Enteral Nutrition

Disclaimer: The following information is meant for general educational purposes only. All health authorities operate under their specific guidelines and protocols. Therefore, all dietetic students and interns should consult their preceptors and governing health authorities for such information.

For patients who are unable to achieve adequate nutrition through an oral diet, enteral feeding is a form of nutrition support that aids in optimizing the health status of such patients. Enteral feeding provides nutrition through a feeding tube into the gastrointestinal tract.

For more information and resources related to enteral nutrition, please visit The American Society for Parenteral and Enteral Nutrition (ASPEN)

This video provides an opportunity for the viewer to work through an enteral case study. It demonstrates the decision making processes involved in enteral nutrition and provides examples of enteral nutrition calculations.


Enteral nutrition (EN) is appropriate when:

  • Gastrointestinal (GI) tract is functional
  • Patient is unable to meet nutritional needs via oral diet, even after nutrient-dense foods have been chosen, possibly due to:
  • Poor appetite
  • Chronic medical condition (e.g. neurological disease)
  • Chronic medical treatment
  • Dysphagia
  • Elevated demands from trauma, wounds and/or illnesses

Specifically for children, EN is appropriate if:

  • Poor growth (e.g. growth velocity, weight-for-height)
  • Inadequate fat stores (refer to triceps skinfold measurements)
  • Excessive total hours spent on oral feeding


Enteral nutrition is contraindicated in some cases, such as:

  • Bowel Obstruction
  • Intestinal Failure
  • Gastrointestinal Hemorrhage
  • Severe Malabsorption

Ethical Considerations

  • Patient competency (may be affected by health status)
  • Patient and/or family wishes

Choosing Feeding Tubes

There are various types of feeding tubes used in enteral nutrition. Some of these include nasogastric, gastric, and jejunostomy tubes. The type of feeding tube chosen should reflect the patient’s nutritional condition and disease state, as well as the expertise of the dietitian and the rest of the health care team.

Considerations for Selecting Feeding Tube and Site of Access
  • Patient prognosis and medical condition
  • Activities of daily living and quality of life
  • Availability of feeding tube experts
  • Potential risks associated with different types of feeding tubes and access sites
  • Required duration of enteral feeding
Considering the Cost of Feeding Tubes

Feeding tubes need to be changed regularly and for most patients, feeding tubes are not covered under health insurance plans. Therefore, it is important to consider the cost when choosing the correct feeding tube. For example, feeding tubes that are more inconspicuous will cost relatively more compared to a tube that is not.

Feeding Regimens

There are various feeding regimens for enteral nutrition, some of which include bolus, intermittent/cyclic, and continuous regimens, or a combination of these methods. The use of pump or gravity may be chosen for an intermittent feeding regimen, while a pump is typically used in continuous feedings. Administration of enteral nutrition is based on the patient's age, disease condition, nutrition status, and condition of the gastrointestinal tract. The administration rate is usually advanced based on tolerance; however, note that initiating and advancing enteral feeds is guided by clinical judgement and individual institutional practices.

When determining the method and administration of enteral nutrition, it is important to consider the various prompting questions:

  • What method of enteral nutrition is appropriate for the patient?
  • Continuous or intermittent?
  • What is the rate of administration?

Enteral Nutrition: How to calculate
Enteral Nutrition Manual for Adults in Health Care Facilities: Pages 14-17

The appropriate weight must be determined in order to estimate nutritional requirements for enteral nutrition.

  • BMI <18 use actual body weight
  • BMI >18 to <30 use actual body weight
  • BMI >30 use adjusted body weight (consider if patient has edema)

In order to choose the appropriate tube feed formula, one must calculate energy, protein, and fluid needs of the patient. Note that different institutions have their own protocols and healthcare professionals may have their own preferences in calculating and estimating these nutrient needs.

Energy Calculations

There are many methods used to calculate energy requirements. Daily energy requirements may be calculated using the following formulas:

1. Based on Weight (kcal/ kg body weight)

Sedentary (kcal/kg) Moderately active (kcal/kg) Active (kcal/kg)
Overweight (BMI > 24.9) 20-25 30 35
Normal weight (BMI 18.5-24.9) 25-30 35 40
Underweight (BMI < 18.5) 30-35 40 45-50

BMI Calculator

2. Harris-Benedict Equation

* Harris-Benedict (Revised)

BMR for men (metric):

BMR = 66.47 + ( 13.75 x weight in kg ) + ( 5.003 x height in cm ) - ( 6.755 x age in years )

BMR for women (metric):

BMR = 655.1 + ( 9.563 x weight in kg ) + ( 1.850 x height in cm ) - ( 4.676 x age in years )

Harris-Benedict (Revised) Calculator

Activity Factors
Sedentary: Little to no exercise BMR x 1.2
Mild activity level: Intensive exercise for at least 20 minutes, 1 to 3 times per week BMR x 1.3 - 1.375
Moderate activity level: Intensive exercise for at least 30 to 60 minutes, 3 to 4 times per week BMR x 1.5 - 1.55
Heavy or Labor-intensive activity level: Intensive exercise for 60 minutes or greater, 5 to 7 days per week BMR x 1.7
Extreme level: Exceedingly active and/or very demanding activities BMR x 1.9

3. Mifflin-St.Jeor

RMR males (kcal/day) = 9.99 x weight (kg) + 6.25 x height (cm) - 4.92 x age (years) + 5

RMR females (kcal/day) = 9.99 x weight (kg) + 6.25 x height (cm) - 4.92 x age (years) - 161

Activity Factors
Sedentary: Little to no exercise RMR x 1.2
Mild activity level: Intensive exercise for at least 20 minutes, 1 to 3 times per week RMR x 1.375
Moderate activity level: Intensive exercise for at least 30 to 60 minutes, 3 to 4 times per week RMR x 1.55
Heavy or Labor-intensive activity level: Intensive exercise for 60 minutes or greater, 5 to 7 days per week RMR x 1.7
Extreme level: Exceedingly active and/or very demanding activities RMR x 1.9

Mifflin-St.Jeor Calculator

4. Ireton-Jones

Ventilator dependent:
IJEE(v) = 1784 - 11(A)+ 5(W)+244 (G) + 239(T) + 804(B)

A = age, W = weight in kg, G = gender (1 if male, 0 if female), T = trauma (1 if present, 0 if not), B = burn (1 if present, 0 if not)

Ventilator independent (not on ventilator):
IJEE(s) = 629 - 11 (A) + 25 (W) - 609 (O)

O = obesity (1 if present, 0 if not)

Ireton Jones Calculator

Protein Calculations

There are many methods used to calculate protein requirements. Requirements may change based on individual needs (e.g. stress, disease state).

Estimated Daily Protein needs = Weight (kg) x Protein Factor*

*Protein Factors:

  • Normal = 0.8 - 1.2 g/kg
  • Stressed (fever, fracture, infection, wound) = 1.2 - 1.5 g/kg
  • Severely stressed (critically ill), stage IV wounds or protein repletion = 1.5 - 2.0 g/kg

Fluid Calculations

There are several factors that may increase or decrease fluid needs. In addition, a portion of the calculated fluid needs will be administered through water flushes.

Based on caloric needs

Estimated Daily Fluid Needs = 1 mL for every kcal consumed

Based on weight

Estimated Daily Fluid Needs = Weight (kg) x Fluid Factor*

*Fluid Factors:

  • 25 mL/kg for congestive heart failure or renal disease
  • 30 mL/kg for average adults
  • 35 mL/kg for patients with infection or draining wounds

Based on age

Estimated Daily Fluid Needs = Weight (kg) x Age Factor*

*Age Factors:

  • Average healthy adult: 30-35 mL/kg body weight
  • Adult 55-75 years: 30 mL/kg body weight
  • Adult >75 years: 25 mL/kg body weight

Fluid Calculator

Although the enteral formulary of various health care institutions may differ, it is important to become familiar with the categories of formulas that are offered (e.g. standard, hydrolyzed, elemental, disease-specific), and when they may be used. Several of these categories can be found in the Nestle and Abbott product guides.

Factors to Take into Consideration

1. Nutritional Goals

  • Will the patient benefit from a disease specific or high protein formula?
  • Will the patient benefit from the use of modular formulas (such as Beneprotein)?
  • Will the formula be consistent with fluid requirements?
  • Is the amount of fibre in the formula appropriate?

2. Digestive and Absorptive Capability

  • What is the most intact formula that can be tolerated (e.g. polymeric, hydrolyzed)?
  • Is fat malabsorption an issue?

3. Patient Status

4. Cost

  • Does the patient have the financial means to access the prescribed formula? (Note: standard, general purpose formulas are typically least expensive)

5. Formula Properties

  • Is the viscosity appropriate for the selected feeding tube?
  • Will osmolality be well tolerated?

6. Current Best Evidence

  • What can be drawn from the current best evidence to guide decisions (e.g. evidence regarding supplemental arginine/glutamine/antioxidants)?


BC Children's Hospital: Types of Tubes
Nutrition411: Feeding Tube Types
Dietitian.org: The Selection and Care of Enteral Feeding Tubes

There are many feeding tolerance issues that may arise during a patient’s enteral nutrition care, and it is important to continually monitor and assess these issues. Often, feeds are stopped due to common beliefs that feeds cause complications such as aspiration, diarrhea, or constipation; however, this may not be the case. Therefore, familiarity with troubleshooting protocols are crucial. Every health authority and individual health care professional may have their own protocols for addressing these issues. For supplemental learning in preparation for handling enteral nutrition care plans, resources from Nestle and A.S.P.E.N. are provided below.


A.S.P.E.N. guidelines for Monitoring Enteral Nutrition Administration Enteral Nutrition Manual for Adults in Health Care Facilities (See Pages 32-44)


  • fiber has not been shown to have an effect
  • check for possible infection (i.e. C. difficile)
  • check patient for possible IBS, IBD, ileocecal valve removal, etc...
  • check medications that may have caused a high osmotic load
  • check tubes and equipment to ensure that it is properly flushed, cleaned, etc...


  • limit narcotics
  • initiate a bowel protocol
  • ensure proper hydration of patient

Gastric Residual Volume

Although commonly believed to assess risk for aspiration, measuring gastric residual volume (GRV) is not commonly done in practice. There is little evidence to support the link between GRV and tube-feeding tolerance. There are currently not even any standardized guidelines in regards to what is considered a high GRV. If GRV levels are believed to be elevated, it is important to explore potential causes of enteral-feeding intolerance. GRV levels are not sufficient enough to warrant a decreased rate of feeding -- leaving the potential for under-feeding and malnutrition. [1]

Things to consider when GRV is high

  • If high GRV leads to issues like nausea and vomiting, try elevating the patient to 45 degrees


Dietitians are aware that refeeding syndrome is a common concern in nutrition support. In general, if a patient is at risk for refeeding syndrome, start at a low feeding rate and increase slowly in accordance to the patient’s tolerance.

Resources for Refeeding Guidelines of Goal Rates

Much Ado about Refeeding (See Page 38, Table 4)

Refeeding syndrome- awareness, prevention and management (See Figure 1)

Return to Dietetics Internship Resources page

source: http://wiki.ubc.ca/Dietetics:Enteral_Nutrition