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Estimating CRI from Pulsatile Waveforms
Pulsatile physiological waveforms (BP, PPG, etc.) encode significant information about the state of the
cardiopulmonary system. Flashback’s data analytics technology is capable of generating accurate models
from noisy high dimensional datasets like the LBNP reference database. This dataset allows us to calculate
reference CRI values for each subject from known LBNP (mmHg), and our analytics system uses these and
accompanying sensor data to create a mapping from waveforms to CRI estimates (see Figure 10Figure
10).
Figure 10 - Estimating CRI
In this case, CRI is based on the IR PPG signal from the Nonin OEM III/8000AA.
Performance of CRI
CRI is a new physiological monitoring parameter which
trends with intravascular volume and can be used by
clinicians, in concert with other hemodynamic measures,
to assess volume status.
CRI uses a standard photoplethysmogram (PPG)
waveform, which makes it noninvasive, compact and easy
to use. It can be applied at any point during volume
changes and does not require reference measurements.
The monitor will display initial CRI estimates after a few
seconds and then updates continuously.
In a 20% blood draw study,
Flashback’s CRI monitors were
demonstrated to be more responsive to volume loss than
standard vital signs. See Figure 11, used with permission,
(Convertino, Howard, et al. 2015).
Figure 11 - Performance of CRI
