Critical Appraisal of a Research Study: NG Tube Placement Methods

This report offers a critical appraisal of a research study conducted by Boeykens, Steeman, and Duysburgh (2014), which investigated the reliability of the auscultatory method and pH measurement for nasogastric tube (NG tube) placement. The study employed a prospective observational cohort study design, placing it within the second step of the hierarchy of evidence. The appraisal assesses the study's methodology, including the efforts to minimize bias through the use of an experienced nurse for observations. The study's objectives, including the comparison of pH measurement and auscultation against radiological verification, are examined, along with the limitations of the pH method due to potential interference from antacids. The report outlines the steps of a prospective cohort study and evaluates how the Boeykens et al. study adhered to these steps, including patient identification, baseline data collection, and data analysis. The report also discusses the statistical methods used, such as descriptive statistics, chi-square tests, and Mann-Whitney U tests. Adverse events during the study and comparisons with previous research on pH cut-off points for NG tube placement are also included. The report concludes by emphasizing the clinical relevance of the study in enhancing patient safety and quality of care.

Running head: CRITICAL APPRAISAL
Critical Appraisal
Name of the Student
Name of the University
Author Note

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In the study of Boeykens, Steeman and Duysburgh (2014), a cohort study method
was used to identify the position of nasogastric tube by using the auscultatory method and pH
measuring method. In this study prospective observational study method was used that is one
type of cohort study. A prospective cohort study is one type of longitudinal cohort study
method in which data is collected from a group of individual within a specific time period.
After collecting the data, it is analysed that how factors are affecting a particular cohort in
that specified time period ( Yang & Land, 2016).
In the hierarchy of evidence, there are 6 steps of hierarchical pyramid and they are
mainly case-control studies, cohort studies, randomized control study ( RCT), critically
appraised individual articles ( article synopsis), critically appraised topics ( evidence
synthesis and guidelines) and on the top of this hierarchical pyramid systematic review is
located ( Murad et al., 2016). In this study by Boeykens, Steeman and Duysburgh (2014), it
is observed that, prospective observational study was used and it is a type of cohort study.
So, it can be said that, this research is in the second step of hierarchical pyramid of the
hierarchy of evidence in research. This large sample size of this study also enhanced the
reliability of this study by reducing the statistical errors of the overall study. While assessing
the risk of bias of this study by Boeykens, Steeman and Duysburgh (2014), it was observed
that, the authors tried reduce the issue of bias as much as possible. As a part of this, all the
observations of pH method, auscultation method and placement of NG tubes were supervised
by the same practice nurse who had immense experience in such works. The authors assumed
that appointment of same nurse might reduce the chances of pH measurement error during the
study procedure.
The study mainly focused to find the reliability of the pH measurement technique
(with a cut-off point of 5.5, with or without antacids). In addition to this, the study also
focused on the auscultatory method against the radiological verification technique. On the

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other hand the secondary objective of this study is to assess the practicability or feasibility of
this in comparison with the pH measurement technique (Boeykens, Steeman & Duysburgh,
2014). The study of Yıldırım et al. (2018), also reported that, the auscultation method is one
of the common technique of checking appropriate placement of NG tubes among the patients.
This study also investigated the effectiveness of auscultation techniques among the patients
with NG tubes. The previous method was not appropriate as the presence of antacid
medication can enhance the gastric pH and this pH enhancement is also observable in the
respiratory placement ( Sun et al., 2015). So it is difficult to locate the position of NG tubes
by using only the pH measurement technique. In addition to this, when the NG tube is placed
in the stomach it is not possible to detect the exact location of the NG tubes as this technique
cannot detect that whether the tube is located near the fundus or near the cardiac sphincter
and this may associated with the complications related to the feeding. Moreover, the low cut-
off level of pH positioning is marked as poor technique as it has very poor level of sensitivity.
In a prospective cohort study, there is five steps and they are identifying the cohort
population or study subjects, obtaining the baseline data on the exposure that is measuring the
exposure level at the initiation of the study, selecting sub-classification of the cohort study,
measuring the outcomes by using previous record and the final step is analysing the data
collected from the overall study. In this study by Boeykens, Steeman and Duysburgh (2014),
it was observed that, the first step that is identifying the study population was maintained in a
proper way as the authors conducted the study at the AZ Nikolaas Hospital in Sint-Niklaas
(Belgium) in between 2009 to 2012. Almost 331 NG tubes were placed in 314 patients who
were admitted in the hospital without any other medical complications. In addition to this all
the baseline data of the patients were collected and even the information regarding intaking of
proton pump inhibitors were also collected as baseline data of the patients. The next step of
the cohort study was not also followed in an accurate manner. Hence there was no

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differentiation of the control and intervention group in this study. So it can be said that, the
third step that is sub-classification of the cohort group is not maintained in this study. The
next step of the cohort study was also well maintained in this study as the all the data
regarding the outcomes of the intervention can are collected in a proper way. The next step
of the cohort study that is the statistical analysis and this step was also maintained in an
accurate manner. After collecting all the data from the cohort subject population, a
descriptive data analysis technique was used to analyse all the data.
In this study, almost 314 patients admitted in the AZ Nikolaas Hospital in Sint-
Niklaas (Belgium) in between 2009 to 2012 were used as sample population for conducting
this research study.
In this research study, it was observed that, the continuous and discontinuous
variables were measured as major variables. The position of the NG tubes were marked as
discontinuous variables and on the other hand the pH range was marked as continuous
variables. Hence, it can be said that, measuring of both the variables were appropriate. In
addition, in order to reduce the bias, all the pH readings were collected by a specific expert
nurse. So it can be said that, the researchers measured all the major variables in a reliable and
valid way. For measuring the location of the NG tubes, X-ray method was used and on the
other hand for measuring the pH, Merck1 pH indicator strip/pH (2.0–9.0,) was used and it is
counted as one of the most effective pH measuring method (Boeykens, Steeman &
Duysburgh , 2014).
After collecting the data, a descriptive statistics technique was used to express the
standard deviation (SD), means, frequencies, percentages. In addition to this, for measuring
the discontinuous variables, the chi-square test was used. On other hand, for assessing the
continuous variable of the study, the Mann–Whitney U test was used ( Cox, 2018). The P

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value of < 0.05 was fixed as significance level for this study. In order to analyse the data, the
statistical program named SPSS version 21 was used in this study (Boeykens, Steeman and
Duysburgh, 2014).
In the study procedure, there was two adverse events. Firstly, the in a patient
misplacement in the lungs was reported and that resulted in an inconclusive auscultation in
that case study. After this, error no symptoms of respiratory distress was reported by the
patients and after x-ray visualization this fact was identified. On the other hand, the NG tube
was placed in comatose patients. The assistant nurse demanded that the NG tube was in the
right place, but the advanced practice nurse was in dilemma. Then, it was observed that, the
NG tube was placed in the patient throat in a curled condition by using the x-ray visualization
technique (Boeykens, Steeman and Duysburgh, 2014).
In previous studies, researchers used pH cut-off point in order to determine the
accuracy of the NG tube placement. In a few previous studies the differentiation of intestinal
placement and gastric placement was investigated. On the other hand a few studies
concentrated on the fact whether the NG tube was placed inside or outside of the stomach.
Among all of the study, a few studies used a low cut-off Ph ( less than 4) for localization of
the tips NG tubes and by using this process only 56% of the NG tubes were determined
correctly. In such type of Ph sensitivity tests, the percentage of misplaced tubes was 82%
with a 55% specificity. On the other hand, in another study, a high Ph cut-off technique was
used. In such cases, the sensitivity was 49% along with 74% specificity. In a study using high
cut-off Ph points, the accuracy level was 90.4%. In this study, a pH cut off value of < 5.5 was
used to determine the successful placement of NG tubes in the stomach of the patients
(Boeykens, Steeman and Duysburgh, 2014). The use of this range of Ph is very much safe in
excluding the lung placement. So it can be said that this study result fitted very much in the
previous research area.

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This research is very much useful in the clinical practice as increasing the NG tube
placement accuracy will enhance the patient safety and quality of care to the patient.
Simultaneously a good quality of care to the patient also helps to reduce the hospital stay of
the patient, treatment cost of the patients in the hospitals (Zimmermann et al., 2015).

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References
Boeykens, K., Steeman, E., & Duysburgh, I. (2014). Reliability of pH measurement and the
auscultatory method to confirm the position of a nasogastric tube. International journal of
nursing studies, 51(11), 1427-1433.
Cox, D. R. (2018). Analysis of binary data. Routledge.
Murad, M. H., Asi, N., Alsawas, M., & Alahdab, F. (2016). New evidence pyramid. BMJ
Evidence-Based Medicine, 21(4), 125-127.
Sun, Z., Foong, S., Maréchal, L., Tan, U. X., Teo, T. H., & Shabbir, A. (2015). A non-
invasive real-time localization system for enhanced efficacy in nasogastric
intubation. Annals of biomedical engineering, 43(12), 2941-2952.
Yang, Y., & Land, K. C. (2016). Age-period-cohort analysis: New models, methods, and
empirical applications. Chapman and Hall/CRC.
Yıldırım, Ç., Coşkun, S., Gökhan, Ş., Pamukçu Günaydın, G., Özhasenekler, A., & Özkula,
U. (2018). Verifying the Placement of Nasogastric Tubes at an Emergency Center:
Comparison of Ultrasound with Chest Radiograph. Emergency medicine
international, 2018.
Zimmermann, K., Holzinger, I. B., Ganassi, L., Esslinger, P., Pilgrim, S., Allen, M., ... &
Stocker, M. (2015). Inter-professional in-situ simulated team and resuscitation training for
patient safety: Description and impact of a programmatic approach. BMC medical
education, 15(1), 189.

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