The effects of malnutrition on the surgical patient are well characterized in the literature but are often overlooked in the
clinical arena. Between 30% and 50% of hospitalized
patients are malnourished. Protein-calorie malnutrition produces
a reduction in lean muscle mass, alterations in respiratory mechanics,
impaired immune function, and intestinal atrophy. These changes
result in diminished wound healing, predisposition to infection,
and increased postoperative morbidity. Although most healthy individuals
can tolerate up to 7 days of starvation (with adequate glucose and
fluid replacement), those subjected to major trauma, the physiologic
stress of surgery, sepsis, or cancer-related cachexia require nutritional
intervention much sooner. Methods to identify those at greatest
need for supplemental nutrition and to adequately address their
needs are discussed in this chapter.
Nutrition screening is the process of identifying patients who are either malnourished or at risk for developing malnutrition. Major
trauma and surgical stress alter the intake and absorption of nutrients,
as well as their utilization and storage by the body. In select
patients (eg, those with severe malnutrition as determined below),
preoperative nutritional support has been shown to significantly
reduce perioperative morbidity and mortality. Although most patients
do not require this level of support, nutrition screening is imperative
to identify the patient at high risk for malnutrition or its sequelae.
A comprehensive nutritional assessment incorporates the initial
history, physical examination, and laboratory testing to provide
a snapshot of the patient’s recent nutritional health.
History & Physical Examination
The history and physical examination are the foundation of nutritional assessment. A complete medical history is essential to identify
factors that predispose the patient to alterations in nutritional
status (Table 10–1). Chronic illnesses
such as alcoholism are commonly associated with protein-calorie
malnutrition as well as vitamin and mineral deficiencies. Previous
operative procedures such as gastrectomy or ileal resection may
predispose to generalized malabsorption or isolated deficiency of
iron, vitamin B12
, or folate. In most cases, the possibility of malnutrition is suggested by the underlying disease or by a history of recent weight loss. Patients with renal failure who require hemodialysis lose amino acids, vitamins, trace elements, and carnitine in the
dialysate. Cirrhotics often suffer from whole-body sodium overload
despite being hyponatremic, and they are typically protein-deficient. Patients
with inflammatory bowel disease, particularly those with ileal involvement,
may develop protein deficiency due to a combination of poor intake, chronic
diarrhea, and treatment with corticosteroids. Furthermore, alterations
in the enterohepatic circulation of bile salts lead to fat, vitamin,
calcium, magnesium, and trace element deficiencies. Approximately 30% of patients with cancer have protein, calorie, and
vitamin deficiencies due either to the underlying disease or to antimetabolite
chemotherapy (eg, methotrexate). Patients infected with HIV are frequently malnourished and have protein, trace metal (selenium and zinc), mineral,
and vitamin deficiencies.
Table 10–1. Nutritional Assessment.
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