data are analyzed using IBM SPSS Statistic version 25
      (IBM Corporation, IBM Corporation Armonk, New York, United States).
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Preterm infants admitted to the Neonatal Intensive Care Unit of St. Orsola-Malpighi
        Hospital
      
Keywords: Near Infrared Spectroscopy; preterm infants; intestinal complications