Evaluation Of Air Microorganism Detection And Purification In Intensive Care Unit

BackgroundPathogenic microorganisms usually diffuse and spread in the form of"aerosols"in the air,which lead to air pollution.When people inhale pathogenic microorganisms continuously,respiratory infections can occur.Air is one of the important media for the spread of pathogenic microorganisms.Pathogens in the air can not only directly cause hospital infections,but also indirectly cause the infections by polluting other medical equipments.Therefore,air quality is closely related to the nosocomial infections in the hospital.The Intensive Care Unit(hereinafter referred to as ICU),a treatment center for various types of critical patients,has many first-aid equipments and plays a very important role in the management and control of hospital infections.The high incidence of nosocomial infections in ICU has also greatly increased the mortality of patients,which is one of the important reasons for the failure of the rescue and the increase in medical costs.Air purification is one of the most important and effective measures to prevent the spread of pathogenic microorganisms,control nosocomial infections,and to ensure the health of critical patients in ICU.The traditional methods of indoor air purification include ultraviolet irradiation method,ozone disinfection method,formaldehyde fumigation method,etc.,but the above methods are carried out under static conditions,avoiding the peak hour.These methods can only temporarily sterilize while cannot effectively inhibit bacteria continuously.At the same time,it is easy to produce secondary air pollution.The above methods are often impossible to really highlight the degree of air pollution in ICU during normal working hours.Therefore,it is extremely critical to monitor the effect of air disinfection under normal activities in the ICU,and explore the evaluation of air disinfection and purification effects suitable for ICU,which is of great significance for improving the level of air disinfection in the ICU and reducing the incidence of nosocomial infections.ObjectiveUnderstanding the changing trends of air microorganisms in intensive care units under dynamic and static conditions;discussing the methods of air purification in ICU;and providing a basis for preventing ICU infections.MethodsThe experiment was carried out in a negative pressure ward with an area of about24m2 in ICU,a laminar flow ward with a total area of 250m2 and a single room area of about 24m2 from Jiahe Hospital of the Eighth People's Hospital of Guangzhou City and was conducted in three parts:Part one:Before and after the diagnosis and treatment of patients in the ICU and the operation of generating aerosols,the plankton sampling method was used to collect microbes in the air at three indoor diagonal sampling locations,and culture and colony counting were undertaken.The air microbial content and distribution of the ICU under relatively static and dynamic conditions was analyzed.Part two:According to the presence or absence of an air purifier and laminar flow system in ICU,the method in part one was used to detect the ICU air microorganisms before the diagnosis and treatment,during the diagnosis and treatment operation,30minutes after the operation,and 60 minutes after the operation to understand the on-site disinfection effect of air purifier and laminar flow system in ICU.Part three:Detect,identify and analyze the air microbial colonies collected in part two,compared with the patient's clear respiratory tract specimen culture results,and evaluate the distribution of air microbes and respiratory tract infection pathogens.Results1.The microorganism concentration in the negative pressure ICU dynamic group is(160.22±93.83)CFU/m~3,which is significantly higher than that in the relatively static group(92.67±34.47)CFU/m~3.The difference is statistically significant(P<0.01).The microorganism concentration in the laminar flow ICU dynamic group is(29.11±19.86)CFU/m~3,which is significantly higher than that of the relatively static group(4.67±5.04)CFU/m~3.The difference is statistically significant(P<0.01).2.The average bacterial concentration of negative pressure and laminar flow ICU after using the purifier at dynamic condition,at the time point of 30min and 60min is significantly lower than that of the unused purifier group.The difference is statistically significant(P<0.01).The bacteria concentration of negative pressure and laminar flow ICU after 30min and 60min using the air purifier decrease significantly compared with the dynamic group(P<0.01);The air bacterial concentration in the laminar flow ICU under the static and dynamic condition,at the time point of 30min and 60min is significantly lower than that in the negative pressure ICU.The difference is statistically significant(P<0.01).The bacterial concentration in the laminar flow ICU without the air purifier decrease significantly after 30 min and 60 min compared with the dynamic group(P<0.05).3.Bacteria in the air of ICU account for about 67.7%of the total microbial composition,of which about 76.6%are Gram-positive cocci,about 6.4%are Gram-negative bacilli,and about 32.3%are fungi(mainly mold).4.The distribution of air microbial colonies in ICU and patients'respiratory tract infection pathogens does not show consistency.Conclusion1.The air microbial concentration in the relatively static negative pressure and laminar flow ICU is qualified.2.During the operation of generating aerosols,the concentration of microorganisms in the air of the ICU significantly increases,and the air purifier and laminar flow system could effectively reduce the microbial concentration under dynamic(aerosol generating operation)status.It is recommended to use air purifier and extend the using time during the diagnosis and treatment in the negative pressure and laminar flow of the ICU.3.The distribution of air microbial colonies in ICU and patients'respiratory tract infection pathogens does not show consistency.