Page 459 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Fluid and Electrolyte Disturbances In Gastrointestinal and Pancreatic Disease 447

has a carbohydrate-to-sodium ratio of 1:1 to 2:1, potas- translocation. Bacterial translocation was assessed by cul-
sium, chloride, an alkali source, and an osmolality turing multiple sites (e.g., liver, pancreas, peritoneal fluid,
between 250 and 310 mOsm/kg. The ideal formula still mesenteric lymph node) and was more likely to be posi-
remains controversial. 118,124 Alkali sources such as tive in dogs that had received parenteral nutrition com-
bicarbonate and citrate also enhance the absorption of pared with enteral nutrition or eicoimmunonutrition
water and electrolytes. 119 (i.e., the addition of probiotics, such as lactobacillus
Clinical trials of ORSs containing complex and bifidobacterium). 136 The best results were achieved
carbohydrates or glucose polymers in place of glucose in dogs that received eicoimmunonutrition followed by
have resulted in decreased volume and duration of diar- enteral nutrition. Jejunal feeding has been advocated,
rhea. A potential explanation for the beneficial effect of especially in cases of acute pancreatitis and is commonly
such solutions is that glucose polymer molecules contain carried out using a gastric tube. Nasojejunal feeding tubes
more glucose residues without delivering a high osmotic may be passed with fluoroscopic guidance. 7,134 Tube
loadtotheintestinallumen.Muchofthebreakdownofthe placement can be accomplished either under sedation 134
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polymer occurs at the epithelial surface, and the smaller or general anesthesia. Tube migration into the stomach
7
molecules do not accumulate in the intestinal lumen. occurred in 1 of 8 and 17 of 20 134 animals with feeding
The relative hypotonicity of glucose polymer solutions tubes initially placed in the jejunum. Surgically-placed
may be the major contributor to their efficacy. 124 gastrojejunostomy tubes also may be used when fluoros-
In children, oral electrolyte solutions can be used to copy is not available. 17
treat mild to severe dehydration even in the presence of
vomiting as long as the patient is able to swallow small Patient Monitoring
4
amounts frequently. A volume equal to the amount For stable patients, minimal monitoring includes regular
that would be given intravenously is appropriate. Reports assessment of vital signs and fluid and electrolyte balance.
of the effectiveness of ORSs in veterinary patients are In patients with systemic abnormalities, monitoring
limited, but favorable results have been reported in the should be more aggressive and should include vital
treatment of uncomplicated acute gastroenteritis in dogs signs, weight, PCV, total protein concentration, fluid
and cats with Pedialyte (Abbott Laboratories, Abbott intake and output, blood pressure (central venous and
Park, Ill.) at a daily dosage of 150 mL/kg body weight arterial), and determination of serum concentrations of
until a bland diet could be reintroduced. 101 Commercial electrolytes and glucose, acid-base status, platelets, and
solutions such as Pedialyte are readily available but usually coagulation status.
contain too much glucose and too little sodium and carry
some risk of hypertonic diarrhea. 101 A more physiologic PROTEIN-LOSING ENTEROPATHY
solution recommended by the World Health Organiza- Hypoproteinemia characterized by a decrease in both
tion contains 90 mEq/L sodium, 20 mEq/L potassium, albumin and globulin often is associated with gastrointes-
80 mEq/L chloride, 30 mEq/L bicarbonate, and tinal disease or blood loss. When total protein or albumin
111 mmol/L glucose. Such a solution can be prepared concentrations decrease to less than 4.0 g/dL or
by adding 3.5 g NaCl, 2.5 g NaHCO 3 , 1.5 g KCl, and 1.5 g/dL, respectively, some type of natural or synthetic
20 g glucose to 1 L of water. 101 colloid replacement can be instituted to prevent intersti-
tial fluid accumulation and pulmonary edema. 126 Benefit
Nutritional Support from colloid administration is often short lived because
Accumulating evidence suggests that providing enteral colloids are rapidly lost into the gut. The short duration
nutrition, rather than nothing by mouth, is beneficial of effect and the expense of colloids have resulted in the
to patients with gastroenteritis or pancreatitis. In one use of colloids for brief support, whereas long-term treat-
study, dogs with parvovirus infection experienced ment is focused on the underlying cause of the protein
increased weight gain, shorter hospital stay, decreased loss. As described previously, ionized hypocalcemia and
morbidity, and a trend toward decreased intestinal hypomagnesemia have been described in Yorkshire
permeability (a risk factor for bacterial translocation terriers with protein-losing enteropathy and may require
and endotoxic shock) when fed through nasoesophageal treatment in some cases. 59 Severe hypomagnesemia
tubes despite the presence of vomiting and diarrhea as (0.8 mg/dL; normal range, 1.6 to 2.3 mg/dL), hypocal-
compared with dogs in which feeding was delayed until cemia, and protein-losing enteropathy also have been
diarrhea and vomiting had subsided. 79 Studies in dogs reported in a 5-year-old castrated male shih tzu examined
with experimentally induced acute pancreatitis have because of anorexia, lethargy, paresis, and abdominal
shown no detrimental effects of enteral feeding, and bet- distention caused by lymphangiectasia and intestinal
ter intestinal morphology and barrier function with inflammation. Treatment included administration of
enteral as compared with parenteral nutrition. 95–97,136 magnesium (0.8 mEq/kg) in a balanced electrolyte solu-
Enteral nutrition is essential to maintain healthy tion and resulted in normalization of serum magnesium
enterocytes, which decreases the likelihood of bacterial concentration to 1.7 mg/dL, as well as resolution of