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Original article
Use of a hand-held bladder ultrasound scanner in the
assessment of dehydration and monitoring response
to treatment in a paediatric emergency department
Kevin Enright, Tom Beattie, Sepideh Taheri
Royal Hospital for Sick Children
Edinburgh, Scotland
Correspondence to
Dr Kevin Enright, 32 Palmerston
Place, Edinburgh, EH12 5BJ,
Scotland, UK;
[email protected]
Accepted 6 August 2009
Published Online First
20 July 2010
ABSTRACT
Background Dehydration is a common concern in
paediatric emergency care. Limited tools are available to
assess reduced urine production, which is commonly
cited as a reliable marker of dehydration.
Objectives To evaluate the utility of a hand-held bladder
ultrasound scanner in monitoring urine production in
children attending the emergency department with
suspected dehydration.
Methods A prospective pilot study was undertaken on
a convenience sample of patients presenting with
suspected dehydration. Serial bladder ultrasound
scanning was performed to monitor urine output.
Dehydration was assessed clinically using the WHO
guide to dehydration assessment. Decisions about
treatment and admission were made independently of
the urine output measurements obtained using the
bladder scanner.
Results 45 children were studied. Using the WHO guide,
33 (73%) had mild dehydration, 8 (18%) had moderate
dehydration and 4 (9%) had severe dehydration. There
was a significant difference in estimated urine production
between those admitted and those discharged
(0.961.2 ml/kg/h vs 1.861.5 ml/kg/h, p¼0.01) and
between those with mild dehydration versus moderate/
severe dehydration (2.361.5 ml/kg/h vs 0.660.7 ml/kg/
h, p¼0.0011). Urine output had been significantly
reduced in those who had received an intravenous fluid
bolus compared with those who had not (0.460.46 ml/
kg/h vs 1.961.6 ml/kg/h, p¼0.001).
Conclusions The hand-held bladder scanner is
a convenient, non-invasive and objective adjunct in the
assessment and management of children attending the
emergency department with suspected dehydration.
a convenient and non-invasive guide to the presence of dehydration. Even minimal volumes of
urine are reliably detected by bladder ultrasound.5
We decided to investigate the scanner’s role in
demonstrating urine production in cases of
suspected dehydration, as an adjunct to clinical
assessment, thus facilitating a better understanding
of dehydration using a non-invasive approach.
METHODS
Setting
Between March and May 2007 we conducted
a pilot study at a paediatric emergency department
(37 000 new patient contacts per year) in a tertiary
children’s hospital. Children presenting with
possible dehydration were eligible for enrolment
and a convenience sample was recruited during
times when the principal investigator (KE) was
present in the department. ‘Possible dehydration’
referred to any patient in whom the diagnosis was
considered by the parents, the triaging nurse or the
clinician. We made no allowance for a child’s past
medical history of chronic illness or prior renal
impairment: our primary aim and outcome
measure was to demonstrate the utility of the
device in documenting serial bladder volumes.
Ethical approval was not sought as this was a noninvasive observational study, with no change to
standard management.
Serial bladder volume measurements were made
independently of clinical assessment and outcomes.
Details of urine production were calculated after
the patient was discharged; decisions about intravenous fluid bolus, oral rehydration, admission and
discharge were all made independently of the urine
volumes obtained using the bladder scanner.
BACKGROUND
Suspected dehydration is a common presentation
to paediatric emergency care, and hospital admission may be required as part of the assessment
process.1
Clinical signs can be insensitive markers of
dehydration,2 certainly at less than 5% fluid deficit,
and interobserver reliability is poor.3 Normovolaemic children produce 1e2 ml of urine per kilogram per hour as an index of normal renal
perfusion.4 Oliguria is an early physiological
response to dehydration.
Quantifying urine production in small children,
particularly in the precontinent age group, poses
a significant challenge. Urethral catheterisation is
not routine in paediatric practice and is rarely
indicated. By measuring urine production, the
hand-held bladder scanner appeared to provide
Emerg Med J 2010;27:731e733. doi:10.1136/emj.2008.063271
Patient assessment
In addition to standard clinical examination all
children were assessed according to the WHO
guide to dehydration assessment (see table 1). This
outlines clinical features that may differentiate
between mild, moderate and severe dehydration.6
Serial bladder scanning was performed at halfhourly intervals (or in some cases hourly intervals,
depending on the level of clinical activity in the
department at the time) and the hourly rate of urine
production was calculated and recorded for each
child. We compared clinical findings with results
obtained with the hand-held bladder scanner.
The device
We used the BladderScan BVI-6200, which is
available in paediatric ward and outpatient settings
731
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Original article
Table 1
World Health Organization guide to dehydration assessment
Mild dehydration
Moderate dehydration
Severe dehydration
Pinch test <1 s
Alert no distress
Drinks normally
Pinch test 1e2 s
Restless or irritable
Thirsty, keen to drink
Pinch test >2 s
Lethargy, sleepy
Not drinking
in many hospitals (see figure 1). It has not been used previously
to assist with monitoring urine production in suspected dehydration in the emergency department. This hand-held device is
light (309 g), non-invasive and easy to use. It gives a reading of
bladder volume within 5 s (over a range of 0 to 200 ml, with
a reported accuracy of 615 ml or 615%). Training was provided
by the product manufacturer to ensure correct use of the device.
The margin for error at low bladder volumes is a potentially
significant drawback to the use of this device over conventional
ultrasound, especially as younger paediatric patients will inevitably
produce smaller volumes of urine.
Data analysis and outcome measures
Results were stored on Microsoft Excel (Microsoft 2005)
and analysed using MedCalc (2005). Unpaired t tests of nonparametric data and Fisher ’s exact test were employed, as
appropriate.
The primary outcome measure of the study was the ability to
document the hourly rate of urine production for each child,
using the hand-held bladder scanner. Secondary outcome
measures were the relationships between the measured urine
production and clinical features of dehydration, patient disposal
and rehydration therapy.
RESULTS
Data were collected for 45 children ranging in age from
4 months to 10 years (median age 24 months and IQR of
12e48 months). Eight (18%) were <12 months old and 27 (60%)
were male.
The hourly rate of urine production can be objectively
demonstrated by bedside ultrasound.
According to WHO criteria, 33 (73%) were mildly dehydrated,
eight (18%) were moderately dehydrated and four (9%) had
severe dehydration. Because numbers were small, we grouped
those with moderate and severe dehydration together for further
analysis.
Significant differences in urine production were demonstrated with reference to the outcome measures: between
mild versus moderate/severe dehydration (2.361.5 ml/kg/h vs
0.660.7 ml/kg/h, p¼0.0011), between admitted patients versus
discharged (0.961.2 ml/kg/h vs 1.861.5 ml/kg/h, p¼0.01) and
between those who received an intravenous fluid bolus and
those who did not (0.460.46 ml/kg/h vs 1.961.6 ml/kg/h,
p¼0.001).
One in four patients were admitted, either for reasons of
dehydration or other illness, or both. However, all of those
admitted with suspected dehydration had impaired urine
production objectively demonstrated. One in 10 of the patients
who were clinically mildly dehydrated and appeared to be
drinking well, had impaired urine production demonstrated,
with a mean hourly volume of <0.5 ml/kg/h. Nine patients
(20%) received intravenous fluids.
DISCUSSION
Suspected dehydration is a common concern among parents and
clinicians and occurs in a wide range of paediatric conditions.
In most cases assessment relies on clinical examination alone.7
Where possible, this includes careful note of fluid intake and urine
output but these are often difficult to quantify. Few patients in
the United Kingdom present with severe dehydration and only
a minority require hospitalisation, so invasive techniques are
rarely indicated.8
Children who tolerate oral fluids while in the emergency
department may nonetheless be dehydrated and may subsequently become unable to meet their fluid needs by oral intake
alone. There is a need for a reliable adjunct to clinical assessment.
It was our experience that the bladder scanner provides realtime feedback on the child’s urine production, including
response to rehydration therapy (fluid boluses, fluid challenges
and oral rehydration programmes). Analysis of this device in our
setting supports its use in emergency care.
Although we have shown that the device provides a quantitative measurement of urine production, it is important to
highlight three limitations to our study: the sample size was
small, accuracy of the readings obtained was accepted at face
value and there was only one investigator and so no opportunity
to assess interobserver reliability.
However, our findings do prompt further research into its
potential role in suspected dehydration, ideally in a prospective,
randomised controlled trial.
CONCLUSION
Serial bladder ultrasound scanning using a hand-held device is
a convenient, non-invasive and objective adjunct in the management of suspected dehydration in the emergency department.
Further study is required to validate the intervention.
Acknowledgements We are grateful to the patients and their parents and to the
emergency department staff who participated in this study.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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Figure 1 BladderScan BVI-6200.
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Images in emergency medicine
Ecstasy overdose and memory loss
A young man was brought to the emergency department unconscious after a day partying. He had taken alcohol, cocaine and
ecstasy. He was intubated and ventilated and had a CTscan, which
was unremarkable. After extubation 2 days later he appeared
confused and remained so despite good oxygenation and normal
cardiovascular parameters. It then became clear that he had
a short-term memory deficit and topographical disorientation.
An MR scan showed bilateral hippocampal damage on T2weighted images (figures 1 and 2). Hippocampal damage typically leads to inability to form new memory, while long-term
memory is usually intact. Hippocampi are particularly vulnerable to hypoxia. They are supplied by the anterior, middle and
posterior hippocampal arteries. The middle and posterior
hippocampal arteries have a rich anastomosis and form an
arcade on the surface of the hippocampi. As these branches come
out at right angles (giving a rake-like appearance), blood supply
is particularly vulnerable to sudden changes in blood pressure:
hence the risk of hypoxia.
Figure 1 T2-weighted MR scan of the patient’s brain. Coronal section
showing damage to the hippocampi (arrows).
Emerg Med J October 2010 Vol 27 No 10
The hippocampi are known to be affected in the earliest stages
of Alzheimer’s disease (which typically causes similar problems
with new memory formation). One also needs to beware of
seizures, as these can occur long after the original insult.
Bernard A Foëx, Ganesh Subramanian, John M Butler
Manchester Royal Infirmary, Oxford Road, Manchester, UK
Correspondence to Dr Bernard A Foëx, Consultant in Emergency Medicine and
Critical Care, Manchester Royal Infirmary, Oxford Road, Manchester, M13 9WL, UK;
[email protected]
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; not externally peer reviewed.
Accepted 5 January 2009
Published Online First 28 July 2010
Emerg Med J 2010;27:733. doi:10.1136/emj.2008.069229
Figure 2 T2-weighted MR scan of the patient’s brain. Horizontal
section showing damage to the hippocampi (arrows).
733
Downloaded from http://emj.bmj.com/ on June 18, 2017 - Published by group.bmj.com
Use of a hand-held bladder ultrasound
scanner in the assessment of dehydration
and monitoring response to treatment in a
paediatric emergency department
Kevin Enright, Tom Beattie and Sepideh Taheri
Emerg Med J 2010 27: 731-733 originally published online July 20, 2010
doi: 10.1136/emj.2008.063271
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