Theatre

Theatre Layout and Design

Close Proximity to Related Facilities

• ICU, A&E, Surgical Wards, Radiology, Pathology

Zones

• Outer Zone: Reception
• Clean Zone: Reception up to the theatre itself
• Aseptic Zone: Theatres
• Disposal Zone: Dirty corridor for disposal

Note: Zones should be linked via corridors that prevent cross-contamination.

Within Theatre

Control of Key Factors

1. Temperature and Humidity:
   • Controlled via ventilation and thermostats.
   • Patients under anaesthesia are at risk of hypothermia.
   • Optimal theatre temperature: 25°C to prevent hypothermia; 19°C for surgical temperature.
   • Solutions: Bair Hugger, warmed fluids, blankets, airflow mattress.
   • Higher temperature needed for paediatric patients due to larger body surface area.
   • Optimal Humidity: Around 50%.
2. Light:
   • Illumination at the wound site should be 40,000 lux.
   • Satellite lights: Positioned directly, although they generate heat and convection currents.

Bacterial Contamination in Theatre

Sources of Infection

1. Patient
2. Instruments
3. Surgeon
4. Airborne (95% of infections)

Airborne Contamination

• Primarily due to people in the theatre (talking, shedding microorganisms, skin, and clothing).
• 90% of airborne bacteria come from below neck level, especially from axillae and groins.

Measuring Bacterial Contamination of the Air

• Measured in Colony Forming Units (CFU) or Bacteria Carrying Particles (BCP) per cubic meter.
• Microbiological Volumetric Slit Sampler: Draws air over a culture plate, incubated for 48 hours, then counts colonies formed.

Frequency of Measurement

• Plenum theatres: Every time they are refurbished.
• Extra clean theatres: Every 3 months.

Acceptable CFU/m3 values

• Plenum: <35 CFU & <1 CFU of Clostridium Perfringens and Staphylococcus Aureus.
• Ultra-Clean: <20 CFU in the periphery and <10 CFU in the centre.

Ventilation

Key Points

• The ideal air system should:
  • Provide a bacteria-free source of air.
  • Use positive pressure to displace contaminated air from the operative field.

How Air Enters the Theatre

• Air enters via roof-level HEPA filters (removing particles of 0.5 microns with 99.9% efficiency).
• Filters must be monitored regularly.

Ventilation Systems

Types of Laminar Flow

• Horizontal Laminar Flow:
  • HEPA filters on walls; airflow across the entire theatre.
  • Reduces infection in total hip replacement but increases infection in total knee replacement.
• Vertical Laminar Flow:
  • Introduced by Charnley.
  • Room within a room concept, air enters through HEPA filters and moves downwards.
  • Most commonly used type.
  • Problems occur if personnel or equipment deflect airflow.
• Exponential Flow (Ex Flow) System:
  • Overcomes vertical flow problems.
  • Air flows down and out in a trumpet shape.
  • Requires fewer air changes per hour.

Clinical Effects of Laminar Flow

• MRC 1982 RCT: Found vertical laminar flow to be more effective in reducing wound contamination.
• Charnley: Demonstrated a reduction in deep infections with laminar flow.

MRC Trial Findings on Reducing Deep Joint Sepsis

Clothing

Ideal Clothing Characteristics

• Prevent shedding of airborne bacteria.
• Effective when wet.
• Allows air and water vapor circulation.

Body Exhaust Suits

• Maintain negative pressure within the gown, preventing bacteria escape.

Surgical Drapes

• Disposable Non-Woven Drapes: Commonly used to prevent bacterial migration.
• Incision Drapes: No independent benefit shown, primarily used to keep body drapes attached to the skin.

Masks

• Recommended for all personnel in orthopaedic procedures.
• Prevent upper respiratory tract bacterial contamination (5% of airborne bacteria).
• Evidence shows only those near the wound need masks.

Gloves

• Protect both the wound and surgeon.
• Glove Changing:
  • Before making an incision (due to contamination during prepping and draping).
  • Before handling implants (due to glove colonization during a procedure).
• Double Gloving: 40% incidence of glove perforation in orthopaedic procedures, so double gloving is advised.