Page 656 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Enteral Nutrition 643

intermittent feeding groups, 48 which is similar to the cramping. These problems can be managed by reducing
recent findings of Holahan et al. It has been previously the feeding rate or solution concentration, or by feeding
thought in veterinary and human medicine that high diets that delay gastric emptying. Fiber-enriched human
GRVs correlated with a higher incidence of vomiting, enteral products are marketed to normalize GI transit
regurgitation, and the incidence of aspiration pneumo- times, but there is little evidence to suggest that these
nia. However, no significant correlation between average products minimize or reduce diarrhea in tube-fed
GRVs (mL/kg) and occurrence of vomiting or regurgita- patients. 91
tion was found in the Holahan study, and only two Cold feeding solutions are thought to be a major cause
patients on EN had aspiration pneumonia, both of which of diarrhea, but research available to support this opinion
had radiographic evidence of pneumonia documented is inconclusive. We have not observed problems with diets
before the start of EN. There is a lack of evidence in vet- fed at room temperature and recommend that diets
erinary medicine to suggest what an acceptable GRV stored in a refrigerator be brought to room temperature
might be, or whether this measurement is a reliable before being tube fed or offered for oral consumption.
means of assessment of gastric intolerance. The authors Bacterial contamination of formulas during reconstitu-
9
conclude that termination of enteral feedings due to ele- tion and administration can also cause diarrhea, so diets
vated GRVs in critically ill dogs may not be warranted, should be handled carefully and not allowed to remain in
particularly in patients not exhibiting signs of vomiting the feeding tube system for more than 24 hours. 40
or regurgitation. Patientproblemsthatmayresultingastrointestinalintol-
erance to feeding include protein malnutrition,
COMPLICATIONS OF hypoalbuminemia from any cause, fat malabsorption, and
ENTERAL FEEDING associated gastrointestinal disorders. Hypoalbuminemia
can lead to malabsorption and diarrhea because intravascu-
Mechanical, gastrointestinal, technical, and metabolic lar osmotic pressure required for nutrient uptake is greatly
complications can occur with enteral tube feeding. reduced. 38 Pancreatic disease, biliary obstruction, ileitis,
Mechanical problems relate to placement (inadvertent bacterial overgrowth, gastric surgery, and intestinal resec-
placement of the tube into the trachea, regurgitation or tion all can lead to varying degrees of fat malabsorption.
vomiting up the tube, or removal of the tube by the Many medical disorders are associated with diarrhea, 50
patient) and maintenance of the tube, including clogged including enteric infections, malabsorption syndromes,
or blocked tubes. Tubes can become clogged if pills are gastroenteritis, mucosal defects, diabetes mellitus, carci-
crushed and forced into the tube, or if food is not ade- noid syndromes, hyperthyroidism, and immunodeficiency
quately flushed out of the tube after bolus feeding or states.
the tube is not capped to leave a column of water in The most important cause of diarrhea in tube-fed
the tube. Flushing clogged tubes with a variety of human patients is concomitant antibiotic or drug use
solutions (cranberry juice and cola beverages have been because it is the most difficult factor to change. Develop-
recommended in the past) may be irrational if the pK ment of diarrhea often results in discontinuation of tube
of the clogging material is not considered. 12 Another feedings in an attempt to reduce the diarrhea that nursing
potential problem that should be considered is drug staff and clinicians associate with liquid feedings. How-
incompatibility with enteral feeding formulas. Potassium ever, the problem may be the antibiotic used or related
chloride elixir is the most commonly reported incompat- to the underlying disease process. By altering the normal
ibility, causing formula precipitation and blocked tubes. 4 gastrointestinal flora, antibiotic usage can also change the
Tube clogging is best prevented by prohibiting its use for fatty acid composition of gut contents, which may
the administration of nonliquid materials and by properly adversely affect sodium and water absorption by the
flushing and capping the tube after each use. To decrease colon. Intestinal bacteria also may ferment undigested
the incidence of tube occlusion, we recommend flushing nutrients, forming organic acids, hydrogen and carbon
the tube with a small amount (3 to 5 mL) of warm water dioxide gas, and ultimately causing diarrhea.
every 4 to 6 hours regardless of the delivery method; this Many antibiotics and drugs have been associated
becomes especially important in small dogs and cats. with diarrhea including penicillins, aminoglycosides,
Most of the gastrointestinal problems caused by cephalosporins, chloramphenicol, clindamycin, aminoph-
enteral feeding result from too rapid administration of ylline,cimetidine,potassiumchloride,digoxin,andmagne-
the solution, or feeding solutions of high osmolality sium-containing antacids. 44 The oral suspensions of some
(>600 mOsm). Solutions entering the duodenum too antibiotics, electrolytes, and other medications are
quickly can cause vomiting, cramps, and diarrhea by over- hyperosmolar, suggesting that these drugs may play a role
whelming the normal neural and endocrine control in the pathogenesis of diarrhea. 78 A study investigating
mechanisms of the gastrointestinal tract. 18 Hyperosmolar the cause of diarrhea in tube-fed patients found that medic-
solutions cause rapid fluid and electrolyte influx into the inal elixirs containing theophylline, as well as liquid
gut lumen, leading to abdominal distention and preparations of acetaminophen, codeine, cimetidine,