With the development of technology and the deterioration of environment,more and more attention was attracted to the research on fluid dynamics in human upper respiratory tract.In this paper,the methods of research on fluid dynamics in human upper respiratory tract were introduced,and the mechanical models of human upper respiratory tract which were constructed by the scholars in the resent years were summarized.In addition,the current status of research on the airflow movements,the transportation and deposition of the particles in human upper respiratory tract was analyzed.The developing trend of this field was prospected as well.

Objective Mobile operating compartment with overpressure protection can provide a safety environment for the patients and the surgical team by minimizing the risk of biochemical contamination through appropriate air filtration, steady overpressure foundation and air distribution scheme. Methods The air movement and the temperature distribution inside the mobile operating compartment with the overpressure protection performance were simulated by the technique of computational fluid dynamics(CFD), the air pattern and the temperature distribution were analyzed. Results The air velocity was under 0.5m/s in the most zone of person activity and the air velocity were distributed uniformly in the mobile operating compartment under the condition of the overpressure protection system. The obvious temperature gradient didn't exist in the vertical plane of the mobile operating compartment. The temperature distribution in the mobile operating compartment was quite uniform and the temperature was almost at 27℃ with the temperature difference of almost 2℃. Conclusion The human thermal comfort is good in the mobile operating compartment and the environment in the mobile operating compartment can satisfy requirements of the operation.

Objective To investigate the transportation of chemico-biological particles(CBP) through the micropassage inside the human body in order to improve chemico-biological protection.Methods Dissipative particle dynamics (DPD) method was used to study CBP transportation through micropassages inside the human body.Results The Poiseuille flow could be ensured by imposing boundary conditions including pressure gradient and no-slip.The axial velocity between fluid particles and CBPs was well matched except the area close to the passage wall.However, CBPs tended to accumulate and the density of CBPs slightly increased, leading to the jam effect and producing particle accumulation.Conclusion The characteristic of CBP transportation is better understood,which can help develop some chemico-biological protection devices according to movement of CBPs and improve the performance of CBPs during chemico-biological protection.

Obiective To study the compartment environmental quality of ambulance against biological contamination for safe and comfortable transportation and treatment of patients. Methods The experimental research and numerical simulation were carried to master the state of compartment environmental quality, Results Compartment environment indexes excel technology demands, such as overpressure/negative-pressure, temperature, biological contamination, vibration and shock as well as noise and luminance, Conclusion The compartment environmental quality of this ambulance is in a good state.

The research on cycle change form of the pressure and the wall shear in human upper respiratory tract can strengthen understanding of the characteristics of the airflow in the place and provide us with a scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol there. In our study, we used large eddy simulation to emulate the pressure and wall shear in human upper respiratory tract in conditions of the low intensive respiratory patterns, and discussed the distributing disciplinarian of the pressure and wall shear in mouth-throat model and trachea-triple bifurcation. The results showed that the pressure gradient variation in human upper respiratory tract was mainly fastened from root of epiglottis to trachea. The minimum pressure at the interim of inspiration was a duplication of the interim of expiration, and located on the posterior wall of the glottis. The pressure gradient variation was evident on trachea and its fork. The wall shear changed with the velocity of the air flow, and its direction changed periodically with breath cycle.
Biomechanical Phenomena ; Bronchi ; physiology ; Computer Simulation ; Epiglottis ; physiology ; Humans ; Mouth ; physiology ; Nose ; physiology ; Pharynx ; physiology ; Pressure ; Pulmonary Ventilation ; physiology ; Respiratory Mechanics ; physiology ; Respiratory Physiological Phenomena ; Respiratory System ; Shear Strength ; Stress, Mechanical ; Trachea ; physiology

Objective To evaluate the effect of transversus abdominis plane (TAP) block on postoperative cognitive function in elderly patients undergoing laparoscopic surgery under general anesthesia.Methods Forty-eight male patients undergoing laparoscopic tension-free repair of inguinal hernia under general anesthesia,aged 65-75 yr,of American Society of Anesthesiologists physical status Ⅱ or Ⅲ,with body mass index of 20-28 kg/m2,were divided into 2 groups (n =24 each) using a random number table method:TAP block combined with general anesthesia group (group TG) and general anesthesia group (group G).Anesthesia was induced with midazolam,cisatracurium besylate,sufentanil and etomidate,and the patients were mechanically ventilated after laryngeal mask airway insertion.TAP block was performed through the anterior superior iliac spine approach,and 0.25％ ropivacaine 30 ml was injected in group TG.Anesthesia was maintained by target-controlled infusion of propofol and remifentanil and muscle relaxation by intravenously injecting cisatracurium.The occurrence of cerebral regional oxygen saturation (rSO2) and low rSO2 events (rSO2 ＜60％) was recorded at 1 min before anesthesia induction (T0),5 min after inserting the laryngeal mask airway (T1),at skin incision (T2),30 min after skin incision (T3),and at the end of surgery (T4).The consumption of propofol and remifentanil was recorded during surgery.Montreal Cognitive Assessment (MoCA) was used to evaluate the cognitive function of patients at 1 day before surgery and 7 days after surgery,and the development of postoperative cognitive dysfunction (POCD,MoCA scores＜ 26) was recorded.Results Compared with group G,the intraoperative consumption of propofol and remifentanil was significantly reduced,rSO2 was increased at T2~,and the incidence of low rSO2 events was decreased,MoCA scores were increased at 7 days after surgery,and the incidence of POCD was decreased in group TG (P＜0.05).Conclusion TAP block can reduce the incidence of POCD in elderly patients undergoing laparoscopic surgery under general anesthesia.

Research on the deposition of inhalable particles in the alveoli of the lungs is important to the causes, development for common respiratory diseases such as emphysema, and even the optimization of clinical treatment and prevention programs of them. In this paper, an experimental model was established to simulate the deposition of terminal bronchioles and pulmonary acinus particles. The deposition rate of inhalable particles with different particle sizes in the pulmonary acinus was studied under different functional residual capacity. The results showed that the particle diameter was an important factor affecting the deposition of particles in the lung alveoli. Particles with 1 μm diameter had the highest deposition rate. With the functional residual capacity increasing, particulate deposition rate significantly reduced. The results of this study may provide data support and optimization strategy for target inhalation therapy of respiratory diseases such as emphysema and pneumoconiosis. The established model may also provide a feasible experimental model for studying the deposition of inhalable particles in the pulmonary alveoli.