Fumaigation Process in Operation Theaters

Fumigation

Arya S.S CRRI

Introduction Surgical site infections (SSIs) are the second most common

cause of hospital acquired infections.

The source of SSIs may be endogenous or exogenous, which

includes surgical personnel ,the operating room environment

(including air), and tools, instruments, and materials brought

to the sterile field during an operation.

By maintaining sterile environment in operation theatre we

can control major part of exogenous infections.

Fumigation is the process by which we can sterilize the

enclosed area by injecting the chemical which will kill or

destroy microbes present in the air.

In 1867 –Dr.Joseph Lister first identifies airborne bacteria

and uses Carbolic acid spray in surgical areas.

He introduced the antiseptic spray to the

operating theatre to disinfect the atmosphere

around the operating table.

It worked by heating water to boiling point in

the upper chamber of the instrument, so that

steam was forced out of the tube on the right.

The carbolic acid in the glass container was

drawn up and mixed with the steam before

being emitted into the air.

Fumigation Fumigation is a process of gaseous sterilisation which

is used for killing of micro-organisms and prevention

of microbial growth in air, surface of wall or floor.

It is generally used in the pharmaceuticals, operation

theatres, hospitals, hotels and offices and wherever

required.

Method of fumigation completely fills an area with

gaseous fumigants to suffocate or poison the

microbes & pests within.

Widely used fumigants include:

• Formaldehyde

• phosphine

• 1,3-dichloropropene

• chloropicrin

• methyl isocyanate

• hydrogen cyanide

• sulfuryl fluoride

• Iodoform

• Methyl bromideFumigation equipment

Formaldehyde

A gas at room temperature, formaldehyde is colorless

and has a characteristic pungent, irritating odor.

When dissolved in water, formaldehyde forms a

hydrate methanediol.

A saturated water solution, that contains about 40%

formaldehyde by volume or 37% by mass, is called

"100% formalin".

A typical commercial grade formalin may contain 10–

12% methanol added to suppress oxidation and

polymerization.

Formaldehyde at approximately 5% in a

solution with water is used as a fumigant

and disinfectant in hospitals.

Formoldehyde kills microbes by alkylating

the amino acids and sulfydral group of

proteins and purine bases.

In order to be effective, the gas has to

dissolve in the film of moisture surrounding

the bacteria, for this reason relative

humidities in the order of 75% RH and

temperature above 22°C.

Formaldehyde molecule

Methods Electric Boiler Fumigation Method: For Each 1000 cu.ft

500ml of formaldehyde added in 1000ml of water in an

electric boiler. Switch on the boiler, leave the room and

seal the door. After 45 minutes switch off the boiler

without entering in to the room.

Potassium Permanganate Method: For every 1000

cubic feet add 450gm of Potassium permanganate

(KMnO4) to 500 ml of formaldehyde. Take about 5 to 8

bowels with equally divided parts of formaldehyde and

add equally divided KMnO4 to each bowel. This will

cause auto boiling and generate fume.

Neutralisation After the initiation of formaldehyde vapour

immediately leave the room and seal it for at

least 48 hours

Neutralise residual formalin gas with Ammonia

by exposing 250ml of Ammonia per litre of

Formaldehyde used.

Place the Ammonia solution in the

centre of the room and leave it for

3 hours to neutralise formalin vapour.

Quantity Example

Operation Theatre

volume=L×B×H=20×15×10=3000 cubicfeet

Formaldehyde required for fumigation=500ml for

1000 cubic feet

So 1500ml Formaldehyde required

Ammonia Required for neutralisation=150ml of 10%

ammonia for 500ml of formaldehyde

So 450ml of 10% ammonia required

Phosphine Phosphine is the compound with the chemical formula

PH3.

It is a colorless, flammable, toxic gas. Pure phosphine

is odorless, but technical grade samples have a highly

unpleasant odor.

Phosphine-producing materials have become the

predominant fumigants used for the fumigation of OT

& bulk-stored grain throughout the world.

It is available in solid formulations of aluminum

phosphide or magnesium phosphide.

When exposed to heat and moisture the formulations

release phosphine, a highly toxic gas.

The time required for release of phosphine will vary

with temperature and formulation.

Phosphine is very toxic to all forms of animal life,

hence exposure of human beings even to small

amounts should be avoided.

Phosphine can be produced via tablets or phosphine

producing equipment.

Phosphine producing Equipment Phosphine Tablets

* Phosphine is generaly used for fumigating huge

quantity of food grain than operation theatre

1,3-dichloropropene & chloropicrin 1,3-dichloropropene & chloropicrin is generaly used as soil

fumigants only

Methyl isocyanate Methyl isocyanate is an intermediate chemical in the

production of carbamate pesticides.

Methyl isocyanate fumes can also be used as a fumigant.

Methyl isocyanate (MIC) is extremely toxic.

It was the principal toxin involved in the Bhopal disaster.

Even small quantity is extremely toxic to humans, so currently

not used in fumigation.

Methyl Bromide Methyl Bromide is most widely used fumigant for

quarantine purposes

It is a preferred fumigant because of its good

penetrating ability, rapid action, high toxicity to a

broad spectrum of micro organisms and pests.

The effectiveness of methyl bromide is based on the

following:

• Dosage of the fumigant

• Duration of exposure

• Temperature

When fumigation is carried out with Methyl Bromide

fumigant, there will not be any residual issues as

aeration can be carried out easily.

Methyl Bromide fumigation can be carried out at the

dosage that varies between 32 grams/ m3 and 80

grams/ m3 as per the requirements.

Methyl bromide is considered to be a significant ozone

depleting substance (ODS) by atmospheric scientists.

Methyl bromide is readily photolyzed in the

atmosphere to release elemental bromine, which is far

more destructive to stratospheric ozone than chlorine.

Preparation for fumigation First the area intended to be fumigated is usually

covered to create a sealed environment.

The fumigant is released into the space to be

fumigated.

The space is held for a set period while the fumigant

gas percolates through the space and acts on and

kills any infestation.

The space is neutralised & ventilated so that the

poisonous gases are allowed to escape from the

space, and render it safe for humans to enter.

Windows, doors should be closed. AC and AHU should

be switched off before starting fumigation.

Area under fumigation, do not enter status label

should be displayed on either side of the entrance.

Fumigants are irritating and toxic to human eye, nose

and throat. Therefore use of nose

mask and goggles while doing

fumigation is advisable.

Under certain conditions formaldehyde can react with

hydrochloric acid and chlorine containing disinfectants

such as hypochlorites to form chloromethyl a potential

lung carcinogen.

HCl and chlorine containing disinfectants must

therefore be removed from areas before fumigation.

Check levels of residual fumigant in the room with

suitable air monitoring equipment(formaldameter or

air sampling tubes).

The procedure is best carried out overnight.

After a period of not less than 12 hours the room

must be well ventilated.

OT is usable only when the level of formaldehyde

is less than 2ppm.

Formaldemeter

Personal care while Fumigation Adequate care must be taken by wearing cap,

mask,foot cover, spectacles.

Formaldehyde is irritant to eye & nose; and it has

been recognized as potential carcinogen.

Immediately leave the room after

the initiation of fumigants.

So the fumigating employee must

be provided with personal

protective equipment.

Advantages of Fumigation Fumigants are toxic to all forms of life. Therefore, it is

possible to control all life stages of Micro organisms.

Fumigation is often the quickest way of controlling an

infestation, saving time and money.

Fumigants can reach where sprays, dusts, aerosols etc

cannot reach.

Reduced residue problems in treated areas.

Fumigants are used where standards call for "zero

Microbial tolerance" in products or living

environments.

Disadvantages of Fumigation¤ Generally Formaldehyde is used for OT fumigation.

Based on the available evidence in OSHA’s record on

Formaldehyde, it determines formaldehyde as

isgenotoxic, showing properties of both a cancer initiator

and promoter.

In humans formaldehyde exposure has been associated

with cancers of the lung, nasopharynx and nasal

passages.

Symptoms of excessive exposure include respiratory

irritation, itchy eyes, runny or stuffy nose, sore throat and

headache.

Formaldehyde allergy Formaldehyde allergy symptoms include redness,

burning sensation, scaling and irritation of skin.

Eye contact can cause pain, burning sensation,

blurred vision and excessive tearing.

Further, formaldehyde can cause difficulty breathing

in allergic individuals, particularly those with asthma

or another respiratory condition.

Alternative methods

Fumigation is an age old process of sterilisation,

of the environment, may be a sick room or

operation theatres.

In spite of brief stay of patients in the operation

theatre, the environment of operation theatre plays a

great role in the onset and spread of infections.

But every hospital should pay good attention in proper

maintenance of air conditioning plants, ventilator

systems, and to have greater control on mechanisms

and personnel involved in disinfection.

Many believe that routine Microbiological monitoring is

most essential but in reality it is not practicable.

Special air flow pattern (the air flow pattern is such

that filtered and purified air circulates and

contaminated air is removed continuously).

There should be restriction of personnel traffic, closing

of OT doors and a good ventilation system.

Standard cleaning, disinfection with appropriate

chemical agents, good theatre practice, discipline, can

provide a microbiologically safe environment.

Fumigation is obsolete in many developed nations in

view of toxic nature of Formalin.

Several new safe chemicals are emerging but

constrains of economy limit the use and several hours

of closure of operation theatres can be curtailed as

with Fumigation.

Aldehydes are potentially carcinogenic and it is

therefore recommended that other agents such as

hydrogen peroxide, hydrogen peroxide with silver

nitrate, peracitic acid and other chemical compounds

of formaldehyde should be used in place of the

currently prevalent practice of using formaldehyde.

These agents are dispersed with the aid of a fogger-

like device inside the theatre environment.

The contact time is about an hour and the theatre can

be used immediately after the contact time.

Fogging method

Emerging Compounds in use for Sterilization of Operation theatres Bacillocidrasant:

A newer and effective compound in

environmental decontamination with very good

cost/benefit ratio, good material compatibility, excellent

cleaning properties and virtually no residues. It has the

advantage of being a Formaldehyde-free disinfectant

cleaner with low use concentration.

Advantages Provides complete asepsis within 30 to 60 minutes.

Cleaning with detergent or carbolic acid not required.

Formalin fumigation not required.

Shutdown of O.T. for 24 hrs. not required.

VIRKON VIRKON is gaining importance as non-Aldehyde

compound

Virkon is proved to be a safe virucidal, bactericidal,

fungicidal, mycobactericidal and non-toxic compound.

It contains oxone (potassium peroxymonosulphate),

sodium dodecylbenzenesulfonate, sulphamic acid; and

inorganic buffers.

It is typically used for cleaning up hazardous spills,

disinfecting surfaces and soaking equipment.

Though Virkon is shown to have wide spectrum of

activity against viruses, some fungi, and bacteria, it

however is less effective against spores and fungi

than some alternative disinfectants. Several other compounds are emerging in the Market

for safer use, may need better resources for utility and implementation.