Management of type 1 (acute) intestinal failure

Abstract

Intestinal failure (IF) is defined as ‘the reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth’. Type 1 IF is short-term and often perioperative in nature. Patients are managed in a multitude of healthcare settings, particularly surgical and critical care areas. Type 1 IF can lead to malnutrition, which is prevalent in hospitals and has significant consequences for patient outcomes. Type 1 IF patients require short-term parenteral nutrition (PN) support; the provision of PN in hospitals should be managed by a multidisciplinary nutrition support team (NST).

Nutritional assessment should include estimating requirements for energy, protein, fluid and electrolytes, based on basal requirements with adjustments for higher demands. All patients should be assessed for risk of refeeding syndrome and managed appropriately. Most patients can be managed using multichamber PN bags. A small minority may require bespoke PN. PN should always be provided with micronutrients and electrolytes.

A central venous catheter is the preferred choice for venous access. All intravenous devices used for PN should be handled using an aseptic non-touch technique. If a catheter-related bloodstream infection is suspected, the diagnosis should be made using paired blood culture sampling.

All patients should undergo ward-based and blood monitoring. The frequency of monitoring may be reduced if PN continues for a longer duration, under NST advice. Daily assessment should also include monitoring for signs of resolution of IF, and the introduction of oral/enteral nutrition.

Summary box.

• Type 1 or acute intestinal failure can lead to malnutrition, and requires short-term parenteral nutrition, the provision of which should be managed by a multidisciplinary nutrition support team.

• Nutritional assessment should include estimating energy and nitrogen requirements, fluid and electrolytes needs, with adjustments for fluid/electrolyte losses. All patients should be assessed for risk of refeeding syndrome and managed appropriately.

• Most patients can be managed using multichamber bags. A small minority may require specially compounded bags. Parenteral nutrition should always be provided with micronutrients and electrolytes.

• A central venous catheter is the preferred route for the provision of parenteral nutrition. All intravenous devices used for parenteral nutrition should be handled using an aseptic non-touch technique. If a catheter-related bloodstream infection is suspected, the diagnosis should be made using paired blood sampling.

Malnutrition and intestinal failure

Intestinal failure (IF) has been defined by the European Society for Clinical Nutrition and Metabolism as ‘the reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth’.¹ Type 1 IF is acute or short-term and usually self-limiting. These patients are often seen in acute settings such as surgical wards and high dependency or intensive care units.^{2 3} If left untreated, type 1 IF can lead to malnutrition due to (1) reduced dietary intake, (2) reduced absorption of macronutrients and/or micronutrients, (3) increased losses or altered requirements or (4) increased energy expenditure (in specific disease processes). This leads to wide-ranging changes in physiological function, which is associated with increased rates of morbidity and mortality.^{4 5}

Nutritional screening should be undertaken in all patients admitted to hospital and then at least weekly using a validated tool, such as the Malnutrition Universal Screening Tool, to assess nutritional status and risk (box 1). All patients should have a nutritional care plan.⁶ The provision of parenteral nutrition (PN) for the management of type 1 IF should be managed in acute hospitals under the supervision of a multidisciplinary nutrition support team (NST) with appropriate training in prescribing PN.⁷

Box 1. Definition of malnutrition⁷.

• Malnutrition is defined as those with:

  • Body mass index (BMI) < 18.5 kg/m².

  • Unintentional weight loss > 10% within the last 3–6 months.

  • BMI < 20 kg/m² and unintentional weight loss > 5% within the last 3–6 months.

• Patients considered at risk of malnutrition are defined as:

  • Little or no nutritional intake for >5 days and/or are likely to eat little or nothing for the next five or more days.

  • Poor absorptive capacity.

  • High nutrient losses and/or have increased nutritional requirements from causes such as catabolism.

PN should be considered in patients who are malnourished or at risk of malnutrition and meet either of the following criteria: (1) inadequate or unsafe oral and/or enteral nutritional intake or (2) a non-functional, inaccessible or perforated gastrointestinal tract.⁷ Patients with a functioning/accessible gastrointestinal tract should always be considered for enteral nutrition first, if they do not meet their nutritional needs by mouth. Efforts should be made to establish enteral feeding where possible, but this should not significantly delay provision of nutrition support. In some cases, it may be appropriate to use PN as a bridge to enteral nutrition.

Typical surgical indications for type 1 IF include postoperative paralytic ileus, small bowel obstruction, bowel perforation and anastomotic leak. Malnourished patients and those who have undergone extensive surgery, especially involving bowel content spillage, may be suitable for early PN. Other non-surgical indications include obstruction related to stricturing Crohn’s disease, cancer-related bowel obstruction, mucositis post chemotherapy/radiation therapy, graft versus host disease and multiorgan failure in the critically ill patient.

Nutritional assessment

Clinical assessment should include estimating requirements for energy (including protein), fluid and electrolytes. Energy provision from PN is obtained from a balanced combination of glucose, lipid and protein (as a source of nitrogen), which is provided together with electrolytes and micronutrients.

Energy and nitrogen requirements

Basal energy requirements are based on resting energy expenditure (REE) as a minimum energy requirement, expressed as kcal/kg. Additional factors (physical activity and diet-induced thermogenesis) are added to provide a figure for total energy expenditure (TEE). In patients with fluid overload, a dry weight should be used for estimating requirements.

Most patients in hospital with an acute illness, (including perioperative patients) have limited mobility and therefore do not require more than 20% additional energy provision above REE. Once refeeding issues have been fully addressed, an appropriate estimation of TEE for patients requiring PN is 20–25 kcal/kg plus 20%.⁷ This requires a dietetic review and appropriate adjustment, in accordance with current practice and recommendations. Nutritional requirements for both energy and nitrogen for specific conditions are outlined in the Parenteral and Enteral Group Pocket Guide⁸ and should be referred to when calculating requirements, although they may need adjusting for acutely unwell patients.

There are limitations with predictive equations, particularly those in intensive care, and a low correlation between these equations and indirect calorimetry has been demonstrated, likely due to the dynamic nature of their metabolic needs.⁹ For this reason, for mechanically ventilated patients, the Penn State University equations may be more appropriate for calculating estimated energy expenditure. These equations incorporate physiological factors such as temperature and ventilator settings and have greater reported accuracy in this patient group. They should only be used by those trained in calculating energy requirements for critically ill patients.¹⁰ Indirect calorimetry may be valuable to help determine REE, particularly in critically ill patients, although it may not be widely available.^{11 12}

Most adult patients with a body mass index (BMI) of 18–30 kg/m², on short-term PN, require 0.16–0.24 g nitrogen/kg/day when meeting full energy requirements.⁸ Energy provided by nitrogen should be included in the assessment of total energy provided by the PN bag.

Equations used to predict energy and nitrogen requirements assume a linear relationship between requirements and weight. This can lead to underestimation of requirements in low bodyweight patients and overestimation in high BMI (>30 kg/m² patients). Therefore, it can be particularly challenging to estimate requirements in these patient groups. Care should be taken particularly during initial feeding to avoid refeeding risks. Lower or higher levels of protein may be recommended in certain conditions such as burns, enterocutaneous fistulae and chronic kidney disease, with liaison with an experienced dietitian to ensure appropriate requirements in these patients.

Fluid requirements

Total maintenance fluid volume of 25–30 mL/kg/day is recommended for hospitalised patients.¹³ For high BMI (>30 kg/m²) patients, the intravenous fluid prescription should be adjusted to their ideal bodyweight, and expert advice sought if the BMI>40 kg/m². Prescribing smaller volumes of fluid (20–25 mL/kg/day) should be considered for patients who are older or frail, have renal impairment or cardiac failure, are malnourished and/or at risk of refeeding syndrome. Patients with type 1 IF may have multiple factors which impact on their fluid requirements (box 2).

Box 2. Consideration for estimating fluid requirements¹³.

Factors to consider when estimating fluid requirements include:

• Excessive losses of fluid and electrolytes from enteral tubes, drains, fistulae, diarrhoea, stoma outputs, etc.

• Current inputs including oral/enteral intake or intravenous nutrition/fluids (including the volume given to administer drugs).

• Patients with acute kidney injury or chronic kidney disease may require a smaller volume of fluid (and potassium, magnesium and phosphate) provision to avoid accumulation. The possibility of sodium retention should also be considered.

• Patients with cardiac impairment/failure may require a smaller volume of fluid (and sodium) provision to reduce the preload on the heart.

• Patients with hepatic impairment/failure may require a smaller volume of fluid (and sodium) provision to limit the accumulation of ascites.

Electrolyte requirements

Standard adult daily electrolyte requirements are described in table 1. Additional electrolytes may be necessary if there are excessive electrolyte losses from vomiting, nasogastric tube aspirates or diarrhoea. These should be administered as separate infusions or, if able, added to the PN bag, under appropriate pharmaceutically controlled environmental conditions. All patients should be assessed for the presence of oedema. If the patient is fluid overloaded, or has several other intravenous infusions, they may require a lower volume of PN. Table 2 provides an estimation of potential additional requirements based on recognised composition of losses from the gastrointestinal tract.

Table 1. Daily electrolyte requirements.

Electrolyte	Daily requirements per kg bodyweight	For A 70 kg person
Sodium	1 mmol/kg13	70 mmol/day
Potassium	1 mmol/kg13	70 mmol/day
Magnesium	0.1–0.2 mmol/kg8	7-14 mmol/day
Calcium	0.1–0.15 mmol/kg8	7-10.5 mmol/day
Phosphate	0.5–0.7 mmol/kg or 10 mmol/1000 kcal (do not exceed 50 mmol/day)8	35-49 mmol/day

Table 2. Composition of some body secretions.

Secretion	Na (mmol/L)	K (mmol/L)
Gastric fluid (vomiting/nasogastric)13	20–60	14
Pancreatic drain/fistula13	125–138	8
Biliary drainage loss13	145	5
Jejunal juice via stoma/fistula13	140	5
Ileal juice via new stoma/fistula13	100-140	4–5
Ileostomy (adapted)13	50–100	4–5
Colostomy8	60	15
Diarrhoea8	30–140	30–70
Normal stool8	20–40	30–60

Refeeding syndrome

Refeeding syndrome describes the adverse clinical and biochemical problems that may result from feeding malnourished patients via any route; oral, enteral or parenteral. Clinicians need to be aware of refeeding syndrome and assume most malnourished patients are at risk.¹⁴ Hypophosphataemia is the most commonly used marker for refeeding problems and commonly occurs when artificial nutritional support is started (especially with carbohydrate) and can result in death. Hypomagnesaemia, hypokalaemia, deranged blood glucose levels and thiamine deficiency may occur. Sodium retention (causing oedema) is common, especially after glucose (and sodium) is given.

Non-protein energy should be given ideally as 50/50 carbohydrate/lipid and initially at less than 50% of estimated requirements. For patients with a high or extremely high risk of refeeding syndrome, a more cautious approach starting at 10kcal/kg/day should be used on initiation of PN.^{7 8} These patients require specialist assessment from a NST; this assessment should include daily review of nutritional requirements and appropriate increments in the provision of nutrition support, ensuring that patients are not underfed. Patients at high/extremely high risk of refeeding syndrome are likely to be deficient in micronutrients as well as being at high risk of Wernicke-Korsakoff syndrome. An intravenous dose of thiamine 200–300 mg should be administered on initiation of PN and continued once daily for 3–5 days with a balanced (and complete) multivitamin and trace element preparation.¹⁵

Parenteral nutrition bag

Most hospitals have a formulary with specific multichamber bags (MCBs) available for use. These may be supplemented with micronutrients by the manufacturer or added locally under appropriate pharmaceutically controlled environmental conditions. Intravenous micronutrients can also be administered alongside the PN by a separate infusion. MCBs are available with or without lipid emulsion. Some hospitals may have the resources to compound or order bespoke PN. These bags may be appropriate for patients with very low electrolyte or fluid requirements, such as those with cardiac failure or chronic kidney disease.

MCBs are of a fixed volume. If these fluid volumes are inappropriate for an individual patient, then using a proportion of a bag or administering additional intravenous fluids alongside the PN bag should be considered. The patient’s fluid and electrolyte requirements should be considered when prescribing additional fluids. If this is not appropriate, then an alternative regimen or, if necessary, a bespoke, ‘tailor-made’ regimen may need to be prescribed. PN contains light-sensitive components that are susceptible to degradation and in some cases can cause harm if precipitates form within the bag. All PN should be light protected during the infusion duration. Light protective covers are usually provided by the PN manufacturer. PN should always be infused via a rate-controlled infusion pump and an intravenous administration set with a filter of no greater than 1.2 µm (microns).¹⁶ As with all medicinal products, patient allergies should be checked before prescribing PN. Lipid-containing PN contains eggs and soya and should be avoided in patients with egg/soya allergies. Manufacturers also advise against the use of lipid PN in patients with some nut allergies. Some micronutrient preparations may also be contraindicated in patients with nut allergies. Always seek pharmacy/manufacturer advice.

On initiation of PN, the infusion duration should be over 24 hours. Patients receiving PN for greater than 14 days should be changed to cyclical, overnight feeding, typically over 12–16 hours each day.⁷ Patients with diabetes will need particular attention to blood glucose monitoring and insulin dosing when transitioning to cyclical PN feeding. There can be challenges matching insulin regimes to PN infusion duration which can result in hyper- or hypoglycaemia. A discussion with the diabetes team should occur before changing to cyclical feeding and avoid changes to PN infusion duration directly before the weekend or when the NST and diabetes team are unavailable. If PN is interrupted or disconnected in a patient who has already received their insulin dose, intravenous glucose infusion (10%–20%) equivalent to the PN regimen and duration will need to be prescribed to prevent severe, potentially life-threatening hypoglycaemia.

Venous access devices

PN is commonly administered through central venous catheters (CVCs) such as non-tunnelled CVCs or peripherally inserted central catheters (PICC). The tip of these devices should be radiologically confirmed as being positioned between the lower third of the superior cava vein and the upper third of the right atrium.¹⁷ See images in figure 1 below demonstrating an incorrectly (figure 1a) and correctly (figure 1b) placed central venous catheter.¹⁸ In some centres, PN may be administered via peripheral venous access devices (short cannulas and midline catheters). This can lead to problems with thrombophlebitis. Peripheral PN should have a final osmolarity <850 mosmol/l to reduce the risk of these complications.¹⁷ If a peripheral cannula is used, the site should be changed every 72 hours to prevent local phlebitis. It is advisable to insert a central venous access device if the need for PN exceeds 7 days to reduce risk of peripheral PN-related iatrogenic harm. For central PN, most hospitals will have policies advising change of CVCs every 7–10 days. If PN duration is extended, a PICC could be considered which can remain in situ for a longer duration. Adherence to strict aseptic non-touch technique during catheter placement (including peripheral cannula), catheter care and connecting/disconnecting PN is vital at all times.

Figure 1. Chest radiographs after insertion of a central venous catheter. (a) Catheter tip (arrowed) too proximal and at high risk of causing a central vein thrombosis. It should not be used. (b) Ideal placement (arrowed) of a central venous catheter.¹⁸.

PN should ideally be infused through a dedicated lumen on a CVC.^{7 17} If the administration set is accidentally or intentionally disconnected from the patient or PN bag, it should not be reconnected due to risk of contamination and bloodstream infection.

Catheter-related bloodstream infection (CRBSI) is a major (and potentially life-threatening) complication for patients receiving PN. Paired central and peripheral blood cultures are required to diagnose CRBSI, using qualitative (differential time to positivity) and/or quantitative assessment. Blood cultures should be taken from every lumen of all central venous access devices, if the patient has multiple lines. Each sample should be appropriately labelled to ensure correct identification and interpretation of results. Efforts should be taken to prevent underdiagnosis or overdiagnosis of CRBSI as this can lead to inappropriate or missed interventions, including CVC removal or an unnecessary delay in the provision of PN.^{19 20} All hospitals should audit their catheter-related blood stream infection rates on an annual basis.²¹

Monitoring

When patients are initially commenced on PN, they should be carefully monitored to ensure they do not develop complications associated with its administration. PN should not be started in any patient who does not have baseline clinical and laboratory monitoring available. It is safer to wait until results of laboratory tests are available. Table 3 describes the minimal monitoring requirements for patient receiving PN. It is important to note that serum albumin concentration is not a marker of nutritional status and therefore should not be used to assess response to PN.

Table 3. Minimum monitoring requirements for patient receiving PN⁷.

Ward monitoring	Temperature, heart rate, blood pressure and respiratory rate, oxygen saturation, level of consciousness or new confusion (NEWS2 score)22	Baseline then 6 hourly
	Blood glucose	Baseline then 6 hourly for 2 days then twice daily if normal blood glucose
	Fluid balance	Baseline then daily
	Bodyweight/MUST score	Baseline then twice weekly
	Venous access entry site	Baseline then daily for signs of infection, inflammation
Blood test monitoring	Urea and electrolytes, calcium, phosphate and magnesium	Baseline then daily
	Full blood count, liver function tests and albumin	Baseline then twice weekly or as indicated

MUST, Malnutrition Universal Screening Tool; NEWS2, National Early Warning Score 2; PN, parenteral nutrition.

Micronutrient screening is not typically indicated in type 1 IF patients, unless there is a clinical need. If required, a C reactive protein level should also be checked as serum levels of many micronutrients are affected by acute phase response, making results uninterpretable. Ideally, micronutrient screening should only be undertaken when the CRP is within the normal range.

Discontinuation of PN

There is no minimum duration for PN support. PN should be stopped once adequate oral and/or enteral nutrition is established, and the indication for PN has resolved. It is common practice to wean PN over 1–2 days as oral diet is established, rather than stopping abruptly. Signs of resolution of type 1 IF usually include return of bowel sounds/activity, reduction in abdominal distension and/or nasogastric aspirates/vomiting and return of appetite or hunger.

In some cases, patients with type 1 IF may develop complications that require longer-term PN, associated with type 2 or type 3 IF. Type 2 IF is associated with complications of abdominal surgery and requires prolonged (>28 days) PN over an extended period of weeks/months. Type 3 IF is a chronic condition, requiring long-term PN.² These patients should be referred to a designated integrated IF or home PN centre.

Summary

Type 1 IF is commonly seen in healthcare settings and is usually short-term. PN may be indicated in patients who are malnourished or at risk of malnutrition, with a non-functioning, inaccessible or perforated gastrointestinal tract. PN should be prescribed after an appropriate assessment has been undertaken, by healthcare professionals with the correct training, and preferably with the support of a multidisciplinary NST. Type 1 IF is short-term and usually self-limiting; therefore, frequent monitoring for resolution of IF is vital to ensure the timely weaning of PN with the establishment of oral/enteral nutrition.

Data availability statement

Data sharing not applicable as no datasets generated and/or analysed for this study.