Preventing Infectious Disease Transmission

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Preventing Infectious Disease Transmission. Thomas P. Fuller ScD, CIH, MSPH, MBA Tech Environmental Massachusetts Nurses Association. Transmission of Disease. Environmental viability, Exposure route, Exposure pathway, Infectious dose, Incubation, Organism size/mass/density, - PowerPoint PPT Presentation


<ul><li><p>Preventing Infectious Disease TransmissionThomas P. FullerScD, CIH, MSPH, MBA</p><p>Tech Environmental Massachusetts Nurses Association</p></li><li><p>Transmission of DiseaseEnvironmental viability,Exposure route,Exposure pathway,Infectious dose,Incubation,Organism size/mass/density,Lethality,Treatment, Communicabilty,Control.</p></li><li><p>Control of Hospital Infections-A Practical Handbook G. Ayliffe (2000)Infection Control TeamPhysicians, ICNs, ManagementICN ActivitiesSurveillance of infections,Rapid identification and investigation of outbreaks,Advice on isolation of patients,Development of policies and procedures to control the spread of infections,Training staff,Preparation of annual statistical reports of infection rates.</p></li><li><p>Hospital IC Goals and MeasuresImprove hand hygiene,Increase environmental cleaning,Improve equipment cleaning,Expand contact precautions, </p><p>As measured by,Increased soap use,# of training sessions,Reduced # of infections, andPersonnel accountability scorecards.</p></li><li><p>Goals Did NOT Include:Discussion of worker safety,Environmental or personal monitoring for infectious agents,Evaluation of disinfection or sterilization techniques of chemicals,Use of engineering controls such as ventilation or filtration,Selection and use of Personal Protective Equipment (PPE),The expertise of an Industrial Hygienist.</p></li><li><p>Healthcare Workers at RiskInjury and illness rate of 10.1</p><p>Greatly under reported due to difficulties in to documentation, job classification, poor categorization of activities, long latent periods {HIV, Hepatitis}, and large varieties of sources and symptoms.</p></li><li><p>Occupational Threats to Naturally Occurring Infectious AgentsExistingTB, HIV, hepatitis, measles, smallpoxEmergingNew agents or strains (SARS, H5N1 flu, MRSA),New vectors (moving between species),New pathways,Possibly more infectious,Possibly more lethal,Super Spreading Events,Less understood (vaccines, treatment, transmission, viability).</p></li><li><p>SARS and Healthcare Workers774 deaths/&gt;8,000 SARS cases worldwide (~9%), Low infectivity, high severity,Many cases hospital acquired (nosocomial),44 deaths/375 cases(~12% in Toronto),42% of SARS cases were healthcare workers Toronto (57% Vietnam) (Booth),Other reported mortality rates range between 34-52%.</p></li><li><p>SARS and Healthcare WorkersTransmission may be via inhalation of aerosols or droplets, or mucous membrane contact with fomites or body fluids,</p><p>Infection rate was directly proportional to time spent in the patients room and illness severity.</p></li><li><p>SARS Hospital Management ShortcomingsFailure to track patient contact history,Lack of healthcare worker surveillance,Failure/availability of ventilation systems and personal protective equipment,Failure to track visitor contacts,Lack of communications and preparednessRecognition of disease, perception of risk, understanding disease, inability to prevent spread.</p></li><li><p>H5N1 Influenza Pandemic Threat</p></li><li><p>Current WHO Phase of Pandemic Alert</p></li><li><p>"It is only a matter of time before an avian flu virus -- most likely H5N1 -- acquires the ability to be transmitted from human to human, sparking the outbreak of human pandemic influenza"Dr. Lee Jong-WookWHO Director-GeneralNovember 7, 2005</p></li><li><p>The Next Pandemic?</p></li><li><p>H5N1 FearsWorlds population is immunologically vulnerable,A new strain for which there are no residual antibodies from previous seasonal influenza outbreaks,An extremely virulent disease, (52-55% mortality).(</p></li><li><p>Industrial HygieneMisunderstood and underutilized,IC is unaware of IH capabilities,Sophisticated IH activities are performed by other departments with little understanding or knowledge of IH principles,Decisions made based on outdated assumptions and poor understanding of IH concepts (e.g. aerosol physics),Difficulty for IH principles an suggestions to be understood or accepted.</p></li><li><p>IH ExpertiseAerosol/particle physics,Ventilation design/operation,Air filtration systems,Exposure assessment and control,Contamination control/decontamination (toxicology),Risk assessment,Personnel Protective Equipment, Respiratory Protection,Biological hazards, andAir monitoring/sampling and analysis.</p></li><li><p>Industrial Hygiene, defined:Anticipation* Recognition*EvaluationControl </p></li><li><p>EvaluationHistorically very little monitoring of infectious agents is done in U.S.,Low germ loads led to the feeling that monitoring didnt provide any useful information at such low levels,As a result few hospitals maintain the equipment or expertise in airborne or surface monitoring for infectious agents,Additionally, not a lot is known about how and what to monitor, viability, and what are acceptable (safe) concentrations.</p></li><li><p>Air Sample ConsiderationsWhen to sample?Commissioning, before occupancy = baseline,Measure all parameters for ventilation assurance and cleanliness,To provide comparison data for future operations,Disease outbreak analysisMeasure all parameters with empahsis on source detection,Surface and air content for dust and fungi,SurveillancePressure is most important,Air exchanges for purging,Non viable particles to assess filtration efficiency,Viable organisms.</p></li><li><p>SAS Air Sampler</p></li><li><p>Interpretation of microbiology DataRank order analysisLowest counts in the areas with best filtrationComparison necessary with outdoor controlQualitative analysisPathogen recovery Temperature selectivityPathogens grow best at &gt;35CFiltration efficacy determined at 25C</p></li><li><p>Surface Monitoring and EvaluationNot historically done to a great extent in health care,Very useful demonstration during the SARS outbreak to demonstrate transmission throughout the hosptial ,cfus per square cm.</p></li><li><p>Control of AerosolsReduce generation at source,Containment at the source,Reduce survival in the environment,General exhaust ventilation,Local exhaust ventilation,Ventilation filtration.</p></li><li><p>AerosolsSolid or liquid particles and the gas in which they are suspended.GasLiquidFog, mist, spray, haze.SolidDust, fume, smoke.Solid or LiquidSmog, cloud.</p></li><li><p>Factors Affecting Aerosol GenerationEnergy InputLow = large particlesHigh = small particles.</p><p>Infectious UnitsOrganisms per unitVolume of original suspension</p><p>Persistence particle size.</p></li><li><p>Aerosol Buildup in Ventilated Space 30 air changes per hour required to maintain or reduce concentrations,Highest concentrations are in work areas,Breathing zone is within 3 feet of source.</p></li><li><p>Filtration SystemsReduce contaminates in the air from local or general exhausts,Variety of efficiencies for aerosols and gases.</p></li><li><p>Engineering ControlsFacility Design - isolationVentilationFiltrationChemicals, gases, irradiative (UV, IR, RF, microwave, heat)IsolationSecurity Systems ?</p></li><li><p>monitorcorridorPositive Pressure Room ControlIntended usage's:positive pressure greater supply than exhaust air volumepressure differential @ &gt;2.5 Pascal's or 0.01"w.g. ideal at 0.03wg or 8 Pascals-range from 2.5 to 8.0 Pa greater than 125 cfm airflow differential supply vs exhaust sealed room, about 0.5 sq feet leakagemonitoring&gt;12 air exchanges per hour </p><p>recirculate air back through filtersclean to dirty airflow, immune compromised patient roomsoperating rooms</p></li><li><p>monitorcorridornegative pressure greater exhaust than supply air volume</p><p>pressure differential @ 2.5 Pascal's or 0.01"w.gsealed room, with about 0.5 sq. feet leakageairflow differential &gt;125 cfmmonitoring</p><p>&gt;12 air exchanges per hour new or 6 ac/hr renovation</p><p>exhaust to outside or HEPA filtered if recirculatedNegative Pressure Room for Airborne Infection IsolationIntended usage's:</p><p>+procedure/treatment rooms</p><p>+bronchoscopy rooms</p><p>+autopsy</p><p>+emergency roomsclean to dirty, airflow</p></li><li><p>Ventilation Controls% outdoor air,ACHVolume, direction, plena,EvaluationFrequency, acceptance criteria, IAQ, humidity, particulates,Filtration,Type, efficiency, testing, maintenance,</p></li><li><p>Ventilation/FiltrationHEPA Filter AssemblyHEPA Filter TechnologyBio-Seal Damper Butterfly typeBio-Seal Damper Dish type</p></li><li><p>Containment System Monitoring Monitors and alarms:HEPA FiltersAirflow VelocityBuilding Exhaust FansPrimary Containment</p><p>Periodic testingPatient isolation roomsNegative pressure labsHospital ventilation and filtration systems</p></li><li><p>Establishing Baseline InformationAir qualityNon viable &amp; viable particles</p><p>VentilationAir exchanges, filtration &amp; pressure</p><p>Operational PracticePreventative maintenanceHousekeepingVisitation </p></li><li><p>Administrative ControlsPolicies/Plans/Programs/ProceduresOversight and ReviewEnforcementAccess Control/Contact/TransportTraining (simulated Labs, medical drills)Vaccination, patient screening and isolation, medical surveillance, prophylaxis and treatment,Cleaning, Disinfection, Sterilization. </p></li><li><p>ActivitiesContinually review infection rates and sources,Track and trend infection data,Develop programs and procedures,Communicate issues and work to develop solutions,Monitor systems and correct deficiencies.</p></li><li><p>Source Management Essential for Airborne Infectious Disease ControlPatient sources need to be recognized and isolated,Environmental sources need to be managed through training and procedural practice,Healthcare facilities must be maintained,New facility design should facilitate infection control measures.</p></li><li><p>Barrier managementSolid versus plastic barriers Short and long term Framed or taped barriersCeilings and doors as barriersSmoke and aerosol controlPressure differential management</p></li><li><p>Contamination ControlNot as well understood in health care as we might like to think (health physics, nuclear power),Little actual experience of workers with real-time monitoring, Little actual awareness of how agents are spread on surfaces or might physically move about,Few measurement methods currently available, basically none in real-time!</p></li><li><p>Contamination ControlConsists of making a best guess of where the agents are likely to be (get),Often there is very little understanding on the part of the medical community of the environmental viability of known organisms, much less unknown ones! (SARS).</p></li><li><p>Contamination ControlSterilization, Disinfection (normal, high level), Cleaning,People, surfaces, equipment,Ensure the methods (procedures) and agents are appropriate for the needs and dont expose patients or workers to undue risks,Chemicals (EtO, glutaraldehyde, formaldehyde, hydrogen peroxide, detergent),Physical agents (microwave, UV, IR).</p></li><li><p>Personnel Protective Equipment ControlsLaboratoriesLabcoats, closed gowns, gloves, glasses, goggles, face shields, booties, respirators, air supplied suits</p><p>Patient CareGloves, respirators, air supplied hoods, gowns, face shields, eyewear,</p></li><li><p>OSHAsRespiratory Protection Standard29 CFR 1910.134Permissible PracticeWritten Program/ProceduresMedical ClearanceFit-Testing and TrainingMaintenanceRecord Keeping</p></li><li><p>Respiratory ProtectionSurgical Masks are used to protect immunocompromised patients,</p><p>Respiratory Particulate Devices (RPD) N95 are recommended for worker protection.</p></li><li><p>Air-purifying RespiratorsNonpoweredParticle-removingGas-vapor removingCombination particle gas vapor removing.</p></li><li><p>Nonpowered Air-purifying RespiratorAdvantagesSmall and compactLightweightSimple constructionDoesnt restrict mobilityLow initial costDisadvantagesCannot be used in oxygen deficient atmosphereCannot be used in IDLH atmospherePoor warning propertiesPossible leakageCannot be worn with a beardHigh costHigh maintenanceLess comfortable, irritates eyes.</p></li><li><p>Powered Air-purifying RespiratorTypesParticle-removingGas-vapor removingCombination particle gas vapor removing.Used when;the agent is known,Air concentrations are known,No other hazards are present,Sufficient OxygenNo chemical hazardsNo radioactive materials.</p></li><li><p>Powered air purifying respiratorAdvantagesNo restriction on mobilityMinimal breathing resistanceCooling affect on wearerCan be worn for long periodsFit tests not requiredCan be worn with beardsDisadvantagesCannot be used in oxygen deficient atmosphereCannot be used in IDLH atmospherePoor warning propertiesFunctional limitations, restricts movementDiscomfort to wearersHigher cost and maintenance</p></li><li><p>Atmosphere Supplying RespiratorSupplied AirAirlineContinuous flowDemandPressure demandHose-MaskWith blowerWithout blower</p></li><li><p>Infection ControlPreventive strategies to limit the spread of infectious agents in the health care setting,Patient to patient,Staff to patient,Patient to staff, and Staff to staff.Extremely important JCAHO, patient satisfaction ratings, financially (stay and treatment durations),Cost of health care.</p></li><li><p>Multidisciplinary TeamsInfection Control CommitteeMedical Doctors, Nurses, Epidemiologists, Administrators, Facilities Management, Risk Management, Industrial Hygiene, Occupational and Environmental Medicine, Central Processing/Product Sterilization.</p><p>2625</p></li></ul>


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