optimisation of nutrition before surgery for 10 marks
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Optimisation of Nutrition Before Surgery (10 Marks)
1. Importance of Preoperative Nutritional Status
Malnutrition is a major risk factor for surgical morbidity and mortality. Malnourished patients are three times more likely to suffer postoperative complications and five times more likely to die compared to well-nourished patients. The metabolic stress of surgery further increases demands for energy and protein, making preoperative optimisation essential.
- Sabiston Textbook of Surgery
2. Nutritional Assessment
Before any intervention, nutritional status must be formally assessed:
History & Examination
- Weight history: unintentional weight loss >5% in 1 month, or >10% over 6 months, indicates nutritional risk
- Dietary history: recent intake, use of supplements
- Physical signs: temporal wasting, peripheral oedema, reduced muscle mass, poor skin turgor, petechiae/ecchymoses, pressure ulcers
- BMI: BMI <18.5 with impaired general condition = severe malnutrition
Screening Tools — NRS-2002 (Nutritional Risk Screening 2002)
The most widely used validated tool. Scores two domains:
| Domain | Mild (1) | Moderate (2) | Severe (3) |
|---|---|---|---|
| Nutritional status | Weight loss >5% in 3 months or intake <50–75% of normal | Weight loss >5% in 2 months or BMI 18.5–20.5 | Weight loss >5% in 1 month (>15% in 3 months) or BMI <18.5 |
| Severity of disease | Chronic illness (COPD, diabetes, oncology) | Major abdominal surgery, stroke | Head injury, bone marrow transplant, ICU (APACHE >10) |
- Score >3 → patient is nutritionally at risk; initiate a nutritional care plan before surgery
- Score <3 → weekly re-screening; consider preventive plan if major surgery planned
- Age ≥70 years: add 1 point
For patients with mild malnutrition only, surgery should not be delayed for nutritional supplementation. Prehabilitation is reserved for severely malnourished patients.
- Sabiston Textbook of Surgery
Biochemical Markers
- Albumin (half-life 20 days): reflects chronic nutritional status; albumin <3.5 g/dL is a strong predictor of postoperative morbidity and mortality
- Prealbumin (half-life 2 days): reflects recent nutritional status
- Transferrin (half-life 8–9 days): must be interpreted in context of iron status
- ⚠️ Both albumin and prealbumin are negative acute-phase reactants — they fall during inflammation/stress, so they are less reliable in acutely ill surgical patients
3. Nutritional Interventions
A. Energy & Protein Supplementation
- Oral nutritional supplements (ONS) rich in energy and protein enhance muscle mass, immune function, and overall nutritional status
- A meta-analysis in Annals of Surgery (2019) showed preoperative nutritional supplementation reduced postoperative complications in GI surgical patients
- Critically ill patients require 1.5–2.5 g protein/kg/day; open abdominal wounds may need an additional 15–30 g/L of peritoneal fluid loss
B. Carbohydrate Loading
- Traditionally, patients fasted from midnight before surgery; modern guidelines recommend clear carbohydrate drinks up to 2 hours before anaesthesia in non-diabetic patients
- Benefits:
- ↓ Insulin resistance postoperatively
- ↑ Muscle glycogen stores
- ↓ Postoperative catabolism
- Improved patient comfort and sense of well-being
- A Cochrane review (2014) found preoperative carbohydrate loading was associated with improved outcomes and reduced hospital stay
- A 2024 systematic review (JPEN J Parenter Enteral Nutr, PMID 38676554) confirms ongoing evolution of carbohydrate loading practice
C. Immunonutrition
Key immunonutrients include:
| Nutrient | Mechanism | Benefit |
|---|---|---|
| Omega-3 fatty acids | Compete with pro-inflammatory omega-6 fatty acids; divert arachidonic acid away from PGE2/LTB2 toward PGE3/LTB5; inhibit neutrophil migration | ↓ Systemic inflammation, ↓ infection rates, shorter hospital stay |
| Arginine | Depleted during surgical stress response; substrate for nitric oxide synthesis and T-cell function | ↓ Infection rates, improved wound healing |
| Glutamine | Fuel for enterocytes and immune cells; supports gut mucosal integrity | ↓ Bacterial translocation |
Each of these has individually demonstrated ability to reduce hospital stays and infection rates following surgery in chronically ill patients.
- Sabiston Textbook of Surgery
D. Micronutrient Optimisation
Deficiencies must be identified and corrected preoperatively:
| Micronutrient | Role | Deficiency Sign |
|---|---|---|
| Vitamin C | Collagen synthesis, wound healing | Scurvy, bleeding gums |
| Vitamin D | Immune modulation, muscle function | Osteomalacia |
| Zinc | Wound healing, immune function | Poor wound healing |
| Iron | Oxygen-carrying capacity | Anaemia |
| Thiamine | Cardiac and neurological function | Heart failure (beriberi) |
A 2025 systematic review (J Acad Nutr Diet, PMID 39306086) specifically emphasises preoperative micronutrient repletion strategies, especially in bariatric surgery patients.
E. Route of Nutritional Support
- Enteral route is preferred — maintains gut mucosal integrity, reduces bacterial translocation, avoids risks of central venous access
- Parenteral nutrition (TPN) is reserved for patients with severe malnutrition who cannot tolerate enteral feeding
- Veterans Affairs TPN Cooperative Trial (1991): overall higher infectious complications with TPN, but severely malnourished patients receiving TPN had fewer non-infectious complications → TPN has a role in select severely malnourished patients only
- Sabiston Textbook of Surgery
4. Weight and BMI Optimisation
- Obese patients: preoperative weight loss improves surgical outcomes and reduces postoperative complications — particularly relevant in bariatric, orthopaedic, and abdominal surgery
- Underweight patients: nutritional prehabilitation over 7–14 days with high-protein, high-calorie supplements before elective major surgery
5. Multimodal Prehabilitation (ERAS Framework)
Nutritional optimisation is one pillar of the Enhanced Recovery After Surgery (ERAS) protocol. Preoperative components include:
- Nutritional assessment and supplementation
- Carbohydrate loading
- Smoking and alcohol cessation (↓ wound infection, ↓ cardiorespiratory risk)
- Exercise/physical conditioning
- Patient education and expectation-setting
ERAS pathways reduce postoperative complications, length of hospital stay, and healthcare costs across colorectal, hepatobiliary, bariatric, and other surgical specialties.
- Schwartz's Principles of Surgery, 11th Edition
Summary Table
| Intervention | Target | Evidence |
|---|---|---|
| NRS-2002 screening | Identify at-risk patients | ESPEN guidelines |
| Protein/energy supplementation | Malnourished patients | Annals of Surgery meta-analysis |
| Carbohydrate loading | All elective patients | Cochrane review 2014 |
| Immunonutrition (arginine, omega-3, glutamine) | Chronically ill/GI surgery | Systematic reviews |
| Micronutrient correction | Documented deficiencies | JPEN guidelines |
| TPN prehabilitation | Severely malnourished only | VA TPN Trial |
| Weight optimisation | Obese and underweight | Multiple RCTs |
Key Principle: Evidence-based preoperative nutrition involves comprehensive assessment followed by individualised, targeted interventions — not a one-size-fits-all approach. The goal is to build metabolic reserve, optimise immune function, and reduce the physiological debt incurred by surgical stress.
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