Monday, April 13, 2020



Dr K K Aggarwal
President Confederation of Medical Associations of Asia and Oceania

Confederation of Medical Associations of Asia and Oceania

532:  What is Medical equipment: Disinfection and sterilization

The type of cleaning, disinfection, and sterilization required depends on the type of medical equipment.

533: What is a Noncritical equipment

Medical equipment that comes into contact with intact skin but not mucous membranes (eg, stethoscopes, blood pressure cuffs, patient care area surfaces)

534: What are Semi-critical equipment

Medical equipment that comes into contact with non-intact skin or mucous membranes (eg, thermometers, endoscopes)

535: What are Critical medical equipment

Medical equipment that comes into contact with sterile tissue or the vascular system (eg, implants, catheters, surgical instruments)

536: How to clean Noncritical medical equipment
They should be cleaned using a disinfectant that kills most bacteria and some viruses and fungi; cleaning these items with an alcohol wipe between uses is often sufficient.

Mobile communication devices such as pagers and cell phones may also become contaminated with bacteria; these devices should be disinfected similarly.

537: How to clean semi-critical medical equipments

They should be free from all vegetative microorganisms, but small numbers of bacterial spores are permissible since non-intact skin and mucous membranes are generally resistant to infection by spores.

538: How to clean critical medical equipment

They must be sterile because any microbial contamination could transmit disease. These items should be purchased as sterile or be sterilized between uses.

539: Can bleach be harmful

Before you start using bleach everywhere, it's important to know that bleach is caustic and can emit potentially lethal fumes.1 That's why it's important to dilute your bleach and ensure that it's not used at full-strength and not mix it with other solutions and chemicals.

The Centers for Disease Control (CDC) recommends using different amounts of bleach and water depending on what is being cleaned. Be sure to follow these steps exactly to make a safe and effective bleach solution that meets your needs.

540:  Can I mix Ammonia with bleach


A: Mixed with bleach converts the chlorine in bleach to chloramine gas. Breathing in the fumes can cause coughing, shortness of breath, and pneumonia.

541: Can we mix acidic compounds such as vinegar or window cleaner create chlorine gas in bleach

No: When mixed with bleach, excessive exposure can cause chest pain, vomiting, and even death.

542: can we add alcohol in bleach
No. Alcohol converts to chloroform when mixed with bleach. Breathing in chloroform can cause fatigue, dizziness, and fainting.

543: How long fresh bleach solution last

Chlorine bleach solution begins to lose its disinfectant power quickly when exposed to heat, sunlight, and evaporation. To ensure the strength of your solution, mix a fresh batch each day and discard whatever is leftover.  Keep out of the reach of children.

544: What is the bleach concentration to clean hard surfaces such as plates and counter tops

Mix 1 cup (240 milliliters) of bleach with 5 gallons (18.9 liters) of water. 

545:  What is the bleach concentration to clean disinfect healthcare facilities

To make a 1:10 solution to disinfect healthcare facilities that may have been tainted by contagions, you'll need 1 part bleach for every 9 parts water. 

545: What to do if bleach [powder gets poured on the skin

If you do get any bleach on your skin, wipe it off immediately with a damp cloth.

546: Do I still need to use soap and water

You can wash the surface with soap and hot, clean water before using the bleach. After applying the beach let the surface you are cleaning air dry.

547: How do I prepare 1% chlorine solution

Guidelines for Preparation of 1% sodium hypochlorite solution
Product                                    Available chlorine                  1percent Sodium hypochlorite
liquid bleach                           3.5%                                        1 part bleach to 2.5 parts water
Sodium hypochlorite liquid    5%                                           1 part bleach to 4 parts water
 NaDCC (sodium dichloroisocyanurate)
 powder                                   60%                                         17 grams to 1 litre water
NaDCC (1.5 g/ tablet) – tablets 60%                                     11 tablets to 1 litre water
Chloramine – powder             25%                                        80 g to 1 litre water
Bleaching powder                 70%                                        7g  to 1 litre water

Approach to disinfection and sterilization of medical devices
Device classification
Devices (examples)
Spaulding process classification/time
EPA product classification
Noncritical (touches intact skin, not mucous membranes)
Stethoscopes, bedpans, blood pressure cuffs, patient furniture
Low-level disinfection: Kills most bacteria, some viruses and fungi. Cannot reliably kill resistant microorganisms (eg, tubercle bacilli, bacterial spores).
Chemical disinfectants; ethyl or isopropyl alcohol, sodium hypochlorite, hydrogen peroxide, quaternary ammonium germicidal detergent.
Hospital disinfectant without label claim for tuberculocidal activity
Time: 10 minutes or less
Semi-critical (touches intact mucous membranes [except dental])
Flexible endoscopes, laryngoscopes, endotracheal tubes, cervical diaphragms
High-level disinfection: Destroys all microorganisms except high numbers of bacterial spores.
Wet pasteurization or chemical disinfectants.* Heat sterilization preferred for between patient processing of heat stable instruments. Follow by rinsing with sterile water.
Time: 20 minutes or more
Thermometers,   hydrotherapy tanks
Intermediate-level disinfection: Inactivates tubercle bacilli, vegetative bacteria, most viruses and fungi. Does not necessarily kill bacterial spores.
Chemical disinfectants; sodium hypochlorite ethyl or isopropyl alcohol, phenolic and iodophor solutions.
Hospital disinfectant with label claim for tuberculocidal activity
Time: 10 minutes or less
Critical (enters sterile tissue or vascular system)
Implants, scalpels, needles, cardiac and urinary catheters
Purchase as sterile. Sterilize by steam under pressure. If heat labile, use ethylene oxide gas or chemical sterilants.
Time: prolonged contact (hours)
EPA: Environmental Protection Agency.
* 2% glutaraldehyde-based products, 6% stabilized hydrogen peroxide, chlorine, peracetic acid.
¶ 2% glutaraldehyde-based products, 6% stabilized hydrogen peroxide, peracetic acid.
Modified with permission from: Rutala WA. APIC guideline for selection and use of disinfectants. Am J Infect Control 1996; 24:313. Copyright © 1996 Mosby, Inc.

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