While consideration for home nutrition support is given to patients who are unable to meet their nutritional needs orally, that is, they have an appropriate indication for HPEN, other factors also must be considered, including insurance coverage, availability of laboratory and nursing support, and an acceptable home environment with satisfactory social support to ensure safe administration. Because HEN and HPN are complex and can be associated with complications, patient selection is important for a successful outcome. Patient assessment begins with a comprehensive nutritional assessment, determination of malnutrition/malnutrition risk, and identification of an indication for home therapy (Table 1) [5,6,7]. Some of the more common indications for HEN include severe oropharyngeal dysphagia due to primary neurologic disorders (vascular or degenerative) and malignancies (head and neck or esophagogastric), gastric outlet obstruction, and severe gastroparesis [8]. In contrast, parenteral nutrition is indicated in disorders where enteral nutrition is poorly tolerated or deemed inappropriate such as severe malabsorptive disorders including short bowel syndrome, high-output stoma or enterocutaneous fistula, severe intestinal dysmotility syndromes including chronic intestinal pseudoobstruction, and chronic bowel obstruction [9].

For the successful home delivery of nutrition support, it is critical that patients be capable of following the procedures for nutrition administration or have a caregiver who can perform these tasks, which are discussed in detail later [10]. As home nutrition support requires the home delivery of supplies, patients/caregivers need to be able to arrange for receipt of any needed formula and equipment. Because of the risk of complications with HPN, formal individualized training for the patient, caregiver, and/or home nurses has been recommended [6]. Patients receiving HEN should also undergo training provided by a multidisciplinary team [5]. Patients and/or their caregivers need to demonstrate an ability to properly administer their nutrition support therapy prior to hospital discharge [11,12].

Finally, HPEN is typically considered for patients who demonstrate a “long and indefinite” need in order for insurance coverage to be obtained [2,8,9]. More information regarding insurance reimbursement for home nutrition support within the United States is discussed below. Given the complexity of HPEN management, a multidisciplinary team is recommended to care for these patients [13].

For patients who require HPN, vascular access with a central venous catheter (CVC) is needed. Tunneled or subcutaneously implanted (i.e., ports) catheters with access to the internal jugular vein or subclavian vein are appropriate for long-term use. If a shorter duration of HPN is anticipated, typically <6–12 weeks, a peripherally inserted central venous catheter (PICC) is another option [14]. The use of a peripheral intravenous cannula or midline catheter is not appropriate for HPN as the tip of neither is appropriately situated in a central vein [14]. The use of femoral venous access is associated with a high risk of infection and venous thrombosis and is not recommended unless other access sites are not available [15]. While there is some controversy over the ideal location for the tip of central venous catheters, it is generally recommended that for PN, the catheter tip should terminate at the junction of the superior vena cava and right atrium to reduce the risk of thrombosis and dysrhythmias [10,14,16].

There are advantages and disadvantages to each type of CVC (Table 2). As such, patients should be included in the decision-making process. The proximal portion of tunneled CVCs exit the skin and, thus, have the injection cap external to the skin surface and may be less appealing from an aesthetic perspective but are generally preferred for administration of HPN. While ports may be appealing to some patients because they are subcutaneously implanted, these CVCs require a needle to be accessed and, in HPN, are generally accessed continually except during the once-weekly changing of the needle. Furthermore, the diaphragm membrane the needle punctures deteriorate over time and periodically may need to be replaced. In the case of a serious catheter-related bloodstream infection (CRBSI) where the CVC is unable to be salvaged, it also is more difficult to remove a port. The use of PICCs has increased over recent years related to their ease of placement and removal, accessibility, safety, and cost-effectiveness [17]. These catheters, however, have also been shown to have a higher risk of thrombosis compared to other CVCs, which limits their use for chronic therapy and are not recommended for HPN [18,19]. An important consideration when choosing a CVC is the number of infusion lumens present. The fewest number of lumens needed is recommended, preferably just a single lumen, as multilumen CVCs are associated with an increased incidence of CRBSIs [20].

For HEN, the optimal route of administration depends upon the anticipated duration of use, adequacy of intestinal function, and risk of aspiration. Available routes of enteral access include transnasal and percutaneous. For patients who are likely to require 30 days or less of enteral nutrition, a nasoenteric tube is the preferred route for administration, although some individuals can be trained to insert and remove a nasogastric tube daily for nocturnal feedings. If HEN is anticipated to be needed >30 days, then a percutaneous route is generally preferred. Percutaneous gastrostomy (and sometimes jejunostomy) tubes can be placed surgically, endoscopically, or radiologically. Skin-level or low-profile gastrostomy devices (i.e., “buttons”) have become popular in individuals who require long-term enteral nutrition support.

Intragastric feeding, as opposed to feeding directly into the small intestine, is preferred, as it is more physiologic and can help activate the normal neural and hormonal pathways involved in digestion and absorption of nutrients [21,22]. Intragastric feeds also appear to buffer gastric acid more effectively and, thus, may provide ulcer prophylaxis [23]. Enteral access via the gastric route is generally easier to achieve compared with postpyloric tube placement. Postpyloric feeding is usually reserved for those who are intolerant of gastric feeding or those at high risk of aspiration of gastric contents.

An assessment of the patient’s calorie, protein, and fluid needs is needed prior to starting EN or PN. While indirect calorimetry is the gold standard for calculation of energy expenditure in critically ill patients, given its limited availability, it has become standard clinical practice for medically stable individuals to use predictive calculations (e.g., Harris–Benedict equation) or weight-based approaches [24]. Subsequent adjustments can be made to a patient’s formula based on weight trends, laboratory studies, urine output, and other clinical factors.

When initiating nutrition support in patients with severe protein energy malnutrition, both PN and EN need to be started slowly and cautiously, preferably in a hospital setting, to monitor for refeeding syndrome. Refeeding syndrome, discussed in more detail later, is a potentially fatal complication and consists of metabolic and electrolyte disturbances in response to the reintroduction of calories after a period of reduced or absent caloric intake [25]. While no standardized approach has been developed to guide the advancement of a nutrition regimen, several protocols exist [25,26,27]. Initiating PN at home requires a suitable patient (i.e., not at risk of refeeding and otherwise medically stable) and close monitoring by a willing patient, the PN ordering provider, and the home infusion company. If any of these is missing, the patient is best served by being hospitalized for initiating PN.

The ideal PN formulation should contain appropriate individualized calories as well as protein requirements and adequate volume while avoiding excessive dextrose and lipids. Trace elements and vitamins are also required in all PN solutions. Insulin and other additives are sometimes included. Typically, HPN is cycled/infused overnight, often over a period of 10 to 14 h via a programmable infusion pump. This will require an increase in the rate of PN infusion to decrease the infusion time, thus allowing the patient to have more independence from the infusion pump. Nocturnal HPN does have its drawbacks, however, including increased interruption of sleep due to increased urination and noise from the infusion pump. As such, some patients prefer to infuse PN during the day. Portable pumps that can be carried in a backpack or tote are available for those who need to infuse PN during the day. Of note, home infusion pumps are usually programmed to infuse the formula with a gradual infusion taper down over the final one or two hours. The taper-down period helps to avoid rebound hypoglycemia when the infusion is finished. In adults, a ramp-up mode is rarely necessary.

For patients receiving EN, several methods for formula administration can be employed. Perhaps the most physiologic technique is bolus administration. This involves using a syringe to infuse a 200–400 mL bolus of formula over 5–15 min at various times throughout the day, similar to how one would eat regular meals. Bolus feeding is preferred for intragastric feedings in active, alert patients with low aspiration risk. For patients receiving gastric feeds who are intolerant to bolus administration, gravity feeding is an alternative option allowing feeds to be administered more slowly into the stomach via gravity flow, generally over 30–45 min. Finally, an infusion pump can be used to administer EN at a controlled rate and is the preferred method for patients receiving jejunal feeds and those receiving gastric feeds who are intolerant to both the bolus and gravity methods. Notably, patients may experience gastrointestinal symptoms such as abdominal distension, cramping, and diarrhea if the rate of feeding is too high. Similar to HPN, most HEN consumers prefer cycled nocturnal feeding as it allows maximal use of the gut and allows normal activities during the day. Rebound hypoglycemia is uncommonly seen in the HEN setting. Compact portable infusion pumps that can be carried around in a backpack or large tote are available for the patient who requires continuous infusion or prefers to infuse during the day.

As noted previously, training of the patient and their caregiver is an essential part of providing HPEN as these are complex nutritional therapies with the potential for serious complications. It has been shown that many potential complications of both HEN and HPN can be minimized or prevented entirely by providing a comprehensive educational curriculum to patients [28,29,30,31]. As part of this process, a psychosocial assessment of the patient’s and caregiver’s physical and mental capacity and ability to administer HPEN is important. Training should encompass topics such as hand hygiene, care of CVCs and/or enteral access devices and sites, formula administration, complication monitoring, and who to contact with questions or concerns [28].

A typical training program should be incorporated into the decision making and discharge planning for all HPEN patients. Training may occur during hospitalization or after the patient has been discharged home by their infusion company and home nurse depending on the institution and available resources. Wherever the education takes place, periodic assessment of patient and/or caregiver knowledge of important elements of HPEN delivery and monitoring should be performed. Several effective teaching strategies have been identified that can be incorporated into the caregiver education process [32]. Patients and/or their caregivers should be required to redemonstrate proper technique and gain approval from their nurse educator(s) before they are allowed to administer HPEN independently at home. If patients are unable or unwilling to perform the necessary tasks for safe administration of home nutrition support, other options should be explored.

In the patient determined to go home on EN or PN, once the patient has demonstrated tolerability to the optimized formula that has been cycled, arrangements can begin for their transition to home. Several factors need to be considered when transitioning a patient from an acute care setting to home. A safety assessment of the home environment is necessary to ensure that patients have the proper resources to continue EN/PN administration after discharge [13]. For U.S. consumers, insurance coverage should be determined as soon as possible to prevent unnecessary hospital discharge delays. This often requires the involvement of a case manager or social worker. A homecare agency and, for patients requiring PN, a home infusion company will need to be selected to assist with formula and supply delivery. As mentioned previously, formal patient and caregiver training should be employed including written and verbal instructions to follow and when to contact their outpatient nutrition support team for questions or concerns [13]. An important step before hospital discharge is to make sure the patient has follow-up care arranged with a physician who will also take responsibility for monitoring laboratory values and the patient’s clinical status and adjusting the PN/EN formula as needed. This physician needs to work closely with a pharmacist, dietitian, and home care nurse when the patient finally goes home.

Patients receiving HPN require routine monitoring that should include body weight, urine output, biochemistry lab studies including micronutrient levels, and bone density measurement [6]. Various monitoring approaches have been suggested; however, none are evidence-based and generally are institution-specific [5,6,26,33]. From a routine laboratory monitoring standpoint, we suggest weekly monitoring of electrolytes and liver enzymes initially following hospital discharge and as the patient’s condition stabilizes, usually after 1 month, the monitoring interval can be increased to every other week, for another 1 to 2 months, then monthly thereafter for most patients. In some, a quarterly schedule is acceptable [28] (Table 4). A complete blood count is usually checked quarterly. Micronutrient levels (vitamins A, B12, folate, D and E, and iron, zinc, copper, and selenium), essential fatty acids, and triglyceride level are checked at baseline and at least annually; more often if deficiencies are identified and supplementation ongoing [33,34,35] (Table 4).

With respect to blood glucose monitoring, levels should also be monitored in patients on HPN to check for hyperglycemia as well as rebound hypoglycemia. Patients should be instructed to check their blood glucose about 1 h after starting the PN infusion and about 1 h after stopping the infusion in all patients who are receiving cyclical PN. If glucose levels remain stable after 1 to 2 weeks, then patients can discontinue monitoring unless a change in PN formula is made. When blood glucose levels are consistently above 180 to 200 mg/dL, regular insulin is often added to the PN formula; the amount should be individualized. Importantly, patients who receive insulin with their PN infusions should continue to monitor their blood glucose levels routinely with each infusion as adjustments may be needed [10].

Patients on long-term PN also require monitoring for the development of metabolic bone disease, including osteoporosis and osteomalacia [34]. One recent study of patients with intestinal insufficiency and intestinal failure requiring PN described a nearly 57% prevalence of osteoporosis [36]. Risk factors include inactivity, malabsorption, low body mass index, chronic inflammation, medications (e.g., corticosteroids), low vitamin D levels, and altered calcium homeostasis, among others [34]. Screening for metabolic bone disease is most commonly performed using bone density testing by dual-energy x-ray absorptiometry (DXA) of the hip and lumbar spine [37]. Guidelines exist that provide recommendations on use of DXA to define osteoporosis, to periodically monitor bone density, and to identify thresholds at which to start specific osteoporosis treatments [38].

Like patients receiving HPN, patients receiving HEN should also be monitored regularly by a multidisciplinary team. Body weight and hydration status should be routinely evaluated to determine adequacy of the EN [5]. Adjustments in enteral formula and water administration can be tailored to each patient. Similar to patients receiving long-term PN, monitoring of routine laboratory studies and micronutrient levels in all patients receiving HEN should be obtained at least annually with more frequent monitoring and supplementation when deficiencies are identified [10]. Bone density screening should also be pursued at regular intervals.