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.