CHAPTER 25—EATING AND FEEDING PROBLEMS
SWALLOWING IN HEALTH AND DISEASE
Swallowing is an important and complex task that can be affected by both normal aging and by diseases that are common in older persons. Treatment of eating and feeding problems varies, depending on the identified cause or causes and contributing factors.
Swallowing can be divided into three phases on the basis of anatomy. First is the preparatory or oral phase, which includes the complex activities of mastication and propelling the food bolus to the back of the mouth toward the pharynx. This stage is under voluntary control. The second or pharyngeal phase is involuntary and involves the initiation of the swallow reflex with propulsion of the food bolus past the laryngeal vestibule and into the esophagus. Execution of the oral and pharyngeal phases of swallowing requires the complex coordination of five cranial nerves and a large number of small muscles in the head and neck, with regulation from cortical input to the medullary swallow center, all in the appropriate sequence, usually within 1 second. The third stage of swallowing is the esophageal phase, during which food is propelled down the esophagus by the action of skeletal muscle proximally and smooth muscle distally; this phase is regulated by its own intrinsic innervation.
Normal aging is associated with several alterations in eating. With advanced age, there is a diminution of the taste sensation, but not of taste discrimination (an older person may be able to distinguish sweet from salty but may need to add more salt to food to taste it sufficiently). Further, olfactory function declines with advancing age, further impairing taste sensation. Salivary function is not clearly reduced with aging, but xerostomia is a common complaint of older persons, usually owing to the adverse effects of medication. Loss of teeth greatly reduces chewing efficiency (ie, the need to chew for a longer period of time and with more chewing strokes to achieve the same level of food maceration), which is only partly ameliorated with dental prostheses. Sarcopenia, or age-related loss of lean muscle mass, may contribute to loss in chewing efficiency and to pharyngeal muscle weakness demonstrated on videofluoroscopic deglutition examination of asymptomatic older persons. Whether aging alone contributes to esophageal dysmotility (so-called presbyesophagus) remains a subject of debate. Esophageal function is probably well preserved, except, perhaps, in very advanced age. In total, these changes with age result in a prolonged duration of each swallow. Further, many diseases that produce dysphagia are more common in older persons.
Dysphagia, or difficulty swallowing, can occur when a disease affects any level of swallowing function. Dysphagia is usually classified as oral, pharyngeal, or esophageal. Oral dysphagia occurs when there is difficulty with the voluntary transfer of food from the mouth to the pharynx. This might be diagnosed, for example, when scrambled eggs are discovered in the cheeks of a demented patient shortly before lunch. The most common cause of oral dysphagia is dementia.
In pharyngeal dysphagia, reflexive transfer of the food bolus from the pharynx to initiate the involuntary esophageal phase of swallowing while simultaneously protecting the airway from misdirection of food is difficult. The affected person may notice coughing, choking, or nasal regurgitation while eating and localize the symptoms to the throat. The most common cause of pharyngeal dysphagia is stroke, but any disease that impairs the swallowing center in the brain stem or the cranial nerves involved (eg, Parkinson’s disease, central nervous system tumor), the oropharyngeal striated muscle (eg, myasthenia gravis, amyotrophic lateral sclerosis), or the local structures involved (eg, retropharyngeal abscess, tumor) may lead to pharyngeal dysphagia. Treatment of both oral and pharyngeal dysphagia involves treatment of the underlying disorder and devising an individualized, often labor-intensive, feeding program.
Esophageal dysphagia presents with the sensation that food has gotten “stuck” after a swallow. Dysphagia for both solids and liquids suggests an esophageal motility disorder (eg, achalasia, scleroderma), whereas progressive dysphagia for solids suggests a mechanical obstruction (eg, cancer, esophageal ring, stricture from mucosal irritation). None of these diseases is unique to the geriatric population, though older persons tend to take more medications and are therefore more likely to experience medication-induced esophagitis (which manifests initially as odynophagia, followed by dysphagia). Common causes of medication-induced esophagitis in older persons are potassium, nonsteroidal anti-inflammatory agents, alendronate, and tetracycline-related antibiotics. (See also the section on dysphagia in Gastrointestinal Diseases and Disorders.)
The misdirection of pharyngeal contents into the airway is termed aspiration. Generally, there are two major sources of aspiration: oropharyngeal flora or gastric contents. Despite this relatively straightforward definition, however, controversy persists over the definition of aspiration pneumonia. Aspiration pneumonia is believed to occur when bacteria arrive in the lungs from the pharynx in a large enough inoculum to overcome host defenses. Pneumococcal pneumonia arises from aspiration of this organism from a colonized oropharynx, however, and is usually not considered an aspiration pneumonia. Aspiration of gastric contents, or Mendelson’s syndrome, usually results in a chemical pneumonitis, and the usefulness of antibiotics in this situation is questionable. Most often, local host defense mechanisms clear the lung of the offending aspirate, without serious clinical impact. It is well established that many healthy individuals episodically aspirate without any important clinical consequences.
Neither aspiration of contaminated oral contents nor of gastric contents is prevented by placement of a feeding tube. Tube feeding is universally cited as a risk factor for major aspiration, and some patients who have never previously aspirated begin to do so after placement of a feeding tube. A 1996 review found no evidence that tube feeding of any sort would reduce the risk of aspiration pneumonia. A common misconception is that jejunostomy tube feeding has lower rates of associated aspiration of gastric contents than gastrostomy does; however, there is no evidence to support this misconception. A single nonrandomized prospective comparison of hand with tube feeding in patients with oropharyngeal aspiration found that hand feeding (personal assistance with oral intake) results in lower rates of pneumonia. No prospective randomized trials comparing hand with tube feeding to reduce aspiration have been published. An active area of clinical research is focused on the role of substance P in swallowing and aspiration and the potential benefit of angiotensin-converting enzyme inhibitors (which prevent the breakdown of substance P) in patients who aspirate, but to date this research is inconclusive.
Several tools may be used to assess swallowing function when oropharyngeal dysphagia is clinically suspected. The most common are the full bedside evaluation, of which there are many variations, and the videofluoroscopic deglutition examination (VDE), a variant of the modified barium swallow. There is considerable controversy regarding the relative efficacy of these tools.
VDE is usually performed by a speech-language pathologist who videotapes the patient swallowing several consistencies of barium-impregnated foods while the patient maintains various head positions. This may permit identification of the food consistency or compensatory mechanisms that minimize fluoroscopic evidence of aspiration. Depending on the results of the VDE, the therapist may recommend swallow therapy or diet modifications, or both. Swallow therapy may be compensatory (eg, turn head toward weaker side while swallowing), indirect (eg, exercises to improve the strength of the involved muscles), or direct (ie, exercises to perform while swallowing, such as swallowing multiple times per bolus). Dietary recommendations generally consist of altering bolus size or consistency of food or of restricting foods of certain consistencies.
Data conflict regarding the usefulness of VDE and subsequent treatment recommendations and derive from small, historically controlled studies rather than larger prospective randomized trials. A systematic review of studies of dysphagia secondary to stroke published by the Agency for Health Care Policy and Research (now the Agency for Healthcare Research and Quality) concluded that evidence was insufficient to recommend one type of swallowing study over another and that data correlating specific findings from any type of examination with clinically meaningful outcomes are lacking.
When an older person experiences difficulty eating, the two main therapeutic approaches are careful feeding by hand or tube. The first requires extraordinary patience and is labor intensive; the latter is an invasive intervention associated with its own risks. Data about either approach are limited, and randomized comparisons have not been done. The role of dietary supplements, if any, in augmenting the caloric intake of hand-fed persons has not been clearly defined. One systematic review suggested a mortality benefit to the use of oral protein and energy supplements in acutely hospitalized or community-dwelling persons older than age 65 years, though the quality of the studies reviewed was not optimal. Functional status does not appear to be improved with oral nutritional supplements in any of the studies evaluating this outcome. (See Table 25.1 for details about the composition of specific feeding solutions.)
The number of percutaneous endoscopic gastrostomy (PEG) feeding tubes placed in patients aged 65 years and older has grown at an astonishing rate over the past decade. Low procedure-related complication rates are often cited; however, long-term studies reveal substantial mortality among tube-fed patients. Despite the popularity of feeding tubes, a review of the literature from 1966 to 1999 found no studies demonstrating improved survival, reduced incidence of pneumonia or other infections, improved symptoms or function, or reduced pressure ulcers with the use of feeding tubes of any type in demented persons who have eating difficulties. Median survival after placement of a feeding tube is well under a year, but it is unknown whether this results from tube feeding or if the need for tube feeding is a marker that death is near.
Complications described with feeding tubes are numerous and include an increased risk of aspiration pneumonia, metabolic disturbances, diarrhea, and local cellulitis. Monitoring for these complications should be meticulous. A study employing a large administrative data set found that 1-year mortality was higher in 5266 nursing-home residents with chewing or swallowing difficulties who were fed with a tube than in those who were not, even when statistically accounting for potential confounding variables. A second study by the same authors of 1386 nursing-home residents with recent progression to severe cognitive impairment found no improvement in 2-year survival in the group who were tube fed, again adjusting for potential confounders. No prospective randomized studies comparing tube and hand feeding have been published, and information on quality-of-life outcomes is sorely needed.
Placement of a PEG or jejunostomy bypasses the oropharynx and the esophagus and allows nutrients and medications to be instilled directly into the stomach or the jejunum and be absorbed by a functioning gut. There is little evidence to support the use of feeding tubes in most debilitating chronic diseases, and in particular the wealth of data demonstrate that their use has no clinical benefit in patients with oropharyngeal dysphagia from dementia. It is clear that neither gastrostomy nor jejunostomy feeding tubes reduce aspiration in comparison with a program of hand feeding, but no randomized trials comparing these interventions have been published. The only disease for which feeding tubes have been shown to be of clinical benefit to the patient is esophageal obstruction, such as from malignancy. For most other disease states, their utility remains unproved.
Contraindications to gastrostomy include the inability to pass an endoscope into the stomach, uncorrectable coagulopathy, massive ascites, peritonitis, and bowel obstruction. After successful placement of a gastrostomy, tube feedings of commercially available canned nutritional supplements can be initiated either as slow gravity boluses over 30 to 60 minutes or as a continuous drip. The feeding tube should be flushed with water before and after each feeding or at least four times a day in cases of continuous feedings.
Consideration of feeding tube placement requires careful examination of the data, with a focus on whether there is evidence of clinical benefit to support this invasive and potentially burdensome approach.
Not all feeding problems, of course, are related to dysphagia, and many contributing factors are quite amenable to therapy. Other approaches to consider in older persons who demonstrate eating or feeding problems are evaluation for depression, elimination of unduly restrictive diets, consideration of individual food preferences, consideration of the environment in which the person eats to improve socialization and reduce disruptive stimuli, examination of the condition of the oral cavity, determination of the needs for personal assistance with feeding, and reduction or elimination of medications that may cause inattention, xerostomia, movement disorders, or anorexia. Small studies have documented improved clinical outcomes in nursing-home residents with the use of flavor enhancers, increased food variety, and attention to the meal ambiance.
■ Finucane TE, Christmas C, Travis K. Tube feeding in patients with advanced dementia. JAMA. 1999;282(14):1365–1370.
This is a thorough review of published studies from 1966 to March 1999 relevant to the topic. Evidence to support the purported benefits of tube feeding to prevent pneumonia or other infections, prolong survival, reduce the risk of pressure ulcers, improve function or quality of life, and provide palliation were sought. No randomized trials comparing hand feeding with tube feeding in this population were found. No data were identified that supported the use of tube feeding in patients with advanced dementia for any of these clinical indications.
■ Marik PE, Kaplan D. Aspiration pneumonia and dysphagia in the elderly. Chest. 2003;124(1):328–336.
This is a comprehensive review of the pathophysiology and evaluation of aspiration in older patients, with some suggestions for treatment. This review does encourage the use of instrumental assessment of swallowing function; however, this is not supported either by data linking the outcomes from these tests to clinical outcomes or by the consensus of experts.
■ Milne AC, Potter J, Avenell A. Protein and energy supplementation in elderly people at risk from malnutrition. Cochrane Database Syst Rev. 2002;(3):CD003288.
This is a systematic review of randomized trials, though of variable quality, that concluded that oral nutritional supplementation reduces mortality but does not impact functional status or quality of life in hospitalized or community-dwelling people over the age of 65 years.
■ Mitchell SL, Kiely DK, Lipsitz LA. Does artificial enteral nutrition prolong the survival of institutionalized elders with chewing and swallowing problems? J Gerontol A Biol Sci Med Sci. 1998;53(3):M207–M213.
A large prospective cohort of nursing-home residents with chewing or swallowing problems was studied for 1 year. Of these 5266 residents, 10.5% had a feeding tube. Of those tube-fed persons who survived 1 year, 25% were able to discontinue tube feeding. The study found that the risk of death (relative risk 1.44) was higher in residents who were tube fed than in those who were not, even after statistical adjustment for potential confounding covariables.
Colleen Christmas, MD