Tidal Breathing Studies
Tidal breathing analysis (TBA) is an attractive method of respiratory
function testing because it can be done without the need for sedation or
the requirement of forced expiratory maneuvers [21]. TBA can be
performed using a face mask and pneumotachometer, but this can be
challenging to apply in infants since it requires the infant to maintain
a seal over the nose and mouth with the mask, which can also potentially
alter infant breathing patterns. Electromagnetic inductance
plethysmography (EIP) measures changes in the electromagnetic field
created by tidal breathing while wearing a metallic vest through which a
low voltage is applied. Sautter, et al used EIP to perform TBA in a
cohort of 36 infants with bronchiolitis [22]. EIP was successfully
performed in 80% of the infants, and a significant increase in the
ratio of the total expiratory time over the inspiratory time (Te/Ti) was
observed after inhalation of normal saline. The ratio of the time to
peak expiratory flow over total expiratory time (Tptef/Te) decreased
after administration of nebulized normal saline, but this change was not
statistically significant. This study demonstrates the feasibility of
using EIP for TBA and suggests that further study of the physiologic
effects of inhaled normal saline in bronchiolitis are warranted.
Traditionally TBA has been done manually, which is a time consuming and
laborious process. A study by Gomes et al. compared two computing
systems, AutoCAD and MATLAB, in their ability to obtain automated TBA
data [23]. Thoracoabdominal area averages calculated with both
systems were comparable, but MATLAB required less time and less user
training to complete. They suggest that it could be used in the clinic
setting to calculate or derive tidal volume measurements.