Assessment of respiratory effort in healthy volunteers: esophageal pressure versus noninvasive monitoring techniques.

Esophageal pressure measurement is considered the gold standard technique for
measuring respiratory effort during polysomnography in the context of
obstructive sleep apnea (OSA) research. However, in clinical practice this
technique is not often used because the insertion of an esophageal pressure
catheter is time-consuming, requires competent staff, the catheter is not
always tolerated or can even disrupt the patient's sleep. There are several
promising non-invasive techniques on the market to measure respiratory effort.
To date, however, little research has been done on how these non-invasive
techniques relate to esophageal pressure measurement.

The aim of the study is twofold: 1) to determine the relationship between
invasive (gold standard) and non-invasive techniques for measuring respiratory
effort. 2) by means of gradations of snoring intensity, the relation between
respiratory effort and snoring intensity is examined. Both research questions
are examined in an experimental study in healthy volunteers.

Through advertisements, a call is made to healthy volunteers to participate in
this study. Volunteers who meet the inclusion criteria, different measuring
instruments will be applied: esophageal pressure catheter, thoracic abdominal
bands, diaphragm EMG, EMG of the m. Sternocleidomastoid, suprasternal pressure
measurement, pulse oximetry, ECG and transcutaneous CO2 measurement. The
examination room is equipped with a microphone for snoring analysis that hangs
one meter above the test subject. During the measurement itself, the test
subject receives a in which the resistance can be adjusted.

In the first phase of the study, volunteers are asked to breathe through a
mouthpiece and the resistance will gradually be increased by 10 mmHg per
session to a maximum of 60 mmHg. In the second phase of the study, the
volunteer is asked to snore with three different intensities, ie soft, harder
and as hard as possible.

There is no direct benefit for the volunteers to participate in this study. The
participants have to come only once to the Centre of Sleep Medicine
Kempenhaeghe in Heeze . The full duration of the examination, application of
the equipment plus measurement, will take approximately one hour. The
potentially most stressful technique during this study is the esophageal
pressure measurement. In some candidate subjects insertion of the esophageal
catheter may not be possible due to nasal obstruction, so that participation in
the study is not achievable. Although esophageal pressure measurement is a
standard clinical technique , in some volunteers the catheter could be
experienced as uncomfortable or even painful, so they might choose to stop the
study. Possible complications of a esophageal catheter are irritation of the
mucous membrane and nose bleeding. The other techniques are not invasive and
the risk of damage is minimal.