Operation Theater Sterilization and Modular Operation... : Delhi Journal of Ophthalmology (2024)

INTRODUCTION

The word sterilization holds the most important place in ophthalmic practice. In Indian history, the sterilization process dates back to 500 A.D. When the father of Surgery, “Sushrutha” instructed the operating team members to clean and fumigate the operating theater with vapors of certain disinfectants before all surgical procedures. In 1827, Joseph Lister also known as the “Father of Modern Surgery,” demonstrated that antisepsis could prevent infections. In the 1880s, Robert Koch introduced the use of mercuric bichloride and carbolic acid spray in surgical areas. Florence Nightingale introduced fundamentals in nursing care whereas Johnson and Johnson introduced antiseptic surgical dressings. This slow but steady development and invention led to the aseptic surgical techniques we follow today and a remarkable reduction in postoperative infection rates in ophthalmology.

Hospital-acquired infections account for about 20% of the infection in developing countries. Source of infection in ophthalmology operation theater (OT) can be because of contaminated solution causing 37% of the infections, contaminated phaco handpiece causing 22.2%, faulty ventilation system causing 11.1%, and bad sterilization technique causing 11.1% of the infections.^[1] Hence, the operating room, instruments, equipment, and OT environment including air have to be taken care of and aseptic measures need to be strictly followed.

TERMINOLOGY

To understand the basics of sterilization, we need to be thorough with some terminologies. Hence, we will brush up with some common terms here itself:

Cleaning

Removal of all contaminates, e.g., soil, organic matter, and large number of microorganisms by washing or scrubbing. It is a useful and essential prerequisite to any sterilization procedure.

Disinfection

It is a process that destroys most of the pathogenic microorganisms except bacterial spores.

Sterilization

It is a process that destroys or eliminates all forms of microbial life including bacterial spores. It is carried out by physical or chemical methods.

Sterilize

It is the total destruction of all living forms.

Sterile

It is free from living microorganisms.

Asepsis

It is the state of being free from living pathogenic organisms.

Fumigation

It is the process of disinfecting an area with certain chemical/gases’ fumes.

Sterilizer

It is the equipment designed to achieve sterilization.

Contamination

It is the process of microbial entry into tissues/body or into any aseptic environment.

Nosocomial

This word is derived from two Greek words, i.e., “nosus” which means “disease” and “komeion” which means “to take care of.” It refers to any hospital-acquired infections.

Chemical indicator

Agents or devices are used to confirm the attainment of one or more of the parameters required for a satisfactory sterilization process.

Biologic indicator

A test preparation which is standardized and makes use of bacterial spores to demonstrate effective sterilizing conditions.

OPERATION THEATER LAYOUT

OT design and location are one of the main topics of discussion while planning an ophthalmic hospital. It should be planned in such a way that it should be away from the noise, dust, outpatient department crowd, and needs proper natural lighting, and ventilation. To maintain all these, it is divided into certain zones:

1. Protective zone [Figure 1]: It includes;


• Rooms for administrative staff
• Changing room for doctors and staff
• Transferring passage for patients, materials
• Storage and record maintenance
• Pre-and postoperative area
• Storage rooms to keep the sterilized objects.


2. Clean zone: It connects the protective zone to the aseptic zone.
It includes;

• Storage area for equipment
• Room for maintenance
• Emergency exit.


3. Aseptic zone: Includes;
• Operating room
• Scrub area.


4. Disposal zone: Includes area for disposal of biohazardous OT waste.

Autoclave room

Autoclave room is designed in a clean zone. It is placed away from the operating room as the moist heat [Figure 2] generated should not enter the operating room because moisture can itself be a nidus for the growth of microorganisms. This room is fitted with an exhaust fan so that the moisture escapes and hence helps in maintaining the sterility of the clean zone.

Operation theater [Figure 3]

Location of the operating room should be away from the noise, dust, and hustle-bustle of the hospital. It should have adequate natural light and proper ventilation. The minimum size of OT should be 6.5 m × 6.5 m × 3.5. Sliding doors are preferred over spring-loaded doors in OT to minimize the generation of air currents during the opening and closing of doors during surgery. The width of OT doors should be approximately 1.2–1.5 m.^[2]

The length of the operation table is approximately 1.8 m and the operation trolley is 0.9 m. There should be adequate working space of 1.2 m around the operation table and trolley. Unwanted equipment and instruments should not be kept in OT. This prevents clutter and helps in the easy cleaning of the OT. A maximum of 5–7 people should be posted in an OT at a time.^[3] This helps in minimizing air currents and hence reduction in hospital-acquired infections.

OPERATION THEATER PARAMETERS

Operation theater parameters according to NABH standards [Table 1].

MODULAR OPERATION THEATER

Modularity is a concept that subdivides a system into smaller parts called modules that can be separately created and then can be used to create a system. In this approach, universal parts of the OT are manufactured in a company and then shifted to the build site for final assembly. The main advantage of this type of construction is the reduction in cost due to universal parts and it takes less time for building the actual site because of the systematic and defined process for assembly. Other advantages are prevention of contamination build-up, long durability, flexibility in design for future expansion, and complete ease of maintenance.

In this system, a continuous flow of highly filtered air is circulated under pressure in the operating field, and air contaminants are removed from the site hence providing a clean environment for every surgery. Other advantages are the ease of cleaning due to less joints, moisture resistance, and vapor permeability which also protect against the growth of microorganisms.

STERILIZATION

Sterilization is one of the most important aspects of ophthalmic OT. The main aim of sterilization is to reduce the risk of hospital-acquired infection in eye. In ophthalmology, endophthalmitis is the most dreaded complication which can lead to permanent vision loss.

We will discuss this under the following heads:

1. OT sterilization
2. Surveillance of OT sterilization [Table 2]


3. Instrument sterilization
4. Surveillance of instrument sterilization.

OPERATION THEATER STERILIZATION

Fumigation and fogging are commonly used techniques for OT sterilization.^[4]

Fumigation

Fumigation process kills microorganisms and prevents growth in air or surface. Formaldehyde is used in this process, either by boiling 40% formaldehyde or by adding it to potassium permanganate.

Method – For a 10 × 10 × 10 feet room, 150 g of potassium permanganate is added to 280 mL of formaldehyde or alternatively 250 mL of formalin is added to 3000 mL of tap water and put in auto mist for 2 h. Windows and doors are closed and OT is sealed overnight.

However, since formalin is pungent, irritant, and has carcinogenic properties, its use has become obsolete these days. Moreover, usually fogging is the preferred method now.

Fogging

In this method, a chemical (N-alkyl-dimethyl-benzalkonium chloride) is dissipated using a fogger.

Method – All appliances such as phaco machine, microscope, and endolaser machine are covered with clean cloth. Place the fogger in one corner of the OT diagonally, facing the roof at an angle of 45° to facilitate equal spread of mist throughout. Flow is regulated by the presence of fine mist on the observer’s hand kept at a distance of 2 feet from the fogger. The presence of water droplets with dripping denotes excess flow and must be reduced. Timer is set at 20 min. Seal the room completely for 2 h. Remove the fogger after 2 h.

It is less toxic than formalin but corrodes steel and damages optics.

Other agents for surface disinfection:

1. Bacillocid – Used for floor and wall cleaning. Ingredients are glutaral, benzyl-C12-18-alkyldimethylammonium chlorides, and didecyldimethylammonium chloride. It is a very safe and fast disinfectant
2. Bacilol – Active ingredient is ethanol, 2propanol, and 1propanol. Mostly used as a spray for instant surface disinfection but does not act on spores.

HEATING, VENTILATION, AND AIR-CONDITIONING SYSTEM

Heating, ventilation, and air conditioning (HVAC) regulate the quality of air on the following parameters to achieve cleanroom standards as per ISO Class 6:^[5]

• Temperature and humidity
• Pressure gradient between zones
• Particulate count.

Heating, ventilation, and air-conditioning system consists of;

• Air handling unit
• Inflow and outflow ducts
• Air-conditioning compressor
• Air blower
• Prehigh-efficiency particulate air (HEPA) filters (3 and 5 filters)
• Laminar air flow plenum with terminal 0.3 HEPA filter.

Types of heating, ventilation, and air conditioning

Horizontal – In this type, it forms part of a wall. It is easy to install but an adequate clean zone is not possible.

Vertical – In this type, room within a room principle is used. Air passes through HEPA filters from ceiling downwards at 0.3 m/s. Vertical system provides clean zone for surgery.

• Advantages [Figure 4]: Minimum chances of infection
• Disadvantage: Costly and high maintenance.

High-efficiency particulate air filter consists of the following parts:

Daily cleaning protocol of operation theater

• Operating room is cleaned first, followed by the sterilization area, block room, and common corridor
• Operating microscope head should be cleaned with Bacillocid solution (a combination of chemically bound formaldehyde, glutaraldehyde, benzalkonium chloride, and alkyl urea derivatives)
• Operating tables, chairs, trolleys, IV stands, etc., are cleaned with antiseptic solution
• Door handles need to be cleaned properly as they have higher chance of contamination
• The floor of the OT is always mopped last, using a two-bucket technique.
• • First bucket: Antiseptic solution-mop first
  • Second bucket: Warm water last.

Cleaning after every case

• All waste from kick buckets is removed
• After each operation, any soiled areas of the floor are cleaned and disinfected (with Bacillocid) (up to 1.5 m away from the table)
• All furniture such as OT table and equipment that came in contact with the patient are cleaned (with Bacillocid).

SURVEILLANCE OF OPERATION THEATER STERILIZATION

Microbiological surveillance of OT is done by 2 methods:

1. Swab method – Usually peptide water swabs are used. It is done once a month.
Swabs are taken from 7 sites in OT – walls, floor, OT table, OT trolley, microscope, AC filter, and microscope. One control swab is also taken, it can be sterile or contaminated but the microbiologist should be unaware of it. Microbiologists should only report against the swab number. This method helps to maintain the reliability of the reports

2. Air sampling – It is done to quantify the microbial count. Done by 2 methods:
• Settle plate method-It is a passive air sampling method. It is done once a month. Agar plates are kept when approximately half the OT list for that day is completed (for the duration equal to the shortest surgical procedure)
• Plates are opened inside the OT and kept at head end of table on Boyle’s apparatus for 20 min.
• Acceptance criteria: Presence of <30 colony-forming units per plate.
• Slit sampler method-active air sampling method. Highly efficient and sensitive device.

Particles from the air are directly impinged on a rotating agar plate, which is incubated. In the Casella slit sampler, the slit is positioned above a turntable on which is agar plate is placed. Can collect up to 95% of water droplet particles sprayed into air. Respiratory secretion droplet nuclei of 0.2 μ can be collected.

INSTRUMENT STERILIZATION

Cleaning of instruments

It is one of the most important parts of OT sterilization. Well-trained and exclusive OT staff is appointed for this purpose. All instruments should be cleaned and sterilized as soon as the surgery is over, to ensure easy and effective removal of debri from all instruments. All instruments are washed under running tap water after wearing gloves. The instruments are then rinsed using distilled/RO water. All instruments are cleaned with a toothbrush, then soaked in opadex (ortho-Phthaldehyde) solution for 15 min. Then again, the instruments are washed with RO/distilled water and placed in an ultrasonic cleaner for 10 min for final cleaning.

If an ultrasonic cleaner is not available, the four-bowl technique is followed.

Instruments are passed through four consecutive bowls:

• Tray 1: (Ortho-Phthaldehyde + Water) - 5 min dip
• Tray 2: (Ortho-Phthaldehyde + Water) - 10 min dip
• Tray 3: Distilled Water - 10 min rinse
• Tray 4: Distilled Water - 10 min rinse.

Ultrasonic cleaner [Figure 5]

It is used for cleaning of instruments with hinges and curved ends.

It works on the principle of sound waves which pass at a frequency of 100,000 Hz or more in liquid. Sound waves generate submicroscopic bubbles which then collapse creating a negative pressure hence removing particulate matter. This is a very efficient way of cleaning as it can clean curved areas and hinges of the instruments. Bacteria disintegrate and protein is coagulated by this process. Instruments should not touch each other inside the ultrasonic cleaner.

This is a very efficient and novel method of cleaning of instruments. However, if it is not available, the four-bowl technique is preferred as explained above.

Cleaning of cannulas

Cleaning of cannulas is best done by an automated instrument rinsing system. However, if it is not available, cannulas should be manually flushed 3 times with distilled water and then 3 times with air. Manual flushing is best done with 20 mL syringe.

After cleaning of all instruments, they are dried by keeping in ambient air or by a dryer. Drying is a very important step before autoclaving as steam cannot percolate the lumen of cannulas or cannulated instruments if wet. Remnant water droplets in the instruments can be a source of microorganism growth.

Various sterilization methods available are:

• Moist heat sterilization (Steam under Pressure)
• Dry heat sterilization
• Ethylene oxide gas sterilization
• Irradiation.

Most commonly used in ophthalmology practice are moist heat sterilization and ethylene tri-oxide (ETO).

Moist heat sterilization

Autoclave works under the principle of steam under pressure.^[6]

High pressure increases the boiling point of water which helps attain a higher temperature for sterilization. It helps in the rapid penetration of heat into deeper parts of instruments.

In the autoclave, water boils at 121°C at the pressure of 15 psi/775 mmHg for 15–30 min.

Steam causes coagulation of proteins causing an irreversible loss of function and activity of microbes by giving off latent heat. It is considered to be the most reliable method of sterilization. It can be done for linens, metals, gas, and fluids. All autoclaved instruments should be used within 48 h and need to be re-autoclaved if unused within this time frame.

Types of autoclaves

1. Pressure cooker type/Laboratory bench autoclaves (N-type)
2. Horizontal type
3. Gravity displacement type autoclave
4. Positive pressure displacement type (B-type)
5. Negative pressure displacement type (S-type).

Pressure cooker type/laboratory bench autoclaves (N-type) [Figure 6]

The newer type has a metal chamber with a tight metal lid that is sealed with a rubber gasket. Its various parts are an air and steam discharge tap, pressure gauge, safety valve, and an electric immersion heater at the bottom of the chamber. In this type, a uniform spread of steam is not achieved.

Horizontal type autoclave [Figure 7]

Double-walled horizontal autoclaves are the most ideal type of autoclave. There is the total destruction of all living microorganisms as there is a uniform spread of steam. It is also national accreditation board for hospitals & healthcare (NABH) acceptable. It is the most commonly used autoclave in ophthalmic practice now.

Gravity displacement type autoclave [Figure 8]

In this type, steam is created inside the chamber by the heating unit in the bottom, which spreads in the chamber for sterilization. It is comparatively cheaper than other types. It is used for the sterilization of (nonporous items) laboratory instruments made of steel and glass and also in the treatment of biohazardous material. This is the most common type of autoclave used in laboratories.

Positive pressure displacement autoclave [Figure 9]

This autoclave is faster and steam is generated in a separate steam generator unit, and then the moisture is transferred into the autoclave. It is the advanced version of the gravity displacement type.

It can be used for the sterilization of media, glassware, solutions, and numerous heat-resistant laboratory accessories. However, the disadvantage is its high cost and a smaller chamber.

Negative pressure displacement type autoclave [Figure 10]

It is the most recommended type of autoclave as is very accurate and achieves a high sterility assurance level. It contains both steam generator as well as a vacuum generator. It is used for the sterilization of media, glassware, and solutions. It is the most expensive type of autoclave.

Dry heat sterilization

In this method of sterilization, heat is absorbed by the outside surface of the device and is transferred through the entire device till the target temperature is attained. Dry heat kills microorganisms by oxidizing molecules. Two types of machines are available – static air type and forced air type. It is inexpensive, does not produce toxic fumes, and does not corrode or rust metal objects. Its disadvantage is that it is relatively slow and many objects cannot withstand the high temperatures. Examples – hot air ovens, flaming, glass bead sterilizers, radiation, and incinerators.

Gaseous sterilization (ethylene tri-oxide)

ETO is an alkylating agent and kills all viruses, bacteria, and fungi including bacterial spores.^[7]

It is used mainly for heat-sensitive materials such as fiber optics, electronics, and plastics. It does not require high temperature, humidity, or pressure, and is noncorrosive. However, the main disadvantage is that it penetrates only DRY materials. Adequate aeration time after running the cycle is necessary to allow dissipation of free toxic gas.

Class 4 indicator is generally used in ETO for checking sterilization. For biological monitoring Bacillus subtilis, spores are used.

Plasma sterilization

It is a novel technique for sterilization. Plasma sterilization is used in two ways – hydrogen peroxide plasma sterilization and vaporized hydrogen peroxide sterilization.^[7] Plasma is generated by introducing a precursor gas or vapor (hydrogen peroxide) into a chamber under low vacuum, then exciting it with microwave or radiofrequency energy. Special packaging made of polypropylene wraps and polyolefin pouches is required. It is suited for objects that cannot sustain high temperature and moisture. However, it is very costly method of sterilization.

IRRADIATION

Three kinds of radiation are gamma rays (from cobalt-60 sources), electron beams, and X-rays.

Gamma irradiation is a physical means of sterilization. Its mechanism is by breaking down bacterial DNA and hence inhibits bacterial division which kills the bacteria. Its main advantage is that it allows sterilization of already-packaged products. It is often called “cold” pasteurization or sterilization depending on the radiation dose.

Advantages of irradiation

• Reaches all parts of objects to be sterilized
• Permits sterilization of heat-sensitive materials
• Relatively low chemical reactivity
• Instantaneous and simultaneous sterilizing effect.

Disadvantages of irradiation

• Carcinogenic
• Requires well-trained staff
• Monitoring of the process is required
• Specially designed equipment is required.

Cleaning of tubing

Cleaning of tubing is of utmost importance in ophthalmology as all machinery such as phaco and vitrectomy machines need tubing which needs proper cleaning before reuse. In the first step, tubing is pressure-dried to remove all particulate matter. In the second step, they are dried at room temperature. Finally, they are ETO/autoclaved. Silicone tubing can be autoclaved, rest tubing are sterilized in ETO.

SURVEILLANCE OF INSTRUMENT STERILIZATION

Surveillance of the sterilization process of instruments is done by monitoring of three parameters – time, temperature, and pressure. Two types of indicators are used for this purpose – chemical and biological.

Chemical indicator [Tables 3 and 4]

The goal of chemical monitoring is to determine whether instrument packages including instruments inside these packages have been exposed to sterilizing conditions.

• It helps to differentiate between processed and unprocessed items thus eliminating the possibility of using instruments which have not been sterilized. They are divided into 6 classes as mentioned in Table 3
• Class 5 chemical indicators are very close to biological indicators when compared in terms of performance.

Biological indicator^[2]

These indicators directly confirm the sterility of the autoclaved items. It is used to validate the sterilization process. Biological indicators use heat-resistant bacterial spores for the same.

• Bacillus stearothermophilus is used for autoclave
• B. subtilis is used for ETO.

Process challenge device [Figure 11]

These are customized devices used to check for the proper functioning of sterilization process/machines. Indicators are placed in this device, the device is closed and then run in autoclave or ETO to check for the functioning of the machines. It is used to monitor various parameters such as time, temperature, and efficacy of the sterilizing process and the sterilizing instrument as well.

Checking sterilization of hollow tubing/process challenge device [Figure 12]

Helix tube of Teflon material of the approximate length of phaco tubing is used. It is one end closed by cork and a chemical indicator is housed in the cork. This is then placed in the sterilization machine and change in the color of the indicators confirms that the sterilization process is complete.

Operation theater etiquettes

From entering the OT complex, changing for OT, and scrubbing for surgery, each process requires a certain decorum to be maintained. Moreover, this is termed as OT Etiquette. It plays a major role in OT discipline and maintaining sterile conditions in OT. Hence, before entering an OT, all ophthalmology residents should be well-trained in this field.

Some OT rules to be followed by all:

• All the people entering the OT area should be strictly controlled
• Anyone with overt infection is not allowed inside the OT
• All persons entering OT should change into freshly laundered clothing
• Nails should be trimmed
• Bare minimal talk inside the OT
• Bare minimal movements.

Hand hygiene

Hand hygiene is one of the most important techniques to reduce the risk of infections in OT.^[6]

Steps for surgical hand wash:

• All jewelry and watches from wrists and hands must be removed
• Warm and RO water is used
• Hands and forearms should be washed 5 cm above the level of elbows
• Antimicrobial agents should be applied on hands in a circular motion
• Lathering should begin at the fingertips of one hand and between fingers, continuing from the fingertip to 5 cm above the elbow
• Rubbing should be done for a period of minimum 3–5 min.

Barrier techniques are also followed to reduce the chances of the spread of infection. Various barrier techniques are:^[6]

1. Headcovers: Used during all procedures inside OT. All the hairs should be covered inside the head cover, in the case of long hairs, it is first toed in a bun and then covered by the head cover
2. Mask: Wearing a mask inside OT reduces the chances of air contamination through the nose and mouth. Disposable mask is mostly preferred
3. Scrub suits: These are freshly laundered clothes which are worn inside OT by all OT staff and doctors after entering OT
4. Surgical gowns: These are worn over scrub suits after surgical hand washing. It is worn in such a way that all the outside of the gown is left untouched
5. Gloves: Gloves protect the doctor/nurse from blood-borne diseases and also protect the patients from the skin flora of the operating surgeon. Gloves can be worn by open gloving or closed gloving techniques.

All these techniques collectively help to reduce hospital-acquired infection and should be well documented and followed religiously. Each and every step has its own importance so we should not ignore any part of the OT decorum as well as the sterilization process.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.