CLINICAL
PRE-OPERATIVE NUTRITION Any form of surgical procedure causes the body physiological stress, the extent to which depends on the severity of the surgery.1 Surgical procedures can have a profound impact on a patient’s nutritional status and this article sheds light on the importance of adequate nutrition in the lead up to surgery. Most surgical procedures do not require a specific diet to be followed prior to surgery other than a well-balanced and healthy diet. We should all be aiming to eat more fruit and vegetables, wholegrains, and oily fish,2 keeping the government Eatwell Guide in mind (see Figure 1). In the UK, it is recommended that we consume two portions of fish a week, with at least one portion (140g) from oily fish.4 We should also choose lean meats and low-fat dairy, as well as heart healthy fats such as olive oil and rapeseed oil. Saturated fat, alcohol and caffeine should be limited to recommended amounts. Most younger and middle-aged people in the UK consume above the recommended daily amount of protein;2 however, people who follow a vegan or vegetarian diet should make sure they are consuming adequate amounts of protein from plant-based sources such as lentils, chickpeas, peanuts, tofu, edamame beans. Elderly people and people with chronic illnesses do not always consume enough protein in their diet, which can lead to muscle loss and sarcopenia, so optimising protein intake prior to surgery is important.5 ESPEN guidelines suggest that healthy older people should have at least 1.0-1.2g of protein per kilogram of bodyweight per day, and those with acute or chronic illnesses may require as much as 1.5g of protein per kilogram of bodyweight per day.6 It’s important that patients are adequately hydrated in the lead up to their surgery to avoid dehydration, as this can cause post-operative complications.7
SPECIFIC DIETARY REQUIREMENTS
In some cases, specific dietary requirements apply. For example, before bariatric surgery, a supervised weightmanagement program is recommended. This involves patients following a verylow-calorie diet (sometimes referred to as a liver-shrinking diet) for several weeks. This dietary approach has been associated with a 10% weight loss and a 15-20% reduction in liver volume, making the surgery easier to perform.8 In addition, patients with diabetes require an individualised approach. The Joint British Diabetes Societies for Inpatient Care have released a specific set of recommendations for the management of adults with diabetes undergoing surgery and elective procedures. During the pre-operative stage, they recommend that clinicians should:9 • assess adequacy of glycaemic control against the urgency of procedure; • consider a referral to the diabetes specialist team; • identify other comorbidities with referral to appropriate teams for optimal management where necessary; • ensure availability of usual insulin and medications; • give the patient clear written instructions for any changes to their medication as well as fasting guidelines prior to admission; • ensure patients with diabetes are not placed on an evening list as this avoids prolonged starvation times.
Harriet Smith RD Freelance Dietitian and Health Writer Harriet is Founder of Surrey Dietitian providing private dietetic consultations and consultancy services, offering evidence-based nutritional advice, backed up by the latest research on food, health and disease. Harriet has written for national, consumer and industry media. www.surrey dietitian.co.uk @SurreyDietitian
REFERENCES Please visit the Subscriber zone at NHDmag.com
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Getting Nan back to her old tricks again!
is a powdered, neutral-tasting carbohydrate loading drink mix for the pre-operative dietary management of patients undergoing surgery. has been shown An Enhanced Recovery Programme including the use of to significantly reduce post-operative hospital stay with a return towards earlier gut 1 function when compared with fasting or supplementary water. Helping patients get back to doing the things that they enjoy sooner.
Preload™ is a Food for Special Medical Purposes and must be used under strict medical supervision. 1. Noblett S, Watson D, Huong H, Davidson B, Hainsworth P, Horgan A (2006) Pre-operative oral carbohydrate loading in colorectal surgery: A randomized controlled trial. Colorectal Disease: 8, 563-569.
A Nestlé Health Science Company
www.vitaflo.co.uk Nutritional Helpine: 0151 702 4937
® Reg. Trademarks of Société des Produits Nestlé S.A.
CLINICAL Figure 1: Government Eatwell Guide3
Eatwell Guide
Check the label on packaged foods
Use the Eatwell Guide to help you get a balance of healthier and more sustainable food. It shows how much of what you eat overall should come from each food group.
Each serving (150g) contains Energy 1046kJ 250kcal
13%
Fat
Saturates Sugars
3.0g 1.3g LOW
LOW
4%
7%
Salt
34g 0.9g HIGH
38% 15%
of an adult’s reference intake Typical values (as sold) per 100g: 697kJ/ 167kcal
of a
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Soya drink
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Whilst there are no general clinical guidelines on vitamin and mineral supplementation prior to surgery, some surgeons may give specific recommendations. For example, pre-operative oral iron supplementation is sometimes used in patients undergoing colorectal10 or joint surgery11 to reduce transfusion requirements. The UK government recommends that people over the age of one should take a daily 10mcg vitamin D supplement,12 particularly during autumn and winter, due to the reduced exposure to sunlight (the main source of vitamin D in the UK). Vitamin D is an important component in musculoskeletal development and deficiency is thought to have widespread consequences for bone healing.13 It is important that patients inform their surgeon of any supplements or herbal remedies they are taking prior to their operation, as these may interact with certain medications. Several potential adverse interactions between commonly used herbal supplements and analgesic drugs are listed below.14
Lower fatad spre
Plain Low fat y o g hu r t
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Per day Source: Public Health England in association with the Welsh Government, Food Standards Scotland and the Food Standards Agency in Northern Ireland
NUTRITIONAL SUPPLEMENTS
Limit fruit juice and/or smoothies to a total of 150ml a day.
Rice
Lentils
Eat less often and in small amounts
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Choose unsaturated oils and use in small amounts
2500kcal = ALL FOOD + ALL DRINKS © Crown copyright 2016
• Non-steroidal anti-inflammatory drugs (NSAIDs) can interact with certain herbal supplements and increase the risk of bleeding. These include: - those with antiplatelet activity (ginkgo, garlic, ginger, bilberry, Dong Quai, feverfew, ginseng, turmeric, meadowsweet and willow); - those containing coumarin (chamomile, motherwort, horse chestnut, fenugreek and red clover); - tamarind; - opioid analgesics can interact with sedative herbal supplements (valerian, kava and chamomile), which can increase central nervous system depression. • Paracetamol can interact with some of the herbal supplements mentioned above (and gingko), which increases the risk of bleeding. • Paracetamol can also react with certain herbal supplements and increase the risk of hepa-totoxicity and nephrotoxicity. These include: www.NHDmag.com August/September 2019 - Issue 147
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CLINICAL - echinacea and kava; - herbs containing salicylate (willow, meadowsweet). OPTIMISING NUTRITIONAL STATUS
Studies have shown that being malnourished prior to surgery is associated with a significantly higher risk of post-operative complications, including surgical site infection.15 A person is classified as malnourished if they meet a set of criteria that includes a low BMI (<20kg/ m2), unintentional weight loss (5-10% of their usual body weight) over the past three to six months and being acutely unwell with little or no nutritional intake for five or more days.16 Guidelines recommend delaying elective surgery in patients with malnutrition until their nutritional status has improved.17 Although obesity is no longer considered a risk factor for post-operative complications,18 it can increase the operating time.19 Nutritional screening is recommended in NICE guidelines for all inpatient hospital admissions in the UK and patients should be reviewed weekly thereafter. Patients should have their height and weight measured during their pre-op assessment and at regular intervals after their operation.20 Unfortunately, research suggests that pre-operative nutritional status of surgical patients is poorly conducted, even though pre-operative weight loss is widely recognised as a post-operative cause of morbidity and mortality.17 FASTING
Prior to surgery, patients are required to fast (usually overnight) to reduce their risk of complications during the general anaesthetic.21 The rationale behind pre-operative fasting is to reduce the volume and acidity of gastric contents, which, in turn, reduces the risk or regurgitation and aspiration of gastric contents into the lungs during surgery. However, there is lack of evidence to support this rationale.17 Most hospitals have their own fasting policies and each hospital will inform their patient of the fasting guidelines prior to their operation. The Royal College of Nursing guidelines for pre-operative fasting in the UK permit low-risk patients to have clear fluids 28
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for up to two hours before surgery and milky drinks and solid foods up to six hours prior to surgery.17 CARBOHYDRATE LOADING
In recent years, carbohydrate loading has received widespread attention. Consuming carbohydrate-containing drinks up to two hours before surgery has been found to be an effective way to attenuate insulin resistance, minimise protein losses, reduce hospital stays and improve patient comfort without adversely affecting gastric emptying.22 Thus, carbohydrate loading has been included in many fast-track surgery protocols; however, components of these protocols have not been subject to critical analysis.17 A 2014 Cochrane review evaluated the findings from 27 randomised controlled trials, which included almost 2000 participants. They found that giving patients at least 45g carbohydrate drinks within four hours of surgery or anaesthesia start time, resulted in patients going home half a day earlier than those receiving a placebo drink following traditional fasting guidelines. However, the carbohydrate drinks had no effect on reducing complication rates. The authors also concluded that the quality of evidence varied, and over half of the studies were at a high risk of bias.23 CONCLUSION
Ensuring that a patient is well-nourished and hydrated prior to surgery is crucial for optimising recovery and clinical outcomes. Dietitians play an important role in ensuring that hospital trusts are implementing appropriate nutritional screening guidelines for all inpatients so that malnutrition can be identified and addressed early on. Common surgical procedures do not require specific pre-operative dietary approaches, other than eating a healthy balanced diet and following hospital fasting guidelines. However, patients undergoing specific surgeries, or those with certain medical conditions, or medications/ supplements, may require an individualised dietary approach, which may require support from dietitians and other healthcare professionals.