Tube feeding in the elderly

The technique, complications, and outcome

T. S. Dharmarajan, MD; D. Unnikrishnan, MD

VOL 115 / NO 2 / FEBRUARY 2004 / POSTGRADUATE MEDICINE

CME learning objectives

• To understand the role of nasogastric and gastrostomy tubes in enteral feeding
• To become familiar with the decision-making process about percutaneous endoscopic gastrostomy
• To learn the prescription, outcomes, and possible complications of tube feeding

The authors disclose no financial interests in this article. Erythromycin is mentioned for an unlabeled use.

Preview: The aging of the US population has meant that more people than ever have physical limitations or dementia that curtails their ability to eat independently. As a result, tube feeding is increasingly used to deliver nutrition. In this article, the authors review the indications, clinical aspects, and possible complications of tube feeding. Long-term outcome and ethical aspects also are discussed. Dharmarajan TS, Unnikrishnan D. Tube feeding in the elderly: the technique, complications, and outcome. Postgrad Med 2004;115(2):51-61

Persons older than 65 years make up 13% of the US population (1). Common characteristics of this age-group include frailty and comorbidity, particularly dementia, which in its advanced stages often leads to the inability to eat independently (2). Dysphagia precludes oral intake in many others. Up to 15% of the elderly in the community and up to 60% of older adults in hospitals and long-term care facilities are malnourished and require supplemental nutrition (1,3).

Malnutrition is associated with altered immune function, delayed wound healing, susceptibility to infection, reduced quality of life, increased caregiver burden, and mortality (3-6). Weight loss may occur even in the absence of a significant cause, a phenomenon associated with anorexia of aging. Deglutition may be impaired in persons with neurodegenerative or cerebrovascular disease (1).

The ability to feed usually is the last activity of daily living to be lost. When persons are no longer able to independently maintain an acceptable caloric or fluid intake, enteral supplementation becomes a consideration. As long as the gastrointestinal tract is functional, the enteral route is preferred to the parenteral route and is accomplished through the use of a feeding tube (7-9). Enteric feeding resembles normal nutrient delivery and maintains villous structure and mucosal immune function (10). The new soft, pliable, and non-irritating tubes have minimized the contraindications to tube feeding.

The decision to tube-feed

All patients who are being considered for tube feeding should undergo a nutritional assessment (5,8). The assessment involves measuring biologic parameters such as total protein, serum albumin, prealbumin, transferrin, and cholesterol; obtaining a total lymphocyte count; performing anthropometrics (eg, serial weight, body mass index, skinfold thickness); and evaluating immune function through anergy testing (1,4,11).

The presence of dysphagia warrants evaluation for reversible causes, gastrointestinal malignancy, thyroid disease, and problems with dentition (3,4,11). Other issues to consider are the presence of depression and an inability to afford food (1). A speech and swallow assessment and a modified barium swallow test or videofluoroscopy help evaluate dysphagia (6,8). Removal of dietary restrictions, review of medications, recognition of patient preferences, and optimization of the patient's environment may improve food intake (2,8,10,11) (table 1).

The decision to initiate tube feeding is made by the healthcare provider after a detailed discussion with the patient or surrogate (in the case of a cognitively impaired patient). A discussion with a multidisciplinary healthcare team about the risks and benefits of tube feeding also is recommended (2,6,12).

Laws about tube feeding and the use of "do not resuscitate" orders differ from state to state (13). Although the concept of tube feeding and its outcomes are controversial, it remains a convenient, effective, inexpensive, and practical means of providing enteral nutrition in some patients. Patients and families should be provided with a realistic picture of the probable long-term outcome of patients who are tube-fed, without providing undue expectations of favorable outcomes (4,12,14).

Choice of feeding tube

Feeding tubes are classified as nasogastric, nasojejunal, gastrostomy (ie, percutaneous, surgical, or radiologic), or jejunostomy (ie, percutaneous or surgical). Nasogastric and percutaneous endoscopic gastrostomy tubes are the most commonly used (3,4,9,14,15).

Ideally, nasogastric tubes are used for short-term gastric access in patients who are expected to recover (eg, patients with stroke, delirium) (5). Nasogastric feeding should not exceed 3 or 4 weeks because of risk of mucosal injury and esophageal stricture (9). Gastrostomy and jejunostomy tubes are used for long-term enteral nutrition (14). In elderly persons, percutaneous endoscopic gastrostomy offers the advantages of not requiring surgical intervention or general anesthesia, a shorter procedure time, and lower morbidity, mortality, and cost (9). Recently, feeding tubes have also been placed using radiologic guidance (5,14). A comparison of nasogastric, percutaneous endoscopic gastrostomy, and jejunostomy tubes is offered in table 2. Nasojejunal tubes, although seldom used, may have a role in situations associated with delayed stomach emptying and gastric reflux.

Nasogastric tubes
These tubes can be inserted easily at the bedside (8,10). In a ventilator-dependent patient, an orogastric approach is used (15). The tube is lubricated, advanced to a predetermined distance (usually 40 to 45 cm) without the use of force, and securely taped to the patient's nose (15). The position of the tube must be confirmed radiologically before initiating feeding; aspiration of gastric contents or air insufflations can be used to make preliminary checks of the position, but they are not diagnostic (8,15).

Complications of nasogastric tube placement include mucosal erosions, esophageal perforation, pleural effusions, and bronchopleural fistulas (10,14). However, these complications are rare with the use of flexible polyurethane or silicone tubes. Tracheal placement of the tube is common in patients with an impaired gag reflex (15).

Gastrostomy tubes
These tubes are the mainstay of long-term enteral feeding (14). Percutaneous endoscopic gastrostomy is the most common technique; about 125,000 procedures are performed annually (16). Complications may be short-term (ie, confined to the tube insertion site) or long-term (ie, pulmonary, metabolic, gastrointestinal, or mechanical) (8,9). The incidence of aspiration events in patients who undergo percutaneous endoscopic gastrostomy is similar to that of patients who have a nasogastric tube.

Jejunostomy tubes
These tubes are used in patients who do not have a stomach and in those in whom recurrent aspiration appears to be a problem--although data do not substantiate a decline in aspiration events with the use of a jejunostomy tube (2,5,9,17). These tubes have a smaller diameter than the other tubes and can clog; jejunostomy feeding can cause diarrhea (3,7-10).

The tube feeding prescription

The main nutrients in all enteral tube feeding formulas are carbohydrates, proteins, and fats; water, electrolytes, and micronutrients compose the remainder. The type and amount of formula should be designed to meet individual needs (8). In general, most patients require a daily caloric intake of 25 to 30 kcal/kg of ideal body weight, a protein intake of 1.2 to 1.5 g/kg per day, a carbohydrate-fat ratio of 60:40, and a daily fluid intake of 30 to 35 mL/kg (4,7,8,15). Requirements are higher in patients with a catabolic state (11).

Formulas
A variety of formulas from several manufacturers are available; they differ in osmolarity, calories per milliliter, and amount of carbohydrate, protein, fat, and fiber (7,8,10). Standard formulas have 1 cal/mL and an osmolarity of 270 to 375 mOsm/L and are 50% to 55% carbohydrate, 15% to 20% protein, and 30% fat (7).

Products are tailored to meet the needs of patients in certain situations. Examples include high fat-low carbohydrate formulas that generate less carbon dioxide and therefore are useful in patients with respiratory failure, low-carbohydrate products for patients with diabetes, and low protein-high carbohydrate preparations with appropriate electrolytes for predialysis patients (table 3). Formulas with fiber are useful in gastrointestinal motility disorders (7). Immune system-enhancing formulas that contain arginine, glutamine, or omega-3 fatty acids are designed for critically ill persons. Products rich in branched-chain amino acids are designed for hepatic encephalopathy (3,7).

Rate, concentration, and technique
Tube feeding is given as a bolus or a continuous infusion. Bolus feedings are used for ambulatory patients and, at times, for caregiver convenience (8). For continuous feeding, the infusion is generally started at a low rate (20 mL/hr) and increased by 20 to 40 mL/hr over 8 to 24 hours to meet nutritional needs (5,7,15). Feedings can be run overnight to supplement partial oral daytime intake.

Isotonic formulas are usually tolerated when started at full strength; hypertonic and elemental formulas are best initiated at half strength (mixed with water in equal proportion) and changed to full strength 24 hours later (3).

The patient's head should be elevated 30° to 45° during feeding and for a half hour to an hour after bolus feeding (8). Gastric residuals should be checked periodically to detect stasis and assess risk of aspiration. For continuous feeding, gastric residuals are monitored while the infusion is in progress; for bolus feeding, residuals should be checked 1 hour after feeding has ended. In general, a residual of less than 150 mL, or less than twice the rate of continuous feeding, is acceptable (5,8,15). Residual checks are recommended every few hours in patients receiving continuous feeding, at least initially, and before increasing the rate of feeding (8,15).

Supplements
Regular feedings may be supplemented with water, protein, fat, or vitamins and trace minerals.

Water: Most formulas contain 70% to 85% water; isotonic formulations contain the most water (8). A typical water requirement is 2 to 2.5 L in 24 hours to maintain a daily urine output of 1.2 to 1.5 L based on volume status. Fluid loss may be insensible (10 mL/kg per 24 hours), febrile (65 to 100 mL per 1°F rise in temperature), or through urine, diarrhea, or vomiting (18).

Additional water is needed in patients who receive high protein-high calorie supplements and in those who have altered cognition, febrile losses, or altered renal concentrating ability--all common situations in elderly persons (3,4,11). Humidified systems minimize ventilator losses. Specialized nutrition pumps are programmable to deliver water and have adjustable volume and flush intervals. Quantification of deficits of water and electrolytes can help guide the correction of hypernatremia and hyponatremia.

Protein and fat: Protein (eg, Casec, ProMod) or fat (eg, Lipisorb, MCT) products or products containing extra calories from carbohydrates (eg, Polycose) may be given as needed. Medium-chain triglycerides are easily absorbed in patients with a malabsorption state (9).

Vitamins and trace minerals: Most formulas are fortified with key vitamins and trace elements. Recommended dietary allowances are usually met when 1.5 to 2 L of the formula are administered in 24 hours (10).

Medications
Elderly persons receiving tube feeding are often given numerous medications that have to be crushed and mixed in solvents before being administered, thus altering their bioavailability. Drug-drug and drug-nutrient interactions may be a consideration (eg, dietary proteins impair absorption of levodopa and carbidopa [Sinemet]) (19). Further, crushing can alter the characteristic release properties of long-acting preparations. Feeding tubes should be flushed with at least 30 to 60 mL of water after administration of medications, to prevent clogging (5,8-10,19).

Complications

Patients who are tube-fed need to be monitored for mechanical, local, gastrointestinal, metabolic, and fluid-electrolyte complications and aspiration pneumonia.

Mechanical and local complications
Blockage of tubes, particularly soft, small-bore tubes, is a common occurrence that alters feeding time and impedes administration of medications. Tubes get clogged more often with bolus feeding and with use of medications or hypertonic or high-fiber formulas (4,8). Blockage can be minimized with regular water flushes during continuous feedings or before and after bolus feedings.

Leakage can occur at tube insertion sites, which should be inspected often for evidence of infection. Nasogastric tubes are uncomfortable and may be dislodged by cognitively impaired patients, leading to injury and increased use of physical and chemical restraints by healthcare staff (10). Percutaneous endoscopic gastrostomy tubes can be reinserted if the dislodgement is discovered soon after it occurs and if the tube has been in place for longer than 2 weeks; the tube position should always be verified radiologically (3,8).

Gastrointestinal complications
Complications such as nausea, vomiting, abdominal distention, cramps, and diarrhea are common with tube feeding (8,10). Cramping and bloating may be associated with hyperosmolar formulas, high-fat formulas, rapid administration, bacterial contamination, or the presence of lactose intolerance. Concomitant drug administration also may have a role. Administration of diluted feedings or decreasing the rate of infusion may provide relief (10). Available formulas are usually lactose-free, thus eliminating the problem of lactose intolerance (7).

Good personal hygiene in handling tube feeding equipment, bags, and formula can decrease bacterial contamination (8,10). Bags and tubing should be changed daily; aesthetically displeasing bags and those that have passed their hang periods should be discarded (8).

Diarrhea is usually unrelated to feedings, even when hypertonic formulas are used (8,15). The most likely causes include infectious etiologic factors and medications (especially ingredients in elixirs, such as sorbitol) (5,7,9). Diarrhea by itself is not an indication to stop tube feedings; slowing the rate of infusion, diluting the formula, adding bulking agents, or reviewing the drug regimen may provide relief (5,10,15). Stool examination and an assay for detection of the Clostridium difficile toxin is appropriate when Clostridium colitis is suspected (7-9,15). On the other hand, constipation may be a problem in bed-bound patients; fiber-containing formulas (eg, Jevity, Ultracal), blenderized preparations, or laxatives can minimize this complication (7).

If residuals are persistently increased, evaluation to rule out mechanical obstruction or ileus should be undertaken. Gastric emptying may be delayed as a result of the use of hypertonic or hypotonic solutions, medications (eg, anticholinergics, antihistamines, antidepressants), and disease processes (eg, diabetes, vagotomy). Delayed gastric emptying may be alleviated by the use of promotility agents such as metoclopramide (Maxolon, Octamide PFS, Reglan) or erythromycin (5,15).

Aspiration pneumonia
Recurrent aspiration from impaired oropharyngeal function has been considered an indication for nonoral means of feeding. However, feeding through a gastrostomy tube or even a jejunostomy tube does not appear to prevent aspiration (2,8,17). Intermittent bolus feeding, high gastric residuals, an impaired gag reflex, dysphagia from any cause, and an altered level of consciousness are associated with an increased risk of aspiration (3,7,10). Tube migration should be ruled out as a cause of recurrent aspiration.

Measures to minimize aspiration include head elevation after eating, adjustment of rates to keep gastric residuals in an acceptable range, and use of slow, continuous feeding rather than bolus infusions when possible (4,8-10). Thus, feeding method and rate need to be individualized.

Metabolic, fluid, and electrolyte parameters
Patients with diabetes need to be monitored for glucose control. Electrolyte and other metabolic derangements may occur and may be related to formula content or concentration or to intercurrent illness (4,7). Periodic monitoring of glucose and electrolyte levels is recommended. Overhydration or loss of salt and water due to diarrhea can result in hyponatremia; inadequate free water administration can cause hypernatremia (8). Potassium, phosphorus, and magnesium levels can be affected by disease and medications, particularly diuretics and laxatives, and may not necessarily be related to feeding.

Outcome and ethical aspects

Most data do not suggest a favorable long-term outcome in elderly tube-fed patients with dementia, generating much controversy (2,8,17-21). In a study of 7,369 patients (22), mean survival after percutaneous endoscopic gastrostomy placement was 7.5 months. In a cohort of 81,105 Medicare beneficiaries (23), the 30-day mortality rate was 23.9%, and the 1-year mortality rate was 63.0%. No significant improvement in nutritional parameters or weight was reported in most of the patients in this group (2,16,17,20).

Tube feeding has not helped prevent or heal pressure sores, nor has it dramatically decreased the incidence of aspiration pneumonia (2,17). On the contrary, aspiration remains a significant contributor to mortality in tube-fed patients. Neither has the quality of life, including patient comfort and surrogate satisfaction, improved substantially (2,16,17,23).

Often, a patient is denied the pleasures of eating from the time the tube is placed (17). In nursing homes, assessments by speech therapists, staffing patterns, and fiscal constraints appear to influence the practice of tube feeding in cognitively impaired patients (24).

Tube feeding is considered a medical intervention, not obligatory care (25). Physicians need to provide information to the patient or surrogate about the benefits, risks, and burdens associated with long-term tube feeding and not encourage undue expectations (12,13,17,21,22). Ethics committees can help physicians reach a consensus on how to proceed. Table 4 summarizes outcomes following percutaneous endoscopic gastrostomy placement in patients with dementia.

Summary

Tube feeding is an art and a science that is increasingly used in our aging society as more people become physically incapacitated or have dementia. Properly used, tube feeding can be helpful. However, patients should be monitored for tolerance and complications and assessed for a possible return to oral feeding. The joy of eating, one of the pleasures in life, should not be denied if at all possible.

References

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Dr Dharmarajan is associate professor of medicine, New York Medical College, Valhalla. He is also chief, division of geriatrics and director, Geriatric Medicine Fellowship Program, Our Lady of Mercy Medical Center, Bronx, New York. Dr Unnikrishnan is a fellow in geriatric medicine, Our Lady of Mercy Medical Center. Correspondence: T. S. Dharmarajan, MD, Division of Geriatrics, Our Lady of Mercy Medical Center, 4141 Carpenter Ave, Bronx, NY 10466.

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