Operation theatre technology

In short

Operation theatre (OT) technology is the applied science of designing, equipping, sterilising and running the surgical suite so that an operation can be done safely, aseptically and efficiently. It covers OT architecture and zoning, air handling, lighting, instruments, electrosurgery, suction, positioning, sterilisation and disinfection, infection control, biomedical waste handling and the technologist's role before, during and after surgery. For a B.Sc Operation Theatre Technology student it is the core paper, examined in theory, practical/viva and record work, and tested again in recruitment for OT Technician/Technologist posts in AIIMS, PGIMER, state health services, ESIC, railway hospitals and corporate chains (Apollo, Fortis, Manipal, Max, Narayana). Day-to-day practice is governed by NABH hospital standards, the Bio-Medical Waste Management Rules, 2016 (as amended) and the Drugs and Cosmetics framework for devices, with CDSCO as the device regulator.

Explained

OT design, layout and zoning

• Purpose of design: physically separate clean traffic from contaminated traffic, so that air, people and materials always move from cleaner to less clean areas, never the reverse.
• Four zones (standard teaching classification):
  1. Protective (outer) zone - reception, changing rooms, staff rooms, stores, patient transfer bay, pre-anaesthetic area.
  2. Clean zone - corridors connecting protective zone to theatre, recovery/PACU, equipment store, sterile store.
  3. Aseptic/sterile zone - the operating room itself and the scrub-up area; strictest discipline and highest air quality.
  4. Disposal (dirty) zone - dirty utility, used-instrument washing area, waste holding; separate exit wherever possible.
• Size: a general OT is commonly about 6 m × 6 m (≈36 m²) with roughly 3-3.3 m ceiling height; specialised theatres (cardiac, neuro, robotic, hybrid) are larger, often 40-60 m², to hold perfusion, imaging and navigation equipment. Exact figures differ between NABH/NBC guidance and institutional norms - follow the local accredited layout.
• Surfaces: non-porous, seamless, washable, fire-retardant; coved skirting with no sharp corners (no dust traps); doors preferably sliding or hands-free; windows sealed; no false-ceiling gaps opening into the OT.
• Modular OT: prefabricated panels (stainless steel, glass-coated steel or HPL), flush fittings, pendants carrying gases and electrical outlets, integrated control panel for temperature, humidity, lights and pressure display. Advantages - hygiene, fast installation, easy maintenance; limitation - high capital cost and vendor-dependent spares.
• Traffic discipline: limited entry, OT-only footwear and attire, no movement in and out during surgery, doors kept shut (door opening is the commonest cause of pressure loss).

Air, temperature, humidity and services

• HVAC chain: fresh air + recirculated air → pre-filter (coarse) → fine filter → cooling/heating coil → HEPA filter at terminal supply → diffuser over the operating table. HEPA removes ≥99.97% of 0.3 µm particles.
• Positive pressure: the OT is kept at higher pressure than the corridor (commonly about 2.5-15 pascals differential, with a visible pressure gauge) so leakage is outward. Infective/isolation theatres may instead be kept at negative pressure.
• Air changes: the widely taught target is at least 20 total air changes per hour with a minimum share of fresh air (about 4-5 ACH); laminar (unidirectional) flow theatres for joint replacement and transplant use very high rates - of the order of 300-600 air changes per hour over a defined canopy, giving near-sterile air at about 0.2-0.45 m/s downward velocity.
• Temperature and humidity: usually 20-24 °C and 40-60% relative humidity. Low humidity raises static-spark and drying risk; high humidity encourages microbial growth and condensation. Paediatric and burns cases are often run warmer.
• Medical gas pipeline system (MGPS): oxygen, nitrous oxide, medical air, carbon dioxide and vacuum through colour-coded pipes with non-interchangeable gas-specific outlets, area valve service units, alarms and a manifold room; nitrous oxide/anaesthetic gas scavenging removes waste gases.
• Electrical safety: isolated power supply with line isolation monitor, equipotential earthing, UPS and generator back-up; no ordinary switches inside the sterile field; antistatic flooring in theatres where flammable agents are used.
• Lighting: ambient 300-500 lux plus a shadowless, cool, focusable surgical lamp giving high illuminance at the field (commonly 40,000-160,000 lux adjustable), colour temperature around 4,000-5,000 K for true tissue colour; LED heads have replaced halogen because of lower heat.

Sterilisation, disinfection and CSSD

• Definitions: Sterilisation destroys all microbial life including spores. Disinfection destroys most pathogens but not all spores. Antisepsis is disinfection of living tissue. Decontamination is cleaning + disinfection to make an item safe to handle.
• Spaulding classification: critical items entering tissue or blood (instruments, implants) → sterilisation; semi-critical touching mucosa (laryngoscope blades, endoscopes) → high-level disinfection; non-critical touching intact skin (BP cuff, table) → low/intermediate-level disinfection.
• Moist heat (autoclave, steam under pressure): the workhorse. 121 °C at 15 psi (≈1.1 kg/cm², 103 kPa gauge) for 15-20 min holding time, or 134 °C at 30 psi (≈2.1 kg/cm²) for 3-4 min in a flash/pre-vacuum cycle. Kills by coagulating proteins; needs steam contact, so air must be removed (gravity displacement vs pre-vacuum).
• Dry heat (hot-air oven): 160 °C for 2 h, 170 °C for 1 h, or 180 °C for 30 min - for glassware, powders, oils, sharp cutting instruments that steam would blunt or corrode.
• Chemical/low-temperature: ETO (ethylene oxide) at 37-55 °C for heat-sensitive items (plastics, electronics) - highly effective but toxic, flammable, needs long aeration; hydrogen peroxide gas plasma - fast, no toxic residue, but not for cellulose/linen or long narrow lumens; formaldehyde; glutaraldehyde 2% immersion (20 min high-level disinfection, 10 h for sterilisation) and ortho-phthalaldehyde for scopes; peracetic acid for automated endoscope reprocessing.
• Radiation: gamma (cobalt-60) for industrial sterilisation of disposables - sutures, gloves, syringes; done by the manufacturer, not the hospital.
• Monitoring - three types, all examinable:
  • Physical: time-temperature-pressure chart recorder, Bowie-Dick test for air removal in pre-vacuum autoclaves.
  • Chemical: autoclave tape, TST strips, Browne's tubes, internal process indicators (indicate exposure, not sterility).
  • Biological (the only proof of sterilisation): *Geobacillus stearothermophilus* spore strips for steam, *Bacillus atrophaeus* for ETO and dry heat.
• CSSD workflow (one-way flow): receiving/dirty → cleaning (manual, ultrasonic, washer-disinfector) → drying and inspection → assembly and packing (with indicators) → sterilisation → sterile store → issue. Shelf life is event-related (packaging integrity), not purely date-based.
• Theatre decontamination: daily damp dusting with disinfectant before the first case, spot cleaning between cases, terminal cleaning at day end, weekly deep clean. Classic formaldehyde fumigation is now largely replaced by hydrogen-peroxide/silver vapour fogging or UV-C because of formaldehyde's carcinogenicity and long contact/exhaust time. Microbiological surveillance by settle-plate/air sampling and swabs is done periodically as per hospital policy.

Instruments, equipment and energy devices

• Instrument classes by function: cutting and dissecting (scalpel/BP handle 3,4,7 with blades 10,11,15,20-24; Mayo and Metzenbaum scissors), grasping and holding (Allis, Babcock, Kocher, Lane's, tissue and dissecting forceps, Doyen's), haemostatic/clamping (mosquito/Halsted, artery forceps, Kelly, Satinsky vascular clamp), retracting (Langenbeck, Deaver, Morris, Czerny, Balfour and Finochietto self-retaining), suturing (needle holder - Mayo-Hegar, Debakey), accessory (towel clip, sponge-holding forceps, bowls, kidney tray, suction tip - Yankauer, Poole).
• Sutures: absorbable (catgut - now rarely used, polyglactin, polyglecaprone, polydioxanone) vs non-absorbable (silk, polypropylene, polyester, nylon, steel); monofilament (less infection, less knot security) vs multifilament (better handling). Gauge runs 5-0, 4-0 … 1, 2 - the more zeros, the finer. Needles: round-bodied for soft tissue, cutting/reverse-cutting for skin and fascia.
• Electrosurgery (diathermy): high-frequency current (about 300 kHz-3 MHz) heats tissue; at these frequencies there is no neuromuscular stimulation.
  • Monopolar: current flows from active electrode through the patient to a large return/dispersive pad; modes - cut (continuous low-voltage waveform) and coag (interrupted high-voltage, fulguration/desiccation). Risk - pad burns if contact is partial; use contact-quality monitoring.
  • Bipolar: current passes only between the two tips of the forceps - no pad needed; safer near nerves, in pacemaker patients and for fine work.
  • Other energy sources: harmonic/ultrasonic (55.5 kHz mechanical vibration, low thermal spread), vessel-sealing bipolar (LigaSure type), LASER, argon-enhanced coagulation, cryoprobe.
  • Hazards: alternate-site burn, capacitive coupling and insulation failure in laparoscopy, direct coupling, surgical smoke (needs smoke evacuator), interference with pacemakers/ICDs, and ignition of alcoholic skin prep - fire triad = fuel + oxidiser + ignition source.
• Suction apparatus: central pipeline vacuum or electric/manual suction; typical adult surgical suction about 300-400 mmHg, far lower for neonates and for tracheal suction. A trap jar and bacterial filter protect the pipeline.
• OT table and positioning: hydraulic/electric table with trendelenburg, reverse trendelenburg, lateral tilt, break and kidney elevation. Positions - supine (most), trendelenburg (pelvic/laparoscopic), lithotomy (obstetric, urological, perineal), lateral/kidney (nephrectomy, thoracotomy), prone (spine), jack-knife/Kraske (anorectal), sitting/Fowler's (shoulder, posterior fossa), lloyd-davies (colorectal). Positioning injuries to guard against - brachial plexus stretch, common peroneal and ulnar nerve compression, pressure sores, compartment syndrome in prolonged lithotomy, and ocular/corneal injury in prone.
• Other core equipment: anaesthesia workstation and monitors (covered in the anaesthesia paper), defibrillator, pulse oximeter, warming devices and fluid warmers, pneumatic tourniquet (thigh ≈ 250-300 mmHg or systolic + margin; recorded inflation time, usually ≤90-120 min before deflation), C-arm image intensifier with lead aprons and dosimeters, laparoscopy stack (camera, light source, insufflator with CO₂ at 12-15 mmHg intra-abdominal pressure, monitor, trocars), operating microscope, autotransfusion/cell saver, perfusion pump for cardiac cases.

Asepsis, sterile technique and the technologist's role

• Scrubbing: surgical hand antisepsis by the WHO-recommended method - 2-5 min with 4% chlorhexidine gluconate or 7.5% povidone-iodine scrub, or an alcohol-based surgical hand rub applied in sequence and allowed to dry; nails short, no nail polish, no rings or wristwatch; hands held above the elbows, water drains elbow-ward.
• Gowning and gloving: gown touched only on the inside; closed gloving for self-gowning (hands never leave the cuff) - preferred; open gloving for catheterisation and after re-gloving; assisted gloving by a scrubbed colleague. Double gloving in orthopaedics and high-risk cases.
• Rules of the sterile field (classic exam list): only sterile touches sterile; the gown is sterile in front from chest to sterile-field level and sleeves to 5 cm above the elbow; tables are sterile only at table-top level - anything hanging below the edge is unsterile; the 2.5 cm (1 inch) border of a drape or package edge is unsterile; moisture carries contamination (strike-through); never reach across a sterile field or turn your back on it; doubtful sterility = unsterile.
• Skin preparation: clipping (not shaving) immediately before surgery if hair must be removed; painting with 2% chlorhexidine in 70% alcohol or povidone-iodine from incision outwards, allowed to dry before draping (alcohol fire risk).
• Surgical Safety Checklist (WHO, three phases): sign-in before induction, time-out before incision (team introduction, patient-site-procedure confirmation, antibiotic prophylaxis within 60 min, imaging, allergies, anticipated blood loss), sign-out before the patient leaves (procedure name, instrument/sponge/needle counts, specimen labelling, equipment problems).
• Counts: sponge, sharp and instrument counts by scrub and circulating person - before incision, before closing a cavity, before skin closure and at shift change; any discrepancy → search, then X-ray; radio-opaque markers in gauze.
• OT technologist's duties: pre-operative - theatre and equipment readiness, trolley setting, checking sterilisation indicators, gas and suction, positioning aids; intra-operative - scrub/circulating role, passing instruments, maintaining the sterile field, specimen handling and labelling, documenting counts and implants; post-operative - instrument decontamination, waste segregation, equipment cleaning and logging, restocking, incident reporting.
• Specimen handling: correct container and fixative (10% neutral buffered formalin, roughly 10 × specimen volume), labelled with patient identifiers and site, entered in the register, never left in the theatre.

Infection control, waste, radiation and legal framework

• Surgical site infection (SSI) prevention bundle: antibiotic prophylaxis timed within 60 min of incision (120 min for vancomycin/fluoroquinolones) and usually stopped within 24 h, normothermia, normoglycaemia, adequate oxygenation, no routine shaving, correct skin prep, minimal traffic, good surgical technique.
• Standard precautions: treat every patient's blood and body fluid as infectious; appropriate PPE; no recapping of needles; sharps into puncture-proof containers; needle-stick injury → wash, report, baseline testing and post-exposure prophylaxis as per hospital protocol within hours.
• Bio-Medical Waste Management Rules, 2016 (amended; under the Environment (Protection) Act, 1986) - four colour categories:
  • Yellow - anatomical and soiled waste, discarded medicines, chemical waste, laboratory and microbiological waste → incineration/deep burial (as permitted).
  • Red - contaminated recyclable plastics: tubing, catheters, IV sets, syringes without needles, gloves → autoclave/microwave then shredding and recycling.
  • White (translucent, puncture-proof) - needles, scalpel blades, sharps → autoclave/dry heat then shredding/encapsulation.
  • Blue (cardboard with blue marking) - glassware, ampoules, vials, metallic implants → disinfection and recycling.
  • Pre-treatment of laboratory/microbiology waste on site, barcoded bags, no mixing, day-to-day records and annual return to the State Pollution Control Board; storage normally not beyond 48 hours.
• Radiation safety (C-arm in OT): AERB regulates medical X-ray use under the SHANTI Act, 2025 (which replaced the Atomic Energy Act, 1962) and the radiation protection rules; principles - justification, optimisation (ALARA), lead apron ≥0.5 mm lead equivalent, thyroid shield, goggles, distance (intensity falls as 1/r²), minimum fluoroscopy time, personnel monitoring badge (TLD/OSL), pregnancy declaration.
• Other legal and quality framework: NABH accreditation standards for hospitals (OT infrastructure, infection control, surgical safety, consent, sterilisation records); informed consent in the patient's language before surgery; CDSCO/Medical Device Rules, 2017 for device and implant regulation and implant traceability; Clinical Establishments Act in states that have adopted it; Transplantation of Human Organs and Tissues Act for retrieval theatres; PCPNDT Act where ultrasound is used; the four Labour Codes in force from 21 November 2025 govern staff hours and safety obligations (they replaced the Factories, Minimum Wages, Industrial Disputes and BOCW Acts); fire safety as per National Building Code provisions for institutional buildings, with smoke detectors, CO₂/dry-powder extinguishers and a practised evacuation plan.

Key points

• Four OT zones - protective, clean, aseptic, disposal; traffic flows clean → dirty and never back.
• Positive pressure - OT kept a few pascals above the corridor so air leaks outward; isolation theatres may be negative.
• HEPA filter - terminal filter removing ≥99.97% of 0.3 µm particles; placed at the supply diffuser above the table.
• Air changes - ≥20 ACH conventional (with ~4-5 ACH fresh air); laminar-flow theatres run several hundred ACH at 0.2-0.45 m/s.
• Temperature/humidity - 20-24 °C, 40-60% RH; outside this range infection, static and condensation risks rise.
• Autoclave - 121 °C/15 psi for 15-20 min, or 134 °C/30 psi for 3-4 min; moist heat coagulates proteins.
• Dry heat - 160 °C/2 h, 170 °C/1 h, 180 °C/30 min; for glass, powders, oils, sharp blades.
• ETO and H₂O₂ plasma - low-temperature sterilisation for heat-sensitive devices; ETO needs long aeration, plasma cannot handle cellulose.
• Biological indicator - spore test is the only confirmation of sterilisation; *G. stearothermophilus* for steam, *B. atrophaeus* for ETO/dry heat.
• Spaulding classification - critical/semi-critical/non-critical decides sterilisation vs high-level vs low-level disinfection.
• Monopolar vs bipolar diathermy - monopolar needs a dispersive return pad (burn risk); bipolar confines current between forceps tips.
• Fire triad in OT - fuel (alcohol prep, drapes), oxidiser (O₂, N₂O), ignition (diathermy, laser); let prep dry before draping.
• Sterile field rules - table-top only is sterile, 2.5 cm package/drape edge is unsterile, moisture = contamination, doubtful = unsterile.
• Closed gloving - used when gowning oneself; hands stay inside the cuff throughout.
• WHO checklist - sign-in, time-out, sign-out; counts at four defined moments.
• BMW Rules 2016 colours - yellow (incinerate), red (autoclave-shred-recycle), white (sharps), blue (glass/metal implants).
• ALARA and shielding - 0.5 mm lead apron, thyroid shield, distance, minimum screening time, TLD badge for C-arm work.
• Prophylactic antibiotic - give within 60 min before incision; usually discontinue within 24 h.

Formulas and examples

Example 1 - Air changes in a general OT. Room 6 m × 6 m × 3 m → V = 108 m³. The AHU delivers 2,200 m³/h to this theatre. ACH = 2,200 / 108 = 20.4 air changes per hour → just meets the ≥20 ACH target. If 20% of the supply is fresh air, fresh-air changes = 0.20 × 20.4 = 4.1 ACH - acceptable against the ~4-5 ACH fresh-air norm.

Example 2 - Laminar flow canopy. A laminar canopy of 3 m × 3 m (9 m²) supplies air downward at 0.30 m/s. Q = 9 × 0.30 = 2.7 m³/s = 2.7 × 3,600 = 9,720 m³/h. For the same 108 m³ theatre, ACH = 9,720 / 108 = 90 ACH for the whole room; within the canopy volume (9 m² × 2.4 m working height = 21.6 m³) the local rate is 9,720 / 21.6 = 450 ACH - which is why laminar theatres are quoted in hundreds of air changes.

Example 3 - Autoclave pressure check. A gauge reads 30 psi. Converting: 30 × 6.895 = 206.9 kPa gauge → absolute = 206.9 + 101.3 = 308.2 kPa, and 30 × 0.0703 = 2.11 kg/cm². Saturated steam at about 308 kPa absolute corresponds to roughly 134 °C - matching the 3-4 minute flash cycle. At 15 psi (103.4 kPa gauge, ≈205 kPa absolute) the steam temperature is about 121 °C, needing 15-20 minutes holding time.

Example 4 - Disinfectant dilution. Hypochlorite is supplied as 5% (50,000 ppm available chlorine). Prepare 10 L of 1% (10,000 ppm) solution for blood-spill decontamination. C₁V₁ = C₂V₂ → 5 × V₁ = 1 × 10,000 mL → V₁ = 2,000 mL concentrate + 8,000 mL water. For a 0.5% (5,000 ppm) surface solution: V₁ = 0.5 × 10,000 / 5 = 1,000 mL concentrate in 9 L water. Prepare fresh daily - hypochlorite loses strength on standing and is corrosive to metal instruments.

Example 5 - Distance as radiation protection. Scatter dose rate beside a C-arm is 120 µSv/h at 0.5 m from the patient. Stepping back to 2 m: I₂ = 120 × (0.5 / 2)² = 120 × 0.0625 = 7.5 µSv/h - a 16-fold reduction from distance alone, before any apron is counted. Over a 30-minute case that is 3.75 µSv instead of 60 µSv.

Where it is used

• Hospital operation theatres and day-care surgical centres: OT Technician/Technologist running scrub and circulating roles in general surgery, orthopaedics, obstetrics, ophthalmology and ENT theatres - government (AIIMS, PGIMER, JIPMER, state health services, ESIC, railway and defence hospitals) and private chains (Apollo, Fortis, Max, Manipal, Narayana, Medanta).
• CSSD and infection control: CSSD technician/in-charge roles, sterilisation record keeping, biological indicator logs, hospital infection control committee support, NABH documentation and audit preparation.
• Cardiac, neuro and transplant theatres: perfusion assistance, cell-saver and heart-lung machine set-up, neuronavigation and microscope handling, organ-retrieval theatre protocols under the transplantation law.
• Modular OT and medical gas industry: installation, commissioning and AMC of modular panels, HVAC/HEPA systems, MGPS and OT lights - companies such as Mindray, Dräger, Getinge, Skanray and Indian modular-OT fabricators; roles in biomedical engineering and application support.
• Endoscopy, cath-lab and OPD procedure rooms: scope reprocessing, laparoscopy stack handling, sterile tray preparation, C-arm radiation safety.
• Teaching, quality and regulatory work: OT technology faculty and clinical instructors, hospital quality/NABH coordinators, biomedical waste officers filing returns with the State Pollution Control Board.

Interview questions

• Q: What are the four zones of an operation theatre? A: Protective (outer), clean, aseptic/sterile and disposal (dirty); the layout forces traffic to move from clean to dirty and never in reverse.
• Q: Why is an OT kept at positive pressure? A: So that air always leaks outward through doors and gaps, preventing contaminated corridor air from entering the sterile field; infectious-case theatres are the exception and may be negative pressure.
• Q: What does a HEPA filter do and where is it placed? A: It removes at least 99.97% of particles of 0.3 µm size and is fitted as the terminal filter at the supply diffuser directly above the operating table.
• Q: Give the standard autoclave parameters and the alternative flash cycle. A: 121 °C at 15 psi for 15-20 minutes holding time, or 134 °C at 30 psi for 3-4 minutes in a pre-vacuum machine.
• Q: How do you prove that a load has actually been sterilised? A: Only a biological indicator proves it - a spore strip of *Geobacillus stearothermophilus* for steam or *Bacillus atrophaeus* for ETO and dry heat; tape and TST strips only show that the pack was exposed.
• Q: Difference between sterilisation, disinfection and antisepsis? A: Sterilisation kills all microbes including spores; disinfection kills most pathogens but not reliably spores; antisepsis is disinfection applied to living tissue.
• Q: Why is bipolar diathermy preferred in neurosurgery or for a patient with a pacemaker? A: Current passes only between the two forceps tips instead of through the body to a return pad, so thermal spread and electrical interference are minimal.
• Q: A diathermy return pad is partially peeled off - what is the danger? A: Current concentrates over the reduced contact area and causes a deep skin burn; the pad must be replaced with full contact on clean, dry, well-perfused, hair-free skin.
• Q: Which areas of a scrubbed gown are considered sterile? A: The front from chest to the level of the sterile field and the sleeves from cuff to about 5 cm above the elbow; the back, axillae and below field level are not.
• Q: What are the colour codes under the Bio-Medical Waste Management Rules, 2016? A: Yellow for anatomical/soiled/pharmaceutical waste, red for contaminated recyclable plastics, white puncture-proof for sharps, blue for glass and metallic implants.
• Q: When is surgical antibiotic prophylaxis given? A: Within 60 minutes before the skin incision (longer lead time for vancomycin or fluoroquinolones), redosed in long cases or heavy blood loss, and normally stopped within 24 hours.
• Q: What are the three components of the fire triad in an OT and how do you break it? A: Fuel (alcoholic prep, drapes, gauze), oxidiser (oxygen and nitrous oxide) and an ignition source (diathermy, laser); let the prep dry fully, avoid pooling, keep oxygen concentration low near the field and keep saline and an extinguisher ready.
• Q: What are the three phases of the WHO Surgical Safety Checklist? A: Sign-in before induction, time-out before incision and sign-out before the patient leaves the theatre.

Common mistakes

• Confusing disinfection with sterilisation, or claiming 2% glutaraldehyde for 20 minutes sterilises instruments - that duration gives only high-level disinfection.
• Quoting autoclave figures wrongly - swapping 121 °C/15 psi with 134 °C/30 psi, or stating total cycle time as the holding time (holding time starts only after the chamber reaches temperature).
• Treating autoclave tape or a colour-change strip as proof of sterility instead of a spore (biological) test.
• Mixing up monopolar and bipolar - forgetting that only monopolar needs a dispersive return pad, and so missing the burn risk in a viva scenario.
• Breaking sterile-field rules in the practical exam: reaching across the field, touching the outside of the gown, using items from below table-top level, or using a pack whose outer 2.5 cm edge has been handled.
• Mis-segregating waste - putting sharps in red bags, or needles with syringes - and forgetting that laboratory/microbiology waste needs on-site pre-treatment.
• Giving vague or outdated statements on practice - naming formaldehyde fumigation as the current standard, or quoting withdrawn IS numbers and old Acts; air-change and pressure figures vary between NABH, NBC and institutional policy, so state the range and the source.

Related topics

Anaesthesia technology basics · Sterilisation and CSSD practice · Hospital infection control and biomedical waste management · Surgical instruments and suture materials · Medical gas pipeline systems and OT HVAC · Patient positioning and peri-operative patient safety