Far from reliable: pH testing in the neonatal intensive care unit

Ongoing pH testing to confirm nasogastric tube position before feeding to reduce the risk of adverse outcomes in adult and paediatric patients: A systematic literature review

BACKGROUND & AIMS

There is no agreed gold standard method to confirm nasogastric tube position before every use. However, many global guidelines recommend testing the pH of gastric aspirates obtained from an NGT before each use. This study aims to determine whether ongoing pH testing has been shown to reduce adverse events. Secondary aims are to determine how frequently aspirates can be obtained, and how often pH correctly confirms ongoing NGT tip position.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed and protocol was published on PROSPERO. Keywords were used to search PubMed, Embase, CENTRAL, CINAHL and MEDLINE. Article assessment for inclusion was completed by two independent authors and risk of bias was assessed using ROBINS-I.

RESULTS

The systematic search and review methodology was followed due to wide variety and high risk of bias in the included studies. One full study and five abstracts met inclusion criteria for the primary aim. The full article contained one instance where pH testing and external NGT length together identified a misplaced NGT. The abstracts identified missed or delayed feeds and medications, and frequent unnecessary X-rays, as negative outcomes of ongoing pH testing. Ten full studies and one conference abstract addressed the secondary aims, but the studies varied widely which prevented meta-analysis and made it difficult to draw conclusions.

CONCLUSIONS

This review confirmed that ongoing pH testing is based on expert opinion due to limited evidence. More primary research is required to determine the clinical impact of ongoing pH testing to confirm NGT position.

Acidity of Enteral Feeding Tube Aspirate in Neonates: Do pH Values Meet the Cutoff for Predicting Gastric Placement?

BACKGROUND

Enteral feeding tubes (EFTs) are commonly used in neonatal practice, but complications from tube misplacement remain a concern. Measuring the pH of EFT aspirate is a recommended method to evaluate EFT placement. A pH value of ≤5.5 is considered predictive of gastric placement. Using this method in infants has been questioned. It is unclear whether infants can produce adequate gastric acid to achieve a pH 5 or less and whether feedings and medications influence pH.

PURPOSE

To report EFT aspirate pH values in infants and to evaluate factors potentially influencing pH values.

METHODS

A retrospective descriptive study was conducted with 1024 infants with 6979 pH values. Demographic and clinical data were collected including type of EFT, pH of gastric aspirate, feeding method, time of last feeding, and administration of acid suppression medications. The frequency of measured pH values of 5 or less was calculated for each covariate.

FINDINGS/RESULTS

The majority (97.51%) of pH values were 5 or less. Orogastric tubes, continuous feeding, a 4-hour or more feeding interval, exposure to medications (proton pump inhibitor, histamine-2 receptor antagonist, or multiple medications) were associated with an increased likelihood of pH values of more than 5. However, with each study variable the majority of pH values were 5 or less.

IMPLICATIONS FOR PRACTICE

These findings suggest EFT pH, a recommended method to evaluate the likelihood of gastric placement, can be successfully used in the neonatal population.

IMPLICATIONS FOR RESEARCH

Future research should prospectively evaluate EFT pH in infants when compared with clinically indicated radiographs. Other factors that might influence pH should be explored including severity of illness, feeding type, and other medications.

The pH of Feeding Tube Aspirates From Critically Ill Infants

BACKGROUND

The extent to which gastric acid inhibitors and feedings affect gastric pH in infants is unclear.

OBJECTIVES

To compare pH values of gastric aspirates from infants according to use or no use of gastric acid inhibitors and feedings.

METHODS

Colorimetric pH tests were used to measure the pH of aspirates from feeding tubes in 54 critically ill infants; 29 of the gastric aspirates were from infants who did not receive acid inhibitors or feedings, 13 were from infants who received acid inhibitors but no feedings, 3 were from infants who received feedings but no acid inhibitors, and 5 were from infants who received both acid inhibitors and feedings. The remaining 4 feeding tubes were in nongastric sites.

RESULTS

Individual pH readings of 5.5 or less were found in 97% of the gastric aspirates from infants with no recent feedings or acid inhibitors, 77% of the gastric aspirates from infants who received acid inhibitors, and 67% of the gastric aspirates from infants with recent feedings. Among 2 esophageal aspirates and 2 duodenal aspirates, 1 of each type had a pH less than 5.5. A pH cut point of 5.5 or less did not rule out esophageal or duodenal placement.

CONCLUSIONS

The pH of gastric aspirates from critically ill infants is often 5.5 or less, regardless of the use of acid inhibitors, feedings, or both. Most likely a cut point of 5.5 or less would rule out respiratory placement because tracheal pH is typically 6.0 or higher.

Use of Temporary Enteral Access Devices in Hospitalized Neonatal and Pediatric Patients in the United States

BACKGROUND

Temporary enteral access devices (EADs), such as nasogastric (NG), orogastric (OG), and postpyloric (PP), are used in pediatric and neonatal patients to administer nutrition, fluids, and medications. While the use of these temporary EADs is common in pediatric care, it is not known how often these devices are used, what inpatient locations have the highest usage, what size tube is used for a given weight or age of patient, and how placement is verified per hospital policy.

MATERIALS AND METHODS

This was a multicenter 1-day prevalence study. Participating hospitals counted the number of NG, OG, and PP tubes present in their pediatric and neonatal inpatient population. Additional data collected included age, weight and location of the patient, type of hospital, census for that day, and the method(s) used to verify initial tube placement.

RESULTS

Of the 63 participating hospitals, there was an overall prevalence of 1991 temporary EADs in a total pediatric and neonatal inpatient census of 8333 children (24% prevalence). There were 1316 NG (66%), 414 were OG (21%), and 261 PP (17%) EADs. The neonatal intensive care unit (NICU) had the highest prevalence (61%), followed by a medical/surgical unit (21%) and pediatric intensive care unit (18%). Verification of EAD placement was reported to be aspiration from the tube (n = 21), auscultation (n = 18), measurement (n = 8), pH (n = 10), and X-ray (n = 6).

CONCLUSION

The use of temporary EADs is common in pediatric care. There is wide variation in how placement of these tubes is verified.