Monitoring and Management of Enteral Feedings

Introduction

III. Monitoring and Management of Enteral Feedings

A. Assessment of GI tolerance

1. Abdominal discomfort. Subjective signs of tube-feeding intolerance include feelings of abdominal fullness, cramping, and pain.

Possible etiologies of GI discomfort that result from the provi-

S E C T I O N I Fundamentals of Nutrition Support Practice and Management

sion of tube feedings include rapid administration of feeding, hyperosmolar solutions, medications, excess air in the stomach or intestines, tube migration from stomach to small intestine, infection, cold formula, bacterial contamination, and fat or lactose intolerance.¹¹

a) If GI symptoms are attributable to hyperosmolar solutions, decrease the concentration of the formula and consider adding glucose polymers or fat to increase calories as needed.

b) If GI symptoms are thought to be caused by medications that are administered through the feeding tube, determine whether it is feasible to dilute the medication, change the form of the medication (ie, change to parenteral), or change to a different medication.

c) If GI symptoms are due to fat intolerance, consider using a formula that contains a higher proportion of fat from medium- chain triglycerides.

d) Intolerance can also be attributed to delayed gastric emptying, motility disorders of the small and large intestine, intestinal spasms or ischemia, and fiber-containing formulas.

2. Nausea and vomiting. Nausea and vomiting may be caused by gastric irritation or atony, rapid administration of the tube-feeding formula, medications, feeding tube migration from the intestine to the stomach, distal obstruction, anxiety, and other disease states. Nau- sea and vomiting may also indicate feeding tube migration, such as a balloon gastrostomy causing a gastric outlet obstruction.

3. Abdominal distension. Abdominal circumference can be measured daily at the level of the iliac crest to monitor changes in abdominal distension. Holding enteral feedings may be indicated if the circumference exceeds the baseline measurement by 8 to 10 centimeters.

4. Bowel sounds. The absence or presence of bowel sounds is not always a good indicator of bowel function. Fluid and air must be present in the GI tract for bowel sounds to be heard. For example, in patients with nasogastric tubes for decompression and suction, bowel sounds may not be heard despite good bowel function.

Conversely, “bowel sounds” may be heard if the suction is not turned off prior to auscultation.

5. Stool pattern. Stool volume, frequency, consistency, and color should be noted for any patient receiving enteral tube feedings.

The patient’s baseline or normal bowel pattern should be noted and used as a basis for comparison.

a) Diarrhea. Strategies to prevent and manage diarrhea include avoiding the provision of antibiotics or medications that cause diarrhea whenever medically feasible, decreasing the osmolal- ity of hypertonic formulas, decreasing the tube-feeding infusion rate, altering the fat source and content when indicated, and increasing fluid replacement.

b) Constipation. Possible dietary causes of constipation include inadequate fiber intake, inadequate fluid intake, or medications that slow peristalsis. Strategies to prevent or manage constipation include using fiber-containing formulas, monitoring that free water intake is adequate, supplementing with prune juice, and identifying medications that may be causing constipation (eg, narcotics) and finding appropriate substitutions when possible.¹¹

B. Aspiration precautions

1. Tube-feeding residuals. Gastric residuals are frequently used to monitor the safety and gastric emptying of tube feedings. When gastric emptying is delayed or gastric secretion is excessive, fluid accumulates in the stomach and may result in vomiting, aspiration, abdominal distention, or cramping. To prevent these poten-

tial complications, the volume of fluid remaining in the stomach during feeding (the residual volume) is measured to monitor the safety of advancing or continuing enteral feeds.^24,25 Gastric motility is affected by disease, mechanical obstruction, and certain medications.²⁶

One episode of high residual volume should not automatically prompt cessation of feedings in the absence of physical exami- nation or radiographic abnormalities; rather, signs and symptoms of intolerance should be monitored carefully.^24–27Patients with frequently elevated gastric residual volumes may benefit from feeding tube placement beyond the ligament of Treitz.²⁶ a) Frequency of checking residuals. Gastric emptying of enteral

feedings can be assessed by checking residuals prior to each intermittent feed or every 4 hours with continuous feeds.¹¹ b) Method for obtaining residuals. Residuals are obtained by

aspirating through the feeding tube with a syringe and mea- suring the formula and fluid withdrawn. The aspirating syringe needs to be fairly large, generally at least 50 mL for small-bore (12F or less) feeding tubes and at least 30 mL for gastrostomy tubes. Smaller syringes exert a higher pressure per square inch and may cause the tube to collapse. If unable to aspirate, inject 3 to 5 mL of air or water into the feeding tube and reattempt.

Residuals contain formula, digestive juices, and electrolytes and therefore should be reinstilled through the feeding tube (unless there is a large amount).

c) Parameters for holding feedings. Isolated episodes of high gastric residuals are not always associated with abdominal symptoms. The amount of gastric residuals obtained depends on the amount and timing of the last feeding, medications, and the location of the feeding tube tip. The patient’s activity and posi- tioning may also affect the gastric emptying rate.¹¹The residual may be clear, indicating the presence of gastric juices, or may contain partially digested formula.

(1) Adults. When a residual reaches ≥200 mL with a nasogastric tube or ≥100 mL with a gastrostomy tube, associated signs or symptoms of intolerance should be assessed.²⁵ (2) Infants and children. Slowing or stopping feedings in infants and children has been recommended if residual volume exceeds twice the hourly infusion volume during continuous feedings or exceeds 50% of the infusion volume during bolus feedings.²⁸

d) It is believed that aspiration from a gastrostomy tube is less likely to yield gastric residuals because of the tube’s posi- tioning in the anterior portion of the stomach, compared with a nasogastric tube. Therefore, high residuals from a gastrostomy tube are more worrisome. If abdominal discomfort or distension is present, feedings should be held. Further workup with roentgenograms may be indicated. If the abdominal exam is benign, feedings should be delayed for at least 1 hour and residuals rechecked. If high residuals persist without associated clinical signs and symptoms, a promotility agent (eg, erythromycin, metoclopramide) may be tried. Another option is to insert a transpyloric feeding tube and perform gastric decompression as necessary. Residuals cannot always be aspirated from jejunal or duodenal tubes.¹¹Intolerance of small-bowel feedings can be identified when a patient expe- riences abdominal distention, discomfort, and/or diarrhea.

If a patient develops feeding intolerance with small-bowel feedings, the previously tolerated formula strength or volume should be reinstituted and feeds gradually advanced as tolerated.⁹

S E C T I O N I Fundamentals of Nutrition Support Practice and Management

2. Head-of-bed elevation. The effect of head elevation in patients fed through small-bore tubes or enterostomies has not been determined; however, the semirecumbent position (≥30°elevation) has been recommended for all tube-fed patients to minimize the potentially life-threatening consequences of aspiration.^29,30Aspi- ration of pharyngeal and gastric secretions can still occur in some patients (even those not fed), and large-bore tubes may disrupt the function of the lower esophageal sphincter (LES), increasing the risk of aspiration.

C. Aspiration detection

1. Clinical signs and symptoms. When a significant amount of enteral formula is aspirated, sudden onset of dyspnea, tachypnea, wheez- ing, rales, tachycardia, cyanosis, decreased oxygenation, anxiety, and agitation can occur. Smaller amounts of formula may be aspirated over time with no apparent clinical symptoms. A subsequent fever can signal the development of aspiration pneumonia.

2. Roentgenogram findings are nonspecific and lack sensitivity for the detection of aspiration. There are many causes of pulmonary infiltrates, including pneumonia, contusion, atelectasis, and hemorrhage. The appearance of new infiltrates in dependent lung fields in a patient lacking other causes of infiltrates suggests aspiration.

3. Use of coloring agents. Blue dye has been used to tint tube-feeding formulas as a method for determining the presence of formula in tracheal aspirates. It was thought that this method would help detect pulmonary aspiration in tube-fed patients. The sensitivity, specificity, and safety of this method have not been adequately evaluated. The percentage of patients who will develop clinically significant aspiration whether or not coloring is detected has not been determined. Most important, a Food and Drug Administration Public Health Advisory issued September 29, 2003, reported blue discoloration and death in patients receiving tube feedings containing FD&C Blue No. 1 dye.³¹Blue discoloration of the skin, urine, feces, and serum has been reported in patients receiving this dye in their tube feedings, and in some the dye has been associated with refractory hypotension, metabolic acidosis, and death. Case reports reveal that critically ill patients, especially those who have increased intestinal perme- ability, are at risk for these complications. Based on these reports, patients with sepsis, severe burns, trauma, shock, surgi- cal interventions, renal failure, celiac sprue, and inflammatory bowel disease may be at risk for systemic toxicity of blue dye absorption from enteral tube feedings. Other disadvantages of this method include the false elevation of gastric pH, positive Hemoccult stool tests, formula manipulation, and the potential to induce an allergic response. Blue food colorings or methylene blue may still be used when checking for fistulas (ie, tracheal- esophageal fistula) in hemodynamically stable patients, if provided in unit-of-use containers (ie, an ampule of methylene blue) to minimize contamination risk.

4. Tracheal glucose measurements. It has been reported that aspiration of tube-feeding formulas may be determined by a positive- glucose result in the tracheal aspirate,³²but the sensitivity and specificity of this method have not been adequately tested. High tracheal concentrations of glucose have been found in intubated patients, both fed and not fed, and often are not associated with clinical evidence of aspiration. High tracheal concentrations of glucose also may be found in diabetic patients with high serum concentrations of glucose.³³

D. Hydration status

1. Assessing hydration status

a) Physical assessment. Possible clinical signs and symptoms of overhydration include edema, high urine output, dilute urine specific gravity, hypertension, respiratory insufficiency, con- gestive heart failure, and rapid weight gain. Possible signs of dehydration include decreased urine output or number of wet diapers in infants; concentrated, strong-smelling urine;

elevated urine specific gravity; dry lips and mucous mem- branes; poor skin turgor; sunken eyes (and fontanelle in infants);

flat neck veins; lethargy; hypotension; tachycardia; elevated blood urea nitrogen (BUN) level; constipation; and rapid weight loss.³⁴

b) Intake and output. In the euvolemic patient, fluid intake should approximately equal output. Fluid can be provided orally, with enteral feedings, or intravenously. Fluid output occurs prima- rily through the kidneys and, to a lesser extent, through the skin and lungs and in the feces. Insensible fluid loss in afebrile adult patients with intact skin approximates 10 mL/kg/day.

Approximately 40 mL/100 kcal per 24 hours replaces insensible losses in pediatric patients.³⁵Fluid needs increase with warmer weather, diarrhea, fever, vomiting, high nasogastric drainage, excessive diaphoresis, polyuria, open wounds, fistula/

ostomy losses, and thermal injuries. These losses should be appropriately replaced with fluid and electrolytes. For each degree of body temperature above 38°C, insensible fluid loss is increased by 5 mL/kg per 24 hours. Diarrhea output should be monitored and replaced milliliter for milliliter.^35,36In addition, liters of fluid can leak from the vascular compartment into the interstitial spaces in patients with vasodilatation or low serum oncotic pressure. In these conditions, fluid intake needs to be increased to compensate for the losses or fluid shifts and to maintain adequate intravascular volume. The clinician should also account for any factors or conditions that may result in fluid retention and could necessitate fluid restriction. Fluid restriction may be indicated in certain disease states, such as cardiac, liver, pulmonary, and renal dysfunction. Electrolyte disturbances and medications can also alter fluid needs.

c) Weight changes. Fluid changes can be determined by daily changes in body weight. One kilogram of weight change is equivalent to 1 L of fluid.

2. Determining fluid requirements. Calculate water needs.

a) Adults. There are several ways to calculate normal free water requirements for enterally fed, afebrile adults.³⁷Either of the following methods is intended to replace urine and insensible fluid losses: provide 1 mL of water per calorie fed, or provide 30 to 35 mL of water per kilogram of body weight per day.

b) Children. See Chapter 2 on nutrient requirements.

3. Providing extra fluids. Fluids can be given orally, intravenously, with medications, with the enteral tube feeding, and as tube- feeding flushes. Additional water requirements can be provided as tube flushes or intravenously. Calculate how much extra fluid a patient needs as follows:

a) Determine how much fluid is being taken in orally and assess the patient’s ability to consistently ingest that amount.

b) Determine the volume of fluids being given intravenously.

c) Determine the water content of the tube-feeding product being delivered. Most infant and pediatric enteral formulas contain approximately 85% to 90% free water (850 to 900 mL per L of formula), while most adult formulas contain 80% to 85% water (800 to 850 mL per L of formula). Calorically dense or concentrated formulas may contain as little as 60% water (600 mL per L of formula).³⁸

S E C T I O N I Fundamentals of Nutrition Support Practice and Management

d) Determine the amount of water being provided with flushes and medications that are being administered via the feeding tube.

e) Subtract the patient’s fluid intake (total of steps a–d) from the daily amount required and provide the remainder throughout the day as water flushes via the enteral feeding tube. Note that if IV fluids are discontinued, water intake by the feeding tube may need to be increased.

f ) Assess the patient’s body weight, presence of edema, BUN, serum sodium, adequacy of intravascular volume, and urine output.

E. Assessment of nutrient intake

1. Assess actual nutrient intake. Calculate the macronutrients and energy being provided from the patient’s oral intake, tube feedings, and dextrose-containing IV fluids. Often patients do not receive their full enteral nutrition prescriptions for various reasons, such as the scheduled administration of medications, tests or proce- dures, or daily therapies.

2. It is important for ongoing assessment of actual intake to determine whether changes in the nutrition support regimen are indicated to provide the daily prescribed volume of formulation more accurately and consistently.

F. Oral stimulation for children

1. Infants and young children who have received exclusive enteral tube feedings or PN for extended periods may experience difficulties when oral foods are introduced.³⁹Early and frequent oral stimulation is necessary in such patients to minimize the potential for developing oral feeding difficulties and aversions.

2. Solid food feedings should be used particularly in infants in the first year of life at developmentally appropriate ages. Even though the nutrients may not be bioavailable, if these behaviors are not initiated and learned at this time, problems such as aversive behaviors toward eating are likely to manifest when the child is physi- ologically able to eat by mouth.⁴⁰

3. If oral intake of fluids or solids is not medically feasible, non- nutritive sucking (sucking on a pacifier while being tube-fed) should be encouraged in infants.

G. Body weight

1. Ideal conditions. If possible, patients should be weighed in the morning—before eating, drinking, or the infusion of the tube- feeding formula but after voiding—using the same scale, and with minimal clothing.

2. Frequency. Patients should be weighed once or twice per week.

More frequent measurements are useful in critically ill patients, in patients whose fluid status is unstable, or in infants and growing children.

H. Biochemical and hematological indices. The use of laboratory values as monitoring parameters during enteral nutrition support is individ- ualized, and the frequency depends on the severity of the underlying medical condition, degree of malnutrition, level of metabolic stress, and presence of nutrient and electrolyte deficiencies.⁴¹Typically, laboratory monitoring is indicated less frequently in patients receiving enteral nutrition than PN because of the ability of the GI tract to reg- ulate the absorption of electrolytes and minerals. However, baseline metabolic and nutrition assessment parameters should be obtained (see Chapter 1).⁴²Follow-up laboratory work is then obtained based on the patient’s clinical status.

I. Maintaining feeding tube patency 1. Method to irrigate the tube

a) Adults. To keep tubes patent, feeding ports should be flushed with warm water (at least 20–30 mL for adults) every 4 hours for continuous feedings as well as before and after each inter-

mittent feeding or medication.⁴³Medications should be administered separately, and 5 to 10 mL of water should be provided between each one. Gastric acids coagulate most intact protein formulations, so it is recommended that a feeding tube be flushed with 30 mL of warm tap water before and after checking for feeding residuals.⁴⁴It is important to subtract the amount of water flushed from the obtained residual volume.

b) Children. Most pediatric tubes are not routinely flushed with water to prevent clogging unless recurrent problems occur. It is important to consider the size of the child when providing flushes. Infants’ feeding tubes should be flushed with only 3 to 5 mL of water before and after medication administration, because they may not tolerate large amounts of calorie-free fluid. Older toddlers are also provided small volumes of flushes following medication administration in an effort to prevent fluid excess.²²

2. Choice of irrigant. No irrigant has been shown to be more effective than water in preventing tube clogging. Water and carbon- ated beverages were shown to be equally effective in preventing tube clogging, and both were superior to cranberry juice. The lower pH of cranberry juice can cause clogging by precipitating certain proteins.⁴⁵

J. The underlying medical condition(s) should be reassessed on an ongoing basis to evaluate the feasibility of transitional feeding and initiating or increasing oral intake.

IV. Complications and Management of

Dalam dokumen The A.S.P.E.N. Nutrition Support Practice Manual, 2nd Edition (Halaman 98-101)