PRESENTED BY ENG. PRISCILLA NAKIBONEKA SANITARY ENGINEER, MINISTRY OF HEALTH, UGANDA.

 This presentation focuses on Engineering methods for the control of infections.  It is structured as follows:  Section 1: Introduction  Section2: Sources of infection  Section 3: Chain of infection  Section 4: Infection control measures  Section 5: Engineering methods  Section 6: Conclusions

 Infection control measures are required to protect health workers and others from infection.  Infection control programme: various practices, used appropriately, restrict spread of infection.  Health care administrators should ensure implementation of infection control programme.  Guidelines prepared by WHO to assist in the implementation of the programme.  Emphasis is put on precautions that should be taken and these include engineering interventions.

 There are three main modes by which health care associated infections are transmitted:  Environment via air, water, food  Devices such as IV lines, suction catheters and respiratory therapy equipment.  Personnel for staff, visitors and other patients.

 Transmission of a pathogen resulting in infection requires the six vital links as follows: i) Causative agent ii) Infectious reservoir iii) Portal of exit from reservoir iv) Mode of transmission v) Portal of entry into the host vi) Susceptible host

 Infection control measures are grouped into two categories: i) Standard precautions: Must be applied to all patients irrespective of diagnosis or infection status. ii) Additional precautions: Specific to modes of transmission (airborne, droplet and contact)

 Standard precautions involve work practices that are essential for a high level of protection to HCW, patients and visitors.  Hand washing and antisepsis  Use of personal protective equipment when handling blood, excretions, body substances etc  Appropriate handling of patient care equipment and soiled linen.

 Additional precautions are taken while ensuring standard precautions are maintained. These include:  Airborne precautions  Droplet precautions and  Contact precautions.

 Engineering interventions are required to enable application of standard and additional precautions. These include i) Design of buildings at health facilities to ensure a) Adequate water supply b) Adequate floor space for wards c) Adequate bed spacing d) Adequate hand washing facilities e) Adequate ventilation for isolation rooms and high risk areas such as theatres and intensive care areas.

 Adequate isolation facilities for airborne, droplet, contact isolation and preventive environment.  Regulation of traffic flow to minimise exposure of high risk patients and facilitate patient transport.  Precautions to control rodents and pests.  Appropriate waste management facilities such as placenta pits, medical waste pits, incinerators etc.

 Detailed design aspects may include the following;  Ventilation;  Should be designed and maintained to minimise microbial contamination.  May be natural ventilation system or a mechanised ventilation system.  Natural ventilation should allow for cross ventilation and adequate sizing of windows.

 Natural ventilation benefits; i) Inexpensive ii) Effective if well designed iii) Low maintenance iv) Sustainable  Natural ventilation limitations include: i) Requires proper design ii) Doesn’t work if windows are closed iii) May not be feasible due to climatic conditions iv) Staff and patients must abide by policies.

 Mechanical ventilation ; i) Exhaust fans ii) Air conditioning systems iii) Air handling units etc  Benefits  Only feasible solution in view of climatic conditions in some areas  May work effectively with good design and maintenance  Does not rely on staff and patients

 Fans should be provided only in recommended areas and their location is critical.  Filters for AC systems should be cleaned periodically and replaced as recommended.  For operating rooms, critical parameters for air control may include; i) Frequent maintenance/validation of efficacy of filters in accord. With manufacturer’s instructions. ii) Pressure gradient across filter bed and in theatre

iii) Air changes per hour (15 minimum) iv) Temperature should be between 20 and 22 degrees centigrade and humidity between 30% and 60% to inhibit bacterial multiplication. v) General areas should be well ventilated if not air conditioned.

 Special air handling for air borne precautions may include interventions such as  Negative air pressure vented to the air is recommended for contaminated areas.  Isolation of patients with infections spread by air by air borne route.  An air handling system with 6-12 ACH with air discharged to outside via filtration.

 Air flow path is critical. Flow should be from clean to less clean.  Ante-room part of isolation units since they prevent backflow of contaminated air into corridors.  In the absence of negative pressure rooms, air conditioning with an exhaust system may be used or well ventilated room. In absence of AC, fan may be used to direct air flow towards open window.

 Other options for cleaning the air include  Air cleaners: of varied types including use of filters, negative ions, ozone generators etc  Ultra Violet Germicidal Irradiation (UVGI): Using radiation to prevent transmission of air borne infections. Air mixing is very critical for good performance.

 Water  Water tanks to have a provision for cleaning and water quality tested periodically.  Cleaning  Floor areas should be designed to allow for ease of cleaning especially in theatres.  Waste management:  For treatment of waste, appropriate specifications should be given for autoclaving.  Appropriate incinerators should be recommended as necessary.

 Waste disposal  Appropriate options should be recommended with necessary design details. Options include - Land fills Medical waste pits Placenta pits Deep burial etc The above examples clearly illustrate the engineering interventions for infection control

 Infection control measures are required at all health facilities to minimise transfer of infections.  Engineering methods play a significant role in the application of standard and additional precautions.  They should be planned, budgeted and implemented for a successful infection control programme.

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