Wounds in Surgical Patients Who Are Obese

Nancy Baugh MS, RN, ANP  Helen Zuelzer MS, NP-C, RN  Jill Meador BSN, RN  Jolie Blankenship RN, CWOCN  AJN, American Journal of Nursing June 2007  Volume 107 Number 6 Pages 40 - 50     Request Permissions

Figure 1. Pressure Ulcer: Before and After DebridementCoauthor Jolie Blankenship states: This patient came to the orthopedic unit for a knee replacement. She was morbidly obese and had type 2 diabetes. I ordered a bariatric bed and simple wound care for her sacrum because it was erythematous. Several days later the nursing staff told me it was worsening (top). I urged the patient to turn and get off her back; she told me this made her uncomfortable, so we found a trapeze bar to help her. She was transferred to a nursing facility three days later. She returned to our ED about one week later, and the physicians told me the smell was one of the worst they'd ever encountered. Staff were getting sick in the operating room when they opened up her ulcer and debrided it (bottom). The patient also had a colostomy placed to avoid fecal contamination. She asked me how her pressure ulcer could have gotten so bad. It should not have come to this.

Hyperglycemia. Strong relationships exist between obesity and metabolic syndrome (which causes insulin resistance, hyperglycemia, dyslipidemia, and hypertension18) and obesity and type 2 diabetes. Perioperatively, the stress response that results in the release of catecholamines such as cortisol, which increase blood glucose levels, can cause hyperglycemia in patients with or without diabetes. Hyperglycemia hinders surgical recovery and wound healing by impairing immunity, inhibiting the inflammatory response, and interfering with collagen synthesis.19 The long-term microvascular changes incurred in diabetes may further impair tissue oxygenation.2

A number of recent studies have demonstrated the benefit of tight glucose control on patient outcomes after surgery. One study found that after cardiac surgery, improvements in glucose control were linked to a reduction in mediastinitis (the researchers defined glucose control as a glucose level of less than 130 mg/dL for more than 50% of the time measured).20 Czupryniak and colleagues found that even mild elevations in blood glucose level—as low as 110 mg/dL, a level consistent with impaired fasting glucose in many obese patients—is a strong risk factor for wound infection after gastric bypass surgery.21 In light of these and other recent findings, the goal of achieving blood glucose levels of less than 200 mg/dL should be reconsidered. Insulin given by infusion may be more effective postoperatively than that administered by the oral or injected route. Hruska and colleagues found a significant decline in the incidence of postoperative wound infection in patients with diabetes who received continuous insulin infusion,22 although such patients require close monitoring to prevent hypoglycemia.

COMPLICATIONS

Surgical wound infection. The following factors significantly increase the risk of surgical site infection: abdominal surgery, procedures lasting more than two hours, three or more comorbidities at the time of surgery, and a contaminated wound.23 Obese surgical patients often have one or more of these factors and also a higher incidence of postoperative hematomas and seromas that may delay wound healing.12

Christou and colleagues reported a 20% wound-infection rate in patients undergoing bariatric surgery at their facility in Canada from 2001 to 2003.24 Skin microorganisms, particularly those of the Staphylococcus genus, are often implicated in postoperative wound infections. Diabetes places patients at high risk for extensive infection with mixed aerobic and anaerobic microorganisms because of poor circulation and high blood glucose levels.23 Moisture in skin folds, particularly in the abdominal pannus, groin, buttocks, and perineum, and under the breasts, provides an optimal environment for fungal growth. And liquids used to prepare the skin for surgery may pool in these areas, causing maceration and tissue breakdown.

Poor surgical wound healing and dehiscence can result from a variety of factors, including diabetes, anemia, and hypoproteinemia,25 in addition to decreased blood flow and tension at the wound edges that can occur in obese patients. Also, obese women undergoing cesarean section are at risk for seroma, infection, and dehiscence.12 Moreover, scar formation may be more pronounced as a result of prolonged surgical-closure times.26 (The presence of scars may make subsequent procedures difficult because scar tissue has less tensile strength than tissue that heals without scarring.) The use of a continuous suture for fascial closure, rather than an interrupted suture, has been found to decrease the incidence of superficial and deep wound complications in obese patients.1

Pressure ulcers occur as blood supply to the tissues is diminished, resulting in ischemia, which can lead to necrosis. The three main causes—pressure, shear, and friction—occur frequently during the treatment of the obese surgical patient. Generally, any external pressure above 32 mmHg will cause capillary occlusion, decreasing the oxygen available to distal tissues. External pressures that exceed this amount for even a short period are as damaging as lower pressures applied over a longer period. For example, the use of blankets, turn sheets, and heating blankets may increase pressures by almost 44 mmHg.27 Patients who are obese are further at risk because their body mass alone exerts increased pressure on dependent tissues; even the weight of a limp extremity can generate enough pressure to produce muscle ischemia.28

Operation times of as little as two and a half to four hours have been shown to significantly increase the risk of postoperative pressure ulcer development.29

Deep-tissue injury may occur after one episode of immobilization combined with pressure and first appears as a deep bruise or reddened, dusky area that may develop into a stage-3 or -4 pressure ulcer. In 2001 the National Pressure Ulcer Advisory Panel recognized it as another type of pressure-related injury.30 It may take days to appear, usually in the lumbar or gluteal region, before progressing to an extensive area of necrosis requiring surgical debridement.31 This tissue destruction is thought to result from not only the ischemia but also the ensuing tissue reperfusion once pressure is relieved.32 Deep-tissue injuries differ from typical pressure ulcers in that the damage begins in the muscle and progresses to the epidermis, rather than the reverse.

The buttocks, the back muscles, and skin folds are at greatest risk for deep-tissue injuries in prolonged operations when patients are in the lithotomy position.7 Gallagher noted that an obese patient is susceptible to atypical pressure ulcers, including deep-tissue injury, from the pressure exerted by the patient's own skin folds or by drains and indwelling catheters.33

Rhabdomyolysis. According to Wiltshire and Custer, a morbidly obese patient undergoing a surgical procedure lasting more than five hours can generate enough pressure on skeletal muscles to produce ischemia and infarction leading to rhabdomyolysis34—a rare but potentially fatal breakdown of skeletal muscle after a mechanical, chemical, or physical injury. Injuries, including those resulting from prolonged pressure, cause the release of intracellular components into the circulatory system. One of these components is myoglobin, an oxygen-carrying protein that gives muscles a reddish-brown color and is nephrotoxic. Renal failure, a significant complication of rhabdomyolysis, results from the myoglobin's obstruction of the renal tubules. Also, loss of structural integrity of the myocyte causes disruption of the cell's sodium–potassium pump, resulting in hyperkalemia, intravascular hypovolemia, and metabolic acidosis.35

Bostanjian and colleagues found that morbidly obese patients are at risk for developing rhabdomyolysis during bariatric surgery,36 and Mognol and colleagues found that about 23% of 66 consecutive patients who underwent laparoscopic bariatric surgery developed the condition.37 Diabetes, hypertension, hypoalbuminemia, and peripheral vascular disease increase the risk of rhabdomyolysis. Postoperative sepsis, hypokalemia, and hypophosphatemia are other potentially preventable risk factors35; other factors include a family history of muscle disease and the use of statins, which have mycotoxic properties that increase the risk of muscle-cell death,36 especially when a statin is combined with a fibrate such as gemfibrozil (Lopid) in a lipid-lowering regimen. Many other common medications and substances increase the risk of rhabdomyolysis in both obese and nonobese surgical patients. These include alcohol, colchicine, erythromycin, and corticosteroids.38 (See Table 1, at left, as well as “Rhabdomyolysis: An Overview,” February 2002.)

Figure 2. Deep-Tissue InjuryCoauthor Jolie Blankenship states: This patient is a black man, age 52, who had head and neck cancer. He spent 12 hours in the OR, and I was called by the nursing staff to evaluate his coccyx several days later (top). He was discharged two days later. Almost two months after this I was called to the clinic by the NP, who wanted me to evaluate his wound (bottom). It was debrided surgically and I arranged for him to be seen at the wound healing clinic for additional follow-up. He obtained a low-air-loss mattress and was provided with home nursing care and dressing supplies.

Table 1. Rhabdomyolysis in Surgical Patients Who Are Obese

NURSING MANAGEMENT

Respect and expertise. Rand and Macgregor found that 80% of severely obese patients surveyed felt that clinicians had treated them disrespectfully.39 Studies have also shown that some nurses believe people who are obese are lazy, unmotivated, demanding, or unattractive.40 Such attitudes can undermine safe and effective care for these patients. Numerous challenges and obstacles may impede care, including the following:

Comments that some clinicians consider benign often insult morbidly obese patients. Table 2, page 45, gives examples of such comments that patients at our facility have reported as insulting and provides possible alternative statements. All clinicians should take the time to explore their biases and consider how best to ensure compassionate care.

Table 2. Offering Sensitive Nursing Care

Preoperative strategies.Assessment and treatment of comorbidities, such as diabetes and hypertension, can improve the patient's perioperative course. Conditions affecting mobility such as degenerative joint disease should be controlled or alleviated to the extent possible. Baseline cardiovascular and respiratory evaluation, including chest X-ray, should be performed, as should blood testing that reflects baseline renal, metabolic, and nutritional status. Troia recommends obtaining baseline arterial-blood gas and oxygenation-saturation levels with the patient supine.41

Clinicians should obtain a comprehensive patient history and discontinue if possible medications or other substances that increase the risk of rhabdomyolysis. These include statins (also known as HMG-CoA reductase inhibitors), although it's not clear for how long these drugs should be withheld.35 Patients, especially those who are obese, should stop smoking eight to 12 weeks before surgery.42

Thorough skin assessment will allow for baseline comparison postoperatively. The nurse should examine the inner aspects of the thighs as well as skin folds for rash, maceration, infection, and breakdown and look for complications such as venous insufficiency and ulceration, candidiasis at the perineum or within skin folds, dermatitis secondary to incontinence, pressure ulcers on sites other than bony prominences, and lymphedema.43

Pressure ulcer risk assessment using the Braden Scale may be performed before and after surgery. The scale assigns a number in each of six subscales: nutrition status, mobility, activity level, the skin's exposure to moisture, sensory perception, and friction and shear.32 A patient whose total score is 18 or below is considered at risk; the lower the score, the higher the risk of developing a pressure ulcer. (See Wound Wise, “Preventing Pressure Ulcers with the Braden Scale,” June 2005.)

Patient positioning. In its 2006 Standards, Recommended Practices, and Guidelines, the Association of periOperative Registered Nurses (AORN) outlines six practices for safe perioperative patient positioning (see “The AORN's Six Recommended Positioning Practices for Surgical Patients,” page 46). Before transfer to the OR a patient's position should be considered. Factors to assess include age, height, and weight; skin condition; comorbidities; the type of anesthesia to be used; and the site of the surgery, so that positioning devices and personnel are available.44

The 2006 AORN Bariatric Surgery Guideline recommends that extra-wide stretchers with fully functioning hydraulics be available.45 Whenever possible the patient should be transported to and from the OR in her or his own bed, minimizing the number of transfers.

Equipment. The OR table should accommodate the weight of the patient. The bed should have a 1,000-lb. capacity with a 600-lb. tilt capacity, as well as a footboard attached to the bottom of the table or bariatric bed.45 Leg extensions will keep the patient from sliding toward the bottom of the bed.46 Double-wide arm boards are also helpful.

Large blood pressure cuffs should be available, but if they're not, a cuff placed around the forearm will allow auscultation of the radial artery. The thickness of the patient's tissues will require the use of extra-long surgical and laparoscopic instruments and extra-wide retractors.41, 45 If a patient has a short, thick neck, airway management and intubation might be difficult, requiring the use of a fiberoptic laryngoscope or bronchoscope for intubation.41, 45 If a tracheostomy is indicated, a tracheostomy tube and thick ties that won't cut into the patient's neck should be used.41, 45 Adipose tissue makes IV access a challenge, and the nurse should plan for venous access, as well as the use of extra long IV cannulas or insertion of a central line if long-term access is anticipated.47

While presurgical weight loss isn't widely recommended for most elective procedures, it may produce some benefit. Studies have shown that patients undergoing bariatric surgery who lost up to 10% of their weight preoperatively had shorter operating times, less blood loss, and greater weight loss at one year.48-50 At our facility, patients scheduled for bariatric surgery participate in a weight-loss program involving a low-carbohydrate, high-protein liquid diet and visits with a dietitian for at least two weeks beforehand. More study is needed to assess the value of preoperative weight loss.

Intraoperative strategies. OR policies should seek to shorten surgical times. Some procedures, such as intubation, may take longer in the patient who is morbidly obese.16 The AORN recommends the use of checklists and protocols, standardized processes, and excellent intraoperative communication among all personnel in order to minimize delays.45 Standardized protocols should stipulate, for example, that patients be evaluated after each intraoperative position change to ensure that circulation isn't impeded and nerves, skin, and tissues aren't being pinched.

Nurses should evaluate the patient's body alignment and tissue integrity at the time of positioning in the OR and anytime after repositioning or moving the patient or her or his bed.44 Careful positioning and the use of pressure-relieving surfaces such as gel pads, with particular attention given to skin folds and bony prominences, is important. The supine position, for example, places pressure on heels, elbows, spinal column, and occiput, increasing the risk of pressure ulcers and other tissue damage.44 Also, when using slings or the lithotomy position, nurses should protect the patient's loose tissue from compression41 and avoid the pooling of preparatory solutions that can change the skin's pH, remove protective oils, and result in maceration. Nurses should place few if any blankets, sheets, and other items under the patient; the layers can interfere with pressure-relieving surfaces.51 And when transferring, nurses should use assistive devices (such as hydraulic lifts and air mattresses) to reduce shear and friction.13

It's important that the patient be kept warm; doing so has been associated with the development of fewer pressure ulcers.52 But warming blankets should not be placed beneath patients, since it greatly increases pressure ulcer risk.51 Hypotension, which reduces tissue perfusion and oxygenation, should also be avoided.51

Readiness includes having the proper equipment and knowing how to use it. A bed designed to accommodate an obese patient will provide an adequate support surface and ease movement. Staff should be well versed in the operation of all equipment; many obese hospitalized patients fear being injured or causing injury to others, and these fears can interfere with treatment.4 Manufacturers' representatives can demonstrate the use of new equipment to staff and teach troubleshooting techniques. Annual revalidation should occur, as should in-service training for new staff members.

Figure 3. DehiscenceThis patient, who was morbidly obese and mentally ill, received a colostomy for rectal prolapse that had resulted from constant straining. She continued to strain after her surgery, and the wound dehisced. The surgeons placed acellular human cadaveric dermis (AlloDerm) at the base of the wound, as pictured here.

Maintenance of skin integrity depends on diligent skin assessment and care. Avoiding hot water, the nurse should use a pH-balanced cleanser, with minimal friction. Reducing moisture on the skin helps in preventing excoriation (the moisture harbored in skin folds encourages fungal growth). Highly absorbent dressings or pads may be placed in skin folds—for example, under the pannus and breasts—to absorb moisture. Oversize abdominal binders should be considered in the obese patient with midline abdominal incisions in order to support the wound and prevent dehiscence.33 Other measures include ensuring the proper function of surgical drains and using barrier creams and topical antifungals.

Respiratory care in patients who are obese supports adequate oxygenation and therefore collagen formation and wound healing. Such care involves incentive spirometry and vigorous pulmonary toileting, supplemental oxygen, monitoring of oxygen saturation, and the use of continuous positive airway pressure for concomitant sleep apnea. Early and continued mobility prevents respiratory complications, skin breakdown, and deep vein thrombosis. The semirecumbent or reverse Trendelenburg position can expand the chest; supplemental oxygen should be administered in the immediate postoperative period, and the oxygen saturation level should be above 94%.41

Postoperative pain management is a challenge because a drug's pharmacokinetics can be altered in adipose tissue. Analgesia must allow early mobility and permit participation in care, while avoiding oversedation. Because anesthetics and opioids are lipophilic, delayed release of these drugs from adipose tissue into the bloodstream may complicate recovery.13 It's therefore important to watch for resedation.

Proper nutrition is important to surgical recovery and wound healing. An obese patient can deplete lean body mass during acute illness or recovery from surgery while maintaining body fat; this can result in a negative nitrogen balance that's detrimental to recovery.12 The patient's diet should be high in protein and micronutrients; caloric intake should be adequate to meet metabolic needs. The goal should be to maintain a positive nitrogen balance and adequate amounts of vitamins A and C, zinc, copper, manganese, arginine, and glutamine, all micronutrients essential to wound healing.53, 54

Glycemic management in patients with diabetes before, during, and after surgery can significantly improve outcomes. Providers should be especially vigilant in preventing rhabdomyolysis in patients with diabetes, hypertension, or peripheral vascular disease.37 (See Table 1, page 44.) Signs and symptoms may be subtle and can include fever, muscle pain, and tea-colored urine. Urine testing may reveal myoglobinuria or proteinuria.34, 38 Bostanjian and colleagues recommend taking serial creatine kinase measurements in high-risk patients.36 Skin lesions should be thoroughly evaluated; blisters, abrasions, or pressure ulcers may mask extensive myonecrosis or skeletal-muscle–cell death.38

Treatment of rhabdomyolysis includes early IV hydration with normal saline, alkalization of the urine using bicarbonate, forced diuresis, and possible hemodialysis. Renal failure is prevented by early and aggressive IV administration of a normal saline solution. Urine alkalization through IV administration of sodium bicarbonate can decrease myoglobin toxicity in the kidneys, and osmotic diuresis with mannitol may help to flush myoglobin out of the renal tubules.38

* “Documentation of surgical positioning should be consistent with AORN's ‘Recommended practices for documentation of perioperative nursing care.’”1Is the patient's position documented? Is there adequate documentation of assessment after each position change during the procedure?

1. Recommended practices for documentation of perioperative nursing care. In: Standards, Recommended Practices, and Guidelines. Denver: Association of periOperative Registered Nurses; 2000. p. 229–31. [Context Link]

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