Evaluation of a non-invasive dynamic light scattering sensor for the measurement of heart rate in neonates.

One of the most important vital parameters that are measured in neonates is
heart rate. This is most commonly detected using electrocardiography (ECG).
Prematurely born infants in particular are known for frequent episodes of
bradycardia (slow heart rate) that require adequate detection because they
indicate low cardiac output. To date electrocardiography is the gold standard
for non-invasive heart rate detection. Pulse oximetry is also common clinical
practice for non-invasive heart rate monitoring, as it provides the blood
oxygen saturation as well. Both ECG and pulse oximetry have a very small signal
amplitude in neonates, which makes it difficult to detect and even harder to
properly quantify the signal. Another major issue is signal distortion by
movement of the neonate and in the case of ECG also electromagnetic
interference. An important remark concerning the measurement of vital signs in
(premature) neonates is their very small size, allowing only a limited number
of sensors for patient monitoring. The company Elfi-Tech has recently developed
a new dynamic light scattering sensor which is able to measure heart rate
through the assessment of skin blood flow with a single sensor. This new
measuring technique is less susceptible to movements of the neonate or to
electromagnetic interference.

Our primary objective is to correlate the measured heart rates between ECG
measurements and the Elfi-Tech dynamic light scattering sensor.

This study is a prospective observational study. After informed consent is
obtained we will measure for 75 minutes with the Elfi-Tech DLS sensor on 5
different sites. This measurement is compared to heart rate measurements
obtained by ECG monitoring at the same time. Also a secondary pulse oximeter
will be attached

We will perform non-invasive measurements for the duration of 75 minutes, the
burden associated with participation is therefore minimal.
When the sensor is placed it does not come into direct contact with the skin,
but is attached to a certified biocompatible double-sided adhesive which
functions as a barrier. These double-sided adhesives have often been used in
neonatal studies and are known to have no consequences for the premature skin.

This DLS sensor contains a divergent class 1 laser source that is safe from any
distance. This means that even when directly viewing this laser with the naked
eye the maximum permissible exposure cannot be exceeded, making it harmless to
the eye. However, considering the frailty of the neonates in which this study
is performed the sensors will be handled with caution and exposing the eyes of
the patients to the laser will be avoided at all times. The rationale is that
even though a class 1 is deemed safe in the general population, the neonatal
retina and the premature retina in particular, is more sensitive. In addition,
information on the consequences of exposing the eye of a neonate to a class 1
laser is lacking.