What is the future of
haemodynamic monitoring?
Steven M. Hollenberg, MD
Professor of Medicine
Robert Wood Johnson Medical School/UMDNJ
Director, Coronary Care Unit
Cooper University Hospital, Camden NJ
“Prediction is very difficult, especially about the future.”
Yogi Berra
Niels Bohr
“The only way to predict the future is to
invent it.”
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Alan Kay
The future of hemodynamic
monitoring
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New technologies
New hemodynamic parameters
New methods of analysis
Methods of evaluation
New technologies
• Implantable monitors
New technologies
• Miniaturization
– Imagers
• X-ray
• MRI
• Ultrasound
– Sensors, effectors, and transmitters
• Surgical instruments
• Analyzers
• Optical sensors
New technologies
• Noninvasive methods of evaluation
– Echocardiography
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•
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Myocardial contrast: visualization, perfusion
Tissue Doppler
Strain rate imaging
Hand-held devices
– Bioimpedance
– Magnetic resonance imaging
New hemodynamic parameters
• Microcirculatory flow and density
• Cardiac power
Cooper MARS Mission


To study the alterations of the sublingual
microcirculatory network in humans with
severe sepsis undergoing early goal-directed
resuscitation
To determine if microcirculatory flow velocity
and perfused vessel density correlate with
conventional hemodynamic parameters in
patients with severe sepsis
Microcirculatory flow in Sepsis
Cardiac Power
Cardiac Power Output [watt] =
Mean Arterial Pressure x Cardiac Output / 451
Estimated In-hospital Proportion Dead
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Cardiac Power Output [(Mean Arterial Pressure*Cardiac Output)/451]
Fincke R, et al. J Am Coll Cardiol 2006; 44:340
New methods of analysis
• Reductionist approach
– Take things apart
– Simple rules will yield simple results
• Output is proportional to input
– Engineering paradigms for hemodynamics
• Heart as a pump
• Electrical analogy with impedance as resistance
Hemodynamic waveforms
• Time series measurements
– Smooth, large-scale continuous signal
– Discontinuous, small-scale, erratic disruptions
(noise)
– Filter out the noise
– Describe the average state toward which
homeostatic mechanisms are heading
Biology is a complex system
• Body is complex, open and dynamic
• System: a group of independent but
interconnected elements that function together
to comprise a unified whole.
• “Emergent” properties: properties of the system
as a whole that cannot be predicted from
individual components
• Fluctuations around the average are not just
“noise,” but convey information
• Healthy variability: nonstationary, nonlinear,
and multiscaled
• Disease is characterized not by loss of
regularity but by loss of complexity
Nonlinear analysis
• Can in theory be automated by computer
• Changes in frequency spectrum
components of variability
• Breakdowns of fractal scaling with disease
• Challenges
– Some of the measures are nonintuitive
– Volume of data to be captured is daunting
– Artifacts are a real problem
– Paucity of therapeutic interventions directed
at nonlinear measures
Evaluation of new technologies
• Monitoring tools would not be expected to
improve outcome unless tied to an
effective therapeutic strategy prompted by
data they provide
• Hemodynamic measures are not used in
isolation but in clinical context
– Thus, a single hemodynamic variable taken
alone is rarely a good predictor of the
response to an intervention
• Implications for trial design
New evaluation paradigms
• Polar ideas that no approach can be
adopted without a pivotal RCT and that
since no approach can be rigorously
tested that theory is enough are equally
constricting
• Consensus conferences
– Uniform definitions
– Uniform processes of evaluation
– Managing differences of opinion
Evaluating existing evidence
and planning new trials
• Surrogate endpoints
– Skepticism is appropriate, but there may be
no alternative
• Tradeoff between power and feasibility
– How should surrogates be developed and
validated?
• Translation of measures of proven efficacy
in clinical trials into effective strategies
when applied broadly
The way forward
• We make our own future
• We need active engagement with the
evaluation and implementation of new
concepts and technologies
– New hemodynamic parameters
– New ways of measurement
– New methods of analysis