Intensive Care Med (1990) 16:252-255

IntensiveCare Medicine 9 Springer-Verlag 1990

Diarrhoea during enteral feeding in the critically ill: a comparison of feeds with and without fibre G.J. Dobb and S.C. Towler Intensive Care Unit, Royal Perth Hospital, Perth, Western Australia Received: 21 July 1989; accepted: 11 December 1989

A b s t r a c t . This randomised double-blind study examined the frequency of diarrhoea in intensive care unit patients given a fibre-containing feed, Enrich, and a fibre-free feed, Ensure. A daily 'diarrhoea score' was calculated from the frequency, volume and consistency of the stools. A score greater than 12 indicated diarrhoea, and greater than 50 severe diarrhoea. Ninety one patients met the criteria for participation: Enrich 45, Ensure 46. The groups were similar in age, sex ratio, feed volume, antibiotic usage, upper gastro-intestinal bleeding prophylaxis and plasma albumin concentrations. Diarrhoea occurred in 16 patients given Enrich and 13 given Ensure, severe diarrhoea affecting 5 and 9 respectively (NS). Forty seven of 343 (14%) Enrich feeding days and 51 of 342 (15%) Ensure feeding days were complicated by diarrhoea - severe diarrhoea: 8 and 12 feeding days (NS). We conclude soy polysaccharide (21 g/L) did not reduce diarrhoea in intensive care unit patients given enteral feeds.

Critical care Dietary fibre

Key words: -

-

Diarrhoea

-

Enteral feeding

Diarrhoea is a well recognised complication of enteral tube feeding. The reported frequency ranges from 2~ in a general hospital population [1] to 68% in patients requiring intensive care [2l. When diarrhoea affects critically ill patients it increases their distress, complicates management and adds to the cost of their care [31. It is reported that adding a fibre source to enteral feeds reduces the incidence of diarrhoea in patients with burns [4]. However, in a placebo controlled trial, a fixed dose of fibre in the form of "Fybogel" (Reckitt and Coleman) 3.5 g twice daily had no effect on the frequency of diarrhoea in intensive care unit patients [5]. Commercial enteral feeds containing fibre are now available. This prospective double-blind randomised trial attempted to de-

termine whether a feed containing fibre can reduce the frequency of diarrhoea when compared to a similar feed without fibre. Patients

and methods

All adult patients starting nasogastric tube feeding in the Royal Perth Hospital Intensive Care Unit were eligible for inclusion in this study. Patients with a recent history of diarrhoeal illness (e.g. Crohn's disease, ulcerative colitis, ischaemic colitis or melaena), patients with special dietary requirements and those who had recent (i.e. within the previous 14 days) gastrointestinal surgery were excluded. Patients who were enterally fed for less than 3 days were excluded from data analysis. Computer randomisation was used to assign patients to receive either Enrich or Ensure, similar iso-osmolar lactose free feeds manufactured for Abbott Australia Pty Ltd. (Table 1). The most significant difference between the feeds is that Enrich contains approximately 21 g/1 of soy polysaccharide as a source o f dietary fibre. The feed assigned to each patient was prepared each day and supplied to the ICU in a sterile 2-1 capacity plastic container. The feed was stored at 4 ~ until just before use and then allowed to come to room temperature before infusion. Each bag of feed was allowed to hang at room temperature for a maximum of 12 h before being replaced. A sterile closed administration set was used to connect the bags of feed to the feeding tube. The administration set contained a burette into which each hour's feed was measured before being given. The daily feed volume is the sum of the hourly volumes for 24 h from midnight to midnight. Before starting the trial,' patients were given a glycerin suppository to reduce problems with spurious diarrhoea. On the first day 40 ml/h o f half-strength feed was infused, increasing to 40 ml of full-strength feed on the second day. On subsequent days the infusion rate was increased on the basis of clinical assessment, generally by 2 0 - 4 0 m l / h / day to a maximum of 120 ml/h. If diarrhoea occurred, the feed volume or strength could be reduced in an attempt to control it. Anti-diarrhoeal drugs were not used. Patients constipated for more than 3 days could be given daily suppositories. Patients remained in the trial throughout standard enteral feeding unless they were discharged from the ICU or reached a maximum of 18 days enteral feeding. After this further data collection stopped. Patients were withdrawn from the trial if they were constipated for more than 7 days so that appropriate treatment could be given. Patient's age, sex, principle diagnosis and details of concurrent medications were recorded. Data collection forms were completed daily with details of the volume and strength of feed given and each bowel evacuation. Diarrhoeal stools were sent for culture and testing for Clostridium difficile enterotoxin.

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G.J. Dobb and S.C. -fowler: Diarrhoea and feeds with fibre

Table 3. Number of patients by diagnostic categories (COAD = chronic obstructive airways disease)

Table 1. Composition of feeds (per 1000 ml) Enrich

Ensure

38.7 36.9 161.6 36.7 40.0 17.5 12.0 40.5 23.0 248.0 23.0 58.0 236.0 3586.0 1.6 1.8 2.1 21.0 6.3 127.0 287.0 31.5 51.0 422.0 480.0 4.6 (1.1)

37.0 37.0 145.0 37.0 40.0 13.0 8.8 40.5 17.5 248.0 17.0 38.0 171.0 2637.0 1.6 1.8 2.1 21.0 6.4 160.0 212.0 32.0 38.0 210.0 450.0 4.4 (1.05)

Diagnostic category Protein (g) Fat (g) Carbohydrate (g) Sodium (mmol) Potassium (mmol) Calcium (mmol) Magnesium (mmol) Chloride (mmol) Phosphorus (mmol) Zinc (~tmol) Copper (~tmol) Manganese ([lmol) Iron (~tmol) Vitamin A (U) Vitamin B 1 (mg) Vitamin B 2 (mg) Vitamin B6 (mg) Niacin (mg) Vitamin BI2 (~tg) Vitamin C (mg) Vitamin D (U) Vitamin E (U) Vitamin K (U) Folate (rtg) mOsm/kg K J / m l (Kcal/ml)

Table 2. Calculation of diarrhoea score ( + + approx. 240 ml) Consistency

Formed Semisolid Liquid

Estimated volume +

++

+++

1 3 5

2 6 10

3 9 15

In a previous study it proved impossible to quantitate diarrhoea accurately by volume or weight. This led to the development of a "diarrhoea score" [5], a semi-quantitative method for determining the severity of diarrhoea based on the frequency, volume and consistency of the stool (Table 2). The values for all bowel evacuations in the 24 h period to midnight each day were added to calculate the daily diarrhoea score. A daily score greater than 12 corresponds to the definition of diarrhoea in some other reports [2]. Statistical analysis was performed using the SAS [6] statistical computer package. Analysis of variance was used to compare means of continuous variables. The daily diarrhoea scores were not normally distributed. The Wilcoxon rank sum test was used to compare scores in the patient groups given Enrich and Ensure. The study was approved by the Royal Perth Hospital Ethics Committee according to the principles of the Declaration of Helsinki.

Results In a 15-month period 137 patients entered the trial. Forty-six had nasogastric feeds for less than three days and were excluded from data analysis. Forty-five of the remainder received Enrich and 46 Ensure.

Enrich

Ensure

9 8 4 2 1 1

13 5 4 1 2 -

1 2 5 4 1 1 1 5

i 3 2 1 2 1 1 2 1 7

Post-operative Multiple trauma Head trauma Complications after open heart surgery Septicaemia Post operative respiratory insufficiency Haemorrhagic shock

Non-operative Acute exacerbation of COAD Pulmonary aspiration Pneumonia Pulmonary oedema Septicaemia Post-cardiac arrest Cardiogenic shock Multiple trauma Seizure disorder Intra-cranial haemorrhage Drug overdose Other

Table 4. Number of patients given specified medications

Antacid Hz-antagonist Sucralfate H 2 and sucralfate Narcotic infusion

Enrich

Ensure

6 7 14 1 13

7 6 2l 0 13

The diagnostic categories for patients in the two groups are shown in Table 3. The Enrich and Ensure groups were well matched for age (47 + 19 v 45 + 19 years), sex (29 M, 16 F v 32 M, 14 F) and medications (Table 4). Patients given Enrich received an average of 2.1 + 1.3 antibiotics while on enteral feeds compared with 2.0+_1.3 in patients given Ensure. The patient groups were also similar with respect to average serum albumin concentration (29.3+-4.3, range 1 8 - 3 7 g/l v 30.3 +5.1, range 17-41 g/l) and feed volumes. Feed volume varied considerably with time and between patients because of nutritional requirements, feed tolerance and the need to fast for investigations and procedures. The smallest feed volumes were on the first day (Enrich 380+ 172 ml, range 8 0 - 9 6 0 ml; Ensure 494 + 265 ml, range 9 0 - 9 6 0 ml) increasing to a mean volume of 1000-2000 ml from day 3 (Fig. i). The differences between the group's mean feed volumes were not significantly different. There was no day during feeding on which the diarrhoea scores for patients given Enrich were significantly different from those in patients given Ensure (Fig. 2). After 15 days the number of patients remaining in each group (3 and 5) was too small for useful statistical analysis. The total number of feeding days was similar in each

254

G.J. Dobb and S.C. Towler: Diarrhoea and feeds with fibre 2000"

80

3 O >

60

[

-i

1000'

1

2

4

9 []

ENSURE ENRICH

40

9

ENSURE

[]

ENRICH

20

6

8

10 11 12 13 14 15

DAYS

4 5

7 8 9 10111213

15

DAYS

Fig. 1. Mean daily feed volumes (ml) in the patients given Ensure and Enrich

Fig. 2. The standardised mean rank for diarrhoea score each day in patients given Ensure and Enrich

group (Enrich 343, Ensure 342). Similar proportions of these were complicated by a DS > 12 (47/343 vs 51/342), a DS >25 (27/343 vs 21/342) and a DS >50 (12/343 vs 8/342). During the trial, 16 patients given Enrich had a DS > 12 (11 a DS > 25; 5 a DS > 50) and 13 patients given Ensure had a DS>12 (10 a DS >25; 9 a DS >50). None of the differences were statistically significant. There were 17 patients receiving Enrich who were constipated throughout enteral feedings as were 24 patients given Ensure (%2 1.37, p = 0.24; odds ratio 1.8, 95O7oconfidence limits 0.7-4.5). Five patients given Enrich and eight given Ensure were withdrawn from the trial after being constipated for 7 days (;(2 0.31, p = 0.58; odds ratio 1.7, 950-/0 confidence limits 0.4-6.6). One patient on Ensure had a positive stool culture with a growth of Candida albicans. There were no other significant isolates and Clostridium difficile toxin was not detected.

Many factors have been associated with diarrhoea during enteral feeding. These include high osmolality, lactose intolerance, antibiotics, antacids, histamine Hz-receptor antagonists and bolus rather than continuous administration [3]. In this study the feeds were of similar osmolality, lactose free and the method of administration was identical. The groups were also similar in the proportion of patients taking the medications recorded. An association between hypoalbuminaemia and diarrhoea is reported in ICU patients [9], though we have been unable to confirm this finding [11]. Nevertheless, the plasma albumin concentration should not have affected the comparison because the Enrich and Ensure fed groups also had similar distributions of plasma albumin concentration. Another potential cause of diarrhoea is changing from a high to a low residue diet [12]. There are theoretical grounds for believing that fibre could reduce the frequency of diarrhoea during enteral feeding. Fibre absorbs water, decreasing the liquidity of the stools. Patients fed Enrich would be expected to produce stools with a 30% greater volume and presumably more soIid consistency than patients fed Ensure (W. Houghton, pers. comm.). The volume component might have caused a bias towards a higher diarrhoea score in patients given Enrich, but this should have been more than balanced by a firmer consistency. The proportion of patients with higher DS was also similar in the two groups, and to obtain those scores fluidity and frequency were important components. Fibre binds bile salts [13] which are irritant to the colonic mucosa and recognised mediators of diarrhoea [14] and has an important role in the nutrition of the colonic mucosa. The colonic mucosa derives 60%-70~ of its nutrition from the bowel lumen, the important substrates being bacterial breakdown products of fermentable fibre, i.e. the short-chain fatty acids, acetate, proprionate and butyrate [15]. In healthy volunteers, short-chain fatty acids are rapidly absorbed by the colon. The transport process is accompanied by absorption of sodium, potassium and water [16] with a trend to increase water absorption with increasing intra-luminal concentrations of shortchain fatty acids. Not all fibre sources, however, have

Discussion

This study failed to find a significant difference in the frequency of diarrhoea between the trial feeds. It was designed so that if the feed with fibre, Enrich, reduced the frequency with which patients had diarrhoea (DS > 12) from 60~ to 35~ it would have a 90~ chance of reaching significance at the p = 0.05 level. This would also have given a 75~ chance of detecting a reduction from 60% to 40~ at the same level of significance [7]. The overall proportion of patients having diarrhoea was only 32%. This is greater than the highest reported figure of 25% in patients having enteral feeds in general hospital wards [8] but less than half that reported by others in enterally fed ICU patients [2, 9]. A previous study from this unit found 56% of patients selected by the same criteria developed diarrhoea during enteral feeding [5]. Despite the lower than expected frequency of diarrhoea this study was large enough to have a 95o/o chance of detecting a 25% reduction in the number of patients having diarrhoea while fed with Enrich [10]. It is therefore unlikely that a clinically important effect has been missed.

255

G.J. Dobb and S.C. Towler: Diarrhoea and feeds with fibre

identical properties with cellulose being less readily digested than the non-cellulose polysaccharide components which include hemicellulose, pectin, guar and plant gums and mucilages. A small particle size increases the digestability of cellulose, but on average only 50% is degraded compared to 100%0 of the water soluble pectin [,17]. The fibre source in Enrich is methylcellulose 21 g/1. The fibre intake was therefore proportional to the total feed volume. Most studies of fibre supplemented enteral feeds have used healthy volunteers or ambulant patients. One [17], which compared two feeds containing soy polysaccharide - Susta II (Mead Johnson Nutritional Division, Evansville, IN) and Enrich - in stable medical patients found no statistically significant difference between stool wet weight on the fibre-containing feeds and Ensure. No adverse clinical effects were noted in patients given the fibre-containing feed, but faecal nitrogen, fat and minerals were greater. In five other controlled trials [18] with and without dietary fibre added to liquid enteral feeds, fibre increased mean daily stool weight in one and had no significant effect in four. Stool frequency was unaffected in three and slightly, but significantly, increased in two of the trials during fibre supplementation. Less information is available on the effects of fibre supplementation in critically ill patients in which the aim is generally to reduce diarrhoea rather than increase stool volume. In patients with burns the addition of Metamucil (Searle Laboratories) was said to reduce the frequency of diarrhoea [4] but a similar fibre source, Fybogel (Reckitt and Coleman), in a fixed dose of 3.5 G 12 hourly had no effect on diarrhoea in ICU patients [5]. In the present study the amount of fibre was not fixed but increased as the volume of feed increased. It has been claimed that Enrich reduces the incidence of diarrhoea in neurosurgical intensive care unit patients [19] in a comparison with Isocal (Mead Johnson, Australia), but the frequency of liquid stools does not appear to be statistically different in the two patient groups (7/17 Isocal, 3/12 Enrich: p = 0.31, Fisher's exact test) by our calculations. Despite the theoretical advantages of fibre, there was no difference in the frequency of diarrhoea between patients given Enrich and those given Ensure in this study. Enrich has the convenience of being pre-mixed, but it costs 52%-120% more than Ensure for the same volume. On the basis of this study, the additional cost would have to be justified by factors other than effect on bowel function for routine use in ICU patients. Acknowledgements. The authors thank the dieticians and nursing staff of the Intensive Care Unit for their cheerful assistance in the conduct of this study. We are grateful to Mrs J. Neave and Miss E. Baarda for typing the manuscript.

References 1. Cataldi-Becher EL, Seltzer MH, Slocum BA, Jones KW (1983) Complications occurring during enteral nutrition support: a prospective study. JPEN 7:546-552 2. Kelly TW, Patrick MR, Hillman KM (1983) Study of diarrhea in critically ill patients. Crit Care Med 11:7- 9 3. Dobb GJ (1986) Diarrhoea in the critically ill. Intensive Care Med 12:113-115 4. Frank HA, Green LC (1979) Successful use of a bulk laxative to control the diarrhoea of tube feeding. Scand J Plast Reconstr Surg 13:193-194 5. Hart GK, Dobb GJ (1988) The effect of a fecal bulking agent on diarrhea during enteral feeding in the critically ill. JPEN 12:465 -468 6. SAS Institute Inc (1985) SAS/STAT Guide for personal computers, version 6 edition. Cary NC:SAS Institute Inc 7. Machin D, Campbell MJ (1987) Statistical tables for the design of clinical trials. Blackwell, Oxford London Edinburgh Boston Palo Alto Melbourne 8. Jones BJM, Lees R, Andrews J, Frost P, Silk DBA (1983) Comparison of an elemental and polymeric enteral diet in patients with normal gastrointestinal function. Gut 24:78- 84 9. Brinson RR, Kolts BE (1987) Hypoalbuminemia as an indicator of diarrheal incidence in critically ill patients. Crit Care Med 15:506-509 10. Detsky AS, Sackett DL (1985) When was a 'negative' clinical trial big enough? Arch Intern Med 145:709-712 11. Towler SC, Dobb GJ (1988) Hypoalbuminaemia as an indicator of diarrheal incidence in critically ill patients. Crit Care Med 16:817 12. Peaston MJ (1966) External metabolic studies during nasogastric feeding in serious illnesses requiring intensive care. Br Med J 2:1367-1368 13. Hillman LC, Peters SG, Fisher CA, Pomare EW (1986) Effects of the fibre components pectin, cellulose and lignin on bile salt metabolism and biliary lipid composition in man. Gut 27:29-36 14. Binder HJ (1980) Pathophysiology of bile acid- and fatty acid-induced diarrhea. In: Field M, Fordtran JS, Schultz SG (eds) Secretory diarrhea. American Physiological Society, Bethesda MD, pp 154-178 15. Roedgier WEW (1988) Bacterial short-chain fatty acids and mucosal diseases of the colon. Br J Surg 75:346-348 16. Rupin H, Simon BM, Soergel KH, Wood EM, Schmitt MG (1980) Absorption of short-chain fatty acids by the colon. Gastroenterology 78:1500-1507 17. Heymsfield SB, Roongspisuthipong C, Evert M, Casper K, Heller P, Akrabawi SS (1988) Fiber supplementation of enteral formulas: effects on the bioavailability of major nutrients and gastrointestinal tolerence. JPEN 12:265-273 18. Silk DBA (1989) Fibre and enteral nutrition. Gut 30:246-264 19. Monypenny FE (1989) Does fibre help reduce the incidence of diarrhoea in the enterally fed neurosurgical intensive care patient? Anaesth Intensive Care 17:223A

Dr. G.J. Dobb Intensive Care Unit Royal Perth Hospital P.O. Box X2213 Perth 6001 Western Australia

Diarrhoea during enteral feeding in the critically ill: a comparison of feeds with and without fibre.

This randomised double-blind study examined the frequency of diarrhoea in intensive care unit patients given a fibre-containing feed, Enrich, and a fi...
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