Monitoring the Tube-fed Patient
Sigrid Kalde, R.D.
Dept. of Gastroenterology, Hepatology and Infectiology, Klinikum Krefeld, D-47809 Krefeld, Germany
phone +49-2151-32-2706, e-mail: kalde_med@klinikum-krefeld.de
Learning Objectives
 To identify different techniques to administer tube feeding (bolus, gravity, continuous
pump-controlled) and their respective advantages and disadvantages
 To list the differential indications for choosing the most appropriate tube feeding
technique
 To describe the clinical signs and symptoms of the most frequent complications of
enteral nutrition therapy
 To list the most relevant variables to monitor nutrition therapy, particularly in oncologic
patients
Introduction
Meanwhile I have been working as a dietitian in a multidisciplinary nutrition team for about
11 years in a department of Gastroenterology. Since June 1990 we have focussed on
enteral nutrition and until now we have documented more than 1,500 enteral tube feeding
patients. Indications for tube feeding, age and sex of the patients, route and type of the
diet regime, complications of the tube feeding, and the physical condition of patients are
being documented. Our patient group comprises mostly oncologic patients, but also geriatric, neurologigal and HIV-infected patients, as well as children with cystic fibrosis or glycogenosis, and mentally handicapped children as well.
In our group the largest experience exists regarding the care of oncologic patients of
whom the majority reqires feeding by a percutanous tube.
Starter Regime
After percutaneous needle puncture of the stomach or surgical manipulation of the stomach or small intestine in the process of placing a feeding tube gastroparesis or ileus may
occur. When bowel sounds are present water may be given to ensure tolerance and proper function of the tube. In our experience, enteral feed can be started 4 hours after PEG
insertion administering 250 ml water followed by 250 ml of a polymeric tube diet on the
same day by continuous or gravity feeding depending on the patient‘s situation.
The average adult with normal renal function will maintain adequate hydration on 35-40 ml
water per kg ideal body weight per day. In clinical practice this goal is not met in a sizeable
proportion of patients. Consequently, there are side effects running a spectrum from defecation problems or constipation to renal failure and severely disturbed consciousness to be
observed in both in- and out-patients. Additional problems such as cardiac or respiratory
failure, fever, or diarrhoea must be taken into account and may require an individually tailored fluid regimen. To calculate the amount of water needed in addition to the volume of
the liquid diet, the water content of the liquid feed must be considered. The amount of
water varies between products ranging from 700 to 880 ml per 1000 ml liquid diet. For the
calculation of the fluid balance other intake apart from enteral feeding must not be
overlooked such as intake from parenteral nutrition or other infusions. This is of articular
importance in periods of weaning the patient from parenteral nutrition and when
commencing enteral nutrition. If there are no infusions and the patient is completely on
enteral intake then the amount of water needed in excess of that provided by the liquid
feed may be supplied by intermittent bolus via the tube; in general, there is no need to
administer this extra fluid by continuous drip. Diluting enteral liquid diets does not make
them more tolerable, and indeed, may even decrease tolerability. Also, it may lead to an
unjustified prolongation of the application time.
The gastrointestinal tract should be used as soon as possible after a tube has been
placed. In most cases a polymeric fiber-containing formula will meet the patient’s requirements. The use of elemental formulae should be restricted to patients with severe absorptive dysfunction of the small bowel and even this indication is being questioned increasingly.
Metabolic problems may be less frequent in enteral than parenteral nutrition. Possible
metabolic complications of tube feeding are
 hyperglycamia
 electrolyte abnormalities
 vitamin and trace element deficiencies
Hyperglycamia may occur due to an inappropriately fast application and a carbohydrate
content rich in readily absorbed sugars, such mono- or disaccharides. This may be a particular problem in elderly insulin resistant patients. In such a situation the use of continuous
pump feeding may be recommended.
Administration Technique
Each modality of administration technique: bolus, gravity or pump-controlled infusion has
its own specific use and complications.
Bolus feeding is the rapid administration of a liquid diet, usually by syringe, for a period of
5-10 minutes every few hours. To meet a patient‘s caloric needs 300-400ml may be necessary on each occasion. This is a reliable method of delivery which can easily be performed by the patient himself or a family member without the need for sophisticated instruction. This administration mode keeps the patient independent from any mechanical
device and is especially valuable for the alert and active patient. Moreover it is not a very
cost-intensive method of delivery.
Bolus feeding, however, is the method with the highest risk of side-effects like abdominal
distension, aspiration, reflux, diarrhea and vomiting. Also, bolus feeding is more likely to
generate high residual volumes (RV).
Gravity feeding can be delivered via a continuous drip using special delivery systems. The
patient’s mobility is very limited due to the need for a recumbent or sitting position to
maintain a sufficient hydrostatic pressure gradient to keep the drip running. This administration technique is the most preferred modality for intragastric feeding. The rate of delivery is not precise and gastroesophageal reflux as well aspiration do occur more often during gastric rather than post-pyloric feeding.
Continuous pump-controlled feeding requires a mechanical device and a power supply
and is the most cost-intensive method of delivery. The most important advantage of pumpcontrolled feeding is the accurate controlled delivery which consequently minimizes the
risk of high residual volumes and the risk of aspiration. Studies have shown that continuous feeding was associated with fewer episodes of diarrhea and aspiration and abdominal distension.
For jejunal feeding the continous pump-controlled infsuion is obligatory in order to minimize abdominal distension, cramps, hyperperistalsis and diarrhea due to inadequatly high
volumes. In critically ill patients and children continuous feeding has been reported superior to gravity feeding in terms of less diarrhea, more positive nitrogen balance and more
weight gain due to improved absorption. After the patient has stabilised and is well adapted to enteral nutrition the feeding techniques may be deescalated switching from continuous pump-controlled feeding to gravity feeding in most cases, as it is said that this gravity
feeding is the most practicable and prefered.
Nocturnal nutrition therapy is only practicable by continuous pump-controlled feeding and
this may be particularly helpful for patients to maintain mobility and freedom during the day
and in situations when other medical interventions or procedures preclude feeding during
the daytime.
The following aspects should be checked when choosing the delivery method:
 Route of enteral access
 Gastrointestnal tolerance of feeding
 Expected period of need for artificial nutrition
 Nutritional status of the patient
 Underlying medical condition of the patient
 Acceptance by the patient
Complications of Enteral Nutrition Therapy
Aspiration is the most severe complication of enteral tube feeding. To reduce the risk of
aspiration during gastric feeding the following precautions should be taken:
 Raise the patient to a 30-45° recumbent position during feeding and for 1 hour thereafter.
 Use intermittent or continuous feeding regimes rather than the rapid bolus method
 Gastric residuals should be checked regularly
Jejunal access is preferable in patients with recurrent tube feeding aspiration or in critically
ill patients at risk for gastric motility dysfunction (e.g. patients with head trauma). This requires to position the tip of the feeding tube beyond the ligament of Treitz. Despite these
measures tubes tend to slip out of position frequently requiring appropriate controls to verify the tube position.
Diarrhea is a common, often misdiagnosed complication of enteral feeding that has many
potential causes:
 Drugs like antibiotics, antacida, magnesium
 Rate of infusion and time of infusion
 Alterations in motility
 Alterations in absorption
 Physiological disturbances
 Temperature of the enteral diet
 Bacterial contamination of the enteral diet
By carefully taking into consideration all potential causes the following strategies may help
to overcome this complication:
 Make use of continuous pump-controlled feeding
 Minimize the rate and infusion time of enteral fluid
 Reduce the antibiotic therapy, if possible
 Try to increase the amount of soluble fibre in the enteral fluid
Finally monitoring the tube fed patient should not be limited to physiological measures like
like serum protein, albumin, total protein, transferrin or the nutritional status of the patient,
but also his quality of life.
References
1. Kirby DF, DeLegge MH, Fleming CR. The American Gastroenterological Association (AGA) Guidelines for the use of
enteral nutrition. Gastroenterology 1995; 108:1282-1301
2. Benya R, Mobarhan S. Enteral alimentation: administration and complications. J Am Coll Nutr 1991; 10: 209-212
3. Mercandante S. Parenteral versus enteral nutrition in cancer patients: indications and practice. Support Care Cancer
1998; 6: 85-93
4. Braga M, et al. Early postoperative enteral nutrition improves gut oxygenation and reduces costs compared with total
parenteral nutrition Crit Care Med 2001; 29: 242-248
5. Braga M, et al. Artificial nutrition after major abdominal surgery: Impact of route of administration and composition of
the diet. Crit Care Med 1998; 26: 24-30
6. Kalde S, Vogt M, Kolbig N. Enterale Ernährung. Stuttgart: Gustav Fischer Verlag, 1999
7. Weiman A, Bischoff SC. Künstliche Ernährung. München: Urban Fischer Verlag, 2001