Encyclopedia of Gerontology and Population Aging

Living Edition
| Editors: Danan Gu, Matthew E. Dupre

Artificial Nutrition at Old Age

  • Rainer WirthEmail author
  • Dorothee Volkert
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-69892-2_117-1



Any method of nutrient delivery, not using the oral route, is defined as artificial nutrition. In general, delivery via the gastrointestinal tract, i.e., enteral nutrition (EN) and via venous blood vessels, i.e., parenteral nutrition (PN) can be differentiated. Fluids and rarely small amounts of other nutrients are sometimes delivered via the subcutaneous route, which is also classified as parenteral nutrition. The procedure of placement of an enteral or parenteral access should be differentiated from the delivery of nutrients via the respective access. Both components of artificial nutrition have different risks and complications. Artificial nutrition may be performed as a short-time (<4 weeks) or long-term intervention. The artificial delivery of nutrients may be supplemental, i.e., in addition to oral or food intake or EN, or total, i.e., without oral food intake. Occasionally, enteral and parenteral nutrition are combined, particularly in intensive care, when it is not possible to cover the demands via the enteral route.


The intake of sufficient amounts of nutrients is an important aim in geriatric medicine. Insufficient food intake for more than a few days results in protein-energy malnutrition, which is mostly defined by low body mass index, reduced muscle mass, weight loss, or reduction of food intake (Cederholm et al. 2018). Malnutrition is a geriatric syndrome which is known to increase the risk of mortality and worsen the health outcome and functional outcome of older patients. It may lead to complications, such as sarcopenia, impaired wound healing, infections, and other. Malnutrition is consequently related to decreased quality of life and increased health care costs.

Protein-energy malnutrition in older persons is mostly of multifactorial etiology. Frequent causes and contributing factors are reduced appetite as a concomitant of acute and chronic disease, dysphagia, chewing problems, dementia, depression, delirium, reduced mobility, chronic pain, gastrointestinal disease, medication side-effects, and social isolation among others. Therapeutic approaches are manifold and should generally be delivered as an individualized and comprehensive intervention (Volkert et al. 2018). Identification and treatment of the individual causes of malnutrition are of superior importance and should be considered whenever possible. Regarding direct nutritional interventions, dietetic counseling, help with meal preparation and food intake, energy- and nutrient-dense meals, food enrichment and fortification, oral nutritional supplements, and enteral and parenteral nutrition are the most important approaches to prevent and treat malnutrition. In general, oral nutritional support should be preferred, and artificial nutrition should only be used, if the aforementioned noninvasive means are not sufficient or not possible.

The effectiveness of nutrition therapy, particularly in the form of oral nutritional supplements, has been demonstrated in many randomized controlled trials (Milne et al. 2009; Cawood et al. 2012; Volkert et al. 2018). This is not true for artificial nutrition, due to methodological and ethical reasons. Regarding artificial nutrition, each method has its specific risks, advantages, and shortcomings that must be weighed against the risks of insufficient nutrition. Both the enteral and parenteral access imply an invasive procedure with specific risks, such as organ lesion, bleeding, and site infections (Table 1).
Table 1

Potential procedure-related complications of different methods of artificial nutrition

Nasogastric tube

Mispositioning of tube with airway affection

Tube dislodgement with airway affection

Pressure lesions of mucous membranes

Epistaxis or other bleeding

Aspiration pneumonia

Percutaneous endoscopic gastrostomy

Organ injury during puncture

Bleeding complications

Hypoxia during sedation

Puncture site infections


Gastric leakage

Buried bumper syndrome

Aspiration pneumonia

Central venous catheter

Organ injury during puncture

Bleeding complications

Local and bloodstream infections

Central venous thrombosis

Catheter obstruction

Port catheter

Organ injury during puncture

Bleeding complications

Local and bloodstream infections

Central venous thrombosis

Catheter obstruction

Peripheral venous catheter

Local and bloodstream infections

Central venous thrombosis

Catheter obstruction

Subcutaneous catheter

Local and bloodstream infections

Local edema

Furthermore, the delivery of nutrients via the enteral or parenteral route also imply specific risk, e.g., gastrointestinal symptoms or infections. These risks are the reason why artificial nutrition is generally classified as medical treatment that needs an individual medical indication and consent by the patient or his proxy (Druml et al. 2016).

Unfortunately, there are and will be no controlled randomized trials about artificial nutrition, because such studies would be unethical. Hence, the potential advantages and risks must be weighed individually, based on the evidence from observational trials and clinical experience.

The enteral route is generally preferred because of its more physiologic approach and markedly less costs. Artificial nutrition is indicated in case of no food intake for more than 3 days or less than 50% of requirements for more than 1 week (Volkert et al. 2018). All recommendations concerning artificial nutrition are mainly based on experts’ clinical experience and may therefore be modified and adapted to the individual situation and patient’s needs.

Depending on the individual prognosis and other circumstances, such as the individual risks of invasive procedures, the aforementioned cut-offs for starting artificial nutrition may be adjusted substantially. In addition, artificial nutrition should be considered as soon as it becomes clear that noninvasive measures are not able to compensate for nutritional deficiencies. Once the decision is drawn, artificial nutrition should be performed without delay. Guidelines recommend feeding via a nasogastric tube as a short-term access up to 4 weeks. If enteral nutrition is expected to be necessary for longer than 4 weeks, placement of a PEG-tube is recommended. A PEG-tube may be also appropriate at an early stage, if the patient is ventilated or does not want or tolerate a nasogastric tube (Volkert et al. 2018; Burgos et al. 2018). In case of parenteral nutrition, a central venous catheter should be used as a short-term access. A port catheter is the ideal approach for a long-term access, whenever a central venous access is necessary, as it is in intestinal failure. As a rule of thumb, patients should reach a total intake of 30 kcal per kg body weight per day. However, the individual requirements may vary substantially.

Key Research Findings

The complication rate of all above-mentioned approaches is reported to be low. Nevertheless, fatal consequences of nasogastric tubes and tube feeding have been observed (Yardley and Donaldson 2010), particularly if the tube position is not controlled properly, i.e., only by abdominal auscultation of inflated air (Metheny et al. 1990). The same is true for percutaneous endoscopic gastrostomy. In mixed cohorts, the procedure related mortality of a PEG insertion is reported to be well below 1% (Wollman et al. 1995; Potack and Chokhavatia 2008). It has to be noted that in most studies complications starting within the first days after tube insertion are classified as potentially procedure related. However, particularly site infections, a frequent complication of PEG (Lipp and Lusardi 2013, 2006; Schrag et al. 2007), are developing several days after PEG insertion and its consequences are therefore frequently not classified as procedure related. Using a broader definition, in an observational study in multimorbid geriatric patients, the procedure-related mortality of PEG-insertion was above 2.0% (Wirth et al. 2012). Likewise, in patients with head and neck cancer, a procedure-related mortality rate of PEG-insertion of 2.2% was observed (Grant et al. 2009).

The survival time of geriatric patients undergoing artificial nutrition is rather poor. In a meta-analysis of cohort studies by Mitchel et al., the survival rates of geriatric patients after PEG-insertion were 81% after 1 month, 56% after 6 months, and 38% after 12 months (Mitchell and Tetroe 2000). Unfortunately, up to now, no study was able to specify which portion of patients with mortality soon after PEG-insertion died due to complications of the procedure and which portion because of their seriously reduced health state. A British enquiry about death after PEG analyzed a total of 719 patients (mean age 80 years) who died within 30 days after PEG-insertion (Johnston et al. 2008). Forty-three percent of the patients in this study died within the first week after PEG insertion. Such a high early mortality rate may be due to disadvantageous selection of patients but also due to procedure-related complications.

The most frequent complication of the procedure of PEG insertion is peristomal wound infection, which occurs in about 27% of patients undergoing PEG insertion without antimicrobial prophylaxis and in 12% of those patients with antimicrobial prophylaxis (Lipp and Lusardi 2013). Meta-analyses have shown that antimicrobial prophylaxis is able to reduce peristomal infections by 64% (Lipp and Lusardi 2013), and this prophylaxis is therefore recommended in most respective guidelines.

A probably common but unrecognized complication of tube feeding is the refeeding-syndrome, particularly in patients with severe malnutrition. Unfortunately, the refeeding-syndrome is not well studied and is thus assumed to be rarely recognized and treated (Pourhassan et al. 2017; Coutaz and Gay 2014). The refeeding syndrome has to be considered in every malnourished patient in whom artificial feeding is started, because it may cause severe and fatal complications (Gariballa 2008). During starvation, the organism develops also a deficiency of electrolytes, of which phosphate, potassium, and magnesium are of special interest for the etiology of the refeeding syndrome. However, the extracellular concentration of these electrolytes is kept in balance for long time and seem to be normal, if measured via serum concentrations. After the start of refeeding, the intracellular requirements of the aforementioned electrolytes increase dramatically and due to a compensatory transcellular shift, the extracellular concentrations decrease markedly, which causes multiple and various consequences (Aubry et al. 2018; Friedli et al. 2017, 2018). The symptoms of the refeeding syndrome are mostly unspecific, e.g., fatigue, weakness, and confusion, and thus mostly overlooked (Coutaz and Gay 2014). The refeeding syndrome occurs irrespective of the route of nutrition, typically 2–5 days after start of refeeding in patients with pronounced malnutrition. The refeeding syndrome may lead to cardiac arrhythmias, cardiomyopathy, encephalopathy, muscle or other organ failure, and finally death. In geriatric patients, it mostly occurs with the clinical picture of delirium. As delirium is a common syndrome in this population, it is not recognized to be associated with nutrition and the refeeding syndrome.

Examples of Application

The question of artificial nutrition frequently arises in acute disease, when patients are not able to eat, due to loss of appetite, low vigilance, vomiting, or other gastrointestinal symptoms. In these cases, artificial nutrition should be performed if patients who eat nearly nothing for more than 3 days or less than half of their requirements for more than 1 week, in order to support the patients to overcome this crisis situation.

The indication for long-term artificial nutrition is mainly considered in three common clinical conditions of older patients: severe dementia, severe dysphagia, and severe general disease.

When the technique of percutaneous endoscopic gastrostomy (PEG) was introduced into clinical routine in about 1990, many patients with severe dementia and low food intake were treated with artificial nutrition via PEG. Since then it has always been a matter of debate if such artificial feeding is helpful for patients with advanced dementia or if it only makes feeding easier and reduces caregiver burden. A survey among US physicians published in 2003 revealed that more than half of the physicians believed that PEG in advanced dementia is standard of care (Shega et al. 2003). Interestingly, about 75% believed that PEG-tubes would reduce aspiration pneumonia and improve pressure ulcer healing and 61% thought that PEG-feeding would improve survival, all of which have never been proven (Shega et al. 2003). A certain learning curve of clinical practice and some observational trials led to fewer insertions in patients with advanced dementia over the recent years. Currently, about 5% of US nursing home residents with advanced dementia undergo a PEG-placement (Mitchell et al. 2016). A comprehensive data base analysis among nursing home residents with advanced dementia and recent feeding problems demonstrated that there is no difference in survival between residents fed orally and those fed via PEG (Teno et al. 2012). Both, clinical experience and results from observational trials have led to guideline recommendations not to perform tube feeding in patients with advanced dementia (Volkert et al. 2015). In patients with less severe stages of dementia, tube feeding may be beneficial and may be performed to overcome a crisis situation associated with other diseases (Volkert et al. 2015).

In older patients with severe oropharyngeal dysphagia, artificial nutrition is indicated to enable adequate nutritional intake and avoid the development of malnutrition (Wirth et al. 2016). In some patients, dysphagia and aspiration risk may be so severe that oral feeding is too dangerous or is far away from covering the nutritional needs. In these cases, it is important to be clear about the underlying disease and the respective prognosis.

Because dysphagia in stroke patients typically resolves after a few weeks, nasogastric tube feeding is often the appropriate measure to safely overcome this initial period without malnutrition and its consequences (Burgos et al. 2018). In neurodegenerative diseases with dysphagia, the pros and cons of tube feeding have to be evaluated with the background of a progressive disease, where oropharyngeal dysphagia typically develops during the advanced stages of the disease. In general, in patients with dysphagia due to Parkinson’s disease, the indication for tube feeding should be more liberal, as a feeding tube also ensures the adequate pharmacological therapy of the patient, which is particularly difficult in advanced Parkinson’s disease. In patients with amyotrophic lateral sclerosis (ALS), the indication for or against tube feeding should depend on the severity of dysphagia, the severity of weight loss, and the type and stage of the disease. In general, the option of tube feeding should be discussed early during the disease, because severe weight loss should be avoided and patients with ALS and reduced lung capacity have a higher complication rate during PEG-placement.

In all these considerations, the individual patient’s preferences and moral concept have priority and should be discussed as early as possible (Druml et al. 2016).

Future Directions of Research

As mentioned before, randomized controlled trials about the effects of artificial feeding would be unethical, because adequate nutrition would be withheld for the placebo group. This limitation might be counteracted by studies comparing early with delayed artificial feeding in patients where the benefit of (early) artificial feeding is unclear, as it has been performed in the FOOD trial (Dennis et al. 2005). This could also be an adequate research approach for other entities, such as Parkinson’s disease and amyotrophic lateral sclerosis.

A key question that is still awaiting answer is at which degree of undernutrition or weight loss, the advantages of artificial feeding outweigh its risks, i.e., the patients most likely will have a net benefit from artificial nutrition. This question should be investigated with priority, as the answer could support the decision-making process in many patients and in an area of poor scientific evidence. Careful observational studies with comprehensive patient characterization are needed to answer this question.


Any method of nutrient delivery not using the oral route is defined as artificial nutrition. Delivery via the gastrointestinal tract, i.e., enteral nutrition (EN) and delivery via venous blood vessels and rarely subcutaneously, i.e., parenteral nutrition (PN) can be differentiated. The indication for artificial nutrition is manifest or impending severe malnutrition. Malnutrition is a geriatric syndrome which is known to increase mortality and worsen health and functional outcome. Correspondingly, the effectiveness of nutrition therapy, particularly in the form of oral nutritional supplements, has been demonstrated in many randomized controlled trials. Unfortunately, there are and will be no placebo-controlled randomized controlled trials about artificial nutrition, because such studies would be unethical. Hence, the potential advantages and risks of artificial nutrition must be weighed individually, based on the evidence from observational trials and clinical experience. No food intake for more than 3 days or less than 50% of requirements for more than 1 week would be the general indication for artificial feeding. Depending on the individual prognosis and the individual risks of invasive procedures, these cut-offs may need substantial adjustment. In older patients with advanced dementia, artificial feeding should be avoided and oral comfort feeding preferred. In contrast, in older persons with reasonable prognosis, such as in patients with a dysphagic stroke, the aforementioned general principles should be applied.



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Authors and Affiliations

  1. 1.Department for Geriatric MedicineRuhr-University BochumHerneGermany
  2. 2.Institut for Biomedicine of AgingUniversity Erlangen-NürnbergNürnbergGermany

Section editors and affiliations

  • Virginia Boccardi
    • 1
  1. 1.Institute of Gerontology and GeriatricsUniversità degli Studi di PerugiaPerugiaItaly