Gastric Lipase Enhanced Nasogastric Tube Study in Neonates
Condition: Neonatal Disorder
MeSH terms: Infant, Newborn, Diseases
Study type: Observational

Summary: 
      The newborn infants who are sick and those who are born prior to due date (preterm) are
      admitted to the neonatal unit. These babies are unable to feed through their mouth, so a
      special tube is passed through their nose to the stomach, nasogastric (NG) tube) to provide
      milk feeds. The bedside nurse inserts the tube and then aspirate some of the fluid from the
      stomach. As the stomach normally produce acid, these aspirate is then tested on a colour
      coded paper strip to check if the fluid is acidic. However, on many occasions this test is
      not very clear. This could be due to misplacement of the tube or the stomach in a newborn not
      being able to produce enough acid. This then leads to re-siting of another tube and following
      the same procedure. Sometimes the clinical team may like to do an X Ray to check the position
      of the tube resulting in unnecessary exposure to radiation. The study will use a special
      chemical added to the currently existing paper test strip which the investigators believe
      will enhance the capability of detecting the correct position of the NG tube. This idea has
      been tested in adults and found to have increased the sensitivity of the test strip
      significantly. Based on the adult study the study will require to test 233 babies to see if
      this increases the sensitivity of correct NG tube placement. Parents of all babies who
      requires an NG tube for milk feeds will be approached and after appropriate consent could be
      recruited to the study. Babies who are clinically very unstable, moribund and those with
      diagnosis of bowel obstruction will be excluded from the study.
    

Detailed description: 
      STUDY OBJECTIVES

      Primary Objective:

      • To determine the sensitivity of the chemical (tributyrin) impregnated pH test strip in
      comparison to the routine pH test strip to increase the sensitivity of detection of correct
      positioning of the nasogastric tube

      Secondary objectives:

        -  To measure the number of nasogastric tube re-insertion attempts that could be avoided if
           the tributyrin impregnated pH test strip was used instead of the standard pH test strip

        -  To determine the number of chest radiographs which could be avoided if the tributyrin
           impregnated pH test strip was used instead of the standard pH test strip

        -  To carry out human factors assessment of perceived usability, trust and acceptance of
           the lipase-based pH test strip

      STUDY DESIGN Prospective point of care diagnostic accuracy study

      Primary outcome

      • Sensitivity of proposed test in determining correct nasogastric (NG) tube position

      Secondary outcomes

        -  Number of chest x rays performed

        -  Time to confirm tube placement

        -  Number of nasogastric tube attempts to get the correct pH

        -  Assessment of human factors - Perceived usability, trust and acceptance from
           professionals' perspective

      Subject selection and setting

      Participants will be recruited from Imperial College Healthcare NHS Trust from the neonatal
      units at both the Queen Charlotte's and Chelsea and St. Mary's hospital sites. Eligible
      participants will be identified by the clinical team and recruited by a member of the
      research team.

      The vast majority of admitted infants will require nasogastric tube insertion as part of
      their clinical management such as preterm infants, sick term infants with hypoxic- ischaemic
      encephalopathy and meconium aspiration syndrome as well as admitted infants for hypoglycaemia
      and jaundice management.

      Study method

      The clinical trial will be a diagnostic accuracy study of two diagnostic tests and will be
      reported in accordance with the Standards for reporting diagnostic accuracy studies (STARD)
      guidelines. The index tests will be (i) the novel tributyrin impregnated pH test strip and
      (ii) standard pH test strip. The reference test used for comparison will be chest x-ray
      performed earlier or later but with the same nasogastric tube in situ; or where this is not
      required 'trial by use' (any chest x-rays undertaken would be decided and authorised by the
      participant's clinical team who are clearly separated from the research team. Undergoing a
      chest x-ray does not from part of screening for the study and is not a requirement of the
      study protocol).

      Ingenza novel lipase/pH test strip

      The test detects the organic acid released from tributyrin, a chemical ester impregnated onto
      pH paper by the action of human gastric lipase that is stable in gastric juice and resistant
      towards antacid medications, as well as unlikely to migrate. Ingenza have impregnated enteral
      pH indicator strips that are in current clinical use with emulsion formulations of
      tributyrin, protected by intellectual property as human gastric lipase substrates. Therefore,
      the novel test strips will provide a positive result in the presence of an acidic environment
      (pH less than or equal to 5.5) or gastric lipase.

      Index testing

      After the tube insertion, the carer will aspirate the tube to obtain a sample of gastric
      fluid. This will be done immediately following insertion or as part of daily position
      confirmation that is routinely performed prior to initiation of nasogastric feeding. The
      aspirate will be used by the healthcare professional, as part of routine care and the
      remaining sample passed to a member of the research team. The healthcare professional will
      test the aspirate routinely and make their decision based on the current standard pH strip
      test. The remaining sample will be used by the research nurse blinded to the standard test,
      to wet the gastric lipase enhanced pH test strip. The research nurse will then independently
      assess the results of the study test paper at two minutes. Digital photographs of both the
      routine and the study test papers will be assessed independently by member of the study team
      to verify the findings. The healthcare professional will be blinded to the results of the
      proposed test strip. The research nurse will record the results of the standard test strip
      only after documenting the result of the proposed test.

      For standard pH strips a pH of ≤5.5 will indicate correct tube placement and >5.5 indicates
      incorrect nasogastric tube position. For the gastric lipase enhanced pH strip test a positive
      result will be determined according to the manufacturer's recommendations.

      INCLUSION CRITERIA

      All infants (preterm and term) who require the insertion of nasogastric tubes for
      supplementary enteral feeding as part of their routine clinical management

      EXCLUSION CRITERIA

      Clinically unstable, critically ill infants Infants undergoing palliative care Infants with
      bowel conditions such as necrotising enterocolitis, bowel obstruction
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All infants admitted to the neonatal unit requiring insertion of nasogastric tube
      
Keywords: nasogastric tube; gastric lipase