Lab 5 . Part 3 - Achieving a sterile field

Goals

1. Isolate surgical site from contaminated areas with an impermeable barrier
2. Provide a sterile working area  

Draping materials

• ideal barrier material is impermeable, easy to sterilize and economical 
• two basic types:  Cloth (woven) or Disposable (nonwoven)

Cloth (woven)

•  typically cotton muslin
• tightness of weave is measured in threads per square inch
  • the higher the number, the tighter the weave and the better the barrier
  • 140 threads per square inch: not  effective barrier (pore size too big)
  • 270 threads per square inch: effective if dry but bacteria can penetrate when wet unless treated with water resistant coating
• reusable
• economical depending on cost of laundering

Disposable (nonwoven)

• made from regenerated cellulose, wood pulp, polyesters, synthetic polymer fibers or combinations
• effectiveness of barrier varies with product
• generally only those reinforced with plastic or polyethylene film are impermeable
• convenient but usually more expensive (depends on labour costs) 

 

• Sterile packs contain surgical drapes, instruments, gowns and gloves

• Sterile packs are double wrapped in cloth to increase storage life
  • Only sterile 24 hours if single cloth wrap
  • Sterile 3 weeks if double cloth wrap
  • sterile as long as wrapping intact (no holes) if sealed in plastic
• Opened by non-sterile person

• Both wraps opened touching only outside so a sterile field is created

 

• Extras are opened and tossed into center of sterile field without reaching over the field 
  WHY?
  Explanation:  Prevents bacteria and skin flakes from the person from falling on the sterile field contaminating it

• Once opened, the peripheral 5 cm in contact with a nonsterile surface is considered contaminated as well as anything below the table edge

For a surface to remain sterile, it must not be touched by a contaminated surface  

Protect your gloves - if they touch a contaminated surface they must be changed

 

• • fold them inside edges of a sterile drape when draping

  • otherwise keep gloves visible

• Avoid shaking the drapes (harder to control edges and creates excess air currents)

• Keep drapes above your waist (inside surgeon's sterile zone)

• Don't reach over the table to drape the far side; walk to other side of table to place the drape (can contaminate gown or drape as lean over)

• Place drapes where they will ultimately lie - do NOT move drape closer to the surgical field as bacteria and dirt from the haired region are pulled toward your sterile field  

“Ground” or “square” drapes

• • generally drapes are applied along each side of a square containing the proposed incision and the immediate surrounding area
  • isolates incision area from the unprepped areas
  • Drapes should be large enough to cover the animal and table

Slit drape (or laparotomy drape)

• • Second layer of drapes
  • Should provide an effective barrier to fluids (ie. treated with water repellent or plastic reinforced)
    • want to see water bead on surface
  • Slit in center that is placed over the proposed incision site
  • Covers the entire field with a single drape
• additional drapes are applied as necessary to ensure the entire animal and table is covered by two layers of drapes

• All the instruments and supplies required for the procedure should be within easy reach
  • entire table should be covered
  • second layer should be waterproof
  • organized so instruments and supplies are quickly available

Options:

1. Large instrument table
   • rolled close to the patient
   • organized so that instruments and supplies are within easy reach
2. Mayo stand 
   • Small movable table that can be moved over surgical field to ensure easy access to instruments
   • useful for simple procedures with minimal instruments and supplies
   • draping
     • covered by “pillow case” to minimize contamination from underneath
     • second drape should be waterproof
     • covering towel gives stable surface

• peripheral 5 cm edge in contact with a non-sterile surface is considered contaminated because may have touched a nonsterile surface
• anything below the table edges is considered contaminated as good chance may have had contact with a non-sterile surface or a person
• If you can't see it → it should be considered contaminated