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Nutrition in Clinical Practice
http://ncp.sagepub.com/
Specialized Enteral Formulas in Acute and Chronic Pulmonary Disease
Ainsley M. Malone
Nutr Clin Pract 2009 24: 666
DOI: 10.1177/0884533609351533
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http://ncp.sagepub.com/content/24/6/666
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InInvited vited ReRevievieww Nutrition in Clinical Practice
Volume 24 Number 6
December/January 2009 666-674
Specialized Enteral Formulas in Acute © 2009 American Society for
Parenteral and Enteral Nutrition
10.1177/0884533609351533
and Chronic Pulmonary Disease http://ncp.sagepub.com
hosted at
http://online.sagepub.com
Ainsley M. Malone, MS, RD, LD, CNSC
Financial disclosure: Ms Malone is a member of the Abbott Nutrition Speaker’s Bureau.
The relationship between pulmonary disease and nutrition is ultimately affecting the disease course. An enteral formula
significant. Nutrition support therapy is common in this with modified lipids designed to modulate eicosanoid produc-
patient population as a supportive and/or therapeutic measure. tion, and therefore influence the inflammatory cascade, is
Historical reports of adverse respiratory function associated available. This article reviews the rationale for use of modified
with high parenteral carbohydrate intakes have been the enteral formulas in both chronic and acute pulmonary disease,
rationale for using high-fat enteral formulas in patients with reviews the available studies evaluating the efficacy of these
chronic pulmonary dysfunction. Theoretically, providing a low- formulas, and provides overall recommendations for the use of
carbohydrate formula will reduce carbon dioxide production, specialized enteral formulas in individuals with pulmonary
result in a reduced respiratory quotient, and lead to associated disease. (Nutr Clin Pract. 2009;24:666-674)
improvement in pulmonary outcomes. In the patient with
acute respiratory distress syndrome, an imbalance of mediators Keywords: enteral nutrition; fatty acids; lung diseases; pulmonary
exists, with proinflammatory mediators being dominant, disease, chronic obstructive; respiratory distress syndrome, adult
significant relationship exists between nutrition their illness. Hospitalized patients with acute respiratory
and pulmonary disease. Whether acute or chronic, failure related to exacerbation of their chronic disease are
A pulmonary disease is associated with an increased candidates for nutrition support because their ability to
risk and incidence of malnutrition. Malnutrition can result adequately consume an oral diet within 5 to 10 days is
1
in further pulmonary system impairment, thereby leading unlikely. EN is the preferred nutrition support modality
1
to negative outcomes. Providing nutrition support to indi- when adequate GI function is present. Ambulatory
viduals with pulmonary disease is common, especially in patients with chronic obstructive pulmonary disease
hospitalized patients. Enteral nutrition (EN) is the modal- (COPD) often receive nutrition supplementation in the
ity of choice unless GI function is impaired, thus requiring form of either oral supplements or enteral tube feedings.
the use of parenteral nutrition (PN). From the perspective The recently published nutrition practice guidelines for
of enteral tube feeding or oral supplement usage, an impor- individuals with COPD by the American Dietetic
tant clinical question is frequently asked: Do patients with Association recommend that for both inpatients and out-
2
pulmonary disease benefit from a specialized formula? patients with COPD and a body mass index <20 kg/m ,
The purpose of this article is to describe the use of special- clinicians should “recommend the consumption of medi-
ized pulmonary formulas in individuals with acute or cal food supplements” because their use is associated with
2
chronic pulmonary disease and to evaluate the evidence increased energy intake and weight gain (rating = fair).
supporting efficacy with this practice. Providing nutrition support to prevent or treat malnu-
trition without exacerbating existing lung disease can be a
Nutrition Support in Pulmonary Disease clinical challenge. Metabolism of macronutrients all yield
carbon dioxide (CO ) oxidative end products, with carbo-
2
Individuals with both acute and chronic pulmonary dis- hydrate (CHO) producing the greatest amount. The respi-
ratory quotient (RQ: amount of CO produced, divided by
ease often require nutrition support during the course of 2
amount of oxygen consumed) can reflect substrate utiliza-
tion. When the value exceeds 1.0, oxygen consumption
From Mt. Carmel West Hospital, Department of Pharmacy, must increase, which in the individual with limited respi-
3
Columbus, Ohio. ratory reserve can lead to an increased work of breathing.
Address correspondence to: Ainsley M. Malone, MS, RD, LD, With significant pulmonary disease, the increased in
CNSD, Mt. Carmel West Hospital, Department of Pharmacy, workload can further impair respiratory function, result-
793 West State Street, Columbus, OH 43222; e-mail: AinsleyM@ ing in respiratory failure or the inability to wean from
earthlink.net. mechanical ventilation. This was clearly demonstrated in
666
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Enteral Formulas in Pulmonary Disease / Malone 667
Table 1. Nutrition Characteristics of Enteral Formulas Designed for Chronic Pulmonary Disease
Manufacturer kcal/mL Carbohydrate, g/L (% total kcal) Protein, g/L (% total kcal) Fat, g/L (% total kcal)
Abbott (Columbus, OH) 1.5 106 (28.2) 62.6 (16.7) 93.3 (55.1)
Nestlé (Minnetonka, MN) 1.5 100 (26.6) 68 (18) 94.8 (55.4)
the 1980s when case reports outlined hypercapnia and hypercapnia. This along with early reports of excessive
respiratory failure in patients receiving high-CHO parenteral overfeeding lends support for the argument that total
4-7
formulations. Standard practice at that time was to caloric intake is more important than intake of CHO in
provide 100% of nonprotein calories as dextrose and preventing adverse ventilatory effects.
provide lipid intermittently as a source of essential fatty
acids. Based on the detrimental effects observed with Ambulatory Outpatients
excessive dextrose intake, practice recommendations were
made to alter PN formulas and provide increased lipid High-fat, reduced-CHO enteral formulas have been stud-
7,8
with reduced dextrose. ied frequently in ambulatory COPD patients with con-
11
flicting results. Angelillo et al in 1985 were the first to
Enteral Nutrition in Chronic report a benefit in respiratory function by decreasing the
percentage of calories provided by CHO. The investiga-
Pulmonary Disease tors studied 14 ambulatory, hypercapnic COPD patients,
altering the CHO portion of an oral diet. CHO intake
The practice of altering macronutrient distribution with ranged from 28% to 78% of total calories. The lowest-
PN to avoid detrimental respiratory effects was also CHO diet resulted in a significantly lower production of
8-10
applied to EN support in the mid-1980s. The rationale CO (P < .002) and lower RQ (P < .001) compared with
2
for using an altered macronutrient formulation suggests those moderate or high in CHO content. The authors
that the provision of a reduced amount of CHO will lead concluded that a lower proportion of CHO calories favor-
to a reduction in CO production, thus minimizing the ably altered respiratory parameters and may be an impor-
2
deleterious respiratory effects observed with high-CHO tant consideration in patients with COPD.
parenteral formulas. Current enteral formula manufactur- In an effort to compare the differences in gas exchange
ers offer 2 types of such formulas (Table 1). Multiple stud- and ventilation between normal patients and those with
18
ies exist evaluating the effects of a high-fat enteral formula COPD, Kuo et al evaluated a high-fat oral liquid diet
on respiratory function and status in those with chronic (55.2% fat and 28.1% CHO) and a high-CHO oral liquid
11-15
pulmonary disease ; these studies produced variable diet (31.5% fat and 54.5% CHO) in 12 stable ambulatory
results depending on the population studied, the method COPD patients and 12 healthy volunteers. Significantly
of feeding used, and the nutrition status of the patients greater increases in oxygen consumption (Vo ) (P < .05),
2
studied. These studies were limited by small sample sizes. Vco (P < .001), and expired minute ventilation (Ve)
2
Overall, in 6 studies with a total of 152 patients (ambula- (P < .001) occurred in the COPD patient group receiving the
tory and hospitalized), the majority of the findings demon- high-CHO diet compared with those receiving the high-fat
strated a lack of clinical benefit with use of such enteral diet. The healthy volunteers experienced no change in
formulas. ventilatory parameters with either diet.
In most of the early reports citing adverse effects with A more recent evaluation of different nutrition supple-
large dextrose intakes, patients received excessive calories ments in ambulatory COPD patients demonstrated different
5,6,16 12
(1.7–2.25 times the measured energy expenditure). In results. In 2001, Vermeeren et al conducted a 2-part evalu-
17
a well-known study by Talpers et al, 20 mechanically ation of nutrition supplements on metabolism and exercise
ventilated patients received either varying amounts of capacity in stable COPD patients. Part 1 compared a 250-
CHO (40%, 60%, or 75%) or total calories (1, 1.5, or 2 kcal load with a 500-kcal load. Part 2 compared a high-CHO
times the basal energy expenditure). Carbon dioxide pro- supplement (60% CHO and 20% fat) with a high-fat supple-
duction (Vco ) was measured in both groups of patients 48 ment (60% fat and 20% CHO). Significant increases in Vco
2 2
hours following a change in nutrient regimen. There was (P < .05), Vo (P < .05), and RQ (P < .01) were observed
2
no significant difference in Vco among the varying CHO when the higher calorie load was consumed. Conversely
2
regimens; however, Vco significantly increased as the there were no significant differences in Vco or Vo between
2 2 2
total caloric intake increased (P < .01). The authors con- the high-CHO and high-fat supplements. The RQ, however,
cluded that avoidance of overfeeding is of greater signifi- was significantly greater in those who received the high-
cance than CHO intake in avoiding nutritionally related CHO supplement (P < .01). In addition, the subjects
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668 Nutrition in Clinical Practice / Vol. 24, No. 6, December/January 2009
complained of dyspnea when consuming the high-fat supple- results. They also suggested that because the underlying
ment. Of particular note, the authors stated that the rise cause of the respiratory failure varied between the
in RQ could not be due to an increased Vco but rather 2 groups, the duration of ventilation may have been
2
was caused by a lower Vo2, reflecting a more efficient affected. However, they concluded that a high-fat enteral
metabolism. They concluded that a lower energy–containing formula appears to be beneficial in patients undergoing
supplement is preferred to one of higher energy content artificial ventilation.
15
because of an improved ventilatory response with the reduced Van den Berg et al conducted a similar study in
calorie intake. They also concluded that a high-CHO 1994, with slightly different results. Their unblinded
supplement is preferable to a high-fat version because the study compared a high-fat formula (55.2% fat and 28.1%
former may increase lung function and result in less dyspnea. CHO) with a standard formula (30% fat and 53.3% CHO)
One important aspect to consider when evaluating in 32 medical patients in the ICU. Patient diagnoses
nutrition modification studies in COPD patients is to included COPD, pneumonia without COPD, and neuro-
identify the nutrition status of the patients studied. It is logic disease. The RQ during weaning was significantly
well-known that malnutrition leads to decreased respira- lower in the high-fat formula group (0.72 ± 0.02 vs 0.86
tory function; are positive results with a high-fat formula ± 0.02; P < .01). There were, however, no significant dif-
more likely to be demonstrated with malnourished ferences in Vco during weaning, and both groups had
2
13
patients? Cai et al designed a study in 2003 to answer similar successful weaning episodes. The authors con-
this question. Sixty COPD patients with documented cluded that a high-fat formula can significantly decrease
weights of <90% ideal body weight were randomized to RQ values in ventilated patients. Nevertheless, it is
consume an oral diet with high-fat supplements or a diet important to consider whether the reported significant
with increased CHO content for 3 weeks. Total daily decreases were of actual clinical significance because the
energy intake remained the same between groups, with RQ was well below 1.0; values higher than 1.0 are associ-
the mean intake of 33.5 kcal/kg in the high-fat group and ated with a significant increase in work of breathing.
32.5 kcal/kg in the high-CHO group. Significant decreases Overall results demonstrating whether a high-fat enteral
in RQ, Vco , Vo , and Ve (P < .05) were observed in the formula vs a standard formulation offers a clinical advantage
2 2
high-fat group compared with the high-CHO group. In to the patient with chronic pulmonary disease are inconclu-
addition, the forced expiratory volume decreased in both sive. One must look closely at the population studied and
groups, although this was only significant in the high-fat the clinical significance of the reported results. When con-
group (P < .05). The authors proposed that this observa- sidering use of such a formula in the hospitalized, mechani-
tion was most likely due to an improvement in nutrition cally ventilated patient, it is important to keep in mind
status (not defined) rather than a change in actual airway potential disadvantages. Delayed gastric emptying and
obstruction. They concluded that in malnourished COPD increased formula costs are reasons to avoid the routine use
patients, pulmonary function can be significantly of a high-fat formula in mechanically ventilated patients.19-21
improved with a high-fat, reduced-CHO oral supplement. As with most nutrition support practices, patient monitoring
is essential. If challenges in ventilatory management occur
Hospitalized Patients with the use of a standard enteral formula, offering an
altered macronutrient formula is an option. Several organi-
Two studies have been conducted evaluating the role of zations have stated that routine use of an altered macronu-
high-fat formulas in weaning patients from mechanical trient formula for those with chronic pulmonary disease is
14 2,22-24
ventilation. In 1988, al-Saady et al studied the effects of not recommended. (See Table 2 for specific recommen-
a modified enteral formula on 20 ventilated patients in an dations and Table 3 for a description of the various organiza-
intensive care unit (ICU). Patients were randomized to tions’ grading systems.) However, in the ambulatory patient
receive either a high-fat formula (55.2% fat and 28.1% setting, where nutrition repletion and weight gain are
CHO) or a standard formula (30% fat and 53.3% CHO) in desired goals, the use of a modified lipid/CHO formula may
amounts equal to their estimated energy requirements. be advantageous to limit potential adverse ventilatory effects
Respiratory failure was due to a variety of underlying during a period of planned overfeeding. It is this setting for
25
mechanisms, some of which included exacerbation of which a pulmonary formula may be best suited.
COPD. Significant decreases in Paco (P < .03), tidal vol-
2
ume (P < .009), and peak inspiratory pressure (P < .046) Nutrition Support in Acute Respiratory
were observed in the high-fat group, whereas these param-
eters all increased in the group receiving the standard for- Distress Syndrome
mula. Time spent on artificial ventilation was 42% less in
the high-fat group compared with time in the standard Acute respiratory distress syndrome (ARDS) is a clinical state
formula group (P < .001). The authors noted that sedative characterized by severe hypoxemia, diffuse pulmonary
26
and muscle-relaxing agents may have affected the overall infiltrates, and respiratory failure. Despite advances in
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