Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + TEST TAKING TIPS Download Section PDF Listen +++ ++ Test Taking Tips Questions tend to revolve around physiology of how wounds heal, that is, secondary intention, myofibroblasts, and which cells are involved in wound healing. The strength layer of bowel/skin is also commonly tested. One should also be familiar with which organs lack certain tissue layers such as the esophagus with no serosa and where the posterior rectus sheath starts/stops. +++ Name the 3 phases of wound healing: ++ Inflammation (1–6 days), proliferation (3 days–3 weeks), maturation (3 weeks–1 year) +++ Name several factors that can inhibit wound healing: ++ Diabetes, infection, ischemia, malnutrition, radiation, steroids, neoplasia, anemia +++ What are the optimal nutrition parameters? ++ Albumin >3 g/dL and prealbumin >16 mg/dL +++ What is primary wound closure (primary intention)? ++ Immediate closure of a wound with suture or staples +++ Most important factor in healing closed wounds by primary intention: ++ Tensile strength +++ What is the most important layer to close for strength in skin lacerations? ++ Dermis +++ How long does it take a surgical incision become "water tight"? ++ 24 to 48 hours +++ What is secondary wound closure? ++ Leaving a wound open and allowing it to heal by granulation, contraction, and epithelialization over time +++ Most important factor in the healing of open wounds by secondary intention: ++ Epithelial integrity +++ What causes contraction in wounds healing by secondary intention? ++ Myofibroblasts +++ What is delayed primary closure? ++ Closing a wound several days (3–5 days) after incision +++ Rate of regeneration of a peripheral nerve: ++ 1 mm/d or 1 in./mo +++ Rate of epithelialization: ++ 1 to 2 mm/d +++ The strongest layer of the bowel: ++ Submucosa +++ The time period that a small bowel anastomosis is at its weakest: ++ 3 to 5 days +++ Name the 2 major events in the process of epithelialization: ++ Migration and mitosis +++ Name the process by which keratinocytes pile up on top of each other at the leading edge of a migration and tumble forward over the top of the heap: ++ Epiboly +++ What cell is the most essential for wound healing? ++ Macrophage +++ This cell is responsible for the movement and contraction of wound edges: ++ Myofibroblast +++ Name the order of arrival of the different cells involved in wound healing: ++ Platelets (not a true cell) Neutrophils (predominant cell type from day 0–2) Macrophages (predominant cell type from day 3–4) Fibroblasts (predominant cell type from day 5 and so on) Lymphocytes +++ Platelet factor 4, β-thrombomodulin, PDGF, and TGF-β are contained in this type of platelet granule: ++ α granule +++ Adenosine, serotonin, and calcium are contained in this type of platelet granule: ++ Dense granule +++ Name the predominant cell during days 0 to 2 of wound healing: ++ Neutrophils +++ Name the predominant cell during days 3 to 4 of wound healing: ++ Macrophages +++ Name the predominant cell present after day 5 of wound healing? ++ Fibroblasts +++ When does the maturation phase usually begin? ++ ~3 weeks after the injury +++ What is the maximal tensile strength that a wound can reach? ++ 80% of original tissue strength +++ Time period for maximum collagen accumulation in a wound: ++ 2 to 3 weeks (mostly type III, then gets converted to type I with maturation) ++ FIGURE 9-1. The cellular, biochemical, and mechanical phases of wound healing. (Reproduced from Brunicardi FC, Anderson DK, Billiar TR, et al. Schwartz's Principles of Surgery. 9th ed. http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.) Graphic Jump LocationView Full Size||Download Slide (.ppt) +++ Time period for a wound to reach its maximal tensile strength: ++ 8 weeks +++ True or false: Denervation negatively affects epithelialization and wound contraction: ++ False; denervation has no effect on epithelialization/wound contraction +++ The number of organisms/cm2 required to retard wound healing: ++ 100,000 organisms/g (105 organisms/g) +++ What is the generally recommended period of time to wait for scar maturation before considering scar revision? ++ 12 to 18 months +++ What can be given to combat the inhibitory effects of steroids on wound healing and epithelialization? Dose? ++ Vitamin A; 25,000 IU daily +++ Necessary cofactor for hydroxylation and cross-linking of proline and lysine in collagen synthesis: ++ Vitamin C (deficiency causes scurvy) +++ Type of scar that extends beyond the boundaries of the original wound: ++ Keloid +++ Type of scar that remains confined to the boundaries of the original wound and contains an overabundance of collagen: ++ Hypertrophic scar +++ The most common type of collagen is: ++ Type I collagen +++ Type of collagen predominantly synthesized in the first 48 hours of a healing wound: ++ Type III collagen +++ Type of collagen located in skin, bone, tendon, and is the primary collagen found in a healed wound: ++ Type I collagen +++ Type of collagen found in hyaline cartilage: ++ Type II collagen +++ Type of collagen in arteries, dermis, and increased in wound healing: ++ Type III collagen +++ Type of collagen that is predominant in the basement membrane: ++ Type IV collagen (type IV found on floor) +++ Type of collagen found in the cornea: ++ Type V collagen +++ Stage the pressure sore: nonblanchable erythema of intact skin: ++ Stage I (can be seen after 30 minutes, resolves after 1–2 hours) +++ Stage the pressure sore: partial-thickness skin loss involving epidermis/dermis: ++ Stage II (can present as blister, forms after 2–6 hours, erythema lasts >24 hours) +++ Stage the pressure sore: full-thickness skin loss with involvement of underlying subcutaneous tissue: ++ Stage III (does not extend through fascia) +++ Stage the pressure sore: full-thickness skin loss with tissue necrosis or extensive destruction of underlying structures (muscle/bone): ++ Stage IV +++ Areas at greatest risk for pressure sores: ++ Ischium 28%, Trochanter 19%, Sacrum 17%, Heel 9%, Occiput of scalp +++ Rules of operative management for pressure sores (name 4): ++ Debride all devitalized tissue Excise entire bursa (can use methylene blue to identify entire bursa) Identify and remodel bony prominences Reliable tissue coverage with appropriate flap without burning bridges for future reconstruction +++ Name the amino acid that is found in every 3 residues in collagen: ++ Proline +++ Name the necessary cofactors for the hydroxylation of proline: ++ Vitamin C, oxygen, iron, and α-ketoglutarate +++ What enzyme is the rate-limiting step in collagen synthesis? ++ Propylhydroxylase +++ Albumin level that puts a patient at risk for poor wound healing: ++ <3.0 g/dL +++ Time period to wait for chemotherapy to have no effect on wound healing: ++ 14 days