08 Assessment of volume status and fluid responsiveness in the emergency department

fluid challenge, the use of the mean arterial
pressure as the clinical endpoint and
the CVP as the “safety limit” has been proposed
[61] and is feasible in the ED setting.
Although it has been shown that B-
type natriuretic peptide is not able to accurately
predict fluid responsiveness in
patients with acute circulatory failure
[64], it might be to identify patients with
systolic cardiac dysfunction and a high
risk for fluid overload prior to a fluid challenge
test.
Innovative continuous
noninvasive concepts for
advanced hemodynamic
monitoring: the future in the ED?
The commonly used hemodynamic measures
in the ED are heart rate and intermittently
obtained noninvasive blood
pressure measurements using oscillometry.
In recent years, however, large studies
revealed severe limitations of the oscillometric
method, for example, in obese
and arrhythmic patients [65, 66]. Moreover,
clinically relevant discrepancies between
invasive arterial catheter-derived
and oscillometrically obtained blood pressure
were demonstrated in critically ill patients
[67].
Invasive advanced hemodynamic
monitoring technologies can still usually
not be applied in an ED setting. In the
future, however, innovative technologies
allowing for a continuous and completely
noninvasive estimation of blood pressure,
CO, and other hemodynamic variables
(e.g., pulse pressure variation, stroke
volume variation) might allow advanced
hemodynamic monitoring even in ED patients.
Among the multiple applications,
the option to monitor changes in CO in
real time during functional tests (PLR,
fluid challenge) via noninvasive continuous
CO measurements appears particularly
intriguing. Since CO and stroke volume
are the hemodynamic variables that
are most reliable in the prediction of fluid
responsiveness [63], their continuous recording
would help to identify those patients
who are not fluid responsive, and
thus might be harmed by further fluid administration
[60]. Together with a potentially
reduced probability of missing rapid
changes in vital parameters [68, 69], continuous
noninvasive monitoring of arterial
pressure and blood flow in the ED may
therefore markedly improve both patient
safety and optimization of volume status
and blood flow.
A variety of noninvasive technologies
have been proposed during the past years
that might contribute to assessing a patient’s
volume status, fluid responsiveness,
and guiding fluid therapy in the ED in the
future. The vascular unloading technique,
for example, has already been proven to be
feasible in continuous noninvasive blood
pressure measurements in the ED setting
[68, 69]. This method uses an inflatable
finger cuff applying pressure to the finger
and contains an infrared transmission plethysmograph
to measure the finger artery
diameter (i.e., blood volume) [70]. The arterial
blood pressure waveform can then
be indirectly deduced from the pressure
that is needed to keep the volume in the
finger artery constant throughout the cardiac
cycle. Another noninvasive technology
that allows continuous blood pressure
monitoring and the estimation of CO is
radial artery applanation tonometry [71–
74]. Additional techniques that allow for
the estimation of CO include thoracic
electrical bioimpedance, thoracic bioreactance,
and pulse wave transit time [75].
As mentioned above, the use of these
noninvasive technologies for continuous
hemodynamic monitoring during the
functional tests for fluid responsiveness
might pose a powerful approach. In this
context, it is important that Cecconi et
al. determined dynamic arterial elastance
(Ea dyn ) by using arterial pulse pressure
analysis obtained by the aforementioned
vascular unloading technology in spontaneously
breathing patients [76]. Ea dyn was
defined as the ratio between pulse pressure
variation and stroke volume variation
during one respiratory cycle. Importantly,
patients who had an increase in
MAP of ≥ 10 % after a fluid challenge possessed
a significantly higher preinfusion-
Ea dyn value than nonresponders. As a result,
a preinfusion-Ea dyn > 1.06 identified
fluid responders with both sensitivity and
specificity of 88.2 %. While awaiting further
validation, these findings underscore
the potential of noninvasive arterial pulse
pressure analysis for the assessment of fluid
responsiveness that appears particularly
well suited for the ED.
At this point, however, these innovative
technologies for continuous advanced
hemodynamic monitoring still need to be
further evaluated in the ED setting with
regard to their clinical applicability and
their measurement performance [77, 78].
Conclusions
The correct assessment of the patient’s
volume status and fluid responsiveness
constitutes a fundamental and yet challenging
task for the effective management
of a wide variety of medical conditions
that physicians encounter in the
ED. In this review, we provide a detailed
guide through a variety of methods applicable
in the ED environment for the
assessment of a patient’s intravascular
volume status and fluid responsiveness.
Based upon history, physical examination,
laboratory tests, and ultrasound we
propose an algorithm to estimate the intravascular
volume status (. Fig. 1). In
addition, we describe the functional tests
to assess fluid responsiveness and their
limitations in an ED setting. In the future,
innovative noninvasive means of continuous
hemodynamic monitoring may allow
advanced hemodynamic monitoring
in the ED.
Authors’ contributions. C. Maurer was
responsible for the conception and drafting
of the review. J.Y. Wagner has made
substantial contributions to the conception,
was involved in drafting, and revised
the manuscript for important intellectual
content. R.M. Schmid revised the manuscript
for important intellectual content.
B. Saugel was responsible for the conception
and drafting of the review. All authors
read and approved the final manuscript.
Corresponding address
B. Saugel MD
Department of Anesthesiology, Center of
Anesthesiology and Intensive Care Medicine,
University Medical Center Hamburg-Eppendorf
Martinistrasse 52, 20246 Hamburg
bernd.saugel@gmx.de
Medizinische Klinik - Intensivmedizin und Notfallmedizin 4 · 2017 |
331