Malnourished patients make poor surgical candidates. Surgery causes physiological stress with a resultant hyper-metabolic state and catabolic response, which is not favoured in the malnourished patient.
A proportion of surgical patients will have a degree of malnutrition owing to their underlying disease process thus reducing their nutritional reserves in the post-operative period. Malnourised patients are at increased risk of post-operative complications such as reduced wound healing, infection and skin breakdown.
Clearly it is important that any patient undergoing elective or semi-elective surgery should be assessed for evidence of malnutrition and where possible this should be corrected or nutrition supported both pre- and post-operatively.
All patients admitted to hospital should be screened for malnutrition and have their nutritional state assessed.
Screening for malnutrition can be achieved using the Malnutriton Universal Screening Tool (MUST). The MUST score can easily be calculated by any health professional, however this may be unnecessary as disease-related cachexia is usually obvious with bedside observation, noting features such as muscle wasting, loose skin, and the patient’s usual clothes no longer fitting*.
Following screening, nutritional assessment requires expert input from a Registered Dietitian (RD). Tools used to assess nutritional state are weight, Body Mass Index (BMI), Grip Strength, Triceps Skin Fold thickness and Mid Arm Circumference.
BMI = Weight(kg) / Height(m)2 (normal range 18.5-24.9 kg/m2)
*Additional features such as aphthous ulcers, angular cheilitis, and pressure sores can provide additional clues
Pre-operative Nutritional Support
If malnutrition is identified then nutritional support may be appropriate as this improves surgical outcomes. The decision when and how to deliver nutritional support, and the timing of subsequent surgery, should be decided on a case-by-case basis.
An appropriate schedule for nutritional support should be given with the assistance and under the direction of a registered dietitian. The type of nutritional support that can be offered will depend largely on the pathology present.
As a general principle, it is always best to give enteral nutrition via the oral route wherever possible (this applies to both pre- and post-operative nutrition). However for many patients it may not be possible to administer sufficient calories via this route and alternative nutrition support strategies will need to be considered.
There is a simple hierarchy of feeding methods that should be followed and applied appropriately.
Hierarchy of Feeding
|If unable to eat sufficient calories||Oral nutritional Supplements (ONS)|
|If unable to take sufficient calories orally or dysfunctional swallow||Nasogastric tube feeding (NGT)|
|If oesophagus blocked/dysfunctional||Gastrostomy feeding (PEG/RIG)|
|If stomach inaccessible or outflow obstruction||Jejunal feeding (jejunostomy)|
|If jejunum inaccessible or intestinal failure (IF)||Parenteral nutrition|
It is important to note that whilst malnutrition should be treated, it should not be a cause for delaying surgery unnecessarily. For example, a patient with active Crohns disease who requires surgery should not have the surgery delayed in order to improve their nutritional state (as it is highly unlikely to be achievable in the presence of active disease).
Patients with Intestinal Failure
Patients with intestinal failure often (but not always) need parenteral nutrition. Timing of surgery is therefore crucial and it is helpful to remember the mnemonic SNAP for such cases:
- Sepsis – any overwhelming infection present must be corrected otherwise feeding will be largely useless
- Nutrition – Once the infection is corrected, suitable nutritional support should be provided
- Anatomy – Define the anatomy of the GI tract so that surgery can be planned
- Procedure – definitive surgery once any infection eradicated, the patient nourished, and the anatomy defined
The Albumin Myth
Whilst a low serum albumin is associated with poorer surgical outcomes there is a common misunderstanding that low serum albumin reflects nutritional state. It does not.
A low serum albumin reflects either chronic inflammation, protein losing enteropathy, proteinuria, or hepatic dysfunction, but does not reflect malnutrition (as witnessed by the fact that patients with severe anorexia nervosa have a normal serum albumin).
The concept of a ‘period of pre-operative feeding to improve the albumin’ is nonsense and unachievable, and it is the underlying cause of the low albumin that should be treated rather than simply feeding the patient.
It is now recognised that the age-old surgical mantra of very slow reintroduction of oral diet and mobilisation post-operatively was misplaced.
The introduction of Enhanced Recovery After Surgery (ERAS) was revolutionary engendering real change and is now an established part of surgical practice. The basic tenets behind ERAS consist of:
- Reduction in ‘Nil By Mouth’ times (fluids up to 2 hours pre-surgery)
- Pre-operative carbohydrate loading
- Minimally invasive surgery
- Minimising the use of drains and nasogastric tubes
- Rapid reintroduction of feeding post-operatively
- Early mobilisation
There is good evidence that early post-operative feeding reduces post-operative complications and the Enhanced Recovery After Surgery (ERAS) protocol is designed to start post-operative feeding as soon as possible (coupled with early mobilisation to reduce muscle loss).
It is now recognised that most surgical patients can safely tolerate an enteral diet within 24 hours of uncomplicated gastrointestinal surgery without increasing the risk of post-operative complications.
Entero-cutaneous Fistulae (ECF) should not produce a knee-jerk reaction for parenteral nutrition, as the proportion of ECF that will heal spontaneously with PN is relatively small. Thus the strategy should be supporting nutrition prior to a likely surgical repair.
The modern nutritional management of ECF is dependent upon the level of the fistula*. High fistula (jejunal) may need support with enteral or parenteral nutrition, whilst low fistulae (ileum/colon) can be treated with low fibre diet. Thus imaging is often critical to deciding how the fistula should be managed effectively.
*The presence of faeculaent material emanating from an ECF is not necessarily an indication for parenteral nutrition and a trial of enteral nutrition is often indicated.
High Output Stoma
The nutritional support and treatment for High Output Stoma (HOS) is dependent upon:
Length of Bowel to Stoma
For a jejunostomy…
Distance From DJ Flexure to Jejunostomy
Probable Nutritional Requirements
|100-150cm||Enteral support +/- IV fluids|
For a colostomy…
Distance From DJ Flexure to Colostomy
Probable Nutritional Requirements
|50-100cm||Enteral support +/- IV fluids|
Presence of Disease
The presence of persistent disease or systemic infection can drive stoma output independent of the length of any residual bowel
Once active disease or infection has been excluded, then a reduction in stoma output can be achieved by:
- Reduction in hypotonic fluids to 500mls/day
- Reduction in gut motility with high dose loperamide and codeine phosphate
- Reduction in secretions with high dose proton pump inhibitors (a twice daily dose)
- Use of WHO solution to reduce sodium losses
- Low fibre diet to reduce intraluminal retention of water
With thanks to Dr JAD Stewart, Clinical Lead, Leicester Intestinal Failure Team, University Hospitals of Leicester