Surgical asepsis, sterilization and disinfection

Principle of Surgical asepsis, sterilization and disinfection

1. Principle of Surgical asepsis, Sterilization and Disinfection Presented by Ganga Prasad Yadav M.V.Sc ., 1 st Semester Veterinary Surgery & Radiology

2. Common Definitions Sepsis: Presence of pathogenic microorganisms, or their toxic products in the tissues of a patient. Asepsis: The absence of pathogenic micro-organisms in living tissues. Aseptic technique: The clean practice used to remove or destroy pathogens and to prevent their spread from one animal/people or place to another animal/people or place. Antisepsis: Prevention of sepsis by the destruction or inhibition of microorganisms using an agent that may be safely applied to living tissues.

3. Common Definitions Antiseptic: A chemical agent that either kills pathogenic micro-organisms, or inhibits their growth on animate (living) tissue. Example: Chlorhexidine Disinfectant: A germicidal chemical substance that kills micro-organisms on inanimate objects. Example: glutaraldehyde . Disinfection: Removal of micro-organisms, but not necessarily their spores and viruses found on non-living objects. Sterilization: complete elimination of microbial viability, including vegetative forms of bacteria and spores by physical or chemical means.

4. Transmission of microorganisms Microorganisms are transmitted by Transmission of microorganisms Hospital Staffs Environment Contaminated Instruments

5. Sources of Contamination Sources of Contamination Surgical personnel Non-sterile barriers: Surgical clothing Scrub tops Surgical head cover Face masks Sterile barriers: Gloves Surgical skin scrub

6. Sources of Contamination Patient Operating theatre environment Surgical equipments

7. Principles of surgery asepsis Followings are the principles of surgical asepsis: 1. Use only sterile items within a sterile field. 2. Scrubbed personnel are gowned and gloved. 3. Sterile personnel operate within a sterile filed (sterile personnel touch only sterile items or areas, unsterile personnel touch only unsterile items or areas.

8. Principles of surgery asepsis 4. Sterile drapes are used to crate a sterile field. 5. All items used in a sterile field must be sterile. 6. All items introduced onto a sterile field should be opened , dispensed and transferred by methods that maintain sterility and integrity. 7. A sterile field should be maintained and monitored constantly. 8. Surgical staff should be trained to recognize when they have broken technique and should know how to remedy the situation.

9. Levels of sterility and disinfection On the basis of magnitude of the risk of infection, the use of surgical instruments and equipments can be classified into three categories:

10. Preparation for Surgery It involves: Surgeon’s preparation: Surgical head cover Mask Surgical shoes Hand scrubbing Hand drying Gowning Gloving Patient preparation : Hair removal skin preparation Patient draping

11. Scrub Solutions Commonly used scrub solutions are: Chlorhexidine Excellent spectrum Ocassionally sensitive to mucous membrane. Povidine iodine - Excellent spectrum - Ocassionally skin sensitive.

12. Wrapping Instrument Packs

13. Folding and Wrapping Surgical Gown

14. Unwrapping of Sterile Packs

15. Hand Scrubbing Technique

16. Steps in Surgical Gloving 1 2 3 6 5 4 Figures: 1- 6 showing steps in surgical gloving

17. Sterilization and Disinfection Destruction of all the microorganisms (bacteria, viruses, spores) from objects (instruments, drapes, catheters, needles, blades) that come in contact with tissue or enter into the vascular space. Disinfection: Process of destroying microorganisms except viruses and spores found in inanimate objects. Methods of sterilization: 1. Physical sterilization 2. Chemical sterilization 3. Gas sterilization 4. Irradiation

18. Physical Sterilization most commonly used sterilization method. used dry or moist heat. 1.1 Dry Heat: Mechanism of Action: Denaturation or destruction of cellular proteins. a. Flaming: Used to sterilized the instruments like blade, needles passing over the flame of gas burner till red hot, destroys bacteria.

19. Physical Sterilization b. Hot air oven: - Most common and effective method of sterilization of metal instruments and glassware. - A temperature of 120⁰C for 8 hours, 140⁰C for 2.5 hours, 160⁰C for 1 hour and 180⁰C for 20-30 minutes is usually sufficient.

20. Physical Sterilization 1.2 Moist heat: Mechanism of action: Denaturation of major cell constituents. a. Boiling: Most effective method of sterilization. 2% sodium carbonate added to boiling water to make alkalinity , that helps in destruction of microbial spore. Uses temperature of 100⁰C for at least 15 minutes to sterilize syringes and needles.

21. Physical Sterilization . b. Autoclaving: Moist heat in the form of saturated steam under pressure. A temperature of 121⁰C under 15 pounds pressure for 15 minutes. Sharp instruments like scissors, needles and other routine instruments of a surgical pack, excluding sharp blade. Fig.: Autoclave

22. Physical Sterilization Flashing : when unwrapped instruments is autoclaved for shorter period of time. Done for critical instruments. A temperature of 131⁰C under 30 pounds pressure per square inch for 4-7 minutes . In field condition, large pressure cooker is used to sterilized surgical instruments and packs under maintained pressure for 45 minutes.

23. Chemical or cold sterilization Refers to immersion of instruments in tray containing disinfectant solutions such as Phenol, Alcohol (ethyl or isopropyle alcohol), Glutaraldehyde , Betapropiolactone , aldehydes (formalin), Chlorhexidine that destroys the pathogenic microorganisms on inanimate objects. Destroy all bacteria except tubercle bacillus.

24. Chemical or cold sterilization Used for sharp edged instruments like scalpel blades and hypodermic needles. Spores and Viruses may not be destroyed so not used for critical instruments. 1. Alcohols: Mechanism of action: by Protein denaturation , metabolic interruption and cell lysis . Isopropyl alcohol (50-70%) and ethyl alcohol (70%) used for spot cleaning and injection site preparation.

25. Chemical or cold sterilization It is corrosive to stainless steel and volatile. At lower concentration, acts as bacteriostatic rather than bactericidal. 2. Aldehyde : Mechanism of action: By protein and nucleic acid alkylation.

26. Chemical or cold sterilization a. Formaldehyde: It is in the form of formalin, 37-40% solution of formaldehyde and water. Capable of killing all bacteria, viruses and spores. Extremely pungent smell, irritating to skin and mucous membranes and has limited application as a cold sterilization agent.

27. Chemical or cold sterilization 40% Formalin is used in fumigator at minimum relative humidity of 70%, temperature 30-40°C to sterilize operation theatre. 180 ml of 40% formalin is used for 1000 cu ft. size of room.

28. Chemical or cold sterilization Uses: Disinfection of organic wastes, hospital floors, walls. Disinfection of membranes in dialysis equipment etc. b. Glutaraldehyde : 2% solution of glutaraldehyde is used for disinfection of lenses, dental equipments, delicate instruments or anesthetic accessories. It is also irritating to skin and mucous membrane and odor, so well rinsed before use.

29. Chemical or cold sterilization 3. Chlorhexidine : An antiseptic agent available in detergent, tincture and aqueous formulations. 0.75-1% solution used for scrubbing. Widely used for preparation of surgical patients and for surgical hand scrubs due to nonirritating property to skin. Effective against gram negative and gram positive organisms, repeated use increases its effectiveness.

30. Chemical or cold sterilization 4. Quaternary ammonium compounds: It is also used in fumigation/fogging of operation theatre for 45 minutes. E xample: Microgen D-125 (a commercial product). It is bactericidal, virucidal and fungicidal disinfectant. 15 ml of concentrate Microgen D-125mixed in 1 litre of water for disinfection every 1000 cu. Ft room in high risk areas like operation theatre, ICU, Pathology laboratory etc.

31. Chemical or cold sterilization 5. Iodine compounds Mechanism of action: released free iodine from carrier molecules and acts as disinfectant. Povidine Iodine ( Betadine ): Bactericidal, virucidal , fungicidal but poor sporicidal activity. Used for cleaning of wounds, scrubbing of hands. 2. Iodophors (7.5%): Used as scrub solution for cleaning dark colored floors and countertops.

32. Chemical or cold sterilization 6. Chlorine compounds Mechanism of action: by chlorination and oxidation of essential molecules. Hypochlorite: 2.5% sodium hypochlorite solution is used. Used for cleaning floor and countertops. Inactivated by organic debris and corrosive to metal.

33. Chemical or cold sterilization 7. Phenol and its derivative: a. Phenol: 2% solution used for disinfection. Acts by disrupting the cell membranes and precipitate cellular proteins. Bactericidal but do not affect viruses and spores. Commonly used as cold sterilint in combination with detergents or soaps to increase the spectrum of their activity.

34. Chemical or cold sterilization b. Crysol : 0.5 – 1% of Crysol used as intestinal antiseptic. c. Lysol: used for disinfection of non-living objects. Examples: Disinfection of floor, Bathrooms, Washbasins, organic wastes such as faeces and urine etc. d. Chloroxylenol ( dettol ): 2% solution of dettol used for antiseptic for intact skin.

35. Gas sterilization 1. Ethylene oxide gas: Effective against all types of microorganisms. Kill microorganisms by altering their normal cellular metabolism and replication through alkylation of protein, ribonucleic acids and deoxyribonucleic acid. Moisture and heat sensitive equipments can be sterilized .

36. Gas sterilization The effectiveness of ethylene oxide gas as a sterilizing agent depends on: a. Gas concentration : 450 – 1500 mg/L. b. Temperature : usually 21- 60⁰C. c. Exposure time : 48 minutes to several hours. d. Humidity : 40%, necessary for lethal action of ethylene oxide.

37. Gas sterilization Used to sterilize Endocope Gloves Catheters Items sealed in plastic etc.

38. Irradiation Radiation used for sterilization is of two types: Ionising and Non- ionising radiation. Ionising Radiation: Uses shorter wavelengh , high intensity and high penetrating radiation to destroy microorganisms. For example: Gamma rays, X-rays. Gamma rays have shorter wavelength with deeper penetration . Used to sterilize pre-packed items: Surgical blades, Swabs, Catheters, Syringes Gowns Drapes Table covers etc. Non- ionising radiation: Uses longer wavelengh having lower energy and penetration. For example: UV rays UV rays (300-400nm wavelength) produced by mercury vapor lamp used to sterilize table surfaces, room.

39. References Small Animal Surgery, 4 th Edition by Theresa Welch Fossum . Text Book of Small Animal Surgery, 3 rd Edition by Douglas Slatter . Ruminant Surgery by RPS Tyagi and Jit Singh. Fundamentals of General Veterinary Surgery by Md. Moin Ansari . Veterinary Surgery Small Animal by Karen M. Tobias and Spencer A. Johnston.

40. Thank You