When a person has an endotracheal tube or tracheostomy
inserted into their airway, the normal humidifying
function of the upper airway is bypassed. Moreover, given the
often critically ill nature of these patients, optimal humidification
of incoming air is even more crucial for these patients.
A number of studies have highlighted the serious adverse
effects of inadequate humidity on respiratory tract structure
and function, including inflammation, necrosis, and increased
viscosity of sputum that may lead to airway occlusion.1 At
present, heated humidification and heat and moisture exchangers
are the most commonly used types of artificial
humidification. Heated humidification may result in overhydration,
which can cause lung damage, bacterial contamination,
and increased inspiratory workload. With heat and
moisture exchangers, there may be an increased risk of
airway occlusion and inspiratory workload.2
A jet nebulizer works by changing a liquid into small
particles that are suspended in an air or gas stream by
directing a high flow of gas (oxygen) over a capillary tube
that is immersed into the fluid to be nebulized. To avoid the
fluid being completely used up in the nebulizer cup, a flow
regulator is connected to the nebulizer cup to ensure that the
fluid input is continuous. Sterile water can be used as a
nebulized fluid for humidification of inspired gases, thinning
of bronchial secretions, and also sputum induction. To avoid
having the jet nebulizer colonized with Legionella or Pseudomonas,
the jet nebulizer should be disinfected or changed
every day.
We would like to point out a few limitations of this
method: (a) The moisture generated by the jet nebulizer
without heating is cold, which may not be suitable for
patients with reactive airway syndromes. To resolve the
problem, we can heat the atomizing fluid by fixing the flow
regulator pipe into the enteral nutrition heating system, which
is near the nebulizer cup. (b) Because of oxygen-driven jet
nebulization, the inspired oxygen concentration may be relatively
high, the FiO2 is not measurable in this setup, and is
therefore less suitable for patients who could require
restriction of their inspired oxygen concentration such as
acute exacerbation of chronic obstructive pulmonary disease.
To make it work with a defined percentage of
administered oxygen, we can connect the setup to Maxtec
oxygen monitors/analyzers.
In conclusion, the combination of continuous oxygendriven
jet nebulization with flow regulation can be used as a
novel, simple, and cost-effective system for the continuous
delivery of humidity for patients with endotracheal tubes or
tracheostomies.