Research and Opinion in Anesthesia & Intensive Care

: 2018  |  Volume : 5  |  Issue : 3  |  Page : 170--177

Comparison between the effects of two enteral nutrition support algorithms on nutrition care outcome in critically ill adult patients

Ahmed M Mohamed, Samia A El- Wakel, Amani A Aly, Nahla M Amin 
 Department of Anesthesia and Surgical Intensive Care, Zagazig University Hospitals, Zagazig, Egypt

Correspondence Address:
Ahmed M Mohamed
Department of Anesthesia and Surgical Intensive Care, Zagazig University Hospitals, Zagazig


Background The use of enteral nutrition (EN) algorithm optimizes nutrition by increasing the intake of calories in critically ill patients, but it does not compensate for loss of feeding time due to frequent interruptions as during fasting for operation or investigation.Aims were to compare implementation of enteral feeding support algorithm based on the SCCM/A.S.P.E.N guidelines and modifications to this algorithm (using a protocol that shifted from an hourly rate target goal to a twenty four hour volume goal). Settings and Design Case control study in the surgical ICU of zagazig university hospital. Methods and Material Patients of group1 were given caloric requirements as five bolus meals, patients of group 2 were given Fresubin by continuous infusion with hourly rate target goal and in Group 3 there was a Shift from hourly rate target goal to 24 hour volume goal and metoclopramide 10 mg I.V. q. 6 hours with the start of EN. Results There were statistically significant differences between groups regarding adequacy of caloric intake in 2nd, 3rd days and the overall adequacy of calories in all four days, where Group 2 provided more EN adequacy than Group 1 (P=0.02, 0.001, 0.01) respectively, and Group 3 provided more calories adequacy than Group1in 3rd day and overall adequacy (P=0.008 and 0.007) respectively. Also Patients in Group 2and 3 started accommodating EN earlier and had less episodes of vomiting than patients in group 1, (P value=0.043 and0.003 respectively). Conclusion The use of EN protocol provides more adequacy of calories and proteins from EN in comparison to bolus meals.

How to cite this article:
Mohamed AM, El- Wakel SA, Aly AA, Amin NM. Comparison between the effects of two enteral nutrition support algorithms on nutrition care outcome in critically ill adult patients.Res Opin Anesth Intensive Care 2018;5:170-177

How to cite this URL:
Mohamed AM, El- Wakel SA, Aly AA, Amin NM. Comparison between the effects of two enteral nutrition support algorithms on nutrition care outcome in critically ill adult patients. Res Opin Anesth Intensive Care [serial online] 2018 [cited 2018 Oct 20 ];5:170-177
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Full Text


Nutrition of critically ill patients is an essential component of their treatment [1]. An understanding of nutrient requirements and its technique of delivery has made the increased survival of critically ill patients possible [2].

Enteral nutrient (EN) support modality is preferred over parenteral nutrient for all patients requiring nutritional support [3] as it is more physiologic, less expensive, and less likely to be associated with hepatobiliary dysfunction [4].

Nutritional support in critically ill or trauma patients had many published clinical practice guidelines [5]. Protocols of EN are tools designed to enable the bedside nurse to initiate, modify, and monitor the administration of EN [6].

Two important guidelines on implementation of nutrient support for the critically ill were published by the Society of Critical Care Medicine (SCCM) (the provision and assessment of nutrient support therapy in adult critically ill patients) and the American Society of Parentral and Enteral Nutrition (ASPEN) [7].

These algorithms do not compensate for frequent interruptions that lead to loss of feeding time, although they use conservative reactionary approaches to optimize nutrient. In addition, motility agents are only initiated after development of manifestations of delayed gastric emptying [6].

Because of complexity of the care of critically ill patients, it is difficult to avoid interruptions of continuous EN, but this may be mitigated somewhat by developing EN protocols aimed at this [5].

Compensation for interruptions of continuous EN was discussed by Heyland et al. [6], as they developed EN protocol that shifted from an hourly rate target to a 24 h volume target.

Benefits from nutritional support therapy were maximized by implementation of nutrition support guidelines and protocols that also minimized complications associated with EN [8].

The aim of this study was to compare between our current practice of EN (bolus meals), implementation of EN support algorithm based on the SCCM/ASPEN guidelines, and modifications to this algorithm (using a protocol that shifted from an hourly rate target goal to a 24 h volume goal) regarding the time of nutrition support initiation, adequacy of calories, and protein received from EN during the first four ICU days from the beginning of EN. We also assessed gastrointestinal tract intolerance (i.e. vomiting) in each practice.

 Patients and methods

After obtaining approval from Institutional Review Board and written informed consent from the patient or his relatives (if the patients is unable to give a consent), this study was conducted on adult patients above 18 years old of both sexes who were admitted to the surgical ICU Zagazig University Hospital from March 2013 until March 2015 and required ventilatory support, where EN was given within the first 24 h of admission by either bolus or infusion protocol.

Exclusion criteria included patients with end-stage renal failure, hepatic failure, and bronchogenic carcinoma, brain-dead patients, morbidly obese patients, ventilator-dependent patients, patients transferred from other hospitals or healthcare facility, and patients with contraindication to EN.

Study technique

For all patients the target caloric requirements was calculated as 25–30 kcal/kg/day, protein requirement was 1.4 g/kg/day, and EN support started within 24 h after admission to ICU, using Fresubin (Fresubin Kabi Ltd., UK) − an unflavored liquid consisting of protein (milk and soy), fat (soy, medium chain triglycerides, linseed, sunflower, and fish oils), carbohydrate (maltodextrin), vitamins, minerals, and trace elements. A volume of 1500 ml of Fresubin original provides 1500 kcal and 57 g of protein and meets the average adult recommended daily requirements for vitamins, minerals, and trace elements.

Enrolled patients were randomly allocated to one of three groups using a computer-generated table of random numbers, and the results were placed in sealed envelopes:Group 1 (control group): there was no standard regimen for using antiemetics or prokinetics. Patients of this group received caloric requirements in five meal boluses at 4 h intervals, with gastrointestinal tract rest from 12 to 8 a.m.Group 2: we used a nutritional support algorithm based on SCCM/ASPEN guidelines [7]. Enteral tube feeds started within 24 h of ICU admission at a rate of 10 ml/h, and then increased by 10 ml/h every 4 h in the absence of significant gastric residuals (i.e. >250 ml over 4 h period) until the target tube feeding rate was reached in each patient (Figure 1).{Figure 1}Group 3: we used the method described by Heyland et al. [6], in which there were only two differences from group 2:Shift from hourly rate target goal to a 24-h volume goal (in which nurses can increase the hourly rate depending on how many hours they have left in the day to ensure that the patient received the 24-h volume within the day).Nurses were given instructions on how to set the hourly rate based on the 24-h volume prescribed; e.g. if the total goal for the day was 2000 ml of a nutritional solution to meet their caloric requirement, then the hourly rate would be 83.3 ml/h. If feeds were held for several hours while the patient underwent surgery, and now there are 10 h left in the day and the patient has only received 700 ml, the new rate would be (1300 ml/10 h) 130 ml/h for the remaining 10 h. Beginning the next day, the target would shift back to 83.3 ml/h. We put a limit of a maximum of 150 ml/h.To start motility agent (metoclopramide 10 mg intravenous every 6 h) at the same time EN is started.

Data collection

The following data were collected:Age, sex, weight, height, Acute Physiology and Chronic Health Evaluation II score, and primary admission diagnosis were recorded for the three groups.The timing of nutrition support initiation (which was calculated from ICU admission to time of initiation of nutrition support therapy).Adequacy of calories and protein (the total amount of energy or protein received from EN is divided by the amount prescribed and expressed as %) over the first four ICU days from the beginning of EN.

In addition, we determined whether episodes of vomiting and ventilator-associated pneumonia had occurred, and determined the incidence of mortality and length of ICU and hospital stay.

Our primary outcome was adequacy of protein over the first 4 ICU days from the beginning of EN. Our secondary outcomes were adequacy of calories and protein received from EN over the first 4 ICU days from the beginning of EN, the timing of nutrition support initiation, to determine incidence of vomiting, and ventilator-associated pneumonia and mortality and length of ICU and hospital stay.

According to a previous study (in which the percentage of protein delivered of target at the fourth day in bolus meals group was 21.5% and continuous infusion groups was 54.7%), using power of 80 and 95% confidence interval, the sample size of our study was 84 (28 in each group) [9].

Data were collected and analyzed by using statistical package for the social sciences, version 20 (SPSS; SPSS Inc., Chicago, Illinois, USA). Data were expressed as median, mean±SD for quantitative variable, number and percentage for qualitative one, and χ2-test and analysis of variance were used when appropriate. P less than 0.05 was considered significant.


This study was performed on 84 patients who were randomly allocated into three groups, each comprising 28 patients. Regarding demographic data (age, sex, weight, height, and BMI) and Acute Physiology and Chronic Health Evaluation II score at admission, there were no statistically significant differences between the three groups (P>0.05) ([Table 1]).{Table 1}

[Table 2] shows that there was no statistically significant difference among the three studied groups as regards admission diagnosis of patients (P>0.05).{Table 2}

[Table 3] shows that there was a statistically significant difference between three groups as regards adequacy of EN on second and third days and the overall adequacy of EN on all 4 days; however, there was no statistically significant difference between three groups as regards adequacy of EN on first and fourth days, where group 2 provided more EN adequacy than group 1 (P=0.02, 0.001, 0.01), respectively, and group 3 provided more EN adequacy than group 1 on the third day and overall adequacy (P=0.008 and 0.007), respectively.{Table 3}

[Table 4] shows that there was a statistically significant difference between three groups as regards adequacy of protein intake on second and third days and the overall adequacy of protein intake in all 4 days; however, there was no statistically significant difference between three groups as regards adequacy of protein intake on first and fourth days, where group 2 provided more protein intake adequacy than group 1 on the third day (P=0.043) and group 3 provided more protein intake adequacy than group 1 on the third and fourth days and overall adequacy (P=0.001, 0.0009 and 0.011), respectively; in addition, group 3 provided more protein intake adequacy than group 2 on third and fourth days (P=0.018 and 0.029), respectively.{Table 4}

[Table 5] shows that there was a statistically significant difference between three groups as regards the time of EN initiation. Patients in groups 2 and 3 started accommodated EN earlier than patients in group 1 (P=0.043).{Table 5}

[Table 6] shows that there was a statistically significant difference between the three groups as regards episodes of vomiting. Patients in groups 2 and 3 showed less episodes of vomiting than those in group 1 (P=0.003).{Table 6}

[Table 7] shows that there was no statistically significant difference between three groups as regards incidence of mortality and pneumonia (P>0.05).{Table 7}

[Table 8] shows that there were no statistically significant differences between three groups as regards length of hospital stay and length of ICU stay (P>0.05).{Table 8}


This study found that the use of EN protocol based on SCCM/ASPEN guidelines resulted in the earlier accommodation of EN, and in providing patients more adequacy of their total needs of calories and proteins from EN in comparison with bolus meals. Twenty-four-hour volume target goal of EN had better overall adequacy of EN and proteins of 4 days through compensation for periods of fasting (for operation or investigation) by increasing the rate of EN infusion in comparison with bolus meals and hourly rate target goal using SCCM/ASPEN guidelines.

Despite the importance of adequate nutritional intake, critically ill patients receiving nutrition through enteral route often receive less caloric and protein intake than recommended. Evidence indicates that critically ill patients given nutrition through enteral route have received mean caloric intake ranging from 50 to 95% of requirements and protein intake from 38 to 82% of requirements [10].

Kim et al. [10] performed a prospective cohort study of 34 critically ill adults who were diagnosed medically and received enteral feeding as a bolus. Energy and protein intake prescribed and received were recorded for 4 consecutive days after beginning of enteral feeding. The causes and duration of feeding interruptions were also recorded. They found that the prescribed energy amount did not reach patients’ requirements even after 72 h of feeding. Enteral feeding was under-prescribed, and the prescribed enteral feeding was even under-delivered, and the authors had no specific protocol in the ICU of slowly increasing volume as indicated by a patient’s tolerance. Therefore, under-prescription contributed significantly to insufficient intake.

Many factors affect the adequacy of EN in ICU patients in the USA. Under-prescription combined with insufficient delivery of prescribed nutrients results in inadequate nutritional intake. Inappropriate stopping and delay in restarting EN cause a large volume of enteral formula to be wasted. Interruptions due to gastrointestinal intolerance of EN, displacement or obstruction of the feeding tube, diagnostic or therapeutic procedures, routine nursing procedures, and airway management result in marked underfeeding in ICU patients [11].

Heyland et al. [6] explained the effect of feeding protocols and why are they needed. There is tendency for hospitalized patients to receive nothing by mouth, to be placed on clear liquids, or to receive inadequate nutrition therapy.

When physicians do initiate enteral feeding, there is a tendency to order insufficient calories (ordering ∼65% of mean goal calories day in and day out). Once feeds are initiated, they are frequently interrupted such that only a fraction of what is prescribed is given. The result is an overall inadequacy in delivery of enteral feeding, and patients receive only ∼50% of goal requirements and may be even lower, with patients receiving as little as 20% of goal calories [12].

The reasons for poor delivery of EN are based primarily on dogma. Failure to initiate EN was shown in one study to be due to concerns for ileus (29.7% of cases), perioperative dietary management (28.8% of cases), and diagnostic tests (7.7%). In 15% of cases, physicians were unclear as to why patients received nothing by mouth. The value of protocols in this situation is related to promotion of feeding patients with ileus, decreasing the number and duration of cessation periods from EN, hastening earlier initiation of feeds, increasing volume, and reducing barriers to delivery of EN [6].

A cluster-randomized controlled trial was performed in the ICUs of 11 community and three teaching hospitals and randomized to the intervention of guideline-driven nurse protocols or control arm. The result was that the ICUs that received an aggressive intervention increased the number of days that enteral feeding was delivered in the first week of hospitalization, improved hospital length of stay by 10 days, and reduced mortality by 10% compared with control ICUs with no protocol [13].

Taylor et al. [14] evaluated three aspects of an enteral feeding protocol (rapid vs. slow ramp-up in the rate, different levels for gastric residual volume, and gastric versus small bowel feeding), and found that a more aggressive regimen nearly doubled the volume of enteral feeding delivered and improved patient outcome.

Our results are in agreement with those of Hurt et al. [15], who performed a prospective trial of trauma patients (n=121) assigned to 1 of 2 groups. The first group received targeted education consisting of strategies to increase intake of early EN. Strategies included early enteral feeding, avoidance of fasting and clear liquid diets, volume-based feeding, early resumption of feeds after procedure, and charting caloric deficits. The control group did not receive targeted education but was allowed to practice in a standard ad-hoc manner. Both groups were provided with dietitian recommendations on a multidisciplinary nutrition team as per standard practice. They stated that volume-based feeds (i.e. prescribing based on total volume of formula to be delivered in 24 h as opposed to traditional rate per hour prescribing) empower the nurse to increase or alter the rate of delivery to make up for lost time, as occurs when patients leave the unit for diagnostic tests or therapeutic procedures.

Heyland et al. [6] developed an EN protocol that shifted from an hourly rate target to a 24 h volume target, and found that patients who were prescribed volume-based feeds achieved almost 90% of their prescribed protein and energy requirements, and their results are in accordance with group 3 in our study.

Lichtenberg et al. [16] evaluated the difference of daily EN volume deficits between a traditionally calculated infusion rate and a compensatory, higher calculated infusion rate in which the 24-h volume was delivered over a 20-h infusion period. (For the 20-h group, the calculated daily requirement of EN was divided by 20 rather than 24 for the higher hourly rate but still delivered for 24 h.) They found that EN was most often held for extubation or procedures. They also found that calculating and prescribing higher EN infusion rates, assuming 20 h of actual infusion daily, improved delivery of optimal nutrient provisions and helped in avoidance of unintended malnutrition by significantly reducing caloric deficit from frequent EN holding, but a higher level of overfeeding was noted in the 20-h infusion group.

Chung et al. [17] examined nutritional support received by blunt trauma patients from eight trauma centers. They grouped patients according to mean daily enteral caloric intake during the first 7 days. Group 1 was given the lowest (0 kcal/kg/day) and group 5 the highest (15–30 kcal/kg/day) number of calories in the first week. They focused their examinations on the patients remaining in the ICU for 8 days or longer and compared clinical outcomes among the groups. They found that the main causes for interruptions to EN were resuscitation, diagnostic imaging, and operative procedures.

Passier et al. [18] conducted a retrospective single-center study in trauma ICU of a university-affiliated teaching hospital. Instead of compensating periods of fasting for operation or investigation procedures by increasing the rate of EN infusion in our study, Passier et al. [18] applied a decreased fasting protocol for patients scheduled for a tracheostomy, permanent feeding tube, orthopedic procedure, inferior vena-caval filter placement, eye surgery, or ear, nose, and throat surgery. Their patients were allowed to receive small bowel feedings until the time of the procedure or gastric feeding until 45 min before the procedure. The authors found that patients in the examination group received more EN and there was no significant difference in complications (including regurgitation and aspiration).

Our results are in agreement with those of Taylor et al. [19], who demonstrated that a change in feeding technique to a volume-based approach increases the intake of EN volume, calories, and protein to patients, without increasing gastric residual volume or vomiting and only slightly increasing diarrhea. This study was a before–after cohort investigation comparing 7 months of patient outcomes during a standard rate-based protocol for EN with the next 7 months after implementation of a volume-based EN protocol plus educational campaign, in a surgical-trauma ICU population. The volume-based Feed Early Enteral Diet adequately for Maximum Effect (FEED ME) protocol is described as a modified PEP uP protocol and was designed to ‘make up’ for lost EN infusion time due to diagnostic testing, radiographic studies, and operations.

Mackenzie et al. [20] evaluated the changes in EN delivery as a result of the implementation of evidence-based nutrition support protocol, and they found improvement in the proportion of patients meeting greater than 80% of their goals in the ICU, and improved overall delivery of EN. However, they did not find a difference in time of initiation of EN between the groups.

The limitation of this study was that this study was not blinded. However, to reduce any bias, the data were collected by observers who were not involved in the study.


An increase in the adequacy of EN calories and proteins taken by the critically ill patients occurs after application of EN algorithm based on the SCCM/ASPEN guidelines and improved more by using a protocol that shifted from an hourly rate target goal to a 24-h volume goal. This study provides a solution to overcome inadequate calories and proteins given to the patient because of frequent interruptions.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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