Wound infection

1. Wound Infection
Prepared by
Pranjal Rokaya
Resident General Surgery
KIST MCTH
30 August 2022

2. Outline
1. Introduction
2. Wound Healing
3. Classification of Wound/SSI
4. Wound Complications
5. Prevention of SSI
6. General management

3. Wound
• Disruption in normal structure and function of skin and soft tissue architecture.
• Infection: Invasion of organism into tissue following the breakdown of local and systemic host
defenses.
• Major complications of trauma and surgery documented for 5000 years.
• Hippocratic teachings: Use of wine and vinegar
• Galen recognized suppuration heralded recovery.
• Koch’s postulates
• Ignac Semmelweis
• Identification of microbes and development of antiseptics.

4. Normal wound healing
1. Hemostatic phase (within minutes)
2. Inflammatory phase (0-3 days)
3. Proliferative phase (3 days to 3 weeks)
4. Remodelling phase ( 3 weeks to years)

6. Types of Wound closure and healing
1. Primary intention
 Wound edges opposed
Normal healing with minimal scar
2. Secondary intention
 Wound left open
Heals by granulation, contraction, and epithelialization.
3. Tertiary intention
Wound initially left open.
Edges later opposed when healing condition favorable.

7. Factors influencing healing of wound
• Site of the wound
• Structures involved
• Mechanism of injury
• Level of contamination
• Loss of tissue
• Local factors (eg. Vascular insufficiency, previous radiation)
• Systemic factors (eg. Malnutrition, DM, steroid use, AIDS)

8. Types of wound
1. Acute Vs Chronic
2. Tidy vs Untidy
 Surgical Wounds/Infection
1. Clean
2. Clean Contaminated
3. Contaminated
4. Dirty
1. Superficial
2. Deep
3. Organ/Space
1. Endogenous
2. Exogenous

10. Classification of Surgical Wound
1. Clean • No hollow viscus entered
• Primary wound closure
• No inflammation
• No break in aseptic technique
1-3 %
2. Clean Contaminated • Hollow viscus entered but controlled
• Minor breach in aseptic technique
• Mechanical drains used.
• Preoperative bowel preparation done
5-8%
3. Contaminated • Uncontrolled spillage from viscus
• Inflammation apparent
• Open traumatic wound
20-25%
4. Dirty • Pus in operative wound, open suppurative wound
• Severe inflammation
30-40%

12. Wound complications
a. Seroma
b. Hematoma
c. Wound Infection (Surgical Site Infection)

13. a. Seroma formation
• Collection of fluid containing fat, serum, or lymph that develops at surgical wound or dead space.
• Common in procedures which create dead space or interrupts lymphatic drainage.
• Presents as palpable SQ fluid collections under or adjacent to a skin incision.
• Diagnosis based on an examination, USG or CT scan.
• An asymptomatic seroma may spontaneously resolve, symptomatic should be aspirated and
pressure dressing applied.
• In refractory seromas, drain can be placed and packed to heal by secondary intention.

14. b. Hematoma
• Collection of blood clots and blood at the surgical site.
• Includes the SQ tissues and may be found in deeper tissue space.
• May be caused by incomplete surgical hemostasis or medical conditions that
impair clotting or conditions that impair hemostasis (eg: cirrhosis, uremia, sepsis).
• Superficial hematoma may present with skin discoloration, SQ swelling and pain
of affected area.
• Hematoma of other location may cause pressure effects and irritation depending
upon anatomic location.

15. ….contd
• If clotting disorders present, bleeding may persist and large hematoma may
present with anemia or hypovolemia.
• The appropriate evaluation of bleeding disorders and anticoagulants to assess
coagulopathy.
• History related to hemostasis such as liver or kidney diseases or a family history
of bleeding disorder should raise concern for hemostatic abnormality.

16. 0-1: Low risk; 2: Intermediate risk; >3 High risk
High risk of bleeding (2-4%): Cardiovascular, Orthopedic,
Surgery of head and neck, Urologic Surgery, Surgery more than
45 minutes.
Low risk of bleeding (0-2%) : Anticipated surgical time <45 mins,
abdominal hernias, cholecystectomy.

17. c. Wound Infection (Surgical Site Infection)
• Infection related to surgical procedure that occurs near the surgical site.
within 30 days following surgery
 90 days following surgery where implant is used.
• Associated with:
 Significant morbidity and mortality.
Transfer to ICU setting.
Prolonged hospitalizations .
 Hospital readmission.

18. Incidence
• In USA, 2-4% annually develop SSI.
• Incidence varies widely ranging from 5-40% depending upon the operative site
and wound classification.
Colon surgery: 10% [4]
Coronary bypass:3.3 to 3.7%
 Vascular surgery :0.16 to 29% [5]
 Caeserian delivery:3.4-30% [6]
Spinal fusion :1.3-3.1%

19. 1. Risk assessment
Patient factors
Older age
Immunosupression
Obesity
Diabetes Mellitus
Malnutrition
Smoking
CKD
Peripheral Vascular disease
Anemia
Radiation
Chronic skin disease
 Local Factors
 Open compared to Laparosopic surgery
 Prior skin preparation.
 Contamination of instruments.
 Inadequate antibiotic prophylaxis.
 Prolonged procedure.
 Local tissue necrosis.
 Blood transfusion.
 Hypothermia.
 Microbial factors
 Prolonged hospitalization.
 Toxin Secretion
 Resistance to clearance.

20. 2. Prevention of Surgical Site Infection

21. a. Patient Optimization
Treatment of active and remote infection as much as feasible.
Treat hypoalbuminemia (six fold increase in SSI vs normal albumin).
Diabetic control.
Laparoscopic procedures are generally associated with lower rates of SSI.
Delay of elective procedures in chemo/radiotherapy patients.
Smoking cessation four to six weeks prior to elective surgery.

22. b. Preoperative preparation
Short preoperative hospital stay.
Washing of hands before and after patient contact.
Antiseptic bath.
Preoperative skin shaving just prior to surgery (hair clipping has lowest rate of
SSI).

23. c. Infection control measures
Use of face mask and protective spectacles.
Waterproof disposable gowns and drapes.
Boots to avoid injury from dropped sharps.
Double gloving.
Removal of false nails, clipping nail length and removal of watches and finger
rings.
Jewelry on head and neck be removed or covered.

24. d. Prophylactic antibiotics
• Effective in reducing the risk of
infection in clean-contaminated and
contaminated operations.
• Used before the bacterial growth
becomes established.
• Intravenous administration at time of
induction is optimal.
• May be repeated 4 hourly in long
operations or unexpected.

26. e. Perioperative measures
• Maintaining normothermia.
• Limiting traffic through operating room.
• Use of laminar air flow; use of novel air barrier system.
• Use of supplemental oxygen prior to surgery.
• Restrictive transfusion reduces risk of SSI.
• Routine application of antiseptic( chlorhexidine/alcohol based) prior to surgery.
• Changing outer gloves and using new instruments for closure in open colorectal surgery.

27. f. Surgical technique
Gentle traction
Effective hemostasis
Removal of devitalised tissue
Minimisation of cautery
Obliteration of dead space
• Antibacterial irrigation a/w lower risk of SSI in intracavitary operations.
• The use of a wound protector reduces SSI compared to standard care.

28. 3. Clinical features
a. Superficial SSI
• Localized swelling, warmth, drainage with or w/o odor, wound breakdown, and separation
• Peri incisional erythema and pain at the incision site.
b. Deep SSI
• Same as above
• More often accompanied by fever and local tenderness
c. Organ/Space SSI
• Malaise, fever, tenderness in body region where the operation was performed without
overlying skin changes.

29. Recognizing necrotising infection
• Periincisional pain is severe and out of proportion to the expected degree of
postoperative pain.
• May have skin discoloration, blistering and devitalization.
• Copious dishwater like drainage, dusky and friable subcutaneous tissue.
• Extent of infection may not be apparent on visual inspection .

30. 4. Diagnosis
• Superficial SSI can be fully evaluated through direct observation.
• Imaging
USG can identify the presence of fluid in subcutaneous tissue.
In deep/organ space infection, CT or MRI may be helpful.
Oral contrast studies in the setting of prior GI resection.
• Gram stain and culture.

31. 5. General management

32. a. Wound exploration and debridement
 The wound should be opened, infected fluid drained and sent for culture.
Wounds that have devitalized edges, purulent collection, and residual suture
material benefit from debridement prior to further management.
 Performed with forceps, scalpel or scissors.
For SSI of laparotomy wounds, the benefits of removal of exposed fascial sutures
outweighed by the risk of evisceration.
Serial debridement until no necrotic tissue remains.

33. b. Irrigation
 Important for decreasing bacterial load and removing loose material.
 Low-pressure irrigation is performed using a syringe.
High-pressure irrigation is performed in an operative setting using a commercial
device.
 Warm isotonic saline is typically used, the addition of dilute iodine or other
antiseptic solutions is generally unnecessary.

34. c. Antibiotic therapy
 Determined by the extent of infection, presence of systemic manifestations, previous
antibiotics, resistance pattern, and patient comorbidities.
Initiated in following clinical circumstances
Cellulitis a/w intact but indurated surgical incision.
Persistent cellulitis in surrounding skin after wound opening.
Subcutaneous or deeper tissue has persistent inflammation after debridement or
drainage.
Implanted material is present within the infected area.
Systemic signs of infection.
Septic shock.

35. d. Wound management
I. Open wound care
The mainstay is healing by secondary intention with serial dressing consisting of
frequent wound packing and removal.
 Disadvantages include chances of recurrent infection, painful and cumbersome for
the patient.
II. Wound packing
 Dressing that maintain moisture and warmth facilitate healing.
Wound fluids contain tissue growth factors that facilitate reepithelialization and
promote autolytic debridement.

36. Gauze moistened with normal saline placed into wound and covered with dry
layers of gauge.
 When the gauge is removed, necrotic tissues are removed with it.
Once debridement is not necessary, packing material should be changed from
gauze to less traumatic materials.
 Dressing changes continued until the wound surface is mostly covered by
granulation tissue
 Can be changed OD or every other day to avoid disturbing the healing process.

39. Ideal dressing
Absorbs excessive wound fluid while maintaining a moist environment.
Protects from mechanical and caustic damage.
Prevents bacterial invasion or proliferation.
Confirms to wound shape and eliminates dead space.
Debrides necrotic tissues.
Doesn’t macerate surrounding viable tissue.
Achieves hemostatis and minimizes edema via compression.
Doesn’t shed fibres of any foreign body.
Minimises dressing changes.
Is inexpensive and transparent.

40. Negative pressure wound therapy
Alternative to wound healing by secondary intention with wound packing.
Can be applied to open wound with a clean, granulating base.
Reduces excess fluid accumulation and increases blood supply.
 Protects the skin from frequent dressing changes.
Relatively contraindicated in conditions where blood vessels or intestines are
exposed.

41. e. Delayed primary closure and reconstrution
Wound that are opened often left to heal by secondary intention.
 The benefit of more rapid wound healing but risk of recurrent infection.
Wound with skin contracture or tissue loss from debridement may require skin
grafting or flap reconstruction.
Nutritional support and meticulous wound care are critical for preparing wound bed.
Presence of granulation tissue in wound bed signals adequate blood and nutrition
supply.

42. Summary
SSI is an infection related to a surgical procedure that occurs near the surgical site within 30 days
of surgery.
 Types: Superficial, deep and organ/space.
Risk factors are similar to those a/w impaired wound healing.
Various infection control methods and good surgical technique help in prevention.
Diagnosis is done by physical examination and occasionally imaging.
Emperic therapy directed at most likely pathogen, culture reports, wound class, prior antibiotics
and resistance pattern.
Wound care involves exploration, debridement, irrigation, dressing, NPWT and closure.

43. References
1. Bailey and love, Texbook of Surgery
2. Sabiston’s Text book of Surgery
3. Swartz's text book of Surgery
4. Hedrick TL, Sawyer RG, Friel CM, Stukenborg GJ. A method for estimating the risk of surgical site infection in
patients with abdominal colorectal procedures. Dis Colon Rectum 2013; 56:627.
5. Inui T, Bandyk DF. Vascular surgical site infection: risk factors and preventive measures. Semin Vasc Surg
2015; 28:201.
6. Dias M, Dick A, Reynolds RM, et al. Predictors of surgical site skin infection and clinical outcome at
caesarean section in the very severely obese: A retrospective cohort study. PLoS One 2019; 14:e0216157

44. Thanks