Comparison of a solid state versus balloon esophageal catheter for the estimation of pleural pressure in healthy subjects

Measurements of esophageal pressure (Pes) as surrogate for pleural pressure are
routinely performed in selected ICU patients to facilitate lung-protective
ventilation and assess breathing effort. Pes is clinically measured via an
esophageal catheter inserted nasally or orally. Current techniques involve
balloon catheters. Unfortunately, the balloon deflates over time, thereby
attenuating the pressure signal, leading to underestimated breathing effort of
the patient. In turn, this can result in prolonged weaning and increased
incidences of ventilator induced lung injury (VILI). Additionally, it is
becoming evident that balloons need to be filled with a custom amount of air,
as the patient's respiratory mechanics, lung volume and mechanical condition of
the balloon all influence its output. Given these possible drawbacks of
balloon-catheters, one might consider using a solid state esophageal pressure
catheter for the measurement of Pes. Another advantage of a catheter with
multiple solid-state sensors is that pressure can be measured at different
locations on the catheter. This may give more information about regional
pressures, compared to the single pressure measured with a balloon catheter.

To evaluate the accuracy of Pes under different levels of inspiratory loading
and positions of the subject, measured with a solid state esophageal catheter
compared to those Pes obtained by a standard balloon catheter.

This is a physiological validation study in healthy subjects.

The goal of this study is to improve the technique to measure respiratory
parameters, which should improve the respiratory support for patients. We do
not expect high risks for participating in this study, as measurements will be
performed on healthy subjects. The burden to the subject of placement of the
catheters used in this study is similar to the placement of a regular
nasogastric feeding tube. From our clinical experience, we consider these risks
minimal, especially when *high-risk subjects* are excluded (upper airway /
esophageal pathology, nasal bleeding disorders) and insertion performed by
well-trained nurses or (technical) physicians. Measurements will take place in
a safe environment (research room at the intensive care unit), where potential
risks can be anticipated immediately. Therefore, we believe that risks are
minimal. All other study procedures involve non-invasive measurements. Subjects
have no direct benefits from participating in this study. However,
participation will benefit to further knowledge and the possibility of
improving monitoring of respiratory mechanics.