Transcript Document
Do We Need Fumigation In Our Indian Operation Theatres?? - Dr. Ajita Mehta President HIS-I Consultant Microbiologist P. D. Hinduja National Hospital & MRC Veer Savarkar Marg, Mahim (West) Mumbai – 400 016 Points to be discussed ………… Critical Parameters for ideal Operation Theatre (OT) Indian Scenario about OT What is Fumigation / Fogging Do we need fumigation in India? What will be the Take Home Message? Critical parameters for OT Filter air through 2 layer beds in series (efficiency of the 1st filter bed being >30% & that of the 2nd filter bed being >90%) HEPA filters (to remove > 0.3 m with an efficiency of 99.97%) Positive pressure Requirement of 15-20 air changes /hour with a minimum of 3 air changes of fresh air (20%). Air should flow from the ceiling & be exhausted near the floor Temperature of 20- 220C, is comfortable & inhibits bacterial growth Relative humidity 30-60% to slow down bacterial growth Laminar airflow (ultra – clean air) & UV radiation have been suggested as additional measures in certain situations (orthopedic operations) Heating Ventilation Air Conditioning (HVAC) Systems HVAC system maintain indoor air temp. & humidity, control odours, remove contaminated air & minimize the risk of transmission of airborne microorganisms Consists of air inlets, filter beds, humidity modification mechanisms, heating & cooling equipment, fan ducts & air exhausts Fumigation is no longer used in the Western Literature as they have all the modern critical parameters required for OT Indian Scenario In India, there are extreme situations in operation theater (OT) facilities, ranging from rooms with fans, window air conditioning, to the more sophisticated laminar airflow systems More than 60-80% of OTs, donot have air handling unit (AHU) & other modern facilities with critical parameters In hospitals that lack heat ventilation air conditioning (HVAC) systems the quality of air in the OT cannot be guaranteed What can we do in such circumstances?? Fogging Nebulization of a disinfectant to decontaminate rooms vacated by patients with communicable diseases. The origin of fogging can be traced to the 19th century when Lister aerosolized carbolic acid to improve antisepsis in operative practice What Is Fumigation? Fumigation consisted of a mixture of formalin (280 ml) and potassium permanganate (150 gm) being placed in a bowl. The room would then be sealed & opened 12-24 hours later. Later on this changed formalin being sprayed with humidification by a spraying device or automist. Temperature 180C & Humidity should be maintained to 600C Different Methods 1. Carboxyl acid & fumigation with Formaldehyde Advantages – Established age old technique Cost effective Disadvantages – a. Carboxylic acid has efficacy as scouring and disinfecting agent b. Time consuming, min 24 hrs turn around time c. Self defeating – OT fumigated with Formaldehyde needs to be force de-aired with unclean air d. Unsafe Formaldehyde is carcinogenic 2. Aldehyde based germicides Glutaraldehyde & formaldehyde (200 ml in 10 liters of water i.e 2%) through fogging machine is the commonly used procedure. Advantages- Effective Disadvantages – a. Leaves sticky residue because of surfactant base b. Self defeating – OT fumigated with Formaldehyde needs to be force de-aired with unclean air c. Unsafe- Formaldehyde has been identified as a carcinogen 3. Silver (Ag) and Hydrogen Peroxide (H2O2) Advantages – a. Has deep penetrating capability b. Has no known resistant strains c. Effective against Bacteria, Viruses, Mycobacteria, Amoeba, Fungi and spore forming organisms A fogging system Droplets~7microns thrust by a motor running at 20,000 RPM to a distance of 15 m Solution Ecoshield – 11% Hydrogen Peroxide and 0.01% dilute sliver nitrate Efficacy of Fumigation / Fogging method Viable bacteria may fail to grow when cultured in the presence of disinfectants Neutralization of disinfectant (ammonia vapours or water) is must before collecting air samples or swabs Lecithin & Tween – 80 in appropriate concentrations are suitable neutralizing agents Environmental contaminants are generally associated with organic residues that bind & deactivate most disinfectants, (least likely to be benefit in those areas contaminated with organic materials such as blood, feces or pus) Fogging hastens the process of setting of airborne microorganisms. Mist, generated by a disinfectant or water would achieve the same process Air sampling is useful to detect aerosols or particles of microorganisms. (requires particle counter & practical method for evaluating efficiency of filters) Air sampler The Unresolved issues of microbiologic sampling are: Lack of standards Lack of Standard protocols for testing Sensitivity of sampler used Such sampling should largely be reserved for epidemiological investigations during outbreaks No studies to demonstrate that fogging actually reduces the incidence of nosocomial infection. The role of contaminated environmental surfaces in causing nosocomial infection remains to be elucidated* Controlled studies at CDC have demonstrated that quaternary ammonium fog does not produce a significant (one log )reduction in bacterial counts of S. aureus or E. coli, even in areas in completely saturated with residual disinfectant* *CDC: National Nosocomial Infections Study Quaterly Report, Third Quarter. 1971: isuued May 1972) In India, studies have not compared standard cleaning practices with fumigation/fogging. No substitute for vigorous scrubbing, washing of surfaces & removing the organic matter Safety of repeated exposure of humans to disinfectant & fog has not been established Inspite of these drawbacks it is the best alternative for - litigation - good & safe hospital practices, - check up of human default - favourable psychological effect on staff & patients - to improve the standard of hospital hygiene & asepsis Points to support Significant reduction in the number of bacteria in the ambient air Effective decontamination of exposed environmental surfaces Decreased risk of infection for housekeeping personnel engaged in terminal cleaning Decreased housekeeping costs Secondary psychological benefits for hospital personnel Take Home Message…… Fumigation is the only alternative however following precautions should be taken Replace formalin with a safer agent like a H2O2 stabilized with a silver salt It has no role in OTs with modern day HAVCs For litigation after fogging do the air sampling & keep the record This is not an alternative to mechanical cleaning of surfaces If surgeries are being performed with window airconditioners fogging would be required on a daily basis not on weekends alone as is practiced (WHO guidelines on prevention & control of Hospital Associated infections SEA-HLM-343. Jan 2002)