Monitoring fetal-to-neonatal pulmonary transition after birth with transcutaneous electromyography of the diaphragm

Directly after birth the lungs are still (partly) filled with amniotic fluids.
Most of the fluids are pushed out of the lungs when the infant moves through
the birth canal, but a certain amount remains. During the first gasps of air
the process of fluid absorption by the pulmonary tissue and subsequent
transportation to the blood starts and in the end the fluids excreted. However,
not all infants are successful in this process to clear the lungs of the fluids
and start sufficient ventilation and gas exchange. Around 5% of the term
infants and 60% of preterm infants fail to aerate the lungs fast enough and
require some form of resuscitation. Increasing the intrapulmonary pressure by
means of positive pressure (Positive end-expiratory pressure, PEEP) and
providing (sustained) inflations are common clinical interventions which
increase the odds of a successful transition of the infant.

Studies that investigated the infant during its pulmonary transition suggest
that the diaphragm, the primary respiratory muscle, plays a crucial role in the
transition. However, till now, no study has investigated the activity of the
diaphragm during this first period of life, during e.g. gasping and/or
resuscitation of the infant.

When the role of the diaphragm can be objectively assessed, this could improve
current methods of guiding the transition, which are mostly based on clinical
assessment. In clinical practice skin colour, heart rate estimates and chest
excursions remain the primary parameters to guide treatment, even though they
can be rather difficult to assess and unreliable.

That is why in this study the electrical activity of the diaphragm will be
studied as a new clinical parameter for the monitoring of the transition. The
activity can be measured with surface electromyography of the diaphragm (dEMG).
Three simple electrodes, similar to the standard chest impedance electrodes,
are used for the registration.

Besides measuring the diaphragmatic activity, cardiac activity is picked up by
EMG as well. In this case the dEMG signal could serve an additional heart rate
monitor (HR-EMG).
This combined approach may have the benefit of both registering
quality/quantity of breathing and heart rate. The latter is normally registered
by pulse oximetry (HR-PO), but heart rate detection with pulse oximetry can be
rather slow (up to 90 seconds for a read-out) and the accuracy in the detection
of heart rate is debateable. Furthermore, comparison between HR-EMG monitoring
and standard chest impedance monitoring (CI) can be used to describe the
accuracy of dEMG as a heart rate monitor. An earlier study in the neonatal
intensive care has already proven that EMG can be used for heart rate
monitoring, but these measurements were done in much less demanding and
stressful circumstances.

This study has the following objectives:

1) To assess if dEMG measurement is feasible during pulmonary transition in the
delivery room
* Does the signal quality (expressed in heart rate and respiratory rate) of
dEMG during the transition agree with the standard monitoring devices for these
parameters?
* Hypothesis: the signal quality of dEMG will be sufficient for clinical use
during pulmonary transition in the delivery room. dEMG is believed to be
feasible and as accurate a heart rate monitor as CI and more accurate than PO.

2) To assess the contribution of the diaphragm to the pulmonary transition
after birth
Hypothesis: Diaphragmatic activity is higher during both inspiration and
expiration during pulmonary transition, and will show a decrease after a period
of time, when breathing becomes more stable and the transition is made.

3) To assess delay of heart rate monitoring with the dEMG technique in
comparison with CI and PO
Hypothesis: dEMG based heart rate monitoring will be feasible (objective 1) and
will be faster in providing a heart rate than PO and will at least be as fast
as standard CI.

4) To assess the effect of changes in respiratory support during the neonatal
transition on the dEMG activity
Hypothesis: providing and/or intensifying respiratory support will reduce dEMG
activity.

This will be a prospective observational multi-center cohort study at the
delivery room and baby room next to the operating room of the Emma Children's
Hospital in Amsterdam and the Willem-Alexander Children*s Hospital in Leiden.
*

The study population will not benefit from participating in this research.
Participation in the study includes the period after birth only and the
measurement is done with a non-invasive technique. This study will expand the
understanding of the pulmonary transition in newborn infants and potentially
also provide feedback and educate caregivers on their efficiency of
resuscitation.