Journal of Trauma Nursing April 15, 1996 SECTION: No. 2, Vol. 3; Pg. 36; ISSN: 1078-7496 IAC-ACC-NO: 19132052 LENGTH: 5675 words HEADLINE: The obese trauma patient: treatment strategies; article includes Continuing Education Offering with examination and answer form BYLINE: Goodell, Teresa Tarnowski
BODY: Despite numerous unique features in the responses to trauma among obese and morbidly obese patients, very little literature exists on the care of the injured obese person. Factors such as body composition, psychosocial factors, coexisting illness, size, and weight necessitate modification to treatment protocols in almost all aspects of trauma care. Adaptations in hygiene, pharmacologic management, pulmonary support, rehabilitation, prevention of complications, and injury detection are needed to provide effective care to injured obese people. Body habitus, technical limitations of equipment, and unique injury patterns may increase the risk of missed injuries in this population. This article reviews the needs of the obese trauma patient and recommends strategies for effective multidisciplinary care.
Key words. Cure strategies, obesity, trauma
The Americans with Disabilities Act (ADA), passed in 1990, requires providers of public services to change policies, practices, and procedures in order to accommodate people with disabilities (U.S. EEOC, 1991). The ADA applies to universities, hospitals, government offices, and other entities to which the public requires equal access. The law stipulates that public entities must make reasonable modifications to accommodate people with special needs, such as the wheelchair-bound, without fundamentally altering the services provided by the agency. The ADA was designed to increase access to disabled people without placing undue burden on the agencies to which the law applies. In the language of the ADA, the law serves "individuals with disabilities," a phrase not usually considered applicable to obese people. The application of this law to the obese population was established by case law since the law's adoption; successive rulings have reaffirmed the protection of the ADA for this population (U.S. EEOC).
The dominant cultural preference for thinness and physical fitness influences attitudes toward people who deviate from the ideal body type. Obese patients encounter healthcare providers with prejudicial approaches brought about by misconceptions of the causes and the experience of being obese. An informal investigation conducted by the author revealed that obese clients had overheard insulting remarks about their body size, were subjected to mistreatment, and distrusted healthcare providers. Asking obese clients to describe their experiences in healthcare settings can be instructional for any provider with an interest in this population.
Definitions
The literature contains various definitions of simple obesity and morbid obesity (Boulanger, Milzman, Mitchell, & Rodreguez, 1992; Burge, Goon, Choban, & Flancbaum, 1994; Dickerson, Rosato, & Mullen, 1986; Jacobson, 1994; Mason, 1987; Pasulka & Kohl, 1989; McKee & Waddell, 1994), as illustrated in Table 1. Body mass index (BMI) is widely accepted as a useful method of defining obesity because it accounts for the percentage of body fat, based on height and weight. The normal BMI is 21 kg/[m.sup.2] for women and 23 kg/[m..sup.2] for men. Broadly defined, morbid obesity refers to persons whose body size limits their health, mobility, and access to places and services that would otherwise be available. For purely practical purposes, a working definition for healthcare providers may be based on the equipment specifications at the facility -- for example, the structural weight limit of a standard hospital bed.
Table 1. Definitions of Morbid, Simple, and Super Obesity
* Morbid Obesity
1. BMI [is less than] 37 kg/[m.sup.2] 2. Over 200% of ideal weight 3. [is less than] 100 lbs. over ideal weight
* Simple Obesity
1. BMI [is less than] 30 kg/[m.sup.2] 2. 20%-40% in excess of ideal weight
* Super Obesity [is less than] 225 percent of ideal body weight
Numerous chronic conditions are caused by or associated with obesity. The risks of chronic illness in obesity are listed in Table 2.
Table 2. Chronic Illness Risks of Obesity
* Cardiovascular disease
* Chronic hypoventilation
* Obstructive sleep apnea
* Hypertension
* Insulin-resistant (type II) diabetes mellitus
* Osteoarthritis
Nutritional Complications
The hyperglycemia and wasting of lean body mass associated with trauma-induced catabolism have special significance for the obese patient. Increased insulin resistance aggravates pre-existing hyperglycemia, causing undesirable diuresis, ketosis, and increased insulin requirements. Weight loss occurs as both lean and adipose tissue are burned for fuel. Muscle mass lost from diaphragmatic, intercostal, skeletal, and myocardial tissue can result in delayed ventilator weaning, slow progress with rehabilitation, and complications related to prolonged inactivity. Despite its technical challenges, weighing the obese patient daily is necessary to monitor nutritional needs and fluid status due to the risk of rapid large weight losses under stress.
Nutritional intake is commonly calculated to meet 100% of measured resting energy expenditure (MREE) in the form of carbohydrates and fat, with protein supplying additional calories. However, some research has shown that this regimen is insufficient to maintain lean body mass and may increase insulin resistance during acute illness in the obese patient (Baxter & Bistriam, 1989). Moderately hypocaloric nonprotein feeding may increase utilization of fat for fuel and spare lean body mass in mildly to moderately stressed obese patients receiving parenteral nutrition (Baxter & Bistrian; Burge et al., 1994; Dickerson et al., 1986). Research is needed to apply the results to enteral feeding and to severely stressed obese patients. The characteristics of standard and hypocaloric nutrition schemes are compared in Table 3.
Table 3 Comparison of Traditional and Hypocaloric Feeding
* Traditional
Non-protein calories 100% of MREE
Protein: 1.5-2.0 gm/kg ideal body weight
Total calories: nitrogen ratio: 150:1
* Hypocaloric
Non-protein calories: 50% of MREE
Protein: 1.5-2.0 gm/kg ideal body weight
Total calories: nitrogen ratio: 75:1
Many reversible and irreversible surgical approaches have been used to achieve weight loss in the morbidly obese. Earlier procedures limited nutrient absorption through the small bowel. Procedures developed later focused on creating early satiety by decreasing stomach size (Linner, 1987). The patient who has had surgery for weight loss in the past may malabsorb nutrients such as B12, iron, calcium, and magnesium (Brolin, Gorman, Milgrim, & Kenler, 1991; Halverson, 1987; Provenzale et al., 1992). Nurses need to be alert to the need to assess for nutrient deficiencies and to supplement essential vitamin and minerals in trauma patients who have had bariatric (related to obesity) surgery.
Skin and Wound Care
A number of factors place obese trauma patients at high risk of skin and wound problems. Moisture in skin folds, immobility, difficulties in turning and inspecting the skin, diaphoresis, delayed wound healing, and the limitations of standard pressure-reduction devices all contribute to an enhanced risk of skin and wound problems.
The therapeutic limit of the inexpensive airloss pressure-reduction mattress overlay used at our facility is 300 pounds. The more costly low-airloss beds with pressure-relief features (e.g., Flexicair[TM]) are ordered for obese patients who are expected to remain in bed for more than a few days. However, the softer mattress surface and greater height from the floor than the standard hospital bed make it difficult and more risky to mobilize patients from low-airloss beds.
For patients beginning to mobilize, a bariatric bed that converts to a chair (e.g., the Bari-800i[TM]) is ideal for promoting mobility while minimizing the risk of injury to patient and caregiver. Features such as an expandable-width bed surface and high side rails promote comfort and safety. Bariatric beds do not employ pressure-relief surfaces, and the stiffer mattress makes mobilization out of bed easier. However, skin breakdown may be aggravated by the stiffer mattress surface. The risks of skin breakdown vs. delayed mobility must be considered in deciding which therapeutic bed to use.
Obese patients with less severe injuries can use a standard hospital bed, provided their weight does not exceed the structural limit of the bed. Standard beds facilitate transportation for diagnostic testing, make mobilization easier, and decrease the stigma associated with "heavy-use" equipment.
Transporting the obese patient for tests or surgery can be challenging. In most cases, the hospital bed is a better choice than a stretcher because of the narrow width and structural weight limits of stretchers. Limiting transfers also decreases the risk of friction or shear injury while sliding from one surface to another. Slider or roller boards should be used to reduce friction when the patient must be transferred from one bed to another.
The weight of the body increases friction and shearing forces when the obese patient moves, whether actively or passively. It has been recommended that the head of the bed be raised as little as possible to prevent shearing injury to the subcutaneous sacral tissue (AHCPR, 1992). However, this recommendation presents a dilemma when the head of the bed must be raised for comfort or ventilator weaning for the obese patient.
Wound infection and dehiscence are more common among the obese population due to the relatively poor vascular supply to adipose tissue (Furnary et al., 1985; Jacobson, 1994). Supporting the wound with one or more extra large elastic binders is useful during transfers, coughing, or other activities that increase pressure on the abdomen or chest. There is some evidence that strict control of blood glucose is beneficial in preventing deep wound infection in obese diabetics (Furnary et al.). In all cases, meticulous wound care is necessary to prevent, detect, and treat wound complications. Prevention of maceration with frequent washing and thorough drying prevents breakdown in skin folds. The moist environment in skin folds encourages microbial growth, which commonly leads to fungal infections in the obese. Placement of a soft folded cloth between the surfaces of skin folds reduces friction and absorbs moisture. Non-medicated powders, e.g. cornstarch, absorb moisture but tend to clump when applied heavily. For this reason, they should be used sparingly if at all. Antifungal powders or creams can be used for actual infection, but are not recommended for routine prophylaxis.
Pharmacokinetics
The obese body is characterized by a higher proportion of adipose tissue and lower proportions of tissue water and lean body mass (Brentin & Sieh, 1991). These alterations account for differing patterns of drug absorption and distribution that can lead to subtherapeutic or toxic drug responses. Although it is beyond the scope of this article to describe specific dosing regimens, nurses should be aware of the factors that influence dosage adjustments and can account for differing responses to drugs with various pharmacokinetic patterns.
The amount of a medication that is absorbed for systemic distribution is influenced by the physiologic characteristics of the administration site (Reynolds, 1993). Drugs administered intramuscularly are likely to be deposited in poorly vascularized adipose tissue, hindering absorption and decreasing the amount of drug available for systemic distribution. Similar phenomena may occur with the subcutaneous and transdermal routes (Brentin & Sieh, 1991). Intravenous administration optimizes absorption, and may be required beyond the normal time frames to achieve acceptable pain relief and enhance rehabilitation. When the intravenous route is impractical, dosage and route adjustments should be made in consultation with the physician and pharmacist to achieve the desired effects of the drug while avoiding toxicity.
Drug distribution is influenced by body fat content and fluid volume status. Lipophilic drugs are highly soluble in fat and, thus, distributed mainly in adipose tissue. Initial dosages of lipophilic drugs are calculated to saturate the large volume of metabolically inactive adipose tissue, with smaller subsequent doses. Examples of highly lipophilic drugs are diazepam, lorazepam, opiate analgesics, propofol, and carbamazepine. In contrast, drugs distributed primarily into lean tissue (e.g., cimetidine, acetaminophen, digoxin) are dosed according to ideal body weight (Cheymol, 1993; Leader & Chandler, 1992)). Hydrophilic drugs (e.g., gentamycin, tobramycin, and neuromuscular blockers) are highly soluble in blood and extracellular fluid, and their concentration is subject to changes in body water content (Reynolds, 1993; Cheymol). Dosages of hydrophilic drugs should be calculated on the basis of ideal body weight. The need for frequent serum drug concentration monitoring may increase as fluids infused during resuscitation and surgery are mobilized and excreted.
There is evidence that factors other than drug solubility can influence distribution (Cheymol, 1993). Research on the metabolism of drugs in obese patients is limited: factors such as coexisting renal or hepatic impairment also can influence the action of drugs. Doses should be adjusted individually and patients closely monitored for effects of over or under-dosage. Routine consultation with a clinical pharmacist who is informed of the patient's status is recommended for very obese patients.
Respiratory failure was the most common cause of death among obese trauma patients in one trauma center's analysis of the causes of higher trauma mortality among the obese (Choban, Weireter, Maynes, 1991). Pulmonary complications clearly present a significant risk to obese trauma victims and warrant aggressive management.
The weight of the chest wall and impingement on the thoracic cavity by a large abdomen limit respiratory expansion in obese patients. In addition, fat deposition in the diaphragm and intercostal muscles impair the mechanics of breathing, decreasing functional residual capacity (FRC), expiratory reserve volume (ERV), forced expiratory volume (FEV), and minute ventilation (MV), as well as causing ventilation/perfusion mismatch (Sugerman, 1987). These functional alterations may be reversed when obese patients lose weight (Hakala, Mustajoki, Aittomaki, & Sovijarvi, 1995; Sugerman).
Obesity hypoventilation syndrome (OHS) occurs when chronic hypoventilation results in hypercapnia and chronic hypoxemia. OHS occurs in a portion of the obese population. Unfortunately, the correlation with excess body weight is not linear and patients who suffer from chronic hypoventilation are not easily identified when injured (Sugerman, 1987).
Sleep apnea syndrome (SAS) can occur as a result of airway narrowing from fat deposition in the upper airway and tongue. Although many patients manage the disorder independently and very successfully, undetected SAS has been
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