Original article
Feeding tube placement: auscultatory
method and x-ray agreement
Sondagem enteral: concordância entre teste de ausculta e
raio-x na determinação do posicionamento da sonda
Revista Gaúcha
de Enfermagem
Posicionamiento de la sonda enteral: concordancia entre el teste de ausculta y rayo-x
Mariur Gomes Beghettoa
Franciele Anzilierob
Dória Migotto Leãesc
Elza Daniel de Mellod
ABSTRACT
Objective: to evaluate the correlation between the auscultation test and X-ray when detecting the position of an enteral feeding
tube.
Methods: cross-sectional study in an intensive care unit in southern Brazil, in 2011. Clinical nurse and nurse researcher performed
auscultation test recording the impressions regarding the placement of an enteral feeding tube in 80 patients. A doctor evaluated the
X-ray. Kappa coefficient and PABAK reviewed the agreements.
Results: The X-ray showed that 70% of the enteral tubes were in the stomach, 27.4% in the duodenum, 1.3% in the esophagus, and
1.3% in the right lung. There was a weak correlation between clinical nurses and nurse researchers (PABAK = 0.054; P = 0.103), clinical nurses and X-rays (PABAK = 0.188; P = 0.111) and nurse researchers and X-rays (PABAK = 0.128; P = 0.107) . The auscultation
test did not detect two risk conditions, enteral feeding tube in the esophagus and the bronchus.
Conclusion: the auscultation test showed little agreement with the X-ray on the enteral feeding tube location.
Keywords: Auscultation. Gastrointestinal intubation. Nursing.
RESUMO
Objetivo: Avaliar a concordância entre o teste de ausculta e o raio-X na detecção do posicionamento da sonda enteral.
Métodos: Estudo transversal realizado em um Centro de Terapia Intensiva do sul do Brasil, em 2011. Enfermeira assistencial e enfermeira pesquisadora realizaram teste de ausculta registrando suas impressões quanto ao posicionamento da sonda enteral em 80
pacientes. Uma médica avaliou o raio-X. Coeficiente Kappa e PABAK avaliaram as concordâncias.
Resultados: O raio-X mostrou 70% das sondas enterais no estômago, 27,4% no duodeno, 1,3% no esôfago e 1,3% no pulmão
direito. Houve fraca concordância entre enfermeira assistencial e enfermeira pesquisadora (PABAK =0,054; P=0,103), enfermeira
assistencial e raio-X (PABAK=0,188; P=0,111) e enfermeira pesquisadora e raio-X (PABAK =0,128; P=0,107). O teste de ausculta
não detectou duas condições de risco, sonda enteral no esôfago e no brônquio.
Conclusão: O teste de ausculta mostrou-se pouco concordante com o raio-X na localização da sonda enteral.
Palavras-chave: Auscultação. Intubação gastrointestinal. Enfermagem.
RESUMEN
Objetivo: evaluar la concordancia entre test de ausculta y Rayo-X en la detección del posicionamiento de la sonda enteral.
Métodos: estudio transversal en un Centro de Terapia Intensiva del sur de Brasil (2011). Enfermero asistencial y enfermero investigadora realizaron teste de ausculta y registraron sus impresiones en 80 pacientes. Una médica evaluó el Rayo-X. Coeficiente Kappa y
PABAK evaluaron las concordancias.
Resultados: Rayo-X mostro 70% de las sondas enterales en el estómago, 27,6% en el duodeno, 1,3% en el esófago y 1,3% en el
pulmón derecho. Hubo débil concordancia entre enfermero asistencial y enfermero investigadora (PABAK =0,054; P=0,103), enfermero asistencial y Rayo-X (PABAK=0,188; P=0,111) y enfermero investigador y Rayo-X (PABAK =0,128; P=0,107). El teste de
ausculta no ha detectado dos condiciones de riesgo, sonda enteral en el esófago y en el bronquio.
Conclusión: teste de ausculta se ha mostrado poco concordante con el Rayo-X en la posición de la sonda enteral.
Palabras clave: Auscultación. Intubación gastrointestinal. Enfermería.
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Rev Gaúcha Enferm. 2015 Dec;36(4):98-103.
DOI: http://dx.doi.org/10.1590/19831447.2015.04.54700
a
Universidade Federal do Rio Grande do Sul (UFRGS),
Escola de Enfermagem, Departamento de Assistência
e Orientação Profissional. Porto Alegre, Rio Grande do
Sul, Brasil.
b
Universidade Federal do Rio Grande do Sul. Escola
de Enfermagem. Programa de Pós- Graduação em
Enfermagem. Porto Alegre, Rio Grande do Sul, Brasil.
c
Universidade Federal do Rio Grande do Sul. Faculdade de Medicina. Programa de Pós- Graduação em
Medicina: Ciências Médicas. Porto Alegre, Rio Grande
do Sul, Brasil.
d
Universidade Federal do Rio Grande do Sul. Faculdade de Medicina. Departamento de Pediatria. Porto
Alegre, Rio Grande do Sul, Brasil.
Versão on-line Português/Inglês: www.scielo.br/rgenf
www.seer.ufrgs.br/revistagauchadeenfermagem
Feeding tube placement: auscultatory method and x-ray agreement
INTRODUCTION
The enteral feeding tube (FT) is the device used to provide calories to patients who are totally or partially unable
to orally digest them(1). The insertion of the feeding tube is
not a complication free procedure. Despite the frequency
in which they occur, due to the potential damages, complications related to the poor positioning of the distal tip of
the FT, with consequent diet administration to the respiratory tract, are those that represent the greatest risk(2-4).
In critically ill patients who are frequent users of these
devices, even greater attention should be given, as common factors such as the adoption of the supine position,
presence of gastric residue, vomiting and mechanical
ventilation use can contribute to the aspiration of gastric
contents(5). The risk of aspiration also increases when the FT
is positioned near the esophagogastric junction, stimulating gastroesophageal reflux, or when shifting occurs after
coughing, nausea and vomiting(6).
There are only a few studies on the insertion technique
and confirmation of the positioning of the FT(7). In practice,
enteral feeding tube placement is described in different
ways. Although the common recommendation is that the
insertion be made blindly (i.e. without the nurse viewing
the path that the FT travels) In these cases there is not, for
example, a standard single FT length to be introduced in
order for the distal tip reach the stomach(4,6-8).
In an attempt to minimize complications related to improper placement of the FT after insertion and prior to diet
administration, clinical bedside trials are adopted to estimate
if the distal tip of the FT is, in fact, in the stomach or intestine.
The auscultation test is the most used verification method
among nurses in clinical practice(7). Another test used is pH
measurement (hydrogen potential) of the waste sucked
through the FT(9-10). Isolated results of these tests, or their combination, supports the opinion given by the nurse regarding
the anatomical location of the distal tip of the FT. However,
there are no studies that document the validation and diagnostic accuracy of these tests to adequately predict the anatomical location of the distal tip of the FT. Thus, the X-ray
diagnosis is still the reference method for this purpose(10).
Considering the large number of patients undergoing
enteral survey procedures, and the potential damage related to diet and medication deposited out of the stomach or intestines, as well as small amount of literature on
the reliability of the means adopted by nurses to establish
the anatomical location of the FT, this study, derived from
a thesis(11), aimed to evaluate the correlation between the
auscultation test and X-rays to detect the positioning of
enteral feeding tube.
METHOD
This is a cross-sectional study conducted in the adult
Intensive Care Unit (ICU) at a university teaching hospital in
Porto Alegre / RS. Data collection took place in 2011.
Adults (≥ 18 years), of both sexes, with enteral feeding
tube recomendations, were consecutively included. Patients undergoing head and neck surgery, diagnosed with
esophageal and / or stomach cancer or other anatomical
changes that could interfere with the insertion procedure
of the FT.
After the attending physician prescribes the enteral feeding tube, the attending nurse (AN), following the
standard institutional recommendation for the insertion,
installed the FT, performed a bedside auscultation test, and
issued an opinion, in writing, about the impression regarding the anatomical location of the FT, registered on own
form provided. The nurse researcher (NR) accompanied all
FT inserts. The insertions were carried out blindly, for purposes of the AN opinion, and the auscultation test was also
performed, with the results being recorded in the independent form used by the AN. All patients were subjected, in sequence, to x-rays to confirm the location of the FT,
since this test is the reference standard for identifying the
position of the distal tip of the FT. Independently, without
information about patients or knowing the impressions of
the nurses, a doctor examined each x-ray, and recorded
the anatomic location of the FT positioning in a specific
form (reference standard). All patients used the same type
of radiopaque FT, with a tungsten distal tip and 10 Fr steel
guidewire (MEDICONER®, Brazil).
In order to evaluate the correlation between the impressions of the nurses and the anatomical location of the
FT, as evidenced by the X-rays, the Kappa coefficient and
PABAK (Prevalence and Bias Adjusted Kappa) were measured.
The sample size calculation was based on data obtained in a study of corpses(12), which found that 72% of
success in the FT insertions into gastric portion using the
same standardized technique at the headquarters of the
institution that carried out this study. To obtain the 0.8 Kappa with a confidence interval of 0.3, significance level of
5% and 80% power, the need to include 79 patients (158
observation pairs) was estimated. The final sample consisted of 80 patients.
The research received prior approval by the Ethics Committee of the institution (Protocol 100314/2010) regarding
its ethical and methodological aspects. The Free and Informed Consent Form (FICF) was signed by assistant nurses who participated in the survey. The FICF was dismissed
for patients due to the fact that no additional risks, beyond
Rev Gaúcha Enferm. 2015 Dec;36(4):98-103.
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Beghetto MG, Anziliero F, Leães DM, Mello ED
those associated with the enteral tube insertion procedure
itself, (a procedure that occured regardless of this study)
were expected. The consent for use of the data was signed
by the researchers and the host institution of the study.
RESULTS
80 procedures were evaluated in 80 patients, whose
age was 55.8 ± 18.1 years, being predominantly men
(61.3%) in use of mechanical ventilation (61.3%).
The X-ray control showed that 70% (n = 56) of the distal
tip FT were located in the stomach, 27.4% (n = 22) in the
duodenum, 1.3% (n = 1) in the third portion of esophagus
and 1.3% (n = 1) in the right lung. There was very weak correlation between the impression of a attending nurse and
the location of the distal tip of the FT, as evidenced by X-ray
(PABAK = 0.188; P = 0.111) between the nurse researcher
impressions and the position of the FT confirmed by X-ray
(PABAK = 0.128; P = 0.107) and between the impressions of
the attending nurse and nurse researcher (PABAK = 0.054;
P = 0.103), as shown in Chart 1.
In one of enteral insertions, based on bedside tests, AN
stated that the location of the FT was unknown, a fact that
did not occur with the nurse researcher. Both did not identified two high risk conditions for patients: FT insertion in
the distal esophagus (n = 1) and the right bronchus (n = 1).
While the nurse researcher identified a greater number of
FT positioned in the stomach (n = 50), the attending nurse
disagreed less about when the tip of the FT was located in
the intestine (n = 10).
In order to identify whether the bedside test performed
by nurses and repeated by the researcher was able to esti-
ATTENDING NURSE
Doctor
(a)
I do not know
Stomach
Intestine
Lung
Esophagus
I do not know
0
1
0
0
0
Stomach
0
42
12
0
1
Intestine
0
13
10
1
0
Lung
0
0
0
0
0
Esophagus
0
0
0
0
0
NURSE RESEARCHER
Doctor
(b)
I do not know
Stomach
Intestine
Lung
Esophagus
I do not know
0
0
0
0
0
Stomach
0
50
17
1
1
Intestine
0
6
5
0
0
Lung
0
0
0
0
0
Esophagus
0
0
0
0
0
ATTENDING NURSE
Nurse researcher
(c)
I do not know
Stomach
Intestine
Lung
Esophagus
I do not know
0
1
0
0
0
Stomach
0
49
7
0
0
Intestine
0
19
4
0
0
Lung
0
0
0
0
0
Esophagus
0
0
0
0
0
Chart 1 – Agreement between the opinions expressed by observers: (a) Doctor (columns) vs. Attending Nurse (lines), (b)
Doctor (columns) vs. Nurse Researcher (rows) and (c) Nurse Researcher (columns) vs. Attending Nurse (lines) and the anatomical location of the distal tip enteral feeding tube. Porto Alegre/RS, Brasil, 2011
Source: Research data, 2011.
The intersections of the same category express the concordance between the evaluators. Data expressed in absolute numbers.
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Feeding tube placement: auscultatory method and x-ray agreement
mate the alimentary tract of the segment in which the distal tip of the FT was positioned, only the results that determined that the distal tip FT was in the stomach or intestine
were analyzed, excluding the location in the esophagus,
lung, or “do not know”. The same low incidence of agreement between doctor and AN (Kappa = 0.215; P = 0.118),
doctor and NR (Kappa = 0.142; P = 0.114) and between NR
and AN (Kappa = 0.052; P = 0.107) (Chart 2) was identified.
DISCUSSION
In the present study, we found that the bedside auscultation test showed little consistency with the image (X-ray)
in the identification of the anatomical location of the distal
tip of the enteral feeding tube. In two of the 80 patients,
the use of the FT without radiological confirmation of its
critical position could have caused damages to patients,
such as diet aspiration or infusion into the respiratory tract,
which did not occur.
Although the use of enteral feeding tubes is common
in hospitals, there are few studies that describe complica-
ATTENDING
NURSE
Doctor
Stomach
Intestine
Stomach
42
12
Intestine
13
10
Stomach
Intestine
Stomach
50
17
Intestine
6
5
NURSE
RESEARCHER
Doctor
ATTENDING
NURSE
Nurse researcher
Stomach
Intestine
Stomach
47
7
Intestine
19
4
Chart 2 – Agreement between the opinions expressed by
observers: (a) Doctor (columns) vs. Attending Nurse (lines),
(b) Doctor (columns) vs. Nurse Researcher (lines) and (c)
Nurse Researcher (columns) vs. Attending Nurse (lines)
regarding the anatomical location of the distal tip of the
enteral feeding tube. Porto Alegre/RS, Brasil, 2011
Source: Research data, 2011.
The intersections of the same category express the concordance between the evaluators. Data expressed in
absolute numbers.
tion rates related to poor positioning and diet and / or drug
administration through this device. A study(13) performed
in different units of a tertiary hospital in the United States,
reviewed radiographic reports evaluating the placement of
enteral feeding tubes. In 3789 enteral feeding intubations
conducted from 2001 to 2004, in 1.3% (n = 50), the distal
tip of the FT invaded tracheopulmonary sites. The similarities with our findings are not only found in the proportion of
poor positioning, but in the fact that the majority of patients
were also on mechanical ventilation (n = 26) and the distal
tip of the FT was located in the right bronchus (n = 34).
Other studies(14-15) show the association between the
use of FT and the occurrence of aspiration pneumonia. In
retrospective analyzes, one of these studies(14) found that
one in three patients using FT had pulmonary complications, and a 59% increase in the probability of dying during
hospitalization when compared to patients using gastrostomy or jejunostomy. Although the theme is relevant, scientific production, mainly of prospective studies, is scarce.
Case studies and case series reporting tension pneumothorax, acute respiratory distress syndrome, aspiration
pneumonia, tracheoesophageal fistula, among other complications related to the use of FT(2-4,16) are found in greater
proportion medical literature, but these publications still
generate low level of evidence.
Given this scenario, and the wide use of auscultation
tests to confirm the anatomical location of the FT(10) in clinical practice, this study aligns with recent publications(17-18)
that compared the use of bedside tests (auscultation test
and pH) to X-rays (reference standard). The first study(17)
evaluated 44 patients admitted to an Intensive Care Unit
(ICU), undergoing enteral intubation by nurses, who also
performed the auscultation test and issued their opinion.
The authors found data that is consistent with the data
herein presented. Of all the procedures, the nurses said that
the tip of FT was in the stomach in 40 cases (90.9%) when
the X-ray showed 39 (88.6%) FT in this location, resulting
in a weak agreement (K = 0.112, p = 0.453). The authors
emphasize that of the five FTs that were not in the stomach
(three in the pylorus and two in the esophagus), four were
confirmed by the nurses as being located in the stomach.
In another study(18), which also evaluated the auscultation and pH tests, 331 enteral intubations were performed
in 314 patients, where 24.2% (n = 76) were admitted to
ICU. The auscultation test was performed in all procedures,
whereas X-rays were performed on 301. A sensitivity of
79% and specificity of 61% of the auscultation test to correctly identify the gastric position of FT was identified. It
is interesting to note that the authors relate the clarity of
auscultation (noise volume) with the probability of correctRev Gaúcha Enferm. 2015 Dec;36(4):98-103.
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Beghetto MG, Anziliero F, Leães DM, Mello ED
ness in locating the position of the FT. They report that in
cases where low sound or no sound was heard, the distal
tip of FT was located in the esophagus (n = 9), lung (n =
3); in the duodenum (n = 2) and the trachea (n = 5). The
authors of these last two studies(17-18) discourage the use of
the auscultation test, suggesting the adoption of pH measurement of gastric residue as a more reliable alternative
to the auscultation test, at the bedside, to determine the
location of the distal tip of the FT.
In the latter(18), the authors suggest that tests resulting
in gastric residue pH values ≤5,5 are predictive of the FT being located in the stomach. However, they admit that this
pH value can also be found when the FT tip in the esophageal position. In the study mentioned above(17), the authors
categorically recommend the use of pH test, although the
study conducted by them included a small number of patients and the role of co-variables involved in the residue
pH values have not been evaluated. Therefore, it is important to note that despite the fact that these clinical studies
suggest good accuracy of the pH test, in practice, it can be
affected by various conditions as alkalosis or metabolic acidosis, use of antacids (proton pump inhibitors and H2 receptor antagonists) or the volume of gastric residue, which
was not adjusted or isolated in recent studies.
In a systematic review(19) on the accuracy of pH and other biochemical markers as predictors of the FT location, the
evidence was considered limited, mainly because there are
no studies with methodological robustness or consensus
regarding the cutoff point for the pH value.
In practice, inserting, identifying and maintaining the
FT in the appropriate anatomical site can be a challenge.
A technology that is more available in hospitals is the ultrasound. There have not yet been sufficiently robust studies to determine the accuracy of this diagnostic test in
confirming the positioning of the FT. But, the researches
available(20-21) suggests that this technology is promising
for clinical practice (close to 100% sensitivity and specificity
between 67% and 100%).
In one of these studies(20), the auscultation the test and
ultrasound were compared with the reference pattern
(X-ray). Interestingly, the authors found higher agreement
with our study when compared to the auscultation test vs.
X-ray (K = 0.484). In this study, ultrasonography was considered by the authors as an efficient method to confirm
the results of the auscultation test in the FT insertion in patients with sensorial loss. Bedside ultrasonography would
have the advantage of reducing radiation exposure, the
time between insertion and confirmation of the FT positioning and enables the daily verification of the FT’s distal
tip location, adding patient safety.
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Rev Gaúcha Enferm. 2015 Dec;36(4):98-103.
Because this is the evaluation of an agreement among
professionals, the limitations of this study may be related to experience both of the attending nurses and nurse
researchers in the detection of the placement of enteral
feeding tubes through the auscultation test. It may be necessary to conduct studies to isolate the effects of variables
such as years of experience or number of enteral feeding
tube insertions in a given period of time, which are not objects in this study.
New clinical studies, with the inclusion of more patients
and adoption of methodologies that promote higher levels of evidence, should be conducted in order to describe
and test other technologies in the identification of the
position of FTs. It is necessary to establish routine performance standards for nursing activities focusing on the improvement in patient safety, given the quality of policies. In
this sense, the findings of this study contribute to support
nursing education, with regard to the safety of the enteral
feeding tube insertion procedure, extending the research
perspective in this area.
CONCLUSION
In the present study, we found that the impression of the
attending nurse and nurse researcher for the clinical trial of
beside auscultation showed little consistency with the image (X-ray) in identifying the anatomical location of the distal
tip of enteral feeding tube. Although the auscultation test is
widely used in clinical practice and taught in nursing education, it should not be used alone, which maintans the X-ray
as a standard examination in that condition.
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Author’s address:
Mariur Gomes Beghetto
Hospital de Clínicas de Porto Alegre – Unidade Álvaro Alvim
Unidade de Internação Clínica.
Rua Álvaro Alvim, 400, Bairro Rio Branco
90420-020 Porto Alegre – RS
Email: mbeghetto@hcpa.edu.br
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Received: 03.06.2015
Approved: 31.08.2015
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