Schwartz's Principles of Surgery ABSITE and Board Review, 9th Ed.

CHAPTER 9. Wound Healing

BASIC SCIENCE QUESTIONS

1. The peak number of fibroblasts in a healing wound occurs

A. 2 days after injury

B. 6 days after injury

C. 15 days after injury

D. 60 days after injury

Answer: B

(See Schwartz 9th ed., p 211, and See Figure. 9-1.)

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FIG. 9-1. The cellular, biochemical, and mechanical phases of wound healing.

2. Macrophages are present in the wound starting on the 4th day after injury until the wound is completely healed. The primary function of the macrophages in wound healing is

A. Intracellular killing of bacteria

B. Collagen production

C. Activation of cell proliferation

D. Modulation of the wound environment

Answer: C

The second population of inflammatory cells that invades the wound consists of macrophages, which are recognized as being essential to successful healing. Derived from circulating monocytes, macrophages achieve significant numbers in the wound by 48 to 96 hours postinjury and remain present until wound healing is complete. Macrophages, like neutrophils, participate in wound débridement via phagocytosis and contribute to microbial stasis via oxygen radical and nitric oxide synthesis (see Fig. 9-2C). The macrophage’s most pivotal function is activation and recruitment of other cells via mediators such as cytokines and growth factors, as well as directly by cell–cell interaction and intercellular adhesion molecules. By releasing such mediators as TGFβ, vascular endothelial growth factor (VEGF), insulin-like growth factor, epithelial growth factor, and lactate, macrophages regulate cell proliferation, matrix synthesis, and angiogenesis. Macrophages also play a significant role in regulating angiogenesis and matrix deposition and remodeling (Table 9-1). Modulation of the wound environment is most likely performed by T lymphocytes in the wound. (See Schwartz 9th ed., p 211.)

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FIG. 9-2. The phases of wound healing viewed histologically. A. The hemostatic/inflammatory phase. B. Latter inflammatory phases reflecting infiltration by mononuclear cells and lymphocytes. C. The proliferative phase, with associated angiogenesis and collagen synthesis.

TABLE 9-1 Macrophage activities during wound healing

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3. The first cells to migrate into a wound are

A. Macrophages

B. T lymphocytes

C. PMNs

D. Fibroblasts

Answer: C

PMNs are the first infiltrating cells to enter the wound site, peaking at 24 to 48 hours. Increased vascular permeability, local prostaglandin release, and the presence of chemotactic substances, such as complement factors, interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-α), TGFβ, platelet factor 4, or bacterial products, all stimulate neutrophil migration. (See Schwartz 9th ed., p 210.)

4. There are 18 types of collagen in the human body. Which two are the most important in wound healing?

A. Type I and III

B. Type III and VIII

C. Type II and X

D. Type VI and XII

Answer: A

Although there are at least 18 types of collagen described, the main ones of interest to wound repair are types I and III. Type I collagen is the major component of extracellular matrix in skin. Type III, which is also normally present in skin, becomes more prominent and important during the repair process. (See Schwartz 9th ed., p 212.)

5. The tensile strength of a completely healed wound approaches the strength of uninjured tissue

A. 2 weeks after injury

B. 3 months after injury

C. 12 months after injury

D. Never

Answer: D

By several weeks postinjury the amount of collagen in the wound reaches a plateau, but the tensile strength continues to increase for several more months. Fibril formation and fibril cross-linking result in decreased collagen solubility, increased strength, and increased resistance to enzymatic degradation of the collagen matrix. Scar remodeling continues for many (6 to 12) months postinjury, gradually resulting in a mature, avascular, and acellular scar. The mechanical strength of the scar never achieves that of the uninjured tissue. (See Schwartz 9th ed., p 213.)

6. How long does re-epithelialization (i.e., complete repair of the external barrier) take in a well-approximated surgical wound?

A. 2 days

B. 1 week

C. 2 weeks

D. 1 month

Answer: A

Re-epithelialization is complete in less than 48 hours in the case of approximated incised wounds, but may take substantially longer in the case of larger wounds, in which there is a significant epidermal/dermal defect. If only the epithelium and superficial dermis are damaged, such as occurs in split-thickness skin graft donor sites or in superficial second-degree burns, then repair consists primarily of re-epithelialization with minimal or no fibroplasia and granulation tissue formation. (See Schwartz 9th ed., p 214.)

7. Which of the following is an important cytokine mediator of wound healing?

A. TGFβ

B. α–interferon

C. Interleukin 12

D. β–Defensin 2

Answer: A

TGFβ is a mediator of wound healing primarily by mediating angiogenesis (see Table 9-2). Alpha interferon, Interleukin 12 and Beta Defensin 2 do not play a major role in wound healing. (See Schwartz 9thed., p 215.)

TABLE 9-2 Growth factors participating in wound healing

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8. The most common mode of inheritance of Ehlers-Danlos Syndrome is

A. Autosomal dominant

B. Autosomal recessive

C. X-linked dominant

D. X-linked recessive

Answer: A

Of the 10 types of Ehlers-Danlos syndrome, 6 are inherited with an autosomal dominant pattern, 2 are autosomal recessive, and 2 are X-linked recessive. (See Schwartz 9th ed., p 215, and Table 9-3.)

TABLE 9-3 Clinical, genetic, and biochemical aspects of Ehlers-Danlos subtypes

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9. Which of the following proteins is defective in patients with Marfan’s syndrome?

A. Collagen type I

B. Fibrillin

C. Lysyl hydroxylase

D. Fibronectin

Answer: B

Patients with Marfan syndrome generally have tall stature, arachnodactyly, lax ligaments, myopia, scoliosis, pectus excavatum, and aneurysm of the ascending aorta. The genetic defect is in an extracellular protein, fibrillin, which is associated with elastic fibers. Patients who suffer from this syndrome also are prone to hernias. Surgical repair of a dissecting aneurysm is difficult, as the soft connective tissue fails to hold sutures. Skin may be hyperextensible, but shows no delay in wound healing. Abnormalities of collagen type III. Lysyl hydroxylase and fibronectin are seen in specific subtypes of Ehlers-Danlos syndrome. (See Schwartz 9th ed., p 216.)

10. Which of the following proteins is defective in patients with osteogenesis imperfecta (OI)?

A. Collagen type I

B. Fibrillin

C. Lysyl hydroxylase

D. Fibronectin

Answer: A

Characteristics of OI are brittle bones, osteopenia, low muscle mass, hernias, and ligament and joint laxity. OI is a result of a mutation in type I collagen. There are four major OI subtypes with mild to lethal manifestations. Patients experience dermal thinning and increased bruisability. Scarring is normal, and the skin is not hyperextensible. Surgery can be successful but difficult in these patients, as their bones fracture easily under minimal stress. Table 9-4 lists the various features associated with the clinical subtypes of OI. Type I collagen is also defective in one of the subtypes of Ehlers Danlos syndrome, as is fibronectin. Fibrillin is defective in Marfan’s syndrome. (See Schwartz 9th ed., p 216.)

TABLE 9-4 Osteogenesis imperfecta: clinical and genetic features

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11. Which of the following components of wound healing is impaired in a child with acrodermatis enteropathica (AE)?

A. Macrophage signaling

B. Formation of granulation tissue

C. Collagen deposition

D. Collagen cross-linking

Answer: B

AE is an autosomal recessive disease of children that causes an inability to absorb sufficient zinc from breast milk or food. The AE mutation affects zinc uptake in the intestine by preventing zinc from binding to the cell surface and its translocation into the cell. Zinc deficiency is associated with impaired granulation tissue formation, as zinc is a necessary cofactor for DNA polymerase and reverse transcriptase, and its deficiency may impair healing due to inhibition of cell proliferation. AE is characterized by impaired wound healing as well as erythematous pustular dermatitis involving the extremities and the areas around the bodily orifices. Diagnosis is confirmed by the presence of an abnormally low blood zinc level (>100 mg/dL). Oral supplementation with 100 to 400 mg zinc sulfate orally per day is curative for impaired healing.

Zinc is the most well-known element in wound healing and has been used empirically in dermatologic conditions for centuries. It is essential for wound healing in animals and humans. There are more than 150 known enzymes for which zinc is either an integral part or an essential cofactor, and many of these enzymes are critical to wound healing. With zinc deficiency there is decreased fibroblast proliferation, decreased collagen synthesis, impaired overall wound strength, and delayed epithelialization. These defects are reversed by zinc supplementation. To date, no study has shown improved wound healing with zinc supplementation in patients who are not zinc deficient. (See Schwartz 9th ed., p 216.)

12. Which layer of the intestine has the greatest tensile strength (i.e. ability to hold sutures)?

A. Serosa

B. Muscularis

C. Submucosa

D. Mucosa

Answer: C

The submucosa is the layer that imparts the greatest tensile strength and greatest suture-holding capacity, a characteristic that should be kept in mind during surgical repair of the GI tract. Additionally, serosal healing is essential for quickly achieving a watertight seal from the luminal side of the bowel. The importance of the serosa is underscored by the significantly higher rates of anastomotic failure observed clinically in segments of bowel that are extraperitoneal and lack serosa (i.e., the esophagus and rectum). (See Schwartz 9th ed., p 216.)

13. Leaks from a bowel anastomosis most commonly occur 5 to 7 days after surgery. The reason is

A. Delayed collagen deposition

B. Increased collagenolysis

C. Breakdown of the initial fibrin seal by intraluminal bacteria

D. Increased macrophage migration from the peritoneum

Answer: B

Injuries to all parts of the GI tract undergo the same sequence of healing as cutaneous wounds. However, there are some significant differences (Table 9-5). Mesothelial (serosal) and mucosal healing can occur without scarring. The early integrity of the anastomosis is dependent on formation of a fibrin seal on the serosal side, which achieves watertightness, and on the suture-holding capacity of the intestinal wall, particularly the submucosal layer. There is a significant decrease in marginal strength during the first week due to an early and marked collagenolysis. The lysis of collagen is carried out by collagenase derived from neutrophils, macrophages, and intraluminal bacteria. Collagenase activity occurs early in the healing process, and during the first 3 to 5 days collagen breakdown far exceeds collagen synthesis. The integrity of the anastomosis represents equilibrium between collagen lysis, which occurs early, and collagen synthesis, which takes a few days to initiate (Fig. 9-3). (See Schwartz 9th ed., pp 216-217.)

TABLE 9-5 Comparison of wound healing in the gastrointestinal tract and skin

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FIG. 9-3. Diagrammatic representation of the concept of GI wound healing as a fine balance between collagen synthesis and collagenolysis. The “weak” period when collagenolysis exceeds collagen synthesis can be prolonged or exacerbated by any factors that upset the equilibrium. (Reproduced with permission from Hunt TK, Van Winkle W Jr: Wound healing: normal repair, in Dunphy JE (ed): Fundamentals of Wound Management in Surgery. New York: Chirurgecom, Inc., 1976, p. 29.)

14. Supplementation with which of the following amino acids may improve wound healing?

A. Glutamine

B. Arginine

C. Alanine

D. Guanine

Answer: B

The possible role of single amino acids in enhanced wound healing has been studied for the last several decades. Arginine appears most active in terms of enhancing wound fibroplasia…. Studies have been carried out in healthy human volunteers to examine the effect of arginine supplementation on collagen accumulation. Young, healthy, human volunteers (aged 25 to 35 years) were found to have significantly increased wound collagen deposition after oral supplementation with either 30 g of arginine aspartate (17 g of free arginine) or 30 g of arginine HCl (24.8 g of free arginine) daily for 14 days. In a study of healthy older humans (aged 67 to 82 years), daily supplements of 30 g of arginine aspartate for 14 days resulted in significantly enhanced collagen and total protein deposition at the wound site when compared to controls given placebos. There was no enhanced DNA synthesis present in the wounds of the arginine-supplemented subjects, suggesting that the effect of arginine is not mediated by an inflammatory mode of action. In this study, arginine supplementation had no effect on the rate of epithelialization of a superficial skin defect. This further suggests that the main effect of arginine on wound healing is to enhance wound collagen deposition. (See Schwartz 9th ed., p 221.)

CLINICAL QUESTIONS

1. Which of the following is seen in patients with Ehlers Danlos syndrome (EDS)?

A. Elevated PT/PTT

B. Spontaneous arteriovenous fistulae

C. Severe internal hemorrhoids

D. Portal hypertension

Answer: A

EDS is a group of 10 disorders that present as a defect in collagen formation. Characteristics include thin, friable skin with prominent veins, easy bruising, poor wound healing, abnormal scar formation, recurrent hernias, and hyperextensible joints. GI problems include bleeding, hiatal hernia, intestinal diverticulae, and rectal prolapse. Small blood vessels are fragile, making suturing difficult during surgery. Large vessels may develop aneurysms, varicosities, arteriovenous fistulas, or may spontaneously rupture. EDS must be considered in every child with recurrent hernias and coagulopathy, especially when accompanied by platelet abnormalities and low coagulation factor levels. Inguinal hernias in these children resemble those seen in adults.’ (See Schwartz 9th ed., p 215.)

2. A patient with epidermolysis bullosa (EB) requires placement of a feeding gastrostomy due to esophageal erosions. What kind of dressing should be placed after surgery?

A. None—leave the wound open to air

B. Steri-strips, gauze, and atraumatic tape

C. Tissue adhesive only

D. Nonadhesive pad with circumferential bulky dressing

Answer: D

EB is classified into three major subtypes: EB simplex, junctional EB, and dystrophic EB. The genetic defect involves impairment in tissue adhesion within the epidermis, basement membrane, or dermis, resulting in tissue separation and blistering with minimal trauma. Characteristic features of EB are blistering and ulceration. Management of nonhealing wounds in patients with EB is a challenge, as their nutritional status is compromised because of oral erosions and esophageal obstruction. Surgical interventions include esophageal dilation and gastrostomy tube placement. Dermal incisions must be meticulously placed to avoid further trauma to skin. The skin requires nonadhesive pads covered by ‘bulky’ dressing to avoid blistering. (See Schwartz 9th ed., p 216.)

3. Which phase of healing is most affected by exogenous corticosteroids?

A. Initial phase of cell migration and angiogenesis

B. Proliferative phase

C. Maturation

D. Scar remodeling

Answer: A

Large doses or chronic usage of glucocorticoids reduce collagen synthesis and wound strength. The major effect of steroids is to inhibit the inflammatory phase of wound healing (angiogenesis, neutrophil and macrophage migration, and fibroblast proliferation) and the release of lysosomal enzymes. The stronger the anti-inflammatory effect of the steroid compound used, the greater the inhibitory effect on wound healing. Steroids used after the first 3 to 4 days postinjury do not affect wound healing as severely as when they are used in the immediate postoperative period. Therefore, if possible, their use should be delayed or, alternatively, forms with lesser anti-inflammatory effects should be administered. In addition to their effect on collagen synthesis, steroids also inhibit epithelialization and contraction and contribute to increased rates of wound infection, regardless of the time of administration. (See Schwartz 9thed., p 220.)

4. Which of the following should be given to promote wound healing in patients receiving steroids?

A. Vitamin A

B. Vitamin B1

C. Vitamin B2

D. Vitamin C

Answer: A

Steroid-delayed healing of cutaneous wounds can be stimulated to epithelialize by topical application of vitamin A. Collagen synthesis of steroid-treated wounds also can be stimulated by vitamin A. (See Schwartz 9th ed., p 220.)

5. How long does protein calorie malnutrition need to be present in patients in order to affect wound healing?

A. Days

B. Weeks

C. 1 month

D. >3 months

Answer: A

Two additional nutrition-related factors warrant discussion. First, the degree of nutritional impairment need not be longstanding in humans, as opposed to the experimental situation. Thus, patients with brief preoperative illnesses or reduced nutrient intake in the period immediately preceding the injury or operative intervention will demonstrate impaired fibroplasias. Second, brief and not necessarily intensive nutritional intervention, either via the parenteral or enteral route, can reverse or prevent the decreased collagen deposition noted with malnutrition or with postoperative starvation. (See Schwartz 9th ed., p 221.)

6. A homeless, malnourished 48-year-old patient is admitted to the ICU after a severe blunt injury. A reasonable daily dose of vitamin C for this patient would be

A. 60 mg

B. 150 mg

C. 400 mg

D. ≥1 gm

Answer: D

Scurvy, or vitamin C deficiency, leads to a defect in wound healing, particularly via a failure in collagen synthesis and cross-linking. Biochemically, vitamin C is required for the conversion of proline and lysine to hydroxyproline and hydroxylysine, respectively. Vitamin C deficiency has also been associated with an increased incidence of wound infection, and if wound infection does occur, it tends to be more severe. These effects are believed to be due to an associated impairment in neutrophil function, decreased complement activity, and decreased walling-off of bacteria secondary to insufficient collagen deposition. The recommended dietary allowance is 60 mg daily. This provides a considerable safety margin for most healthy nonsmokers. In severely injured or extensively burned patients this requirement may increase to as high as 2g daily. There is no evidence that excess vitamin C is toxic; however, there is no evidence that supertherapeutic doses of vitamin C are of any benefit. (See Schwartz 9th ed., p 221.)

7. A previously healthy 18-year-old woman is involved in a housefire and is admitted with 60% deep partial thickness burns to the ICU. A reasonable daily dose of vitamin A for this patient would be

A. 1000 mg

B. 2500 mg

C. 10,000 mg

D. 25,000 mg

Answer: D

Vitamin A deficiency impairs wound healing, whereas supplemental vitamin A benefits wound healing in nondeficient humans and animals. Vitamin A increases the inflammatory response in wound healing, probably by increasing the lability of lysosomal membranes. There is an increased influx of macrophages, with an increase in their activation and increased collagen synthesis. Vitamin A directly increases collagen production and epidermal growth factor receptors when it is added in vitro to cultured fibroblasts. As mentioned in the section Steroids and Chemotherapeutic Drugs, supplemental vitamin A can reverse the inhibitory effects of corticosteroids on wound healing. Vitamin A also can restore wound healing that has been impaired by diabetes, tumor formation, cyclophosphamide, and radiation. Serious injury or stress leads to increased vitamin A requirements. In the severely injured patient, supplemental doses of vitamin A have been recommended. Doses ranging from 25,000 to 100,000 IU per day have been advocated. (See Schwartz 9th ed., p 222.)

8. The ideal time to administer prophylactic antibiotics to a patient undergoing a colon resection is

A. 8 hours before surgery with a dose repeated at the time of incision

B. 2 hours before surgery with a dose repeated at the time of incision

C. 1 hour before surgery

D. At the time of incision

Answer: C

Antibiotic prophylaxis is most effective when adequate concentrations of antibiotic are present in the tissues at the time of incision, and assurance of adequate preoperative antibiotic dosing and timing has become a significant hospital performance measure. Addition of antibiotics after operative contamination has occurred is clearly ineffective in preventing postoperative wound infections. (See Schwartz 9th ed., p 222.)

9. A 28-year-old patient with chronic granulomatous disease is scheduled for cystoscopy under general anesthesia. Which of the following tests should be obtained preoperatively?

A. Pulmonary function test

B. Echocardiogram

C. Abdominal ultrasound

D. EKG

Answer: A

Chronic granulomatous disease (CGD) comprises a genetically heterogeneous group of diseases in which the reduced nicotinamide adenine dinucleotide phosphate–dependent oxide enzyme is deficient. This defect impairs the intracellular killing of microorganisms, leaving the patient liable to infection by bacteria and fungi. Afflicted patients have recurrent infections and form granulomas, which can lead to obstruction of the gastric antrum and genitourinary tracts and poor wound healing. Surgeons become involved when the patient develops infectious or obstructive complications. The nitroblue tetrazolium reduction test is used to diagnose CGD. Normal neutrophils can reduce this compound, whereas neutrophils from affected patients do not, facilitating the diagnosis via a colorimetric test. Clinically, patients develop recurrent infections such as pneumonia, lymphadenitis, hepatic abscess, and osteomyelitis. Organisms most commonly responsible are Staphylococcus aureusAspergillusKlebsiellaSerratia, or Candida. When CGD patients require surgery, a preoperative pulmonary function test should be considered because such patients are predisposed to obstructive and restrictive lung disease. Wound complications, mainly infection, are common. Sutures should be removed as late as possible because the wounds heal slowly. Abscess drains should be left in place for a prolonged period until the infection is completely resolved. (See Schwartz 9th ed., p 224.)

10. Which of the following should be performed in a patient with a suspected Marjolin ulcer?

A. Hyperbaric therapy for 6 weeks

B. Zinc supplementation

C. Oral tetracycline for 6 weeks

D. Biopsy

Answer: D

Malignant transformation of chronic ulcers can occur in any long-standing wound (Marjolin ulcer). Any wound that does not heal for a prolonged period of time is prone to malignant transformation. Malignant wounds are differentiated clinically from nonmalignant wounds by the presence of overturned wound edges. In patients with suspected malignant transformations, biopsy of the wound edges must be performed to rule out malignancy. Cancers arising de novo in chronic wounds include both squamous and basal cell carcinomas. (See Schwartz 9th ed., p 224.)

11. Which of the following is considered the most effective therapy for venous stasis ulcers?

A. Supplemental vitamin A

B. Topical antibiotic ointment

C. Compression therapy

D. Hyperbaric therapy

Answer: C

The cornerstone of treatment of venous ulcers is compression therapy, although the best method to achieve it remains controversial. Compression can be accomplished via rigid or flexible means. The most commonly used method is the rigid, zinc oxide–impregnated, nonelastic bandage. Others have proposed a four-layered bandage approach as a more optimal method of obtaining graduated compression. Wound care in these patients focuses on maintaining a moist wound environment, which can be achieved with hydrocolloids. Other, more modern approaches include use of vasoactive substances and growth factor application, as well as the use of skin substitutes. Most venous ulcers can be healed with perseverance and by addressing the venous hypertension. Unfortunately, recurrences are frequent in spite of preventative measures, largely because of patients’ lack of compliance. (See Schwartz 9th ed., p 225.)

12. Which of the following is most likely to cause a diabetic ulcer?

A. Uncontrolled hyperglycemia

B. Large vessel ischemia (peripheral vascular disease)

C. Small vessel ischemia

D. Neuropathy

Answer: D

It is estimated that 60 to 70% of diabetic ulcers are due to neuropathy, 15 to 20% are due to ischemia, and another 15 to 20% are due to a combination of both. The neuropathy is both sensory and motor, and is secondary to persistently elevated glucose levels. The loss of sensory function allows unrecognized injury to occur from ill-fitting shoes, foreign bodies, or other trauma. The motor neuropathy or Charcot foot leads to collapse or dislocation of the interphalangeal or metatarsophalangeal joints, causing pressure on areas with little protection. There is also severe micro and macrovascular circulatory impairment. (See Schwartz 9th ed., p 225.)

13. A teenage, African American girl presents with large keloids on both earlobes 12 months following ear piercing. Which therapy should be added to surgical debulking of the lesions?

A. None—surgical resection alone is sufficient as the initial therapy

B. Intralesional corticosteroids

C. Pressure earrings

D. Radiation therapy

Answer: B

Excision alone of keloids is subject to a high recurrence rate, ranging from 45 to 100%. There are fewer recurrences when surgical excision is combined with other modalities such as intralesional corticosteroid injection, topical application of silicone sheets, or the use of radiation or pressure. Surgery is recommended for debulking large lesions or as second-line therapy when other modalities have failed. Silicone application is relatively painless and should be maintained for 24 hours a day for about 3 months to prevent rebound hypertrophy. It may be secured with tape or worn beneath a pressure garment. The mechanism of action is not understood, but increased hydration of the skin, which decreases capillary activity, inflammation, hyperemia, and collagen deposition, may be involved. Silicone is more effective than other occlusive dressings and is an especially good treatment for children and others who cannot tolerate the pain involved in other modalities.

Intralesional corticosteroid injections decrease fibroblast proliferation, collagen and glycosaminoglycan synthesis, the inflammatory process, and TGFβ levels. When used alone, however, there is a variable rate of response and recurrence, therefore steroids are recommended as first-line treatment for keloids and second-line treatment for HTSs if topical therapies have failed. Intralesional injections are more effective on younger scars. They may soften, flatten, and give symptomatic relief to keloids, but they cannot make the lesions disappear nor can they narrow wide HTSs. Success is enhanced when used in combination with surgical excision. Serial injections every 2 to 3 weeks are required. Complications include skin atrophy, hypopigmentation, telangiectasias, necrosis, and ulceration.

Although radiation destroys fibroblasts, it has variable, unreliable results and produces poor results with 10 to 100% recurrence when used alone. It is more effective when combined with surgical excision. The timing, duration, and dosage for radiation therapy are still controversial, but doses ranging from 1500 to 2000 rads appear effective. Given the risks of hyperpigmentation, pruritus, erythema, paresthesias, pain, and possible secondary malignancies, radiation should be reserved for adults with scars resistant to other modalities.

Pressure aids collagen maturation, flattens scars, and improves thinning and pliability. It reduces the number of cells in a given area, possibly by creating ischemia, which decreases tissue metabolism and increases collagenase activity. External compression is used to treat HTSs, especially after burns. Therapy must begin early, and a pressure between 24 and 30 mmHg must be achieved in order to exceed capillary pressure, yet preserve peripheral blood circulation. Garments should be worn for 23 to 24 hours a day for up to 1 or more years to avoid rebound hypertrophy. Scars older than 6 to 12 months respond poorly. (See Schwartz 9th ed., p 226.)

14. The risk of small bowel obstruction in the first 10 years after left colectomy is

A. 5%

B. 10%

C. 20%

D. 30%

Answer: D

Intra-abdominal adhesions are the most common cause (65 to 75%) of small bowel obstruction, especially in the ileum. Operations in the lower abdomen have a higher chance of producing small bowel obstruction. After rectal surgery, left colectomy, or total colectomy, there is an 11% chance of developing small bowel obstruction within 1 year, and this rate increases to 30% by 10 years. (See Schwartz 9thed., p 227.)

15. Intra-abdominal adhesions can be decreased after laparotomy by

A. Frequent irrigation to keep bowel surfaces moist

B. Using antibiotic irrigation at the completion of the case

C. Wrapping anastomoses in hyaluronic acid sheets prior to closure

D. Using only monofilament sutures in abdominal wound closure

Answer: A

There are two major strategies for adhesion prevention or reduction. Surgical trauma is minimized within the peritoneum by careful tissue handling, avoiding desiccation and ischemia, and spare use of cautery, laser, and retractors. Fewer adhesions form with laparoscopic surgical techniques due to reduced tissue trauma. The second major advance in adhesion prevention has been the introduction of barrier membranes and gels, which separate and create barriers between damaged surfaces, allowing for adhesion-free healing. Modified oxidized regenerated cellulose and hyaluronic acid membranes or solutions have been shown to reduce adhesions in gynecologic patients, and have been investigated for their ability to prevent adhesion formation in patients undergoing bowel surgery. Wrapping of the bowel suture area or placement in the proximity of the anastomoses with these substances is, however, contraindicated due to an elevated risk of leak. (See Schwartz 9th ed., p 227.)

16. A healthy 20-year-old presents to the emergency room with a large, contaminated laceration that he received during a touch football game. Which of the following solutions should be used to irrigate this wound?

A. Sterile water

B. Normal saline

C. Dilute iodine solution

D. Dakin’s solution

Answer: B

Irrigation to visualize all areas of the wound and remove foreign material is best accomplished with normal saline (without additives). High-pressure wound irrigation is more effective in achieving complete débridement of foreign material and nonviable tissues. Iodine, povidone-iodine, hydrogen peroxide, and organically based antibacterial preparations have all been shown to impair wound healing due to injury to wound neutrophils and macrophages, and thus should not be used. (See Schwartz 9th ed., p 228.)

17. Once the wound described above has been irrigated and débrided, which suture should be used to close the subcutaneous layer?

A. Biologic absorbable monofilament (plain gut)

B. Synthetic absorbable monofilament

C. Absorbable braided

D. None of the above

Answer: C

In general, the smallest suture required to hold the various layers of the wound in approximation should be selected in order to minimize suture-related inflammation. Nonabsorbable or slowly absorbing monofilament sutures are most suitable for approximating deep fascial layers, particularly in the abdominal wall. Subcutaneous tissues should be closed with braided absorbable sutures, with care to avoid placement of sutures in fat. Although traditional teaching in wound closure has emphasized multiple-layer closures, additional layers of suture closure are associated with increased risk of wound infection, especially when placed in fat. Drains may be placed in areas at risk of forming fluid collections. (See Schwartz 9th ed., p 228.)

18. An alginate dressing is best used in which of the following wounds?

A. An open traumatic wound

B. An open surgical wound

C. An infected wound

D. A partial thickness burn wound

Answer: B

Alginates are derived from brown algae and contain long chains of polysaccharides containing mannuronic and glucuronic acid. The ratios of these sugars vary with the species of algae used, as well as the season of harvest. Processed as the calcium form, alginates turn into soluble sodium alginate through ion exchange in the presence of wound exudates. The polymers gel, swell, and absorb a great deal of fluid. Alginates are being used when there is skin loss, in open surgical wounds with medium exudation, and on full-thickness chronic wounds. (See Schwartz 9th ed., p 229.)

19. Which of the following topical agents has been shown to improve healing in diabetic foot ulcers?

A. Epithelial growth factor

B. TGFβ

C. Platelet derived growth factor BB

D. Endothelial growth factor

Answer: C

At present, only platelet-derived growth factor BB (PDGF-BB) is currently approved by the Food and Drug Administration for treatment of diabetic foot ulcers. Application of recombinant human PDGF-BB in a gel suspension to these wounds increases the incidence of total healing and decreases healing time. Several other growth factors have been tested clinically and show some promise, but currently none are approved for use. A great deal more needs to be discovered about the concentration, temporal release, and receptor cell population before growth factor therapy is to make a consistent impact on wound healing. (See Schwartz 9th ed., p 231.)