APPLIED NUTRITIONAL INVESTIGATION

Hypocaloric Enteral Tube Feeding in Critically IllObese Patients

Roland N. Dickerson, PharmD, Kathryn J. Boschert, MA, RD, Kenneth A. Kudsk, MD, andRex O. Brown, PharmD

From the Department of Clinical Pharmacy and and the Department of Surgery,University of Tennessee Health Science Center, Memphis, Tennessee, USA; and the

Nutrition Service, Regional Medical Center, Memphis, Tennessee, USA

OBJECTIVE: We respectively compared the nutritional and clinical efficacies of eucaloric and hypocaloricenteral feedings in 40 critically ill, obese patients admitted to the trauma or surgical intensive care unit.METHODS: Adult patients, 18 to 69 years old, with weights greater than 125% of ideal body weight,normal renal and hepatic functions, and who received at least 7 d of enteral tube feeding were studied.Patients were stratified according to feeding group: eucaloric feeding (�20 kcal/kg of adjusted weight perday; n � 12) or hypocaloric feeding (�20 kcal/kg of adjusted weight per day; n � 28). The goal proteinintake for both groups was approximately 2 g/kg of ideal body weight per day. Clinical events andnutrition data were recorded for 4 wk.RESULTS: Patients were similar according to sex, age, weight, body mass index, Second Acute Physiologyand Chronic Health Evaluation score, Trauma score, and Injury Severity Score. The hypocaloric feedinggroup received significantly fewer calories than the eucaloric group (P � 0.05). The hypocaloric grouphad a shorter stay in the intensive care unit (18.6 � 9.9 d versus 28.5 � 16.1 d, P � 0.03), decreasedduration of antibiotic therapy days (16.6 � 11.7 d versus 27.4 � 17.3 d, P � 0.03), and a trend towarda decrease in days of mechanical ventilation (15.9 � 10.8 d versus 23.7 � 16.6 d, P � 0.09). There wasno statistically significant difference in nitrogen balance or serum prealbumin response between groups.CONCLUSION: These data suggest that hypocaloric enteral nutrition support is as least as effective aseucaloric feeding in critically ill, obese patients. Nutrition 2002;18:241–246. ©Elsevier Science Inc.2002

KEY WORDS: obesity, enteral nutrition, outcomes, hypocaloric feeding, nitrogen balance

INTRODUCTION

Nutrition support in critically ill, obese patients can pose uniqueproblems for clinicians. Many of these patients have preexistingchronic diseases related to their obesity such as diabetes mellitus,coronary artery disease, hypertension, respiratory abnormalities,hyperlipidemia, degenerative joint disease, endocrine abnormali-ties, and hepatobiliary disease that are likely to complicate evenroutine hospital care. In addition, obese patients are more likelythan their non-obese counterparts to develop postoperative com-plications such as wound dehiscense, nosocomial infections, re-spiratory complications, and delayed cardiac recuperation.1–3 Spe-cialized nutrition support is often given to obese patients duringthe perioperative period if the patient cannot eat in an effort toreduce morbidity. Unfortunately, energy expenditure of obese pa-tients is widely variable and their energy needs are difficult topredict accurately.4 As a result, nutrition intake could easily begiven in excess, leading to problems of overfeeding that mayfurther exacerbate some of their chronic diseases. Clinicians haverecognized this problem and have developed alternative ap-proaches to the metabolic management of obese hospitalized pa-tients, which include hypocaloric, high-protein feeding.5–7

Data for the use of hypocaloric, high-protein feeding weredeveloped in obese patients receiving parenteral nutrition. From apractical standpoint, it is easier to change the macronutrient con-

tent of parenteral nutrition solutions than to alter the componentsof preformulated enteral solutions. However, the benefits of enteralfeeding over parenteral feeding are well established,8 and clini-cians have made substantial efforts to provide enteral nutritionwhenever possible to critically ill patients. A literature search wasunsuccessful in identifying any published reports regarding the useof hypocaloric feeding by the enteral tube feeding route in criti-cally ill, obese patients. The purpose of this study was to evaluatethe nutritional and clinical efficacies of hypocaloric versus euca-loric enteral feedings in critically ill, obese patients.

MATERIALS AND METHODS

Forty critically ill, obese patients admitted to the Elvis PresleyTrauma Center or Surgical Intensive Care Unit of the RegionalMedical Center at Memphis who received enteral tube feedingswere studied retrospectively. Patients were identified from theNutrition Support Service records from December 1996 to January2000. Entry criteria included adult patients, 18 to 69 y old, whohad sustained multiple trauma and required enteral tube feeding forat least 7 d. Only patients with preresuscitation body weightsgreater than 125% of ideal body weight (IBW)9 were included.Patients excluded from analysis were those who received animmune-enhancing diet, had hepatic dysfunction (as shown by aserum bilirubin � 3 mg/dL or a history of cirrhosis or hepatitis),human immunovirus infection, gastrointestinal malabsorptive dis-orders, renal dysfunction (serum creatinine � 1.5 mg/dL), preg-nancy, or a history of malignancy. The study was approved by theInstitutional Review Board of the University of Tennessee Health

Correspondence to: Roland N. Dickerson, PharmD, Department of ClinicalPharmacy, University of Tennessee Health Science Center, 26 SouthDunlap Street, Memphis, TN 38163, USA. E-mail: rdickerson@utmem.edu

Nutrition 18:241–246, 2002 0899-9007/02/$22.00©Elsevier Science Inc., 2002. Printed in the United States. All rights reserved. PII S0899-9007(01)00793-6

Science Center and the Regional Medical Center at Memphis. Theneed for informed consent was waived.

The patients were stratified according to a eucaloric or hypoca-loric regimen. Eucaloric or hypocaloric feeding was given to theobese patient at the discretion of the nutrition support service. Agoal rate to achieve 25 to 30 kcal/kg of adjusted weight per day astotal caloric intake (non-protein and protein kilocalories) wasestablished for the eucaloric feeding regimen. A hypocaloric feed-ing regimen was defined as a caloric intake of less than 20 kcal/kgof adjusted weight per day (total caloric intake including non-protein and protein kilocalories). A goal protein intake of approx-imately 2 g/kg of IBW per day was established for the eucaloricand hypocaloric feeding groups. The enteral tube feedings weremanaged by the Nutrition Support Service. Enteral nutrition wasadministered to each group as a standard high-protein feeding byuse of Isosource VHN (Novartis Nutrition, Minneapolis, MN,USA) or a supplemental high-protein feeding with the addition of20 to 25 g of a protein powder supplement (ProMod, Ross Labo-ratories, Columbus, OH, USA) to the standard high-protein for-mula, as described in Table I. These calorie and protein intakes forhypocaloric feeding of obese patients are similar to and derivedfrom previously published work regarding hypocaloric high-protein parenteral feeding in obese patients.5–7,10

Eucaloric- and hypocaloric-fed patients followed the same en-teral feeding protocol. Feedings occurred within the first 5 d afteradmission to the intensive care unit (ICU). Enteral feeding wasbegun at 25 to 50 mL/h and advanced by 25-mL increments onceor twice daily as tolerated until the desired goal rate was achieved.For patients fed into the stomach, gastric residuals were checkeddaily every 4 to 6 h. If the gastric residuals were greater than 150mL, the feedings were stopped, the residual was placed back intothe stomach, and rechecked 4 h later. If the residual was less than150 mL, the feedings were resumed. For persistent elevated gastricresiduals, the patient was started on prokinetic (e.g., metoclopra-mide or erythromycin) therapy.11 The amount and consistency ofbowel movements and amount of feedings received daily wererecorded. The patients’ abdomens were assessed routinely at leastfour times daily by the nursing staff, once daily by a member of theNutrition Support Service, and the patient was interviewed regard-ing any clinical gastrointestinal symptomatology.

A 24-h urine collection for urea nitrogen was collected duringthe first week after initiating enteral nutrition and approximatelyweekly thereafter until the patient no longer required specializednutrition support. Nitrogen balance (NBAL) was estimated fromthe following formula:

NBAL (g/d) � protein intake (g/d)/6.25

� urine urea nitrogen (g/d) � 4

If the patient’s serum urea nitrogen was changed by 5 mg/dL ormore during the NBAL determination, the resultant body ureanitrogen accumulation was added to the nitrogen losses, as previ-ously described.12 Serum prealbumin and albumin concentrationswere obtained weekly as part of the routine laboratory monitoringby the Nutrition Support Service.

Injury severity13 and Trauma14 scores were calculated at hos-pital admission. The Second Acute Physiology and Chronic HealthEvaluation scores15 were calculated for each patient within the first24 h of initiating tube feeding. Weight was determined from thebed scale. The patient’s adjusted weight was calculated if thecurrent body weight was greater than or equal to 130% of thecalculated IBW9 by the use of the following formula:

adjusted body weight � (current body weight � IBW)

� 0.25 � IBW

Height was determined by tape measure. Demographic, clinicaloutcome, and nutrition response data were collected.

Clinical data including length of hospital stay, ICU stay, anddays of mechanical ventilation were recorded. Days on antibiotictherapy were monitored; no efforts were made to ascertain whetherthe therapy was empiric or therapeutic. Infectious events such assepsis, pneumonia, intra-abdominal abscess, and empyema wererecorded. Pneumonia was evident by clinical signs and symptomsand confirmed by bronchoalveolar lavage with the presence of atleast 105 colony-forming units/mL. Intra-abdominal abscess orperitonitis or an empyema was evident by purlent collection in theabdominal or thoracic cavity requiring drainage by laparotomy,thoracostomy tube, or catheter placement directed by computedtomography. The patients experiencing sepsis were identified ac-cording American College of Chest Physicians consensusdefinitions.16

All continuous data were expressed as mean � standard devi-ation. Statistical analyses were performed using SPSS version 6.1for Windows (SPSS Inc., Chicago, IL, USA). The t test forindependent variables was used to compare the single measure-ments between the two groups. These pairwise comparisons wereconfirmed by non-parametric analysis using the Mann–Whitney Utest to ensure that any observed differences were not attributable todifferences in population distribution. All nominal data were testedfor statistical significance with Fisher’s exact test or chi-square testof homogeneity. For data expressing the same variable measuredon multiple occasions over time, repeated measures analysis ofvariance (RMANOVA) was performed to detect differences inthese measurements between the two populations. The populationswere tested for sphericity and then the univariate RMANOVA wasconducted if the assumption was correct. If the sphericity assump-tion was rejected, then the multivariate RMANOVA was per-formed. The significance testing and reported p values were two-sided for all variables. P � 0.05 was considered statisticallysignificant.

RESULTS

Forty enterally fed, obese patients from the trauma or surgical ICUwere enrolled into the study. Fourteen (10 hypocalorically fed and4 eucalorically fed) patients were collected during the first 13 mo,9 (5 hypocalorically fed and 4 eucalorically fed) patients from thesecond year, and 17 (13 hypocalorically fed and 4 eucaloricallyfed) patients were identified from the final 13 mo of the studycollection period. Twenty-seven patients sustained multiple inju-ries after a motor vehicle accident, four had intestinal obstructionor perforation, three experienced a fall, two had gunshot wounds tothe head or face, two had been assaulted, one was a pedestrianstruck by a motor vehicle, and one was a victim of an all-terrainvehicle accident. Fourteen patients’ injuries were complicated byclosed-head injuries.

TABLE I.

NUTRIENT COMPOSITION OF FEEDING FORMULAS

Type of formula

Standardhigh-protein

feeding

Supplementalhigh-protein

feeding

Calories (kcal/mL) 1.0 1.0Protein (g/L) 62 62Protein supplement (added to feeding; g/L) 0 25Total protein (g/L) 62 87Total kilocalies (including protein

supplement)/mL1.0 1.1

NPC: N2 77:1 54:1

NPC: N2, ratio of non-protein calories to nitrogen

242 Dickerson et al. Nutrition Volume 18, Number 3, 2002

Twelve patients who were fed an average of more than 20kcal/kg of adjusted weight per day were assigned to the eucaloricfeeding group. The remaining 28 patients who received fewer than20 kcal/kg of adjusted weight per day were assigned to the hy-pocaloric feeding group. All patients received intragastric feedingsby a nasoenteric or orogastric feeding tube except for two patientsin the hypocaloric feeding group who received jejunostomy feed-ings. Ten of 12 patients in the eucaloric group received thestandard high-protein feeding formula, and 18 of the 28 patients inthe hypocaloric feeding group received the supplemental high-protein feeding formula. The remaining patients in each groupreceived the alternate formula. Two patients in the hypocaloricfeeding group required short-term parenteral nutrition for 2 and5 d, respectively, until enteral nutrition was reestablished. Onepatient in the eucaloric group received short-term parenteral nu-trition for 6 d until enteral nutrition was reestablished. The interimparenteral nutrition formulas were designed to emulate the caloricand protein intakes of the enteral formulation being given to thepatient.

The demographic information for the groups is presented inTable II. There was no difference in age, weight, body mass index,Acute Physiology score, Second Acute Physiology and ChronicHealth Evaluation score, Trauma score, and Injury Severity scorebetween groups. Most patients had multiple trauma from motorvehicle accidents and several patients experienced chronic healthcomplications associated with their obesity (Table III). There wasgradual attrition in the number of subjects as they were able toresume a regular diet and not require enteral feedings (Table IV).Details regarding the average caloric intake for each week aregiven in Table IV. The hypocaloric feeding group received signif-icantly fewer calories than the eucaloric feeding group for the first3 wk of nutrition support therapy, with a statistically insignificanttrend observed by week 4 in a limited number of subjects (sevenand six patients per group by week 4). Average daily protein intakefor each week was similar and not statistically significant betweengroups for 3 of the 4 wk of the study; however, a significantdifference in protein intake was observed between groups duringweek 2 (Table IV). Due to various orthopedic or surgical proce-dures, high gastric residuals, and other temporary interruptions,tube feedings were intermittently discontinued in some of thesecritically ill, obese patients, resulting in decreased caloric andprotein intakes. This is not particularly surprising, as others haveshown that hospitalized tube-fed patients receive significantly lessthan what is prescribed.17

Blood samples for serum levels of prealbumin and albuminwere drawn after the initiation of nutrition support on mean days2, 9, 16, and 23 of feeding. Univariate RMANOVA did notdemonstrate an overall difference in serial prealbumin and albuminconcentrations between groups (P � not significant [NS]; Figs. 1and 2, respectively). Initial serum prealbumin concentrations werelow in both groups; but the concentrations increased over time inboth groups (Fig. 1). Serum albumin did not change significantlyover the observation period for either group (Fig. 2). NBALs weredone on mean days 6 (n � 12 and 25 for the eucaloric andhypocaloric groups, respectively) and 14 (n � 10 and 11, respec-tively) of feeding (Fig. 3). Protein intakes at the time of the firstNBAL determination were 1.81 � 0.46 and 1.58 � 0.52 g/kg ofIBW per day (P � NS) for the eucaloric and hypocaloric groups,respectively. Protein intakes for both groups during the secondNBAL were 1.95 � 0.40 and 1.99 � 0.53 g/kg of IBW per day(P � NS), respectively. Both groups were near nitrogen equilib-rium and no significant differences in NBAL were evident betweengroups. Both groups had mean negative NBALs for weeks 1 and2 balance studies (Fig. 3). There were insufficient NBAL deter-minations thereafter for meaningful comparisons.

Daily serum glucose was averaged each week. There was noclinically or statistically significant difference in average serumglucose concentrations between the eucaloric and hypocaloricgroups for weeks 1 (143 � 22 versus 147 � 32 mg/dL, P � NS,respectively), 2 (156 � 38 versus 141 � 32 mg/dL, P � NS,respectively), 3 (142 � 27 versus 139 � 30 mg/dL, P � NS,respectively), and 4 (142 � 32 versus 133 � 24 mg/dL, P � NS,respectively).

Clinical outcome data are presented in Table V. The hypoca-loric group had a significantly reduced ICU stay by 10 d (P �0.03) and decreased duration of antibiotic therapy by 10 d (P �0.03). A statistically insignificant trend toward a decreasing dura-tion of mechanical ventilation by 8 d was also evident in thehypocaloric group (P � 0.09). The number of episodes of infec-tious complications, such as pneumonia, presence of intra-abdominal abscess or empyema, or sepsis, did not differ betweengroups (Table V).

TABLE II.

PATIENT DEMOGRAPHICS DATA

Eucaloric feeding* Hypocaloric feeding† P

Male/female 4/8 10/18 NSAge (y) 43.3 � 15.5 45.0 � 16.6 NSWeight (kg) 102 � 36 118 � 41 NSWeight (%IBW) 168 � 62 188 � 65 NSBMI (kg/m2) 36.0 � 12.4 41.3 � 13.7 NSAPS 15.7 � 4.4 15.6 � 6.8 NSAPACHE II score 18.1 � 5.1 17.2 � 6.7 NSTrauma Score 9.9 � 2.6 11.1 � 5.5 NSISS 24.4 � 4.9 22.2 � 14.5 NS

* � 20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 12† �20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 28.APACHE II, Second Acute Physiology and Chronic Health EvaluationII; APS, Acute Physiology Score; BMI, body mass index; IBW, idealbody weight; ISS, Injury Severity Score; NS, not significant

TABLE III.

ADMISSION DIAGNOSES AND PREVALENT CHRONICCOMPLICATIONS OF OBESITY

Eucaloricfeeding*

Hypocaloricfeeding†

MVA with multiple injuries 7 20Assault 2 —SBO, perforated intestinal tract 1 3Fall 1 2GSW 1 1ATV accident — 1Pedestrian struck — 2CHI 6 8Chronic complications of obesity

Diabetes mellitus 2 5Hypertension 2 4Sleep apnea — 3CAD/CABG — 1

* � 20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 12.† � 20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 28.ATV, all-terrain vehicle; CABG, coronary artery bypass graft. CAD,coronary artery disease; CHI, closed head injury; GSW, gunshot wound;MVA, motor vehicle accident; SBO, small bowel obstruction

Nutrition Volume 18, Number 3, 2002 243Hypocaloric Enteral Feeding in Obesity

DISCUSSION

Critical illness is associated with hypercatabolism and the resultantloss of body cell mass.18 Despite aggressive nutrition support,critically ill patients continue to exhibit net protein catabolismbecause the anabolic effects of nutrition support cannot overcomethe profound catabolic effects of critical illness.19,20 Providingaggressive, hypercaloric nutrition support can be particularly prob-lematic in critically ill, obese patients because they have physio-logic alterations that may impede tolerance of nutrition support.Fluid intake may need to be restricted because critically ill, obesepatients are at increased risk for pulmonary edema and congestiveheart failure.21 Aggressive nutrition support will result in increasedcarbon dioxide production,22,23 which may further increase therespiratory work and impair weaning of the ventilator-dependentpatient with obesity.21 Excessive caloric intake also can promotelipogenesis causing hepatic steatosis and hepatic dysfunction,24

which is also a concern in the obese population due to a preexistinghigher incidence of fatty liver.25 Some obese patients are diabeticand prudent administration of carbohydrate is warranted becauseaggressive nutrition support is associated with hyperglycemia.26

The literature indicates that the obese patient is at extreme riskfor complications during feeding and, in particular, the detrimentaleffects of overfeeding. This is particularly poignant because it is

difficult to estimate the actual caloric needs of the sick, hospital-ized obese patient4 and overfeeding might be easily and uninten-tionally accomplished by conventional enteral or parenteral feed-ing methods. However, hospitalized patients with obesity also aremore likely than their non-obese counterparts to develop postop-erative complications such as wound dehiscense, nosocomial in-fections, respiratory complications, and delayed cardiacrecuperation.1–3 Therefore, it is important to provide specializednutrition support to reduce these morbid events in the critically ill,obese patient who cannot eat.

Hypocaloric nutrition support was implemented in these criti-cally ill, obese patients as a means of providing effective nutritionsupport without overfeeding complications associated with hyper-caloric nutrition support. Our data indicated that patients whoreceive hypocaloric nutrition support require fewer days in theICU, fewer days on antibiotic therapy, and a trend toward fewerdays on mechanical ventilation compared with those who receivedeucaloric nutrition support (Table V). Our data are unique in thatwe are the first to report nutrition and clinical outcomes withhypocaloric, specialized nutrition support by the enteral route incritically ill patients with obesity.

Although others have suggested that short-term hypocaloricfeeding might be preferable in all patients with critical illness,10,27–30

TABLE IV.

NUTRITION SUPPORT ADMINISTRATION

Eucaloric feeding(n�12)

Hypocaloric feeding(n�28) P

Enteral feedings initiated (d) 3.8 � 1.5 3.3 � 1.4 NSDays required to achieve goal rate 2.9 � 1.2 3.3 � 1.3 NSDays of specialized nutrition support 26.3 � 14.8 15.4 � 10.8 �0.02Average caloric intake (kcal/kg IBW/d)

Week 1 (n � 12, n � 28) 21.5�4.9 16.2�4.8 �0.01Week 2 (n � 12; n � 23) 30.3�9.9 19.3�6.4 �0.001Week 3 (n � 10; n � 9) 29.9 � 4.9 21.7 � 3.8 �0.001Week 4 (n � 7; n � 6) 28.9 � 5.6 22.2 � 7.3 �0.05

Average caloric intake (kcal/kg ABW/d)Week 1 (n � 12, n � 28) 18.5 � 4.4 13.4 � 4.1 �0.001Week 2 (n � 12; n � 23) 25.6 � 5.9 15.7 � 5.1 �0.001Week 3 (n � 10; n � 9) 25.9 � 5.5 18.6 � 3.2 �0.01Week 4 (n � 7; n � 6) 24.7 � 6.5 19.2 � 4.6 NS

Average caloric intake (kcal/kg CBW/d)Week 1 (n � 12, n � 28) 18.5 � 4.4 13.4 � 4.1 �0.001Week 2 (n � 12; n � 23) 25.6 � 5.9 15.7 � 5.1 �0.001Week 3 (n � 10; n � 9) 25.9 � 5.5 18.6 � 3.2 �0.01Week 4 (n � 7; n � 6) 24.7 � 6.5 19.2 � 4.6 NS

Average protein intake (g/kg IBW/d)Week 1 (n � 12, n � 28) 1.29 � 0.26 1.14 � 0.38 NSWeek 2 (n � 12; n � 23) 1.83 � 0.54 1.37 � 0.47 �0.02Week 3 (n � 10; n � 9) 1.85 � 0.32 1.53 � 0.45 NSWeek 4 (n � 7; n � 6) 1.70 � 0.42 1.35 � 0.49 NS

Average protein intake (g/kg ABW/d)Week 1 (n � 12, n � 28) 1.11 � 0.24 0.95 � 0.30 NSWeek 2 (n � 12; n � 23) 1.55 � 0.33 1.11 � 0.36 �0.01Week 3 (n � 10; n � 9) 1.59 � 0.34 1.30 � 0.33 NSWeek 4 (n � 7; n � 6) 1.47 � 0.41 1.16 � 0.32 NS

Average protein intake (g/kg CBW/d)Week 1 (n � 12, n � 28) 0.82 � 0.22 0.65 � 0.24 �0.05Week 2 (n � 12; n � 23) 1.13 � 0.27 0.74 � 0.27 �0.01Week 3 (n � 10; n � 9) 1.19 � 0.34 0.92 � 0.22 NSWeek 4 (n � 7; n � 6) 1.10 � 0.43 0.84 � 0.14 NS

ABW, adjusted body weight; CBW, current body weight; IBW, ideal body weight; NS, not significant

244 Dickerson et al. Nutrition Volume 18, Number 3, 2002

we used a more conservative approach and applied this techniqueto obese patients at risk for overfeeding complications and withabundant caloric reserves. We are not the first to implementhypocaloric feeding in obese patients. Greenberg and Jeejeebhoy31

examined 12 moderately ill (but not with postoperative or post-acute injury) overweight patients and gave 0.83 or 1.83 g � kg�1 �d�1 of intravenous protein without non-protein calories. Theyconcluded that 2 g/kg of IBW per day promoted positive NBAL.This was followed by the case series of Dickerson et al.5 whofound net protein anabolism in 13 mild to moderately stressed,parenterally fed, obese patients given 50% of their measuredresting energy expenditure as non-protein kcal and approximately2 g/kg of IBW of protein per day. Subsequently, in a small,prospective, randomized, blinded trial, obese patients were givenparenteral nutrition as a hypocaloric regimen (50% of measuredenergy expenditure as non-protein kilocalories, n � 9) or a euca-loric regimen (energy intake equal to measured energy expendi-ture, n � 7) with 2 g/kg of IBW of protein per day for each group.7Mean NBALs were similar between groups. In a follow-up study,Choban et al. repeated the experiment in 30 obese patients requir-

ing parenteral nutrition. Thirteen of those 30 patients were ICUpatients who were distributed nearly equally between feedinggroups. Fourteen patients were assigned to receive 22 kcal/kg ofactual weight per day (36 kcal/kg of IBW per day) and 16 received14 kcal/kg of actual weight per day (22 kcal/kg of IBW per day).Both groups received 2 g/kg of IBW per day of protein. Theyreceived this feeding regimen for a maximum of 14 d and thenreceived a conventional eucaloric feeding regimen, if continuednutrition support was indicated. NBAL was the predominant end-point and no difference was found between groups.

Our study examined the use of hypocaloric feedings by theenteral route in comparison with previous studies where patientswere given parenteral nutrition. One concern with our data may bethat, although there were no differences in NBAL between theeucalorically and hypocalorically fed groups, both groups’ meanNBALs were near nitrogen equilibrium but negative during weeks1 and 2 of feeding. This is in contrast to the previous four studies

TABLE V.

CLINICAL OUTCOMES

Eucaloricfeeding*

Hypocaloricfeeding† P

Duration of hospital stay (d) 37.2 � 22.7 29.6 � 14.0 NSDuration of ICU stay (d) 28.5 � 16.1 18.6 � 9.9 �0.03Duration of mechanical

ventilation (d)23.7 � 16.6 15.9 � 10.8 �0.09

Episodes of pneumonia 8 12 NSIAA or empyema 0 1 NSSepsis 4 4 NSDuration of antibiotic

therapy (d)27.4 � 17.3 16.6 � 11.7 �0.03

Survival 11/12 28/28 NS

* �20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 12† �20 kcal � kg�1 � d�1, adjusted weight as described in MATERIALSAND METHODS; n � 28.IAA, intra-abdominal abscess; ICU, intensive care unit; NS, not signifi-cant

FIG. 1. Serum prealbumin recovery with eucaloric and hypocaloric feed-ing. No differences were noted between groups for any given day (P � notsignificant). *P � 0.05 versus day 2, **P � 0.06 versus day 2.

FIG. 2. Serum albumin response with eucaloric and hypocaloric feeding.No differences were noted between or within groups (P � not significant).

FIG. 3. Nitrogen balance measurements during weeks 1 and 2 of enteralfeeding. No significant difference was found between the eucaloric andhypocaloric feeding groups for either week (P � not significant).

Nutrition Volume 18, Number 3, 2002 245Hypocaloric Enteral Feeding in Obesity

where a positive mean NBAL was achieved.5–7,31 Two plausibleexplanations may be provided for the observed negative NBALs inthis study. First, our population was comprised of critically illpatients residing in the trauma or surgical ICU. We recentlyinvestigated the efficacy of an anabolic steriod in similar types of(non-obese) multiple trauma patients and found that NBALs weremarkedly negative by �9 to �15 g/d over the first 10 d ofnutritional intervention.32 This marked negative NBAL occurreddespite an aggressive protein intake greater than 2 g � kg�1 � d�1.Considering the severity of illness in our population, it was notparticularly surprising to find that our patients had negativeNBALs during the first 2 wk of the study. A second potentialexplanation may be that the mean protein intakes of 1.6 to 2 g/kgof IBW per day during the balance determinations were insuffi-cient in critically ill patients with obesity. Studies on optimalprotein intake for the critically ill, obese subpopulation is lacking.Therefore, it is unknown whether giving more protein could havesignificantly improved the NBALs during the first 1 to 2 wk in ourcritically ill, obese population while the patients were metaboli-cally stressed.

In summary, we examined the nutrition and clinical outcomesof critically ill, obese patients who received eucaloric (�20kcal/kg of adjusted weight per day) or hypocaloric (�20 kcal/kg ofadjusted weight per day) enteral feeding. NBALs and serum pro-tein responses were similar between groups and not significantlydifferent. Clinical outcomes favored the hypocaloric group, withsignificantly fewer days in the ICU, fewer days of antibiotictherapy, and a trend toward fewer days on a ventilator; however,length of hospital stay was not significantly different. Hypocalorichigh-protein enteral feeding might provide some unique advan-tages in providing nutrition support to obese patients who are atrisk for overfeeding complications because fewer non-protein cal-ories would be required. These data suggest that hypocaloricfeeding in critically ill, obese patients is at least as favorable aseucaloric feeding. However, it must be pointed out that this was aretrospective analysis and not a randomized, controlled trial. As-signments of feeding regimens were based on the discretion of theNutrition Support Service. As a result, a selection bias as to whoreceived the eucaloric or hypocaloric regimen cannot be excluded.A large, prospective, randomized, double-blind trial is warrantedto confirm the clinical outcome of the superiority of hypocaloricenteral feeding over eucaloric enteral feeding in critically ill, obesepatients.

REFERENCES

1. Choban PS, Heckler R, Burge JC, Flancbaum L. Increased incidence of nosoco-mial infections in obese surgical patients. Am Surg 1995;61:1001

2. Pasulka PS, Bistrian BR, Benotti PN, Blackburn GL. The risks of surgery inobese patients. Ann Intern Med 1986;104:540

3. Printen KJ, Paulk SC, Mason EE. Acute postoperative wound complications aftergastric surgery for morbid obesity. Am Surg 1975;41:483

4. Feurer ID, Crosby LO, Buzby GP, et al. Resting energy expenditure in morbidobesity. Ann Surg 1983;197:17

5. Dickerson RN, Rosato EF, Mullen JL. Net protein anabolism with hypocaloricparenteral nutrition in obese stressed patients. Am J Clin Nutr 1986;44:747

6. Choban PS, Burge JC, Scales D, Flancbaum L. Hypoenergetic nutrition support

in hospitalized obese patients: a simplified method for clinical application (seecomments). Am J Clin Nutr 1997;66:546

7. Burge JC, Goon A, Choban PS, Flancbaum L. Efficacy of hypocaloric totalparenteral nutrition in hospitalized obese patients: a prospective, double-blindrandomized trial (see comments). JPEN 1994;18:203

8. Kudsk KA, Croce MA, Fabian TC, et al. Enteral versus parenteral feeding.Effects on septic morbidity after blunt and penetrating abdominal trauma. AnnSurg 1992;215:503

9. Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm 1974;8:65010. McCowen KC, Malhotra A, Bistrian BR. Stress-induced hyperglycemia. Crit

Care Clin 2001;17:10711. MacLaren R, Kuhl DA, Gervasio JM, et al. Sequential single doses of cisapride,

erythromycin, and metoclopramide in critically ill patients intolerant to enteralnutrition: a randomized, placebo-controlled, crossover study. Crit Care Med2000;28:438

12. Blumenkrantz MJ, Kopple JD, Gutman RA, et al. Methods for assessing nutri-tional status of patients with renal failure. Am J Clin Nutr 1980;33:1567

13. Baker SP, O’Neill B, Haddon W Jr, Long WB. The injury severity score: amethod for describing patients with multiple injuries and evaluating emergencycare. J Trauma 1974;14:187

14. Champion HR, Sacco WJ, Carnazzo AJ, et al. Trauma score. Crit Care Med1981;9:672

15. Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity ofdisease classification system. Crit Care Med 1985;13:818

16. Abraham E, Matthay MA, Dinarello CA, et al. Consensus conference definitionsfor sepsis, septic shock, acute lung injury, and acute respiratory distress syn-drome: time for a reevaluation. Crit Care Med 2000;28:232

17. Abernathy GB, Heizer WD, Holcombe BJ, et al. Efficacy of tube feeding insupplying energy requirements of hospitalized patients. JPEN 1989;13:387

18. Monk DN, Plank LD, Franch-Arcas G, et al. Sequential changes in the metabolicresponse in critically injured patients during the first 25 days after blunt trauma.Ann Surg 1996;223:395

19. Shaw JH, Wolfe RR. An integrated analysis of glucose, fat, and protein metab-olism in severely traumatized patients. Studies in the basal state and the responseto total parenteral nutrition. Ann Surg 1989;209:63

20. Shaw JH, Wildbore M, Wolfe RR. Whole body protein kinetics in severely septicpatients. The response to glucose infusion and total parenteral nutrition. Ann Surg1987;205:288

21. Marik P, Varon J. The obese patient in the ICU. Chest 1998;113:49222. Talpers SS, Romberger DJ, Bunce SB, Pingleton SK. Nutritionally associated

increased carbon dioxide production. Excess total calories vs high proportion ofcarbohydrate calories. Chest 1992;102:551

23. Askanazi J, Carpentier YA, Elwyn DH, et al. Influence of total parenteralnutrition on fuel utilization in injury and sepsis. Ann Surg 1980;191:40

24. Sheldon GF, Peterson SR, Sanders R. Hepatic dysfunction during hyperalimen-tation. Arch Surg 1978;113:504

25. Choban PS, Flancbaum L. Nourishing the obese patient. Clin Nutr 2000;19:30526. Rosmarin DK, Wardlaw GM, Mirtallo J. Hyperglycemia associated with high,

continuous infusion rates of total parenteral nutrition dextrose. Nutr Clin Pract1996;11:151

27. McCowen KC, Friel C, Sternberg J, et al. Hypocaloric total parenteral nutrition:effectiveness in prevention of hyperglycemia and infectious complications—arandomized clinical trial. Crit Care Med 2000;28:3606

28. Lohlein D. Principles and indications of hypocaloric parenteral nutrition. WorldJ Surg 1986;10:64

29. Muller TF, Muller A, Bachem MG, Lange H. Immediate metabolic effects ofdifferent nutritional regimens in critically ill medical patients. Intens Care Med1995;21:561

30. Patino JF, de Pimiento SE, Vergara A, et al. Hypocaloric support in the criticallyill. World J Surg 1999;23:553

31. Greenberg GR, Jeejeebhoy KN. Intravenous protein-sparing therapy in patientswith gastrointestinal disease. JPEN 1979;3:427

32. Gervasio JM, Dickerson RN, Swearingen J, et al. Oxandrolone in trauma patients.Pharmacotherapy 2000;20:1328

246 Dickerson et al. Nutrition Volume 18, Number 3, 2002