Enteral nutrition support.

Continuing education and the APD program

This quiz is an ideal activity for APD members to include in your CPD log, where it relates to personal learning goals. Record the time taken, to the nearest hour, to complete the quiz and any associated research.

This quiz has been prepared by the NSW Enteral/Parenteral Interest Group. Correspondence should be directed to Suzie Ferrie, Interest Group Secretary, Department of Nutrition and Dietetics, Royal Prince Alfred Hospital, Camperdown NSW 2050, email [e-mail].

Introduction

Several surveys have indicated that 30% to 40% of hospital patients are malnourished. Appropriate nutrition support may reduce hospital complications, length of hospital stay, cost of hospital stay, and even mortality (1) The dietitian is an essential part of nutrition support management, ensuring that suitable nutrition support strategies are chosen, any problems or risks are identified early, the individual patient's needs are met, and inadequate or excessive feeding is avoided.

1. Which of the following are possible reasons to consider tube feeding in patients who have had a stroke?

a. reduced level of consciousness

b. dysphasia 

c. arm or facial weakness

d. dysphagia

e. a, c and d.

2. Which of the following is not a valid reason for avoiding the use of a nasogastric tube (NGT)?

a. the patient has a recent fracture to the base of skull, increasing the risk of a dangerous tube misplacement 

b. the patient has no bowel sounds, therefore the gut may not be working, increasing the risk of aspiration

c. the patient has acute pancreatitis, and feeding into the stomach would stimulate pancreatic activity and exacerbate the pancreatitis

d. the platelet count is low (12 X [10.sup.9]/L), increasing the risk of a significant bleed upon insertion of the tube

3. A patient is identified as being at high risk for refeeding syndrome and has to start tube feeding. After a thorough medical assessment, what is the most appropriate nutritional management?

a. start enteral feeding as soon as possible, according to the hospital's standard protocol. (i.e. using a standard feeding formula and advancing the feed rate by 30-40m L/h every four hours until goal feed rate is reached)

b. start a trial of water via the nasogastric tube for 24 hours, then start enteral feeding according to the hospital's standard protocol

c. review the patient's electrolyte levels, liaise with the medical officer to chart appropriate supplementation, and request that the patient is kept nil by mouth overnight. In the morning, start enteral feeding according to the hospital's standard protocol

d. review the patient's electrolyte levels, liaise with the medical officer to chart appropriate supplementation, and start enteral feeding immediately at a low rate (such as 30% to 50% of the patient's estimated needs), increasing only very slowly

4. What supplementation may be appropriate in a patient at risk of refeeding syndrome?

a. supplemental phosphate, magnesium and potassium

b. thiamin 

c. a general multivitamin 

d. all of the above may be needed, and a restriction of fluid and/or sodium may be required initially as well

5. Which of the following medications interact with enteral feeds?

a. Sinemet (levodopa)

b. Lipex (simvastatin)

c. Dilantin (phenytoin)

d. both a and c

6. Early postoperative enteral feeding has been suggested to benefit many patients, reducing infectious complications and length of hospital stay (2). Which group might be at risk from aggressive early feeding?

a. those who have experienced a significant blood loss during surgery and poor post-operative urine output

b. those with significant loss of weight pre-operative, who were fasted for a significant period

c. those whose surgery involved perforation or anastomosis of the gastrointestinal tract

d. both a and b

7. Which of the following is a reasonable estimate of fluid needs for an elderly person?

a. 30 ml/kg actual body weight

b. 1500ml per day

c. 35-45 ml/kg actual body weight

d. either a or b

8. Which pair includes the two most common causes of diarrhoea in someone receiving tube feeding?

a. antibiotics, and contamination of the feeding formula with bacteria or yeasts

b. high osmolality of the feeding formula, and high-dose sedatives

c. being on a liquid diet, and excessive feed rate

d. formula being given too cold, and patient is bedbound

9. A critically ill intensive care patient is receiving nasogastric feeds, using a standard feeding formula. Which of the following is not a valid reason to stop the feeds?

a. the patient has developed copious diarrhoea

b. the patient has no bowel sounds

c. the nurse aspirated the stomach contents and the aspirate amount was 190mL

d. all of the above

10. Which group has the highest osmolality overall?

a. medications in liquid form, clear fluid diet, 2 Cal/mL formula

b. paediatric formulae, formulae made up from powder, high-fibre formulae

c. high-fat formulae, high glycaemic-index formulae, elemental formulae

d. feeding formula diluted with water, baby formula, renal formulae

Answers

1. e

Stroke patients can experience multiple impairments that affect their ability to eat, leaving them vulnerable to malnutrition (3). Oral feeding of patients with a reduced level of consciousness may be unsafe. Patients who are dependent on assistance with feeding, e.g. due to arm or facial weakness, are likely to have reduced, and possibly inadequate, oral intake (4). Patients with swallowing difficulties or dysphagia may require tube feeding, either to meet their total needs, or to supplement an inadequate oral intake (especially if a texture-modified diet is needed.) The presence of any or all of these neurological or motor deficits can either prevent or severely limit a patient's ability to meet nutritional and fluid requirements (5). Dysphasia is a disorder of language function and does not require nutritional intervention.

2. b

Bowel sounds are not an adequate indicator of the patient's ability to tolerate feeding. Fasted patients, and those receiving mechanical ventilation, swallow less air and therefore have fewer bowel sounds. Additionally, most bowel sounds are heard in the stomach and colon regions, but most nutrient absorption occurs in the small bowel, which may recover function within a few hours of major abdominal surgery (6). Early feeding can stimulate gastric emptying. The other three reasons are valid. In patient (a), an orogastric tube may be preferable (7). In patient (c), jejunal feeding would be more acceptable (8), however recent evidence suggests that gastric feeding may still be possible without significantly different outcome (9). In (d), a platelet count less than 20 represents increased risk of a significant blood loss with the trauma of NGT insertion. However, enteral nutrition is protective against gastrointestinal bleeding, and some doctors are still willing to insert a soft fine-bore NGT under these conditions (10).

3. d

The refeeding syndrome consists of the metabolic disturbances that may be induced by feeding when malnourished patients are refed, whether orally, enterally or parenterally (11). Such disturbances may include hypophosphataemia, hypokalaemia, hypomagnesaemia, vitamin deficiencies, fluid or glucose intolerance or both, and resulting, potentially fatal, complications (11-13). Feeds are started at a low rate, to enable electrolyte disturbances to be corrected promptly, and are only increased when levels are normal, taking several days to reach goal rate (11,12). Identifying patients at risk of refeeding syndrome is the first step to prevent complications. Before feeding, abnormal serum levels of phosphate, potassium and magnesium need to be corrected (12). Normal levels may be misleading (11,13) and the patient should be monitored closely for at least the first two weeks of refeeding.

4. d

In addition to correcting electrolyte levels, it is important to give thiamin and a multivitamin (12,13). It may be necessary to restrict fluid and/or sodium (12), due to fluid intolerance.

5. d

Levodopa (used in Parkinson's Disease) competes with dietary amino acids for blood-brain transport. It is recommended that feeds be stopped for an hour after levodopa is given, to avoid interference (14). Tube feeding appears to reduce the absorption of phenytoin (an anti-convulsant drug), making it difficult to establish the appropriate dose. It is recommended that phenytoin not be administered concomitantly with an enteral feeding preparation (14) and that feeds be stopped two hours before phenytoin is given, and resumed two hours afterwards. In ICU, frequent drug level monitoring may make this unnecessary. Phenytoin can be given intravenously to avoid any interactions, however this is not practical in the home setting. More frequent phenytoin level monitoring may still be required.

6. d

(a) represents patients whose gut might not be adequately perfused. Feeding a poorly-perfused gut will increase blood circulation to the gut, but this may cause reperfusion injury, or the increase in perfusion may be at the expense of adjacent gut tissue, causing damage and, at worst, necrosis (15). (b) represents patients at risk of refeeding syndrome (12). Both groups (a) and (b) benefit from very slow, cautious feeding with careful monitoring. Evidence in the literature suggests that (c) are patients who do benefit from early feeding, although surgical tradition often prevents these patients from being fed early (16,17).

7. d

Dehydration can be debilitating in an elderly person. Constipation, hypotension and mental confusion can often be the result of fluid imbalances (particularly dehydration). A minimum intake of 1500ml per day is recommended for all healthy older adults (18).

8. a

The most common causes of diarrhoea are disturbance in gut flora (due to antibiotics) or introduction of pathogens in contaminated feeds (19). A liquid diet does not cause diarrhoea on its own, although without any fibre the stool may become looser than normal (20). High osmolality, and high feeding rates, do not usually cause diarrhoea in the absence of some other cause of malabsorption (19-21). Diarrhoea is often poorly-defined, and this can lead to irrational and inconsistent management. Careful record-keeping (in terms of frequency/volume and consistency) is important.

9. d

None of these are valid reasons to stop feeding, in the absence of other evidence. Diarrhoea is rarely caused by tube feeding (19), and in most cases does not improve if the feed is stopped, so other strategies should be tried first. Bowel sounds are not an adequate indicator of gut function (6). A single large gastric aspirate does not indicate inadequate gastric emptying (22), and feed tolerance should be assessed in terms of patient comfort and abdominal distension as well as looking at the trend for gastric emptying (23,24).

10. a

Many medications, and items given on a clear fluids diet, have osmolalities up to ten times that of a tube feeding formula (25). It is often assumed that a high osmolality can cause diarrhoea, however the evidence is not conclusive, and some studies suggest otherwise (26).

References

1. Green C. Existence, causes and consequences of disease related malnutrition in the hospital and the community, and the clinical and financial benefits of nutritional intervention. Clin Nutr 1999;19(Suppl 2):3S-38S.

2. Lewis S. Egger M, Sylvester PA, Thomas S. Early enteral feeding versus "nil by mouth" after gastrointestinal surgery; systematic review and meta-analysis of controlled trials. BMJ 2001;323:773-6.

3. Perry L. McLaren S. Nutritional support in acute stroke: the impact of evidence-based guidelines. Clin Nutr 2003;22:283-93.

4. Unosson M, Ek AC, Bjurulf P, von Schenk H. Larsson J. Feeding dependence and nutritional status after acute stroke. Stroke 1994;25:366-71.

5. Wojner A, Alexandrov A. Predictors of tube feeding in acute stroke patients with dysphagia. Clinical issues: Advanced practice in acute critical care 2000;11:531-40.

6. Moss G. Maintenance of gastrointestinal function after bowel surgery and immediate enteral full nutrition. II, Clinical experience, with objective demonstration of intestinal absorption and motility. JPEN 1981;5:215-20.

7. Ferreras J, Junquera L, Garcia-Consuegra L. Intracranial placement of a nasogastric tube after severe craniofacial trauma, Oral Surg, Oral Med, Oral Pathol, Oral Radiol, Endod 2000;90:564-6.

8. Windsor A, Kanwar S, Li A. Compared with parenteral nutrition, enteral feeding attenuates the acute phase response and improves disease severity in acute pancreatitis. Gut 1998;42:431-5.

9. Imrie CW, Carter CR, McKay CJ. Enteral and parenteral nutrition in acute pancreatitis. Best practice in research in clinical gastroenterology 2002;16:391-7.

10. Cook D, Heyland D, Griffith L. Cook R, Marshall J. Pagliarello J. Risk factors for clinically important upper gastrointestinal bleeding in patients requiring mechanical ventilation. Crit Care Med 1999;27:2812-7.

11. Crook M, Hally V, Panteli J. The importance of the refeeding syndrome. Nutrition 2001;17:632-7.

12. Brooks M, Melnik G. The refeeding syndrome: an approach to understanding its complications and preventing its occurrence. Pharmacotherapy 1995;15:713-26.

13. Solomon S. Kirby D. The refeeding syndrome: a review. JPEN 1990;14:90-7.

14. MIMS online http://mims.hcn.net.au

15. Marvin R, McKinley BA, McQuiggan M, Concanour CS, Moore FA. Nonocclusive bowel necrosis occurring in critically ill trauma patients receiving enteral nutrition manifests no reliable clinical signs for early detection. Am J Surg 2000;179:7-12.

16. Moore F, Moore EE, Jones TN, McCroskey BL, Peterson VM. TEN versus TPN following major abdominal trauma--reduced septic morbidity. J Trauma 1989;29:916-23.

17. Carr C. Ling KD, Boulos PB, Singer M. Randomised trial of safety and efficacy of immediate postoperative enteral feeding in patients undergoing gastrointestinal resection. BMJ 1996;312:869-71.

18. Guidelines for the use of parenteral and enteral nutrition in adult and paediatric patients. JPEN 2002;26(Suppl): S51A.

19. Bowling T. Enteral-feeding-related diarrhoea: proposed causes and possible solutions. Proc Nutr Soc 1995;54:579-90.

20. Zimmaro D, Rolandelli RH. Koruda MJ, Settle RG, Stein TP, Rombeau JL. Isotonic tube feeding formula induces liquid stool in normal subjects: reversal by pectin. JPEN 1989;13:117-23.

21. Kandil H. Opper F, Switzer B, Heizer W. Marked resistance of normal subjects to tube-feeding-induced diarrhoea: the role of magnesium. Am J Clin Nutr 1993;57:73-80.

22. Lin H, VanCitters G. Stopping enteral feeding for arbitrary gastric residual volume may not be physiologically sound: results of a computer simulation model. JPEN 1997;21:286-9.

23. McClave SA, Snider HL, Lowen CC, McLaughlin AJ, Greene LM, McCoombs RJ, et al. Use of residual volume as a marker for enteral feeding intolerance: prospective blinded comparison with physical examination and radiographic findings. JPEN 1992;16:99-105.

24. Proceedings of the North American Summit on aspiration in the critically ill patient. JPEN 2002:26(Suppl)Nov-Dec.

25. Dickerson RN, Melnik G. Osmolality of oral drug solutions and suspensions. Am J Hosp Pharm 1988;45:832-4.

26. Keohane P, Attrill H, Love M, Frost P, Silk D. Relation between osmolality of diet and gastrointestinal side effects in enteral nutrition. BMJ 1984;288:678-80.