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Preoperative Assessment and Optimisation of Nutrition in Surgical Patients

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Why Nutrition Matters Perioperatively

• Impaired wound healing
• Increased susceptibility to infection and surgical site complications
• Electrolyte abnormalities and fluid imbalance
• Organ dysfunction (renal, cardiac, hepatic)
• Gastrointestinal fistula formation
• Prolonged hospital length of stay and higher health-care costs
• Increased mortality

Sabiston Textbook of Surgery, Schwartz's Principles of Surgery 11e, Current Surgical Therapy 14e

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Part 1: Preoperative Nutritional Assessment

1.1 History

1.2 Physical Examination

1.3 Anthropometric Measures

• Skinfold thickness
• Mid-arm circumference and muscle area
• Calculated BMI

1.4 Biochemical Markers

Important caveat: Albumin and prealbumin are both negative acute-phase proteins — they fall during inflammation or acute illness independent of nutritional intake. Reliance on these values in isolation is inadequate and can be misleading; they must be interpreted in the full clinical context.

1.5 Validated Screening Tools

Nutritional Risk Screening (NRS-2002) — Most widely used

Sabiston Textbook of Surgery

Other Screening Tools

• PONS (Perioperative Nutrition Screen): Modified version of the Malnutrition Universal Screening Tool (MUST); considers BMI, recent weight change, recent decreased dietary intake, and preoperative albumin
• NUTRIC Score: Validated for critically ill and injured patients in the ICU
• Malnutrition Screening Tool (MST): Patient-reported; assesses weight loss and appetite loss
• Mini Nutritional Assessment Short-Form (MNA-SF): Validated for older adults

NSQIP/AGS Severe Nutritional Risk Criteria (any one of):

1. BMI <18.5 kg/m²
2. Serum albumin <3.0 g/dL
3. Unintended weight loss >10% within 6 months

Morgan & Mikhail's Clinical Anesthesiology 7e

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Part 2: Preoperative Nutritional Optimisation

2.1 Who to Optimise

• NRS-2002 score ≥3
• BMI <18.5 kg/m² or >40 kg/m² (obesity also increases nutritional risk)
• Serum albumin <3.5 g/dL in well-hydrated, non-acutely ill patients
• Recent significant unintentional weight loss
• Cancer, IBD, cirrhosis, chronic renal failure, chronic systemic inflammation

2.2 Energy Requirements

25–30 kcal/kg/day (using dry or usual body weight)

Schwartz's Principles of Surgery 11e

2.3 Protein Requirements

• Healthy adults: 0.8 g/kg/day
• Surgical/critically ill patients: 1.2–2.0 g/kg/day
• BMI >30 (obese): higher protein intake recommended
• Burns, polytrauma: up to 2.5 g/kg/day

2.4 Route of Nutritional Support

• Lower cost
• Avoidance of vascular access risks
• Preservation of gut mucosal integrity and barrier function
• Reduced bacterial translocation
• Maintained intestinal immune function

2.5 Vitamins and Minerals

• In patients with an uncomplicated course, standard dietary intake usually meets micronutrient needs
• Patients on elemental diets or total parenteral nutrition (TPN) require complete vitamin and mineral supplementation
• Most IV vitamin preparations do not contain vitamin K, B₁₂, or folate — supplementation must be ensured
• Essential fatty acid supplementation may be necessary in patients with depleted adipose stores
• Trace minerals (zinc, selenium, copper) should be provided in TPN

2.6 Preoperative Oral Nutritional Supplements (ONS)

• High-protein oral supplements should be initiated
• Immunonutrition formulas (containing arginine, omega-3 fatty acids, glutamine, nucleotides) have been trialled preoperatively in major GI cancer surgery — evidence of reduced infectious complications in specific populations

2.7 Prehabilitation

• Exercise/physical conditioning
• Psychological preparation
• Optimisation of comorbidities

2.8 Avoiding Overfeeding

• Increased O₂ consumption and CO₂ production
• Prolonged mechanical ventilation requirement
• Hepatic steatosis
• Hyperglycaemia and increased infection risk
• Suppressed leukocyte function

2.9 Glycaemic Control

• Hyperglycaemia inhibits wound healing, promotes inflammation and infection, and contributes to multiorgan dysfunction
• A balanced approach is critical: minimise hypoglycaemia and moderately control hyperglycaemia

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Part 3: Special Situations

Obese Patients (BMI >30)

• At risk of concurrent malnutrition despite excess calories — micronutrient deficiencies are common
• Higher protein targets required (up to 2 g/kg ideal body weight/day)
• Pre-bariatric surgery patients: 2025 meta-analysis (PMID 40362842) confirms benefits of preoperative nutritional interventions on outcomes

Elderly Patients

• Liver mass and albumin production decline with age
• MNA-SF or SNAQ recommended for screening
• Malnutrition is common and independently predicts adverse postoperative outcomes; often coexists with frailty
• Screen for dysphagia — impacts nutritional intake and aspiration risk

Cancer Patients

• High prevalence of cancer-associated malnutrition and cachexia
• Nutritional support cannot fully reverse cancer cachexia but can attenuate it
• Early dietitian involvement is recommended
• Major abdominal surgery scores as "moderate" disease severity on NRS-2002

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Summary Algorithm

ALL SURGICAL PATIENTS
        ↓
Preoperative Nutritional Screening (NRS-2002, PONS, MST)
        ↓
    Score ≥3 or severe risk criteria met?
   /                                    \
  YES                                    NO
   ↓                                      ↓
Refer to dietitian                  Weekly rescreening
Full nutritional assessment         Standard care
  ↓
Optimise energy (25-30 kcal/kg/day)
Optimise protein (1.2-2.0 g/kg/day)
Enteral route preferred
Oral nutritional supplements if needed
Micronutrient repletion
Glycaemic optimisation
Consider prehabilitation programme
  ↓
Reassess before surgery
Postoperative: restart nutrition plan early

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