Autoclaves – principles and function Dr. S. Parthasarathy MD. DA. DNB. PhD., FICA., Dip. software based statistics

What we don’t want after surgery Infection Lister started – 1867 We continue Asepsis and sterilization Numerous methods

Physics !! Water boils at 100 degrees Boiling point is 100 degrees Supplied heat – temperature rises only up to 100. then liquid turns into vapor

Physics The boiling point will vary with ambient pressure In pondicherry – it is 100 In ooty – it may be only 80 If we create high pressures it may boil only at 120 degrees

Physics supplied heat to water Steam comes out at 100 ------- Close the chamber to create high pressure Boiling point rises to 120 Steam generated at 120 instead of 100 High temperature is ideal to sterilize

Pot and the pressure cooker Rice cooked more effectively and faster in pressure cookers High temperature which does than pressure

Autoclave It was invented by Charles Chamberland in 1879 Still it rules ??

Uses Medical Industrial Chemical All instruments Linen Towels Gauze pieces Mopping pads All except sharp instruments Plastic, Screw drivers Medical Industrial Chemical

No ---------------- yes

Double walled

Mechanism Water down – close Heat Displaces air ?? ( kitchen ) Steam to pressure – -- 200 kpa Switch off ( 121 degrees) 15 minutes Pressure release – moist heat ?? Use 1 atm = 100 kpa = 14.6 psi

Indicators

Chemical !!

Empty glassware and unwrapped instruments Empty glassware and unwrapped instruments. Sterilizing time 15 minutes, drying 10 minutes. Wrapped instruments, rubber gloves, tubes and catheters, and sutures being reautoclaved. A common regime is 0.7 kgcm, (10 lb per square inch) for 20 minutes. Fabrics and dressings. Sterilizing time 20 minutes, drying 15 minutes. Liquids in flasks and bottles. Sterilize 100 ml bottles for 20 minutes, 300 ml bottles for 30 minutes, 500 ml bottles for 35 minutes, 1000 ml bottles for 40 minutes,

Advantages Nontoxic to patient, staff, environment Cycle easy to control and monitor Rapidly microbicidal including spores Least affected by organic/inorganic soils among sterilization processes listed Rapid cycle time Penetrates medical packing, device lumens

Disadvantages Deleterious for heat-sensitive instruments Microsurgical instruments damaged by repeated exposure May leave instruments wet, causing them to rust Potential for burns

summary Thank you Sterilization methods Principle Types Methodology Advantages Disadvantages Thank you