Adult Parenteral Nutrition

Publication: 25/04/2012  --
Last review: 24/06/2021  
Next review: 24/06/2023  
Clinical Guideline
ID: 2920 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2021  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Adult Parenteral Nutrition


  • To provide a high quality parenteral nutrition (PN) service to patients where oral or enteral feeding is not a viable or complete option.
  • To foster a co-ordinated, multidisciplinary approach to PN support.
  • To act as a source of information and advice on the management of PN.

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Guideline for the Administration of Parenteral Nutrition in Adults.  This document provides a referral pathway alongside guidance on indications for parenteral nutrition, venous access, monitoring and complications.

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Parenteral nutrition (PN) consists of protein, carbohydrate, fat, electrolytes, trace elements and vitamins which is administered intravenously.  PN is indicated in patients with a compromised nutritional status, where oral or enteral feeding is not a viable option.[1]  Oral and enteral nutrition should always be optimised first line as these are safer routes of feeding offering lower rates of mechanical, septic and metabolic complications. 

In an acute hospital setting, PN is generally administered to patients with a non-functioning, inaccessible or perforated gastrointestinal tract (types I and II intestinal failure - see table below).[2]  It is also less commonly used to improve and maintain the nutritional status of severely malnourished patients who are being prepared for surgery.  Home PN (HPN) is used for patients with either type II OR type III intestinal failure, i.e. those with inadequate amounts of functioning gut to maintain nutritional health long-term.

Type of Intestinal Failure





Acute, short-term and usually self-limiting condition e.g. post-operative paralytic ileus

Prolonged acute condition, often in metabolically unstable patients, requiring complex multi-disciplinary care and

intravenous supplementation over periods of weeks or months

e.g. patients with complex fistulising disease.  This may be reversible eventually, after several months of PN and subsequent restorative surgery

Chronic condition, in metabolically stable patients, requiring intravenous supplementation over months or years. It

is usually irreversible

e.g. patients who are stable following previous extensive surgery for ischaemic gut

Administration of PN is a complex process, requiring accurate assessment of the patient’s nutritional requirements, placement of an appropriate feeding line, care of the line, monitoring of electrolytes and blood chemistry.  It has the potential for many serious metabolic and non-metabolic complications and therefore it is essential that it is only given to appropriate patients with close monitoring.  

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Referral Criteria

The following criteria are based primarily on the European Society of Parenteral and Enteral Nutrition (ESPEN) Guidelines 2017[3]  They represent common diagnoses and indications which may require parenteral nutrition.  The list is not exhaustive, and other indications can be discussed with the nutrition team.

  • Fistulae: high output or proximal gastro-intestinal
  • Intestinal failure (types I, II and III)
  • Bowel obstruction (functional or mechanical)
  • Palliative PN (often for patients with bowel obstruction due to a slow-growing malignancy, though other clinical scenarios will be considered
  • Actual / anticipated prolonged ileus
  • Intractable vomiting
  • Intractable diarrhoea / high stoma output
  • Severe acute pancreatitis exacerbated by enteral feeding
  • Severe graft versus host disease
  • Enteral route unattainable

The risks attached to PN use are likely to outweigh the potential benefits unless parenteral nutrition is provided for at least 5 days.  Thus if resumption of oral or enteral nutrition is anticipated within this time, PN is unlikely to be required.[3]  If the clinical team is unsure, all patients should be discussed with the nutrition team.

Referral Pathway - In hours

All referrals to start the same day must be received by the nutrition team by 10am (Mon – Fri).  If the required blood results and clinical information are unavailable then PN may not be provided until the next day. The bloods required are FBC, U&E, adjusted calcium, phosphate and magnesium.

PN should be administered via a central vascular access route where possible. The referral form is available on the intranet under ‘Trust Structure’ > ‘Gastroenterology and Endoscopy’ > ‘Nutrition’ > ‘Parenteral Nutrition’.

The referral form must be completed and signed by doctor or ANP under the direction of an ST3 level doctor or above, then emailed to

The Nutrition Team should then be contacted to confirm receipt of referral.  The nutrition team will assess the patient and document their assessment plan on PPM+.  The medical team will be contacted if more details are required or if we believe the case needs to be discussed further.

Once PN is commenced the nutrition team will review the patient on a regular basis  (Mon – Fri).  A formal MDT occurs every Monday afternoon (MDT outcome documented  on PPM).  Any changes to the nutrition treatment plan will be documented on PPM and discussed with the referring team where necessary.  The following will be documented when a patient is reviewed:

  • Overall progress
  • Fluid balance (where available and relevant)
  • Temperature
  • Current nutritional support
  • Any changes to the components or route of feed
  • Suggestions on medication changes if required (i.e. to optimally manage short bowel syndrome)
  • Suggestions on frequency of blood monitoring if required (but see guide below)

It is expected that the referring team will keep the nutrition team informed of any major changes to the patient’s overall clinical management.

Referral Pathway - Weekend and Public Holidays

For non critical care patients, please follow referral pathway above and the nutrition team will review on the next working day.

For critical care and HDU patients, please refer to the Critical Care Parenteral Nutrition Protocol.  

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Treatment / Management

Initial Monitoring/ Biochemistry

It is essential for all patients on PN to be monitored very carefully, so that adverse events are detected early.  Refeeding syndrome can result in severe fluid and electrolyte shifts with metabolic complications in those undergoing refeeding.  This is covered in more detail in ‘Guidelines for the management of Adult Patients with Refeeding Problems Undergoing Enteral or Parenteral Feeding.[4]  In particular replacement of thiamine and other B vitamins is essential (i.e. Pabrinex vials I and II once daily for a minimum of 3 days with guidance from the nutrition team)

To ensure that PN is prescribed safely and appropriately it is necessary to monitor blood biochemistry daily initially. Before commencing PN, the following blood results MUST be available from the preceding 48 hours:

  • Urea and electrolytes
  • Liver function tests
  • Adjusted calcium, phosphate, magnesium
  • Daily urea and electrolytes, calcium, phosphate and magnesium are required when PN starts, until the nutrition team deem stable
  • Trace element (zinc, copper, selenium) level monitoring should be guided by the nutrition team.

On the ward, the following observations should be performed regularly:


Heart rate

Blood pressure


CLESS score

Fluid balance (including loose stools and vomit)

Blood sugar: should be monitored on a 6 hourly basis until full requirements are met and ‘random daily’ thereafter (i.e. at different times of day).  Any hypo/ hyperglycaemia episodes should be managed according to the latest LTHT guideline.


  Ongoing monitoring

  • If indications of biochemical instability (results outside of normal limits), then check the following daily: U+Es, Ca2+, PO4, Mg2+  until further guidance from the nutrition team
  • If no indications of biochemical instability, then check the following regularly three times a week : U+Es, LFTs, Ca2+, PO4-, Mg2+
  • Consider monthly vitamin levels (Vitamin A, E and D) if appropriate plus 3 monthly ferritin, B12 and folate as guided by the nutrition team

Home Parenteral Nutrition (HPN) Patients  who are admitted

  • If patients are admitted for a reason unrelated to their PN (e.g. elective, non-GI surgery; other medical issue), U+Es, LFTs, FBC, Ca2+, PO4, Mg2+ should be taken on admission.   
  • If line sepsis is suspected, please see below, plus here.  These patients may need a period of time off PN, but their usual HPN prescription will be uploaded on PPM+ as ‘Home PN Script’ to guide daily fluid volume requirements and electrolyte requirements.  
  • Deranged electrolytes and issues with fluid balance may also contraindicate the use the patient’s usual home PN.  
  • If, following clinical assessment, the patient’s HPN is not appropriate, then an alternative equivalent volume of intravenous fluid +/- electrolyte will be prescribed in lieu of their usual HPN.  
  • If the patient is diabetic/ insulin dependent, please ensure their blood sugars are monitored carefully, with appropriate adjustments to their medications.  
  • A nutrition team referral will be required to ensure the patient is reviewed by the nutrition team during their inpatient stay.  

Venous Access for PN

Any line used needs to have a lumen dedicated to the administration of PN.

Peripheral Cannulae:

Peripheral cannulae are not ordinarily used for PN administration due to the rapid onset of phlebitis.


These catheters are inserted in or above the antecubital fossa to a maximum length of 25 cm, terminating in the upper arm/axillary region.  They are very similar in appearance to Peripherally Inserted Central venous Catheters (PICCs) and should be dressed, accessed, secured and routinely observed in the same manner.  Midlines will be labelled as such using a bright green identifying sticker. It is important to remember, however, that the tip is positioned in a peripheral vein where the blood flow is 5-10 times lower than that achieved in a central vein.  This means the types of parenteral feed that can be given through this catheter are limited to those with a lower osmolarity.

The major problems with midlines are infection, occlusion and thrombophlebitis.

Occlusion: The line must be flushed immediately once the infusion is complete in the manner detailed in the Trust CVC management guideline.[5]

Intermittent occlusion is usually due to kinking of the line.  Initial placement of the midline away from the antecubital fossa minimises the opportunity for occlusion.
If recurrent occlusion necessitates the PN being stopped, then the PN must be disconnected and the line must be flushed.  Once PN is disconnected, it cannot then be reconnected.  Avoid line removal until a member of the nutrition team has assessed the patient as it may be possible to clear the occlusion with a thrombolytic agent (see CVC management guideline).[5]

Phlebitis: PN is a highly osmotic solution prone to causing irritation of veins with subsequent phlebitis and venous thrombosis when administered via a midline.  The earliest indication is usually pain in the upper arm during PN infusion.  This will be followed by upper arm oedema, erythema, tenderness, fever and sometimes a palpable venous cord.  If a patient develops pain, contact the nutrition team for advice.  If pain is persistent or severe, stop the PN infusion and flush the line as described above.  Avoid line removal until assessed by a member of the nutrition team, unless severe thrombophlebitis is present, or the patient’s pain cannot be adequately controlled.

Central Venous Catheters (CVCs):
Central venous catheters are the main route of venous access for PN.

Several types can be used for PN infusion (see below).

CVCs should not be used for PN administration until their position has been confirmed.  See section  5.5 of CVC Management guideline.[5]

For non-tunneled lines, a subclavian approach is preferred to the internal jugular route as it provides improved patient comfort and a reduced risk of catheter infection. The nutrition team may decide to use a non-tunneled internal jugular catheter if the benefit of nutrition outweighs the risks.

A femoral CVC is not considered suitable for PN infusion, except in the exceptional circumstance where it is life-saving and interventional radiology are unable to establish a safer route of administration

  • Single-lumen CVCs:
    These are the CVC of choice for short to medium term PN administration, as they are associated with a lower risk of septic complications compared to multi-lumen lines.  However other patient factors may necessitate the use of a multi-lumen central venous catheter.
  • Multi-lumen central venous catheters:
    If multi-lumen catheters are used for PN administration, one lumen should be dedicated for PN only (EPIC 3, 2014).[6]  If PN administration is likely to last for longer than 7-10 days consideration should be given to exchanging the catheter to a PICC.
  • Peripherally inserted central catheters (PICCs):
    A PICC is, by definition, a type of central venous catheter, as the tip sits near to the cavo-atrial junction.  As with any other central venous catheter, the tip position needs to be confirmed prior to use.  They are inserted via peripheral venepuncture in the antecubital fossa or upper arm.  PICCs may be single or multi-lumen.  One lumen should be reserved for the sole use of PN.  PICCs are generally better tolerated by patients than internal jugular CVCs and have lower infection rates.  PICCs can be used for the duration of the treatment.
  • Tunneled and implanted central venous catheters (e.g. Hickman, Broviac, Port-a-cath):
    These catheters require theatre/ radiology for placement.  They are indicated for long-term PN therapy and prior to their request a discussion to determine their suitability should be had with the nutrition team.  Their advantages include a reduced rate of catheter sepsis.  These catheters are self-retaining due to a cuff which encourages ingrowth of fibrous tissue.  This process generally takes about 3 weeks, and until this time they must be secured in the same manner as a non-tunneled CVC.

If the patient already has a pre-existing long term line (e.g. patients undergoing chemotherapy) consideration should be given to using it for PN.

The following catheters are not to be used for the administration of PN:
• Arterial catheters
• Swan-Ganz catheters
• Peripheral cannulas (used in other centres, but midlines preferred at LTHT)

Caution should be exercised in using the following for PN administration:
• Femoral CVCs
• Vascular catheters

Where there is any doubt the advice of the nutrition team should be sought.

Line Care and PN Management

PN infusions:. PN bags are made in the pharmacy aseptics department and are generally delivered to the ward the same afternoon.

PN is an intravenous medicine and should be treated accordingly in line with LTHT Injectable Medicines Code. [7]  PN bags should be stored in the ward medication fridge until required.  If there is a problem with the bag or prescription, and the feed is not started, then store it overnight in the medication fridge.

When hanging PN infusions, the covering light-protective bag should be used.  An administration set that has been used for lipids must not be used for longer than 24 hours.[5]  If the infusion is interrupted, or if only a part of the bag has been prescribed, the PN must be taken down and the remainder of the feed discarded.

The three types of PN bags used are ‘off the shelf’, ‘tailored standard’ and ‘custom’.  ‘Off the shelf’ and ‘tailored standard’ bags are those provided with a standard content of protein, fat and carbohydrate. The electrolyte, trace element and vitamin content can be altered to individual requirements in a ‘tailored standard’ bag.  Custom bags are used for longer term PN patients, or for those with particular requirements that cannot be met by the ‘tailored standard’ bags.

Out of date or unused PN should be removed from the medicines fridge regularly to avoid possible errors of administration.

Commencing and Changing PN Infusion: CVC and midline dressings:
CVCs and midlines should be dressed as stipulated in the LTHT CVC guideline.[5]

It may be more appropriate to cover established, long-term (i.e. tunneled) CVCs with sterile gauze and tape.  Where patients are used to caring for their own long-term lines or ports they may not cover them at all.  Any catheter should have a clean exit site at all times, and where a dressing is used it should be intact.

Needlefree devices:

These should be changed every 24hours if lipid has been infused through them. Non-lipid infusions require changing every 72hours.

Flushing lines:
The catheter should be flushed before and after use, using a minimum of a 10ml syringe, as detailed in the LTHT CVC guideline.[5]  There is no need to stop a PN infusion merely to flush the catheter.

Removal of CVCs:
CVCs should be removed at the earliest opportunity if no longer required.  CVCs must be removed by competent staff.   Non-tunneled CVCs may be removed in ward areas by competent staff.   Due to the difficulty of freeing the cuff, tunneled catheters should be removed by someone who has demonstrated competency, in a controlled environment.

A protocol for removal of non-tunneled CVCs can be found in the LTHT CVC guideline.[5]

Management of Suspected Central Venous Catheter Infection.

Full LTHT guidelines are here[8]

CVC infection can occur in 3 forms:

  1. Catheter Related Blood Stream Infection (CRBSI) - often a history of pyrexia, rigors etc. after feed is started
  2. Exit site infection - erythema +/- exudate at the exit site of the tunneled line
  3. Tunnel infection - pain along the tract +/- erythema

For anybody presenting with a history consistent with CRBSI, timed, paired peripheral and catheter cultures (from each lumen) should be taken to allow for Differential Time to Positivity testing (if the catheter culture is positive significantly (>2 hours) before the peripheral culture, this implies line sepsis). 

The aim is always to salvage tunneled lines if the organism allows. Further information and initial antibiotic protocols are here.[8]  Patients should always be discussed with the nutrition team.

Stopping PN

The anticipated endpoint of treatment with PN should be discussed at the time of referral if at all possible.  The decision to discontinue PN should be made jointly by the referring team and the nutrition team and documented on PPM+..

In many patients, enteral nutrition and PN may run concurrently and need to be titrated against each other as GI function returns.  As a general rule PN will be stopped once successful enteral feeding is established (or is likely to be so within the next 72 hours if there are vascular access problems).

Some patients require PN at home, either in the medium term (prior to restorative surgery) or long-term (e.g. short bowel syndrome).  This should be considered early, to allow patients to come to terms with all that is involved, initiate training to manage their line (if appropriate) and stabilise them on an intravenous feed.

If the decision to withdraw active treatment is taken by the referring clinical team, PN would usually be discontinued too.

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Record: 2920
  • To ensure patients receiving parenteral nutrition are under the care of the nutrition team.
  • To ensure that all aspects of the patient’s nutritional management are explained, discussed and agreed with the patient,  ward or departmental staff, and with the patient’s family if appropriate.  This includes, but is not exclusive to, parenteral nutrition.
  • To provide an effective and efficient referral pathway.
  • To liaise with the patient’s primary consultant and team in an advisory capacity on clinical issues affecting the patient’s nutritional management.
  • To promote oral/ enteral nutrition when the gut is accessible or functioning.
  • To monitor the patient’s condition and need for continued nutritional support, managing changes appropriate to the patient’s condition.
Clinical condition:

Intestinal Failure

Target patient group: All adult patients within LTHT who receive, or are considered for, parenteral nutrition.
Target professional group(s): Pharmacists
Secondary Care Doctors
Secondary Care Nurses
Allied Health Professionals
Adapted from:

Evidence base

A. Meta-analyses, randomised controlled trials/systematic reviews of RCTs
B. Robust experimental or observational studies
C. Expert consensus.
D. Leeds consensus (where no national guidance exists or there is wide disagreement with a level C recommendation or where national guidance documents contradict each other)

  1. National Institute for Health and Care Excellence. Nutrition support in adults: oral nutrition support, enteral tube feeding and parenteral nutrition. Clinical guideline [CG32]. NICE, 2006
  2. Lal S, Teubner A, Shaffer JL (2006).  Review article: intestinal failure.  Alimentary Pharmacology & Therapeutics 24 (1):19-31
  3. Weimann A, Braga M, Carli F, Higashiguchi T, Hubner M, Klek S, Laviano A, Ljungqvist L, Lobo D, Martindale R, Waitzberg D, Bischoff S, Singer P (2017). ESPEN Guideline: Clinical Nutrition in Surgery. Clinical Nutrition 36: 623-650.
  4. Guidelines for the Management of Adult Patients with Refeeding Problems Undergoing Oral, Enteral or Parenteral Feeding (LTHT)
  5. Guideline for the Insertion, Management, Replacement and Removal of Central Venous Catheters in Adults and Children (LTHT)
  6. Loveday HP, Wilson JA, Pratt RJ, Golsorkhi M, Tingle A, Bak A, Browne J, Prieto J and Wilcox M (2014) epic3: National Evidence-Based Guidelines for Preventing Healthcare-Associated Infections in NHS Hospitals in England.  Journal of Hospital Infection 86(1):S1-70
  7. Leeds Teaching Hospitals Injectable Medicines Code
  8. Guideline for Management of Infected Long-term Intravascular Access Devices in Adults (LTHT)

Approved By

Trust Clinical Guidelines Group

Document history

LHP version 2.0

Related information

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