Study On Distribution Characteristics Of Indoor Particulate Matter And Bacteria In ICU

The infection is still one of the serious problems existing in the cleanroom.As the key department of the hospital,ICU is a place where indoor critical patients are concentrated.Due to the complicated work content,low patient resistance and large flow of people,the department is prone to cross-infection.The distribution of particulate matter and bacteria has an important impact on cross-infection,so the study of indoor bacterial and particulate matter distribution has a guiding role in reducing indoor infection.Firstly,the model analysis method is used to establish a prediction model of indoor particulate matter concentration in ICU under one time return air condition system.From the theoretical point of view,the effects of outdoor particulate matter concentration,dust generation,particle sedimentation and resuspension on indoor particulate matter concentration were analyzed.The experiment method was used to analyze the influence of outdoor,personnel and nursing on the indoor particle size and bacteria concentration.Finally,the spatial distribution of indoor airflow and different particle size was simulated by RNG turbulence model and Lagrangian discrete model.And for the problems existing in the ICU,the blocking countermeasures to avoid cross-infection are proposed.The specific contents and conclusions are as follows:(1)Based on the common return air conditioning system in ICU,the indoor particle prediction model of ICU was established,and the influencing factors of indoor particulate matter concentration were analyzed from the theoretical point of view.The results show that under the conditions of other parameters,the indoor particulate matter concentration increases with the increase of outdoor particulate matter concentration and indoor dust source dust generation;resuspension of particulate matter is one of the factors that increase the concentration of particulate matter in the room;the sedimentation of particulate matter has a positive effect on the reduction of indoor particulate matter concentration.(2)The concentration of indoor particulate matter and bacteria in the general and nursing state were tested by on-site experiment,and the influence degree of outdoor environment,personnel and nursing on the indoor particle size and bacteria concentration was analyzed.Studies have shown that the indoor particulate matter concentration is affected by both outdoor environment and personnel;when the outdoor particulate matter concentration is high,the indoor particulate matter concentration is mainly affected by the outdoor environment,and when the condition is opposite,it is mainly affected by personnel;the nursing operation increases the indoor particulate matter and bacterial concentration;after treatment,the concentration of fine particles and bacteria in the room was lower than that before the treatment,but for the coarse particles,there was no significant change before and after the treatment.(3)Through the numerical simulation of the particle size distribution of different particle sizes in the ICU under normal conditions,it is found that no matter the particle size,the concentration of particles near the patient and the return air side is large,and the bottom of the bed and the corner are locations where particles and bacteria are easily deposited but not easily discharged.Large particles are basically deposited on the surface of the ground or objects after being released from the pollution source,and are not easily discharged to the outside with the airflow.According to the above problems,this paper proposes improvement measures from the aspects of fresh air,personnel,purification equipment,sputum disinfection and airflow organization.Through the study of the distribution of particulate matter and bacteria concentration in ICU,the results can provide reference for indoor air quality and cross infection control.