| Biological particles in the air that enter an wound during surgery can result in surgical site infections(SSIs).SSIs contribute substantially to the increased medical expenses,morbidity and mortality of patients.Therefore,the control of airborne biological particles in the operating room is particularly important.However,the surgical process is a dynamic process,and the airflow distribution and the diffusion behavior of biological particles under dynamic conditions will become complicated and unknown.In this paper,numerical simulation method combined with dynamic mesh technology was used to study the airflow disturbance and the diffusion law of biological particles under the dynamic behavior characteristics of operating room.At the same time,the control effect of biological particles under differe nt air supply patterns in operating room was compared.First,the basic theory of numerical simulation was introduced,and the experimental data of published literatures was used to verify the turbulence models and the particle discrete phase model in the numerical simulation.Then a dynamic scenario experiment simulation was carried out in a full-scale surgical laboratory,and the airflow velocity and biological particle spatial concentration were measured.Based on the experimental boundary conditions,the numerical models were applied to simulate the above dynamic scenarios,and the distribution characteristics of biological particles were analysed.Meanwhile,the measured data was compared with the simulated data to further verify the reliability of the numerical models used.Subsequently,the verified numerical models and dynamic mesh technology were used to simulate a circulating nurse walking during the operation.It was found that the circulating nurse walking had no effect on the airflow near the pat ient,but it interfered with the airflow above the instrument table and caused the biological particles to spread to the area above the instrument table,which increased the possibility of biological particles depositing on the surgical instrument and the potential infection risk of SSIs.But reducing walking speed can help reduce this risk.The same method was used to simulate the entire process of the surgical staff entering the operating room.It was found that the entry of surgical staff increased the air volume into the operating room and caused a large number of biological particles to enter the operating room.And as the walking speed of the surgical staff increased,the air volume into the operating room and the biological particle intrusion ratio also increased.Finally,the airflow field distribution and the biological particle control effect of the operating room were studied under different air supply patterns,and it was found that the temperature-controlled air supply had the best performance in maintaining the air cleanliness in the operation area.In addition,it was also found that the air cleanliness of the operating area not only depended on the airflow supply rate of the ventilation system,but also related to the airflow distribution,which was significantly affected by the obstruction of the operating lamp and the surgical staff and its thermal plume.Although the ventilation system can better control the diffusion of biological particles in the operating room and keep the air in the operating area clean,reasonable activities of surgical staff during the operation are very necessary to reduce the concentration of biological particles in the operating room.The research results in this article provide references for the ventilation design o f the operating room and guidance for the activities of the surgical staff during the operation. |
