Manual of Clinical Nutrition Management III- 16 Copyright © 2013 Compass Group, Inc.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE
Discussion
Chronic obstructive pulmonary disease (COPD) is an incurable condition that results in progressive
obstruction and inflammation of the airways. COPD is the umbrella term for chronic bronchitis, emphysema,
and a range of lung disorders. COPD results from airway obstruction and reduced expiratory flow (1). As
COPD progresses, the work of breathing increases to 10 to 20 times that of a person with normal lung
function (2). The main symptoms of COPD include dyspnea, possibly accompanied by wheezing, and a
persistent cough with sputum production (2). Other symptoms include physical signs, such as a barrel chest
related to hyperinflation of the lungs, and hypoxemia and hypercapnia (2). Severe COPD can lead to cyanosis
caused by a lack of oxygen in the blood. In some cases, cyanosis can lead to heart failure as a result of the
extra work required by the heart to get blood flow to the lungs (3). Patients with COPD often experience
compromised nutrition status caused by inadequate nutritional intake and the inability to meet energy
expenditure requirements (2). In addition, fat-free mass and bone mineral density are lower in people with
COPD (4). The malnutrition associated with COPD has been termed pulmonary cachexia syndrome (2).
Patients with pulmonary cachexia syndrome have a progressive reduction in lean body mass due to factors
associated with medical management, including medications, and changes in metabolism and energy intake
(2). The prevalence of malnutrition, as indicated by a body mass index (BMI) less than 20 kg/m^2 , may be as
high as 30% in persons with COPD, and the risk of COPD-related death doubles with weight loss (5).
The most common cause of COPD is exposure to tobacco smoke. Tobacco smoking accounts for an
estimated 80% to 90% of the risk for developing COPD^ (6-8). Other risk factors are secondhand smoking, air
pollution, and occupational exposure. Alpha 1 - antitrypsin deficiency, the only known genetic abnormality that
causes COPD, accounts for less than 1% of COPD cases in the United States (7). Pulmonary function tests, or
spirometry, are used to diagnose COPD (2). Forced vital capacity (FVC) is the amount of air that can be
forcibly blown out after full inspiration, and forced expiratory volume in one second (FEV 1 ) is the amount of
air that can be forcibly blown out in one second. Both measurements are used to determine airway
obstruction. A ratio of FEV 1 to FVC that is less than 0.70 is a diagnostic indicator of COPD (8).
The major treatment goals for persons with COPD are to maximize functional capacity, prevent secondary
medical complications, and improve quality of life (2,8). To achieve these treatment goals, medical
management of COPD includes smoking cessation or avoidance of environmental smoke and pollution;
pharmacologic therapy (eg, bronchodilators, corticosteroids or steroids, antibiotics, and diuretics);
pulmonary rehabilitation through aerobic exercise and upper extremity strength training or oxygen therapy;
and maintenance of nutritional status (2,7-9).
Nutrition Assessment and Diagnosis
Malnutrition is associated with the wasting and subsequent weakness of respiratory muscles (2,8). Eight
studies of the weight and body composition of persons with COPD were recently reviewed (9). The prevalence
of malnutrition (as defined by a BMI <20 kg/m^2 ) was as high as 30%, and the risk of COPD-related death
doubled with weight loss (Grade II)* (9). Even in the 70% of COPD patients with BMIs greater than 20 kg/m^2 , the
fat-free mass index and bone mineral density were lower than in healthy controls (Grade II) (9). Long-term
corticosteroid therapy, which compromises immune function, combined with respiratory muscle weakness
caused by malnutrition predisposes patients with COPD to respiratory tract infections such as pneumonia.
Corticosteroids play an important role in wasting syndromes by inhibiting protein synthesis and promoting
protein catabolism (2). The wasting effects of steroids seem to be dose dependent; doses greater than 60
mg/day lead to reduced respiratory muscle strength and delayed recovery of muscle function (2). Patients
with COPD who are malnourished may have lower lung function measurements, more dyspnea, and lower
nutritional intakes than patients who are not malnourished (Grade II) (9). Lastly, patients with COPD may have
more impairment with activities of daily living (Grade II) (9).
A comprehensive nutritional assessment that includes a physical assessment and assessments of energy
intake (by using indirect calorimetry), biochemical values, medications, and anthropometrics is needed to
identify relevant nutrition diagnoses (2). An evaluation of BMI and muscle mass or muscle strength is a useful
indicator of malnutrition in COPD patients (2,9). Clubbing, which is a thickening of the flesh under the toenails
and fingernails, is a common physical trait found in patients with COPD. The nail curves downward, similar to
the shape of the round part of an upside-down spoon. Although the cause of clubbing is still unknown, it is
thought that COPD causes vasodilation in the distal circulation that leads to hypertrophy of the tissue of the