Could the use of bedside lung ultrasound reduce the number of chest x-rays in the intensive care unit?
Brogi et al. Cardiovascular Ultrasound
Could the use of bedside lung ultrasound reduce the number of chest x-rays in the intensive care unit?
0 Department of Anesthesia and Intensive Care, IRCCS San Raffaele Scientific Institute , Via Olgettina 60, 20132 Milan , Italy
1 Institute of Clinical Physiology - National Research Council , Pisa , Italy
2 Department of Anesthesia and Intensive Care, University of Pisa , Pisa , Italy
3 Department of Emergency Medicine, San Luigi Gonzaga University Hospital , Orbassano, Torino , Italy
4 Department of Medicine, University of Udine , Udine , Italy
Background: Lung ultrasound can be used as an alternative to chest radiography (CXR) for the diagnosis and follow-up of various lung diseases in the intensive care unit (ICU). Our aim was to evaluate the influence that introducing a routine daily use of lung ultrasound in critically ill patients may have on the number of CXRs and as a consequence, on medical costs and radiation exposure. Methods: Data were collected by conducting a retrospective evaluation of the medical records of adult patients who needed thoracic imaging and were admitted to our academic polyvalent ICU. We compared the number of CXRs and relative costs before and after the introduction of lung ultrasound in our ICU. Results: A total of 4134 medical records were collected from January 2010 to December 2014. We divided our population into two groups, before (Group A, 1869 patients) and after (Group B, 2265 patients) the introduction of a routine use of LUS in July 2012. Group A performed a higher number of CXRs compared to Group B (1810 vs 961, P = 0.012), at an average of 0.97 vs 0.42 exams per patient. The estimated reduction of costs between Groups A and B obtained after the introduction of LUS, was 57%. No statistically significant difference between the outcome parameters of the two groups was observed. Conclusions: Lung ultrasound was effective in reducing the number of CXRs and relative medical costs and radiation exposure in ICU, without affecting patient outcome.
Acute care; Ultrasound; Imaging; Ultrasound; X-Rays; Imaging; X-Rays
Critically ill patients frequently need thoracic imaging
due to the constant evolution of their clinical conditions.
Computed tomography (CT) scans remain the gold
standard imaging technique for thoracic evaluation, but
transportation of patients outside the ICU is difficult and
potentially harmful [
]. Chest CT scans expose patients to
large doses of radiation and should be reserved for specific
situations (e.g., the evaluation of mediastinal pathologies
and confirmation of pulmonary embolism) [
chest X-ray (CXR) is still considered the standard of care
for many diagnostic applications in the Intensive Care Unit
(ICU). However, this imaging technique has important
methodological limitations and often shows low accuracy
]. Furthermore, it is important to consider
radioprotection issues. Multiple radiologic imaging exams result in an
increased incidence of radiation-induced cancer in the
Bedside sonography has become essential in the ICU
for many common applications. Particularly, lung
ultrasound (LUS) has been shown to be superior to CXR as a
diagnostic tool for the diagnosis of some lung conditions
in critically ill patients (i.e., pneumothorax, pleural
effusion, consolidation, Ventilator-Associated-Pneumonia)
]. Consequently, LUS may be considered a valid
alternative to CXR in some specific situations.
Potentially, a systematic application of LUS may be associated
with a reduced use of routine CXR and chest CT scans,
without affecting patient outcome while reducing
radiation exposure [
]. Also, the use of bedside LUS could
lead to reduced medical costs, as ultrasound scanners
are relatively low-cost regarding maintenance and high
durability compared to other imaging modalities [
In our ICU the routine use of LUS was introduced in
July 2012: since then, we have performed a daily LUS
round in our critically ill patients. The first aim of our
study was to evaluate whether the routine daily use of
LUS in our ICU influenced the number of diagnostic
CXRs performed in our critically ill patients. The second
aim was to estimate the effective reduction of medical
costs and radiation exposure that was achieved by the
introduction of LUS.
This single-center, observational, retrospective cohort
study took place in a university hospital in Italy from
2010 to 2014. We retrospectively analyzed our
prospectively collected database. After approval by the Research
Ethics Committee of Pisa (approval number 979, 07/04/
2016), 4134 consecutive adult patients were enrolled in
the study. Written informed consent was obtained from
all the patients. This study adheres to the applicable
STROBE guidelines. Data extraction was performed
independently by two authors (S.M., S.A.) and any
discrepancy resolved prior to final analysis by discussion
with a third authors (B.E.).
We recruited adult patients admitted to our ICU from
January 2010 to December 2014, who needed thoracic
imaging during the ordinary clinical work-up. The
inclusion criteria were as follows: age > 18 years, ability to
provide written consent, and clinical indications for
thoracic imaging test.
In the second half of 2012, we implemented
ultrasound as the thoracic imaging technique of choice in
our ICU. From then on, physicians could decide to use
LUS instead of CXR for the first diagnosis, follow-up
and monitoring of pleural-pulmonary conditions in the
critically ill patients admitted to our ICU.
The cohort was divided into two groups using
temporal criteria, as follows:
A. In Group A, we included patients admitted to the
ICU from January 1, 2010 to May 31, 2012. During
this period LUS was not yet implemented as a
standard practice in our ICU and was only used
sporadically on a consultancy basis. In this period,
thoracic imaging was based on CXRs or thoracic CT
scans as the standard of practice.
B. In Group B, we included patients admitted to the
ICU from June 1, 2012 to December 31, 2014. In
this period, thoracic ultrasound was introduced in
our ICU and implemented as the standard of care
for many applications: physicians could choose to
rely on LUS with or without integration with
radiology methods. During that period, the imaging
technique of choice was LUS, then, in case of
clinical doubt or technical problems, X- Rays were
used to overcome the issue.
At the bedside, anterior-posterior chest radiography
was performed in the supine position following standard
technique using a portable X-ray unit; radiologists were
responsible for reading and interpreting the digital
imaging. In our ICU during the selected period (2012–
2014), three trained critical care physicians performed
LUS. The operators had acquired the level of
competence defined by the American College of Chest
]. Trained physicians had performed theoretical
courses, simulated practice on manikins (at least 50
scans) and had subsequent formal supervised practice
]. The examination consisted of a bilateral scan of the
anterior and lateral chest wall with patients in the supine
position. A microconvex probe was used as the first
choice for LUS. Then, to help resolve cases where
diagnostic doubt remains, higher frequency probes were
chosen for a better visualisation of the pleural line and
subpleural space. The probe was positioned
longitudinally in order to visualise the “bat sign” (the pleural line
and two ribs), then, placed in transversal plane. Chest
wall was examined in 8 areas with one scan for each area
]. All regions were scanned with ultrasound in order
to assess pleural sliding, presence and possible number
of A- and B-lines, pleural effusion, pneumothorax, lung
consolidation and diaphragmatic mobility. When
indicated, two dorsal scans per side were added
(consolidations, aeration monitoring) [
]. Ultrasound diagnoses of
lung disease were defined according to the International
Consensus Conference on Lung Ultrasound [
findings were reported on the clinical notes.
For all patients we recorded sex, age, ICU-admission
diagnosis (trauma, medical, surgical patients), SAPS II
score, duration of ICU stay and ICU mortality. We
recorded and compared the number of CRXs performed
in Group A and Group B and the costs linked to CXR
prescriptions between the two groups.
The data were entered into a spreadsheet (Microsoft
Excel) and analyzed using SPSS (IBM SPSS software
version 21). Demographic data are shown as means and
standard deviation where appropriate. Analysis of data
was performed using two-tailed Mann-Whitney test or
Student t-test where appropriate: a value of P below 0.05
defined the significance. Cost for each medical exam was
gathered from our regional price list.
A total of 4134 medical records were identified that fulfilled
our inclusion criteria: 1869 patients in Group A and 2265
patients in Group B were included in our analysis.
Demographic characteristics are shown in Table 1.
Before the introduction of a routine use of LUS, we
requested 1810 chest X-rays for diagnosis and follow-up
(an average of 0.97 chest X-ray per patient) with an
estimated cost of 47,060€. After the introduction of a routine
use of LUS, we required 961 chest X-rays for diagnosis
and follow-up (an average of 0.42 chest X-ray per patient)
with an estimated cost of 24,986€. The significant
differences in the total number of CXRs, average number per
patient and estimated cost obtained before and after the
introduction of routine application of LUS, are shown in
Table 2. In Group B we observed a reduction in the
number of CXR and relative cost by 57%, in comparison to
Group A (Fig. 1). No statistically significant difference was
observed in SAPS II regarding duration of ICU stay and
ICU mortality between the two groups.
In this study, we evaluated the influence that introducing a
routine daily use of LUS may have on the number of CXRs
and relative costs, in a polyvalent ICU. We found that the
implementation of daily LUS examination leads to a
statistically significant reduction in the number of CXRs without
affecting the outcome. The cost savings associated with the
reduction in the number of CXR was also remarkable. We
did not find a decrease in the number of chest CT scans
between the groups. The overwhelming majority of our
sample consisted of surgical patients requiring a brief
postoperative intensive care monitoring. For short ICU stays,
the implementation of LUS seems of high significance,
because, conventionally, X-rays are often routinely performed
just before the patients’ transfer.
Regarding demographic and admission data, we
decided to compare the two groups mainly on the basis of
SAPS II because this score is valuable in predicting risk
Data are presented as mean and [standard deviation] or as percentage (%)
where appropriate. SAPSII = The Simplified Acute Physiology Score II,
ICU = Intensive care unit
of mortality and it provides a reliable and effective
estimation of the overall clinical condition of the patients at
]. Consequently, we decided not to present
the specific admission diagnosis and we categorized
patients only on the base of three diagnoses: trauma,
surgical and medical patients.
LUS was shown to be essential in our modern ICU,
since it is a safe, fast bedside technique that may replace
CXR for many applications. Moreover, the decreased
radiation exposure represents a considerable improvement
in safety and patient care. The carcinogenic effects of
Xrays are extensively documented. The mechanism of
radiation damage arises from the interaction between
high-energy X-rays and biological material leading to
radiation-induced mutations (a phenomenon known as
“stochastic effect”) and to radiation-induced cell death
(known as “deterministic effect”) [
]. Stochastic effects
occur without a specific threshold dose of radiation;
consequently, the risk of developing cancer from
radiation exposure is essentially stochastic. Moreover,
physicians have to take into account the cumulative risk of
radiation exposure and that different imaging techniques
require different doses of radiation. For instance, one
chest CT scan has an effective radiation dose of 8 mSv,
equivalent to 400 CXRs [
]. Furthermore, doctors have
to consider that the risk for each dose also depends on
age (higher in children, because of rapid dividing cells
and life expectancy) and gender (higher in women).
Consequently, the responsible use of imaging tests is
vital in clinical practice. Inappropriate application of
X-ray imaging is socially and economically unjustifiable.
At the bedside with critically ill patients, CXR also
suffers from methodological limitations (i.e., supine
anterior-posterior vs upright posterior-anterior views,
non-collaborating patient vs patient controlling his
breath, possibility of adjunctive lateral views). These
aspects, along with the presence of other concomitant
lung diseases and complexity of critically ill patients,
contributes to poor-quality CXR imaging and the
possibility of wrong interpretations [
In this scenario, bedside point-of-care LUS has led to
important changes in clinical practice, as it allows
clinicians to rapidly answer specific questions, to guide
therapy and to assess the efficacy of ongoing interventions,
with high diagnostic accuracy and specificity. In 2004
Lichtenstein et al. evaluated the diagnostic accuracy of
auscultation, bedside CXR and LUS in comparison to
thoracic CT in patients with ARDS. These Authors
showed that bedside CXR and physical examination had
a lower sensitivity, specificity and diagnostic accuracy
than LUS in the diagnosis of some lung conditions (i.e.,
pleural effusions, interstitial syndrome, alveolar
]. With the progression of literature on the
topic and affirmation of a concept that has recently
become evidence-based, the use of point-of-care
ultrasound in the ICU has increased dramatically. Lee et al.
] conducted a retrospective study in order to estimate
the expected change over years in the use of imaging
tests. They found a decrease in second-level imaging
tests (CT by 21% and MRI by 6%) together with an
increase in the use of ultrasound by 18.9%, and as a
direct consequence a decrease in medical charges, without
affecting patient outcome. In 2015, Zieleskiewicz et al.
] investigated retrospectively the effect of ultrasound
chest imaging on the reduction of CXRs and medical
costs. They observed a statistically significant decrease
in the number of CXRs due to the introduction of
ultrasound in their ICU, without affecting mortality. Indeed,
they did not find a decrease in the number of chest CT
scans. Furthermore, Peris et al. [
] published an
observational control study on 376 intensive care patients.
The patient cohort was divided into two groups using
temporal criteria (before and after the introduction of
routine LUS). The data showed a statistically significant
decrease in the number of CXRs and CT scans
performed after the implementation of LUS. The conclusion
of these Authors was that LUS may be used as an
alternative to thoracic radiology [
] without affecting patient
]. Moreover, LUS is a valuable tool for
selecting patients who effectively need a more advanced
imaging technology (i.e., CT scan, MRI), thus
contributing to reducing the number of inappropriate ionizing
The well-known and repeatedly cited limitation of
sonography is operator dependency. A correct ultrasonography
examination is directly related to operator skill, training,
and experience. However, a combination of increased
medical knowledge, ultrasound proficiency and appropriate
training of operators could reduce errors [
LUS is mainly based on simple basic signs and in many
studies was shown to be highly reproducible in the hands
of operators with different skills and experience, although
the importance of correct training is always emphasized.
Definitely, the benefits of implementing LUS in the ICU
usually outweigh the pitfalls, if sonography is performed by
trained physicians [
Our study presents several limitations. First of all, due
to the retrospective nature of the study, it was not
possible to gather information about the clinical indications
for performing an imaging technique or when CXR was
requested on the basis of US findings. For the same
reason, it was not possible to evaluate how many chest
x-rays or LUS examinations were normal and how many
were pathological in the two groups. Second, the use of
CXR or US was at the physician’s discretion, which may
vary depending on the individual’s sensitivity and
consideration. Since LUS is a relative novelty and is still
considered a possible alternative, it was not feasible to
set up a standard protocol for comparison. For these
reasons, the reader should consider that the measured
decrease in the number of CXRs observed in our study
may not necessarily correspond to other situations. A
future study on the subject should be performed, applying
fixed protocols based on the evidence-based superiority
of LUS in some applications. Third, it was not possible
to collect information on overall mortality but only on
ICU mortality, as patients were not followed-up after
discharge from the ICU.
In conclusion, this study shows the importance and
effectiveness of LUS in reducing the number of CXRs performed
in an academic polyvalent ICU. Routine LUS application,
even when only left to the discretion of the caring
physician, allows decreasing the use of ionizing procedures as
well as related biological and economic costs.
No external funding declared.
Availability of data and materials
Are available from the corresponding author on reasonable request.
EB (first author) acquisition of data, analysis and interpretation of data,
drafting/revising the manuscript, control and guarantee that all aspects of
the work was investigated and resolved. EB approved the final manuscript.
EB (corresponding author) acquisition of data, analysis and interpretation of
data, drafting/revising the manuscript, control and guarantee that all aspects
of the work was investigated and resolved. EB approved the final manuscript.
AS acquisition of data, analysis and interpretation of data, drafting/revising
the manuscript, control and guarantee that all aspects of the work was
investigated and resolved. AS approved the final manuscript. MS acquisition
of data, analysis and interpretation of data, drafting/revising the manuscript,
control and guarantee that all aspects of the work was investigated and
resolved. MS approved the final manuscript. LG acquisition of data, analysis
and interpretation of data, drafting/revising the manuscript, control and
guarantee that all aspects of the work was investigated and resolved. LG
approved the final manuscript. LV acquisition of data, analysis and
interpretation of data, drafting/revising the manuscript, control and
guarantee that all aspects of the work was investigated and resolved. LV
approved the final manuscript. GV acquisition of data, analysis and
interpretation of data, drafting/revising the manuscript, control and
guarantee that all aspects of the work was investigated and resolved. GV
approved the final manuscript. FF study concept and design, acquisition of
data, analysis or interpretation of data, drafting/revising the manuscript,
control and guarantee that all aspects of the work was investigated and
resolved, critical revision of the manuscript for important intellectual content,
study supervision. FF approved the final manuscript.
Ethics approval and consent to participate
Ethics approval was obtained by the Research Ethics Committee of Pisa
(approval number 979, 07/04/2016). Written informed consent was obtained
from all the patients.
Consent for publication
Etrusca Brogi has no conflict of interest to declare. Elena Bignami has no
conflict of interest to declare. Anna Sidoti has no conflict of interest to
declare. Mohammed Shawar has no conflict of interest to declare. Luna
Gargani received a speaker’s honorarium from GE Healthcare. Luigi Vetrugno
has no conflict of interest to declare. Giovanni Volpicelli has no conflict of
interest to declare. Francesco Forfori has no conflict of interest to declare.
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