Evidence Outcome Summary
Synthesis Topic/PICO Question: In hospitalized patients with feeding tubes (nasogastric/orogastric) with initial x-ray verification of placement, does ongoing placement verification prior to feeding/medication administration using pH testing of gastric aspirate as compared to current practice (audible air injection, distal tube length) impact the occurrence of adverse outcomes/events (e.g. delay in feeding/med admin, aspiration, etc.)
Sources of Evidence
LOE:
Quality:
One sentence summary of what the study is
about
Population:
Setting:
List the findings in bullet format
Reason(s) you wouldn’t use this evidence
Author’s conclusions and the bottom line
result(s)?
Do the results answer your question?
(Use of pH as on-going confirmation
method?)
Additional comments
1. Perry, A., Kaiser, J., Krueger, K.,
and the 2022 ENA CPG Committee (2023). Gastric Tube Placement Verification
[Clinical practice guideline]. Emergency Nurses Association.
LOE:
Level II
Quality:
High
ENA CPG, updated from its 2014, 2017 and 2019 version
Lit search 2016-2226, total of 5980 items found, full
review 211, 25 included in evidence analysis, 9 as background information
-The
use of auscultation is no longer recommended nor reliable
-Reliability
of the use of PH ranges from 84%-97%
_Adding
lipase increases sensitivity to 97.2% with 100% specificity (no bedside test for lipase currently available)
-**PPIs
may reduce ability for PH confirmation
-In
pts over 4 weeks old, PH less than 5 is acceptable, if 5 or greater, XRay is
required
n/a
-XRAY remains the gold standard-
-PH testing when part of a mixed-method confirmation i.e.
auscultation, tube marking, PH etc is an acceptable means to confirm NGT/OGT
-Ph less than 5
appears to be a reasonable cut off
yes
Confirmation accuracy is greater when aspirate and
non-aspirate methods used, recommend auscultate, aspirate for pH with visual
inspection
There is moderate evidence to support the use of PH testing
as a component of a multiple-method bedside verification
2.
Northington, et
al (2022)
LOE: V
Quality: Weak
Survey completed by 205 nurses in 166 institutions
(pediatric) to determine how NG/OG placement is verified: 42% use pH, 24% use Xray
Reporting a combination of
radiograph and pH measurement, 88% of pediatric
nurses selected evidence-based methods for NGT placement verification
placement.
Weak-survey
While progress has
been made toward using the EBP methods of pH measurement and/or abdominal
x-ray to verify NGT placement, further education is needed to establish this
as a standard of care among nursing organizations
no
An EBP standard of care needs to be established
3. Lin (2020)
LOE:
Level V (Systematic Review & Meta-Analysis of observational studies)
Quality:
Moderate
To evaluate diagnostic performance of methods used to
assess gastric tube placement verification in neonates, infants and children.
– 8 studies, 911 participants, evaluated 9 index tests
– pH testing with cutoff values ≤6 for gastric tube
position confirmation was the only index test subjected to meta-analysis,
with the summary sensitivity and specificity being 0.77 (95% confidence
interval [CI] 0.56–0.90) and 0.42 (95% CI 0.16–0.73).
–
Other methods (color of aspirate, auscultation, carbon dioxide testing,
ultrasound, bilirubin, pepsin, trypsin, separately or in combination with the
above methods) showed great variations in sensitivities and specificities.
– 6 out of 8 studies used for meta-analysis showed a high
degree of heterogeneity for diagnostic estimates.
– Revealed a moderate summary sensitivity and a low summary
specificity for pH cutoffs ≤6. This finding suggests that pH ≤ 6 may not be
sufficiently accurate to detect the gastric tube position, which does not
support recommendations from multiple guidelines.
– The conclusion of the inability of pH ≤ 6 for detection
of gastric tube position in the studied population can only be drawn with
caution because of the heterogeneity of studies.
– Paucity of data and methodological variations in studies
make it difficult to arrive at any conclusions regarding the diagnostic test
accuracy of pH ≤ 4 or 5 and other index tests in detection of gastric tube
placement.
– Well-designed studies to strengthen current evidence are
recommended.
Yes/no-paucity of data
The studies included in the meta-analysis had heterogeneity
(3 different cutoff values, 2 types of instruments of pH meter and pH paper,
different populations of fasting and fed) so the conclusion needs to be
considered with caution (p. 658).
pH testing with cutoff values ≤6 for gastric tube position
confirmation was the only index test subjected to meta-analysis, with the
summary sensitivity and specificity being 0.77 (95% confidence interval [CI]
0.56–0.90) and 0.42 (95% CI 0.16–0.73).
4. Metheny (2019)
LOE:
Level V
Quality:
High
This is a review of worldwide guidelines for placement
verification of NG tubes.
-All
indicate radiographic confirmation as the gold-standard verification of
initial placement.
-11
guidelines discuss pH as an adjunct method of placement verification; 9
guidelines discuss specific safe cutoff values; 4 discuss pH ranges between 1
and 4 as safe
-Wide geographical variety of guidelines advocating for
significantly varied methods of confirming placement.
-Unable to confirm primary data of each contributing
guideline author
-Radiographic confirmation of initial placement cannot be
replaced by other available methods
-pH safe cutoff not established firmly, wide disagreement
among guidelines.
yes
Helpful as an investigational look into global
best-practice
: pH is vetted as a method and ranked highly in terms of
safety; does not advise against radiologic confirmation as default.
5.
Dias et al.,
2019
LOE:
IV
Quality: High
Cross-sectional,
double-blinded diagnostic test study. Sample: n = 162 neonates, average age
32.92 gestational weeks.
-No
relationship between pH values with age or diet. -Aspirate: No relationship
between aspirate color and placement -Use of gastric secretion inhibitor
drug: pH was higher (>5.5), but only in small sample
-Radiographic
placement verification: 98.77% correct placement. -Comparison of pH test and
radiographs: 96.25% sensitivity.
-Accuracy
of pH test with cutoff of 5.5 showed high sensitivity compared to x-ray
verification.
Population
Accuracy of pH test with cutoff of 5.5 showed high
sensitivity compared to x-ray verification.
yes
Neonates
6. Irving (2018)
LOE:
Level V
Quality:
High
Presents
the challenges of bedside NG-EAD (Nasogastric-enteral access device)
placement and ongoing location verification.
Review the current state of the science for verification of
bedside placement of nasogastric tubes and ongoing assessment of tube
location in children.
Abdominal
radiograph is the gold standard.
In lieu of
or when abdominal x-ray is not available, accurate measurement of enteral
tube insertion length, gastric pH testing, and visual observation of gastric
aspirate are acceptable non radiologic methods for assessing tube placement.
Specificies children who are high risk (neonates, children
with neurological impairment, children in an obtuded state, children who are
encephalopathic, have a decreased gag reflex, or are sedated or critically
ill) recommends an x-ray.
Auscultation
as a means of verifying NG-EAD placement is discouraged in the literature and
is no longer supported by clinical practice organizations.
Yes,
speaks to our current practice.
Despite the accuracy of pH and enzyme testing, if NG-EAD
placement or location is uncertain, an abdominal radiograph is warranted, as
it is accepted as the confirmatory method to verify NGEAD placement.
X-Ray is goldstandard
pH is reliable method of verifying NG-EAD location in
children
radiograph recommended to confirm
location when no aspirate is obtained
Yes (children)
Ph and noting distal tube length are acceptable for
placement verification
7. Boullata (2017)
LOE:
Level V
Quality:
High
Aspen Guidelines
Do not rely on the auscultatory method alone to
differentiate between gastric and respiratory placement or between gastric
and small bowel placement.”; “Healthcare
professionals cannot rely on auscultatory methods to differentiate
between gastric and bronchopulmonary tube placement because auscultatory
methods cannot distinguish tubes improperly placed in the lung or coiled in
the esophagus from properly positioned tubes.”
Mark the
exit site of
a feeding tube
at the time
of the initial placement and
document either the incremental marking on the tube or the external length of
the tube in the medical record.” [does not give frequency]
Gastric fluid typically is clear and colorless or grassy
green or brown with a pH of 5 or less.
Several studies demonstrating the use of pH testing indicate a pH
of ≤5.5 from tube aspirate is adequate
to check the position of the tube in the stomach.”
Although observing for respiratory symptoms is warranted
during EAD insertion, malpositioning may occur without any apparent symptoms.
8. Ni (2017)
LOE:
Level IV
Quality:
Moderate
Using a decision analytical modelling approach to compare
the relative safety of different methods used to verify the placement of NG
tubes in the stomach.
Population: 104 cases with documented feeding tube
misplacement. Total of 2368 adverse event reports submitted to NRLS (National
Reporting and Learning System)
Setting: UK
-UK already follows safety guideline that uses pH testing
of NG tube aspirate as a method of initial placement verification followed by
chest xrays but US does NOT
-cost analysis not done
-only focused on patients with successful aspirations
-analysis assumed chest xrays were 100% accurate
-excluded pediatric cases
-before
use of tube, using pH test cut-off of 5 is the safest way to verify enteral
tube location
Yes-adults
Uses pH as method of initial verification.
Yes,
could provide guidance for using pH as a method of ongoing verification.
9. Clifford (2015)
LOE:
Level V (integrative review)
Quality:
Moderate
Integrative review and synthesis of literature on the most
accurate methods of enteral tube placement and placement verification along
with recommendations for practice.
Lit Search bet May-August 2014 (CINAHL, MEDLINE, PubMEd:
studies published Jan 2009-June 2014 in English only, limited to 0-18 year
old patients).
56 pediatric & adult articles
7 national guidelines dating from 1993-2014
-only xray gold standard verification method
PH:
-AACN recommends PH 5 or less for ongoing placement
verification
-feeding/meds can alter gastric pH, but evidence suggests
there was no major difference in pH with patients on acid-blocking meds (p.
157)
Gastric aspirate appearance:
-most helpful to determine stomach vs intestine placement,
but use with other methods
Tube marking:
-marking does not confirm that tube has not moved/coiled so
only use in conjunction with other methods
Auscultation:
-proven unreliable, suggest use of this method be
discontinued
Limitations:
-lack of neonatal evidence
-mostly low levels of evidence
-outdated evidence (dating from 1993-2014)
-UK sources of data included, but they have different
practices (e.g. UK uses pH as first-line verification, xray as second-line)
-place enteral tube via NEMU method
-xray is gold standard but not practical for verification
prior to each use of tube
-no other verification method on its own is as accurate as
xray
-consider using combo of 2 or more methods of verification
-use analysis of gastric aspirate color and pH along with
assessment of tube marking to confirm there has been no migration
-algorithm
may help as decision making tool with follow up quality improvement studies
and data collection
10. Boeykens (2014)
LOE:
Level IV
Quality:
High
Prospective observational study to determine the
reliability of pH measurement compared to auscultatory method (N 241)
-98.9%
accuracy compared to x-ray with pH ≤ 5
-auscultation
method elicited 94.2-72.1% accuracy
-A pH
of ≤ 5.5 aspirate reading is adequate to check the tube placement
-Auscultatory
method is unreliable
A point of care testing for pH testing is cumbersome due to
many regulatory requirements.
However, with a new testing technology available this
method could be used at bedside by clinical nurses
pH
testing is the 2nd best method compared to the gold standard of x-ray method
for tube verification.
Rather
than using the auscultation method, bedside verification of feeding tube
should be based on pH testing along with the tube length during insertion
Using
a cut off of ≤5.5 for gastric pH was reliable indicator of stomach placement
even if patient was on antacids. Auscultation-only method is not as reliable
as gastric pH testing or x-ray
**
There
is insufficient evidence supporting the use of auscultation to confirm accurate
gastric tube placement in the emergency department
With
the possibility of RightSpot technology/products availability, pH testing
should be adopted as a safe practice for feeding tube bedside confirmation
11.
Ellett et al.,
2014
LOE: II
Quality: High
Prospective comparative design, secondary analysis. Data
originally from single blind randomized controlled trial. Sample: N = 276
children, 24 weeks to 212 months of age requiring .nasogastric/orogastric
tube placemen
-pH meter vs paper had ICC
agreement 0.76.
-pH as a tool to verify GT
placement in the stomach has specificity of 87-92.2% but cannot identify
placement errors (esophagus or gastroesophageal junction).
– Optimal method to determine
correct tube placement in the stomach: lack of aspirate from tube
(sensitivity 34.9%, PPV 66.7).
-Aspirate alone led to multiple
misidentified placement locations.
Aspirate alone led to multiple misidentified placement
locations
12. Stock et al., 2008
LOE:
6
Quality:
Weak
Design: prospective, observational study Sample: n=404
children
-No difference in pH for
gastroenteritis vs. non-gastroenteritis
. -Tube placement confirmed by pH
alone in > 84%. pH higher than 4 was associated with incorrect placement;
however, all pts. did not receive radiograph for confirmation
pH testing only useful if aspirate can be obtained
Children, single ED
13.
Northwell
System policy (adult/peds) June 2023
An X-ray verification is required
to confirm placement prior to initiations of feedings/medication
administration.
For non-high risk pediatric
patients, pH testing may be used to confirm placement
-Ng/Og bedside confirmation prior
to Xray may consist of pH with a value between 1-5.5
14.
Northwell
Nursing Clinical Competency, “Nasogastric Tube Maintenance” 12/19
Attaches a syringe with 10-20 mL of air to the end of the tub.
– Injects air while auscultating the abdomen with a stethoscope.
– Listens for “whooshing” sound
– Aspirates stomach contents and notes amount, color,
consistency, and odor
– If unsure of placement obtains order for x-ray to confirm
placement.
Does not match with policy or standards of practice
