Discussion
Patients with severe traumatic brain injury are often accompanied by
different degrees of respiratory disorders. In order to prevent the
deterioration of the condition, tracheotomy is often required. After
tracheotomy is conducted, airway humidification must be performed,
otherwise the airway mucosa will be injured and even neuron dysfunction
will be brought about15. Patients with
severe traumatic brain injury are often hospitalized for a long time,
choosing appropriate airway humidification can effectively help severe
patients reduce the occurrence of complications and reduce patient pain.
In this study, we selected three relatively common humidification
methods and compared their effects on airway humidification in patients
with severe traumatic brain injury. Through the evaluation of the
relevant indicators, we found that all three methods can effectively
maintain the patient’s respiratory related indicators in the normal
range, and the C method has comparative advantages.
In this study, the first 7 days were chosen to evaluate these three
methods, for that the clinical data in the first 7 days were relatively
intact, and the patients usually transferred to better hospitals or the
near-home hospitals for further therapy. In this study, we chose to give
the spontaneous breathing patients with low speed of oxygen at the acute
injury stage to ensure the oxygen supply of the brain, and to gain
higher SpO2 and lower respiratory rate. Given the fact
that 67% of the patients suffering cerebral hypoxia after severe brain
injury in acute injury stage, and over oxygen supplement usually induce
injury to the lung tissue, we chose 7 days as our study duration to give
oxygen supplement. Some previous
studies13,
16 indicated that C method usually gains
better SpO2, while our results showed that the
SpO2 was lower and respiratory rate was higher in group
B and C than group A, and no difference was observed between group B and
C. The reason may be that, the cold air flow in group A cause the airway
contraction and prevent the oxygen exchange, and the supplement of
oxygen to the patients diminished the differences between group B and C.
As we know, the blood oxygen concentration will decrease when the airway
spasm by cold air or the patient
coughs17, and
temperature of inspired gas is closely related with the airway
function18. In the B
and C methods, air flow is heated and humidified, which is more
comfortable and does not easily cause the patients’ airway reaction.
When the airway is cut, the warming and humidifying process of the upper
respiratory tract to the gas disappears. Therefore, as the airway opens
up, the viscosity of the phlegm in each group increases, but the B and C
methods can slow this process. Compared to B and C methods, method A is
usually gained worse humidification effects, mainly insufficient. In
addition, patients with severe traumatic brain injury often need to use
a large amount of dehydrating agents, thereby aggravating the dryness of
the airway, which is more likely to cause viscous scab in the airway and
increase the chance of lung infection in the patient19. For these reasons,
the patients in group A need the least sputum intake operation, but were
easy to form phlegm scab
At present, HME is a commonly used airway humidification methods in
major hospitals, mainly considering its highly effective humidification
effect 20. However, Boots et al. believes that HME
will increase airway resistance after 24 hours of usage, so they need to
be replaced every day 21. A method is relatively
cost-effective, humidifying, but it is not stable, and it is prone to
subjective judgments by nurse, thus forming excessive or insufficient
humidification, and following a large amount of foam secretions, then it
caused cough or shortness of breath, and reduced oxygen saturation. And
the nurse needs to continuously observe the amount of humidification,
which would increase the workload
B method is designed to use the moisture the patients exhaled to get a
better humidification effect, so it can reduce airway stimulation and a
good humidification effects just as C method, but the excreted sputum
will be directly adsorbed on the filtration network. If the sponge was
contaminated by the sputum, the nurse staff needs to clean the sputum
adsorbed sponge frequently (about 2 hours/times), which greatly
increases the workload. And when the nurses change the contaminated
sponge with high frequency, the heat and moisture was released, and the
patients were easy to suffer insufficient humidification and increase
the viscosity of the sputum. Although the suction times of method B is
less than method C, the nurses need to use extra time to deal with the
sponge, and then the nursing load would not significantly be reduced.
The use of a humidifier and an unused humidifier can significantly
increase the relative humidity and temperature of the air
flow22, as in this
study, the C method can provide the best humidity, temperature, and
reduce airway spasm, which is conducive to the formation and discharge
of sputum. The excretion of sputum is benefit for reducing the incidence
of secondary pneumonia. Though the outlet tubes of the device in C
method is not suitable for the patient’s movement, it is suitable for
patients with severe traumatic brain injury whom lay in bed for long
time. In this study, the data were collected from our trauma center, and
we focused on the humidification effects to STBI patients, but our
results may not limited on the airway nursing of STBI patients, our
conclusions may also serve for the other patients that need high quality
of airway humidification. The shortage of this study was that, it was a
retrospective study, instead of a strictly controlled randomize clinical
trial, and the recruit of the patients is not randomized. In addition,
we focused to evaluate the humidification effects of these three methods
in the first 7 days, consecutive studies might be carried out to
evaluate the long-term effects of the three methods.