Disease-related malnutrition (DRM) continues to be a common problem among hospitalised patients despite growing evidence describing both its clinical and economic consequences. A recent study by the British Association of Parenteral and Enteral Nutrition¹ involving 1,670 patients found that, in Ireland, over one-third of patients admitted to hospital are at risk of malnutrition, and one-quarter of all patients are at high risk. 

Surgical patients are particularly vulnerable and it is estimated that more than 30% of malnourished patients are on surgical wards.¹ Although the link between nutritional status and surgical outcome is well documented, only 24% of Irish hospitals have a screening tool policy in place.¹

Aetiology of DRM

The aetiology of DRM is complex. Malnutrition occurs where dietary intake is insufficient to meet nutritional requirements, impaired digestion and absorption, excess nutrient losses or a combination of these factors. 

Patients undergoing major surgery for upper and lower gastrointestinal (GI) cancer (oesophageal resection, gastrectomy, colorectal surgery etc.) often present with pre-existing malnutrition due to the effects of the underlying pathology and its associated symptoms. 

Dietary intake can be severely impaired by persistent nausea, vomiting, progressive dysphagia, odynophagia and early satiety, resulting in chronic anorexia and weight loss. 

Nutrient absorption may be impaired or excess losses incurred due to diarrhoea, inflammation, fistulae or by partial/complete obstruction within the gut. Where there is a combination of reduced intake, high losses and increased nutritional requirements, nutritional depletion is an inevitable consequence. 

At diagnosis, up to 87% of oncology patients will have lost weight, the severity of which will depend upon the primary tumour site.² Cancer cachexia – a complex syndrome characterised by progressive, involuntary weight loss, anorexia, and a systemic pro-inflammatory process resulting in multiple metabolic derangements – is frequently observed in surgical patients with malignant disease, and can result in significant reduction in nutritional status.²

Malnutrition and surgical outcome

It is well known that malnutrition has a negative impact on post-operative clinical outcome. Malnourished patients have a significantly higher incidence of post-op complications including impaired wound healing,^3,4 nosocomial infections,⁵ sepsis and pneumonia,⁶ compared to their better-nourished counterparts; and malnutrition itself is considered an independent risk factor for the incidence of infectious complications.^7,8

The incidence of post-operative complications is higher in malnourished patients with upper GI and colorectal cancer,¹⁰ and those undergoing major intra-abdominal surgery.⁶ Malnourished surgical patients have a significantly higher rate of mortality,⁶ longer length of hospital stay and generate higher healthcare expenses.⁷

Preoperative screening and nutrition support

Approximately 40% of patients may be at nutritional risk preoperatively,^10,11 therefore early identification and management of ‘at-risk’ candidates is key to ensuring a positive surgical outcome. Ideally, all surgical candidates should undergo nutritional screening upon admission, using a validated screening tool such as the Malnutrition Universal Screening Tool (MUST)¹² or another locally agreed validated tool. 

Screening is a rapid procedure involving the identification of characteristics known to be associated with malnutrition (eg. unintentional weight loss over a defined timescale, lack of nutritional intake, etc.) and the initiation of a defined care plan outlining how to treat and monitor the patient thereafter. 

If deemed at ‘high risk’ of malnutrition, patients can then be referred to a dietitian for comprehensive nutritional management. At present, only 24% of Irish hospitals have a screening tool policy in place and only 52% have screening results linked to a care plan.¹

In candidates with severe nutritional risk due to undergo major surgery, preoperative nutritional support using oral nutritional supplements (ONS) is recommended for approximately 10-14 days prior to surgery, even if surgery has to be delayed, to allow improvement in nutritional status.¹³

Preoperative nutrition support for five to seven days with ONS or an enteral enriched with immune modulating substrates (arginine, π-3 fatty acids and nucleotides) may be of benefit to cancer patients undergoing major upper abdominal surgery, regardless of their nutritional risk.¹³

Perioperative nutrition support

Traditionally, perioperative nutritional care has involved a number of practices which impact upon nutritional status. 

Preoperatively, patients were fasted from midnight, with no solid food post-bowel preparation, and post-operatively they would remain nil per os (NPO) to allow bowel rest until bowel sounds or passing of flatus were observed. 

In recent years, evidence has shown that such routines can have a major impact upon the stress response to surgery, the return to normal physiological function, tolerance to feeding and overall nutritional and functional status post-operatively.¹⁴ Enhanced recovery of patients after surgery (ERAS) has become an important focus of perioperative management. 

From a metabolic and nutritional standpoint, perioperative care should aim to reduce the stress of surgery, minimise catabolism and support anabolism through:

• Avoidance of long periods of preoperative fasting
• Re-establishment of oral feeding as early as possible after surgery
• Integration of nutrition into the overall management of the patient
• Metabolic control, ie. of hyperglycaemia
• Reduction of factors which exacerbate stress-related catabolism or impair GI function
• Early mobilisation.¹³

Preoperative fasting from midnight is unnecessary in most patients.¹³ Even 12 hours of preoperative fasting has been associated with prolonged recovery after uncomplicated surgery.^15,16 Patients should be in the fed state rather than the fasted state when they go to theatre, hence clear fluids can be taken up until two hours, and solid foods up to six hours prior to anaesthesia.¹³

Preoperative carbohydrate loading with a clear carbohydrate-rich beverage before midnight and then two to three hours prior to surgery can significantly reduce post-operative insulin resistance,¹⁷ allowing for an increased anabolic state, preserved lean body mass, greater benefit from post-operative nutrition support¹⁸ and reduced risk of hyperglycaemia. 

In response to surgical trauma, there is an increase in basal metabolic rate (BMR), the release of inflammatory mediators, ie. cytokines and acute phase proteins along with the activation of stress hormones. The release of these mediators causes a change of metabolism to the catabolic state whereby visceral and muscle protein, fat and glycogen are broken down to provide substrates for wound healing and immune response.¹³

If this process is prolonged or excessive, progressive depletion of muscle mass and fat stores can ensue, and such depletion is magnified if there is pre-existing malnutrition. Minimising the development of catabolism and returning the patient from the catabolic state to one of anabolism is an important post-operative therapeutic goal, and one in which nutrition has a central role. Post-operative nutritional support should be commenced without delay (ie. within 24 hours) in nutritionally ‘at-risk’ patients:

• If it is anticipated that the patient will be unable to eat for > 7 days perioperatively (even in well nourished patients)
• If oral intake is likely to be inadequate, ie. < 60% of recommended intake for > 10 days
• If there is obvious undernutrition at the time of surgery.¹³

Patients who will require post-operative nutritional support, whether through the oral, enteral or parenteral route, should be identified and referred to a dietitian for appropriate nutritional management, ideally prior to surgical intervention, to allow time for repletion of nutritional status in the preoperative phase. 

Those who have undergone major abdominal surgery are at high nutritional risk post-op, particularly where surgery involves removal of a significant portion (or all) of the oesophagus, stomach or small bowel. In these candidates, early post-operative enteral feeding distal to the anastemosis via surgically placed jejunostomy is beneficial, safe, well tolerated^13,19 and will facilitate longer-term nutritional support if needed. Nasojejunal tube feeding is also well tolerated¹⁹ and may benefit those who are likely to need short-term nutritional support. In the short-to-long term, GI surgical patients may experience nutrition-related side-effects as a result of surgery.

Conclusion

In conclusion, early identification and management of disease-related malnutrition is key to ensuring a positive surgical outcome. 

All surgical patients should be screened on admission (or earlier, in the outpatient setting, for example) to allow timely and effective nutritional management. Within the Irish hospital setting the routine use of nutritional screening tools is highly inadequate and much improvement is needed.

References

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