What factors delay the process of wound healing
Malnutrition, diabetes, jaundice, uremia, steroids, chemotherapy and smoking.
What are the different types of wound healing?
Primary intention (suture promotes rapid re-epithelialization w/minimal scar). Secondary intention (just let the open wound heal w/o suturing). Tertiary intention (leave open for a few days to allow for granulation tissue, then suture, leaves less scar than secondary intention).
When can patients begin to lift more than 10-20 pounds post-op
6 weeks. Collagen accumulates in the scar until 3 weeks after. Cross-linking and development of breaking strength continues through 6 weeks.
A patient presents a few months after repair of a ventral hernia with a 4cm fascial defect that bulges when he coughs. What could cause this and how do you treat him?
Fascial dehiscence due to infection, suture failure or fascial weakness. This needs surgical repair.
A patient presents 6 months after surgery and complains of continues redness, sensitivity and ugliness. What do you do?
R/o suture abscess and observe until the scar stabilizes. If the wound is hypertrophic, recurrence is common unless treated with local steroid injections and pressure dressings.
What is different about a keloid when compared to a hypertrophic scar?
A keloid spreads outside the immediate area of the incision. Treat with revision, local steroid injections and compression.
When are oral or IV abx appropriate for surgical site infections?
When wound cellulitis appears to spread despite wound drainage and debridement.
Why heal by secondary intention?
This allows bacteria to be removed rather than accumulate in an abscess in a wound that was contaminated.
When would you consider using a skin graft for a wound you let heal by secondary intention due to infection?
If the wound is deep and healing is slow a skin graft will decrease wound contraction by 60% and hasten healing because granulation tissue will revascularize the graft (inosculation) and allow re-epithelialization of the wound. Bacterial count in the granulation be must be less than 10^5 to do the graft.
When would you consider healing by third intention?
Pt with post op surgical site infection that was well managed for a couple of days and has low bacterial counts in the wound bed. Suturing it shut allows for more rapid healing.
When does collagen start to appear in a healing wound
10 hours. Collagen production peaks around 5-7 days.
What gives collagen its strength to hold wounds together?
It has low tensile strenght until procallagen peptides are cleaved and cross-linking of collagen by fibroblasts occurs.
What cells are responsible for contractures?
Myofibroblasts cause wound contraction when wounds are allowed to heal by secondary intention.
What growth factors are most important in the healing process?
PDGF (chemotactic for fibroblasts, PMNs and macrophages. TGF-beta (increases collagen synthesis). FGF (hastens wound contraction). EGF (stimulates epithelial migration, mitosis and wound epithelialization).
Management of clean wounds
These have low risk (< 2%) of infection because no entry was made into GI, respiratory or GU tract and no active infection. Wounds can be closed primarily w/o abx (unless mesh or other foreign body is used for repair).
Management of clean-contaminate wounds
<3% chance of infection because the GI, respiratory or GU tract is entered, but prepared mechanically and with abx 1 hour preoperatively and single postoperatively dose (1 to 2.5 multiplied by drug half life in hours will tell you when to give it postoperatively). Wound is typically closed primarily with 10% risk of infection.
Management of contaminated wounds
< 5% chance of wound infection due to gross spillage of stool or infected material from the biliary, respiratory or GU systems. Typically left to heal by secondary or tertiary intention. Some surgeons say a 50% risk of infection with primary closure is acceptable because you can reopen it.
Infection rate of previously infected wounds like an appendiceal abscess
> 50% infection rate
Phases of wound healing
Inflammatory (0-7 days w/PMNs then macrophages, then lymphs). Proliferative (4-21 days w/fibroblasts). Remodeling ( 3 weeks to 1 year w/fibroblasts)
Indications for prophylactic antibiotics for surgery
Clean-contaminated cases, implantation of a device or prothetic material, immunosuppression or poor blood supply.
What procedures merit prophylaxis against endocarditis?
Respiratory tract: tonsillectomy/adenoidectomy, operations involving respiratory mucosa and bronchoscopy w/rigid scope. GI tract: esophageal sclerotherapy for varices, esophageal stricture dilation, ERCP, biliary tract surgery and operations involving intestinal mucosa. GU tract: prostate surgery, cystoscopy and urethral dilation.
Standard general abx prophylaxis for dental, oral, respiratory tract or esophageal procedures.
Amoxicillin (2g adults, 50mg/kg po for kids)
Standard abx prophylaxis for patients that cannot tolerate po medications scheduled for dental, oral, respiratory tract or esophageal procedures.
Ampicillin (adults 2g IM/IV, 50mg/kg IM or IV for children)
Abx prophylaxis for dental, oral, respiratory tract or esophageal procedures when patients are PCN allergic
Clindamycin (Adults 600mg po or IV, children 20mg/kg po or IV), cephalexin/cefadroxil (Adults 2g, children 50mg/kg po), azithromycin/clarithromycin (Adults 500mg po, children 15mg/kg po), cefazolin (adults 1g IV, children 25mg/kg IM or IV)