1. Wound Healing and Suture Knowledge
ASR Certification Prep
Kim Bayer, SRS, BS, CVT, LATg

2. Tissue Handling / Technique
Goal is to minimize trauma
Gentle
use minimal tension with tissue
Retractors should be placed to avoid excessive tension
Proper use of instruments
DO NOT CRUSH
Use Proper Technique
Keep Tissue Moist
Dry tissue is dead tissue
Minimize Time

3. Incisions Heal side-to-side, not end-to-end
There is little advantage to making an incision too small to easily view the surgical site

4. Tissue Handling / Technique
Different surgical techniques induce different levels of damage
cutting with sharp instrument
minimal traumatic
cuts / divides the cells
little adjacent cell damage
cutting with scissors
causes crush and tear trauma
relatively traumatic
adjacent cell damage

5. Tissue Handling / Technique
blunt dissection between / along tissue planes
minimal trauma

6. Tissue Handling / Technique
clamping tissue with hemostats / etc.
causes crushing of the cells
very traumatic
causes release of vasoconstrictors, clotting factors
proper for clamping vessels for ligation / hemostasis

7. Tissue Handling / Technique
provide gentle retraction with proper instruments

8. Tissue Handling / Technique
Keep Tissue Moist
“The solution to pollution is dilution”
Irrigate, rinse the incision surgery site
Lavage, irrigate body cavities

9. Hemostasis Bleeding should be stopped whenever possible
Excessive bleeding may cause hematomas or increase dead space
Hematomas prevent wound apposition and retard healing
Blood is a natural food for micro-organisms and a large clot will help protect them from the body’s immune system
Bacteria inside the clot will be protected
Bleeding may be slowed or stopped by applying pressure, clamping, electro/thermocautery, and with various chemicals
Excessive pressure may lead to tissue necrosis

10. Dead Space and a Clean Wound
Remove all non-essential material
Wounds with excessive debris should be thoroughly lavaged with an appropriate sterile fluid (isotonic saline, LRS, Tis-U-Sol, etc.) to flush them away
Dead Space is an open area in closed tissue
Filled with room air, it prevents tissue apposition, provides a space for blood and other fluid influx, and may harbor micro-organisms

11. Dead Space

12. Classification of Wounds
Clean
Standard surgical wound
Clean-contaminated
Clean wounds that are contaminated by entry into a viscus resulting in minimal spillage of contents
Contaminated
Lacerations, fractures, gross spillage from the GI tract, resulting from a break in aseptic technique
Within 6 hours of initial colonization a wound can be infected

13. Classification of Wounds
Dirty-infected
Caused by perforated viscera, abscesses, or a prior clinical infection
Ongoing infection at time of surgery may lead to a 400% increase in infection rates

14. Problems Infection Dehiscence
The source of infection should always be determined
Before closure of an infected wound the wound should be drained, debrided, and a small opening or drain left in
Dehiscence
Wound reopens
May result from too much tension on tissue, improper suturing technique, or improper suture materials

15. Wound Healing
Skin and fascia are the strongest but regain tensile strength quite slowly
Stomach and small intestine are weak, but heal quickly

16. Physiology of Wound Healing
Phases of Wound Healing
Inflammatory Phase
Migration /Proliferation Phase
Maturation Phase
Healed
Incision
Inflammatory
Migration /Proliferation
Maturation

17. Physiology of Wound Healing Inflammatory Phase 0 - 5 Day
can be prolonged
inflammatory and “clean-up” process
plasma, cells, fibrin, blood components
neutrophils, monocytes
remove debris
“remove the trash”
epithelialization / migration (as early as 48 hours)
clinically characterized by swelling, redness, warmth
strength due to suture
Incision
Inflammatory

18. Physiology Inflammatory Response Clinical Signs Course / Duration
swelling
redness
warmth / heat
Course / Duration
peak within 24 hours,
subsiding by day 3
Inflammation results in pain / discomfort

19. Wound Healing-Phases Phase 1
Inflammatory response causes an outpouring of tissue fluids, accumulation of cells and fibroblasts, and increased blood supply
Leukocytes produce enzymes to dissolve and remove damaged tissue debris

20. Wound Healing-Phases Phase 1 (day 1 to 5) Inflammatory response phase
Fluids flow into the wound and a scab forms
Localized edema, pain, fever, and erythema present
Basal cells migrate over the incision from the skin to cover the wound
Closure material is the primary source of tensile strength

21. Wound Healing-Phases Phase 2
Fibroblasts begin forming collagen fibers in the wound
Beginning of the return of tensile strength

22. Wound Healing-Phases Phase 2 (day 5 to 14)
Fibroblasts migrate toward the wound site
Begin forming collagen fibers
Tensile strength rapidly increases
Lymphatics recanalize
Blood vessels bud
Granulation tissue forms
Capillaries develop

23. Physiology Maturation Phase begins ~ day 14 and continues for months
collagen fibers become oriented along the “stress” line of the incision and form crosslinks
increases tensile strength
contraction
Incision
Healed
Maturation

24. Wound Healing-Phases Phase 3
Sufficient collagen is now laid down to withstand normal stress

25. Wound Healing-Phases Phase 3 (day 14 until done)
Tensile strength continues to improve for as long as one year
Skin regains 70 to 90% of its original strength
Collagen content remains constant but cross-links with other fibers
Scar is formed which grows paler as new vessel construction tapers off
Wound contraction occurs over a period of weeks or months

26. Wound Healing Types First Intention Second Intention Third Intention
Wound edges brought together during closure at the time of surgery
Second Intention
Wound is left open and heals from the bottom up
Slower than first intention and creates more granulation and scar tissue
Third Intention
Wound is initially not closed and remains open until a granulation bed formed, then the granulated tissue is closed using standard techniques
Useful in infected wounds
Infected tissue should not be closed or it will dehiss
Infection is resolved naturally, or with topical and systemic treatments

27. Closure / Suturing Proper Apposition Restore alignment of the tissues
close / decrease dead space
balance adequate closure with too much suture
suture is a foreign body and too much can effect healing

28. Closure / Suturing Proper Suture
use minimal size suture that has sufficient strength
knot security
absorbable vs. non-absorbable

29. Sutures Ideal suture material
All-purpose, composed of material which could be used in any surgical procedure (the only variables being size and tensile strength)
Sterile
Nonelectrolytic, noncapillary, nonallergenic, and noncarcinogenic
Nonferromagnetic, as is the case with stainless steel sutures
Easy to handle

30. Sutures Ideal suture material
Minimally reactive in tissue and not predisposed to bacterial growth
Capable of holding securely when knotted without fraying or cutting
Resistant to shrinking in tissues
Absorbed with minimal tissue reaction after serving its purpose
Doesn’t exist!

31. Sutures Surgeon should select suture materials for
High uniform tensile strength (quality)
Permitting use of finer sizes
Suture should be the smallest diameter that will do the job
Consistent uniform diameter
Sterile
Pliable for ease of handling and knot security
Freedom from irritating substances or impurities for optimum tissue acceptance
Predictable performance

32. Sutures Size Generally stated in “oughts”; i.e., 3-0, 5-0, etc.
2-0 is larger than 4-0, 0 is larger than 2-0, etc.
Some suture and wire is larger than 0, then numbered 1 and higher
2 is larger than 1, 6 is larger than 1, etc.
From smallest to largest:
7-0, 3-0, 0, 1, 3, 7, etc.

33. Sutures Monofilament Monofilament is a single strand
Passes through tissue easily, won’t harbor micro-organisms
Ties easily
May be weakened by crushing (clamping in forceps or needle holders)
Has more “memory”
Continues to hold the shape as it lay in the package
Good for percutaneous sutures
Knots may slip over time due to the slipperiness of the suture

34. Sutures Multifilament Multifilament is a bundle of strands, like rope
Affords greater tensile strength, pliability, flexibility, and knot security
May harbor micro-organisms and “wick” them down the suture
Should not be used for percutaneous sutures

35. Sutures
Absorbable
Absorbable suture holds temporarily but gradually loses tensile strength and is eventually mostly or completely absorbed

36. Absorbable Sutures Surgical Catgut: Plain or Chromic
Absorbed by proleolytic enzymatic digestive process.
Polyglactin 910 : Vicryl®
Polyglycolic acid: Dexon®
Poliglecaprone 25: Monocryl®
Polydixanone: PDSII®
Polyglyconate: Maxon®
Absorbed by Hydrolysis

37. Sutures Nonabsorbable
Nonabsorbable suture will retain tensile strength and not be absorbed
Many nonabsorbable sutures (silk) will lose some tensile strength over time
Useful for device fixation, areas of extreme tension, slow healing areas, or percutaneous skin sutures
Selected for procedures where the suture should be permanent

38. Non-Absorbable Sutures
Monofilament Polypropylene:
Polyester Fiber: Mersilene®,
Dacron®, Ethibond®, Ti.cron®
Monofilament Nylon: Ethilon®,
Dermalon®
Braided Nylon: Nurolon®, Surgilon®
Silk
Surgical Stainless Steel Wire

39. Conventional Cutting Needle
needle body is triangular and has a sharpened cutting edge on the inside
Primarily used for skin closure.

40. Reverse Cutting Needle
cutting edge on outer curve
For tough, difficult-to-penetrate tissues

41. Taper Point Needle needle body is round and tapers smoothly to a point
Used for soft, easily penetrated tissues

42. For blunt dissection and suturing friable tissue
Blunt Point Needle
Taper body
For blunt dissection and suturing friable tissue

43. Spatula Needle
flat on top and bottom with a cutting edge along the front to one side
Primarily used for eye surgery

44. Surgeon’s Knot
Extra throws do not add appreciable strength to the knot and may, in fact, weaken it while adding extra bulk
An initial double throw followed by one or two single throws is more than sufficient
The exception is nylon monofilament sutures, where two successive double throws are useful to prevent slippage

45. Suture Patterns Simple Interrupted
Maintains strength and tissue position if one portion fails
Requires more time and suture material
Has minimal holding power against stress

46. Suture Patterns Horizontal Mattress Tension suture
Useful in skin of dog, cow, and horse
Rapid and involves less suture material
Difficult to apply without excessive eversion
Should pass just below the dermis

47. Suture Patterns Horizontal Mattress
Tightness should be such that the skin edges just meet

48. Suture Patterns Vertical Mattress Tension suture
Stronger than the horizontal mattress
Time consuming and requires more suture material

49. Suture Patterns Cross-mattress Tension suture
Brings tissue into good apposition
Useful in suturing stumps (amputations)
Also useful for rib apposition and abdominal muscle closure

50. Suture Patterns Gambee or Crushing Useful in intestinal anastamoses
Permits minimal leakage
May reduce fluid passage through the lumen underneath
Crushing is similar to a vertical mattress pattern

51. Suture Patterns Simple Continuous
Usually used for lines no longer than 5”
Involves one diagonal pass and one perpendicular pass
Provide minimal tension-holding but hold tissue together in good apposition
Creates a good seal
More prone to failure if any portion is broken

52. Suture Patterns Running Both deep and shallow passes advance
Regularity more difficult
Slightly faster than a simple continuous pattern
Weaker than a simple continuous pattern

53. Suture Patterns Ford Interlocking
More stable in the event of partial failure or breakage
Provides greater tissue stability
Uses more suture material

54. Suture Patterns Lembert Closes hollow viscera
Provides inversion and creates a good fluid-tight seal

55. Suture Patterns
Halsted
Combination mattress and Lembert pattern

56. Suture Patterns Connell
Begun with a single inverting vertical mattress suture
Continues for the length of the incision

57. Suture Patterns Cushing
Modified Connell where the needle and suture do not enter the lumen
Provides a better fluid-tight seal than the Connell pattern

58. Suture Patterns Parker-Kerr
A single layer of Cushing covered by a single layer of Lembert
Used for infected uterine stumps and some bowel closures
Provides complete clamping to prevent leakage during suturing

59. Suture Patterns
Rochester-Carmalt forceps are used to clamp the lumen shut and then slowly withdrawn while placed suture is tightened to prevent spillage of contents

60. Suture Patterns Guard Modified Cushing
Closes incisions of the rumen, intestine, and uterus
Needle does not enter the lumen
Starts slightly higher than start of incision

61. Suture Patterns Continuing Everting Mattress
Provides increased strength
Rapid placement

62. Suture Patterns Subcuticular
Does not penetrate the surface of the skin
Rapid and uses little suture material
Used to close the upper-most layer of the skin incision
Requires no suture removal

63. Suture Patterns Subcutaneous
May use simple interrupted, simple continuous, or horizontal mattress
Simple continuous is fast and eliminates dead space

64. Suture Patterns Quilted
Exteriorized skin suture through plastic tubing to resist excessive tension and stress
Useful for high-tension closures

65. Suture Patterns Far-far, Near-near Tension pattern
Overlapping suture pattern provides extra strength but requires extra suture material

66. Suture Patterns Near-far, Far-near Tension pattern
Overlapping suture pattern provides extra strength but requires extra suture material

67. Suture Patterns Mayo Mattress
Useful for midline abdominal closures, abdominal hernia repair, and secondary cleft palate repair

68. Suture Patterns Bunnell Used for apposing tendons
Requires a high degree of closure strength
Uses non-absorbable suture
Uses a double-armed suture

69. Suture Patterns Modified Bunnell Used for apposing tendons
Requires a high degree of closure strength
Uses non-absorbable suture
Uses a single-armed suture

70. Suture Patterns Cerclage Wiring Used for fracture repair
Wire/pin placed in the bone center to hold it together
Wire winds about the bone under the periosteum

71. Suture Patterns Hemicerclage
Wire goes through holes drilled in the bone

72. Suture Patterns for Specific Tissues
Skin- simple interrupted, horizontal mattress, vertical mattress, continuous apposing or everting
Subcutaneous tissue- simple continuous
Fascia- simple continuous (primary), simple interrupted, vertical mattress, far-near, near-far, Mayo mattress
Peritoneum- simple continuous (two-layer), and simple interrupted
Very thin and fragile in horse, close muscle instead

73. Suture Patterns Vessels- simple interrupted and simple continuous
Viscera- direct appositional Cushing suture
Muscle- simple continuous, simple interrupted, and horizontal mattress
Tendons- Bunnell
Bone- hemicerclage and cerclage

74. References
Clinical Textbook for Veterinary Technicians; McCurnin, D.M.; W.B. Saunders Co., Philadelphia, 1994
Ethicon Wound Closure Manual; Available at
Fundamental techniques in Veterinary Surgery;
Knecht, C.D.; Allen, A.R.; Williams, D.J.: Johnson, J.H.; W.B. Saunders Philadelphia, 1981
Davis + Geck Veterinary Suture Manual, 1991