Enhanced Recovery After Surgery (ERAS)

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Enhanced Recovery after Surgery (ERAS) pathways refer to evidence-based, multidisciplinary, patient-centred strategies developed for each surgical specialty to achieve early recovery and reduce post-operative complications.

This approach has been adopted in most hospitals across the UK for various elective surgeries, especially colorectal and orthopaedic procedures.

The main goals for ERAS pathways include:

  • Pre-operative optimisation and preparation for surgery
  • Reducing the stress response to surgery
  • Early recovery and return to normal daily function
  • Reducing post-operative complications, mortality and morbidity
  • Decreased length of hospital stay
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Stress response to surgery

Surgery is a significant physical stressor that triggers a cascade of hormonal, metabolic and immune responses aimed at maintaining homeostasis and promoting healing. Below are several key aspects of the stress response to surgery.

Neuroendocrine response

The hypothalamic-pituitary-adrenal (HPA) axis is activated in response to surgery, leading to the release of corticotrophin-releasing hormone, which stimulates the release of adrenocorticotrophic hormone (ACTH) from the anterior pituitary gland.

ACTH induces the release of cortisol from the adrenal glands. Cortisol acts on tissue receptors, leading to hyperglycemia and peripheral insulin resistance. It also has roles in suppressing the inflammatory and immune responses of the body.

Sympathetic nervous system (SNS) activation

SNS is activated during surgery resulting in the release of catecholamines such as adrenaline and noradrenaline. These hormones increase heart rate, blood pressure and respiratory rate in order to redirect blood flow to vital organs.

Metabolic changes

Surgery can lead to alterations in metabolism, including increasing energy expenditure, protein breakdown, and gluconeogenesis, which results in hyperglycaemia.

Hyperglycemia is a major factor causing poor wound healing, prolonged hospital stays, and an increased risk of nosocomial infections.

Fluid and electrolyte imbalance

Surgical trauma can result in significant fluid shifts, electrolyte disturbances and dehydration. Sympathetic nervous system induced activation of the renin-angiotensin-aldosterone (RAAS) system causes aldosterone and anti-diuretic hormone levels to increase in the body, leading to sodium and water retention.

Components of ERAS pathways


Preoperative assessment aims to identify patients’ risk factors and subsequently tailor the surgical technique, anaesthetic technique and location of postoperative care. Comorbidities such as diabetes, asthma, ischemic heart disease and hypertension are optimised during this period.

Patient education

Patient education is an essential part of an ERAS protocol. Patients and their carers should receive verbal and written information on risks associated with the procedure, length of stay, preoperative fasting and carbohydrate loading, pain management, postoperative mobilisation and oral intake.

At this stage, instructions about stopping regular medications where necessary should also be given. The primary aim is to give patients a joint responsibility for their recovery and facilitate adherence to the protocol in a step-wise manner.

Fasting and bowel preparation

Traditionally, patient preparations such as fasting from midnight or bowel preparation were widely practised. However, many of these interventions have been found to cause more adverse effects.

As explained above, ERAS pathways aim to blunt the body’s stress response, which is characterised by its catabolic effect. Prolonged preoperative fasting increases metabolic stress, hyperglycemia, and insulin resistance. A Cochrane review has demonstrated evidence to reduce fasting periods to 2 hours preoperatively for clear fluids and 6 hours for solid food for elective surgeries.

A carbohydrate-rich drink is also recommended (800mls at bedtime, 400mls up to 2 hours before surgery) to minimise protein catabolism and insulin resistance.

Bowel preparations for colorectal and other abdominal surgeries have adverse effects on hydration and electrolyte balance. Two large multi-centre randomised controlled trials have shown that there is no benefit from bowel preparation in colorectal surgery, and there is evidence that they may increase complications such as post-operative ileus.

Venous thromboembolism

Venous thromboembolism is a major perioperative complication, and adequate prophylaxis includes mechanical devices such as intermittent compression kits and the use of low molecular weight heparin.

Smoking cessation

Smoking cessation is also required to minimise the incidence of respiratory complications. Currently, many prehabilitation pathways, such as cardiopulmonary exercise testing, are being implemented to assess physical fitness and optimise patients before major surgery.


Surgical factors

Where possible, minimally invasive techniques should be used to enhance wound healing, return normal gastrointestinal function, decrease blood loss, and reduce hospital stay. If an open technique is necessary, transverse incisions should be made, as they have been shown to reduce postoperative pain.

Nasogastric tube insertions are associated with increased morbidity and should be avoided in elective cases. Antibiotic prophylaxis should be administered before skin incision, and a second dose should be administered for procedures >4 hours or when blood loss >1.5L.

Anaesthetic factors

Current evidence suggests decreased opioidsΒ and patient-controlled analgesia (PCA) as part of ERAS pathways. A multimodal analgesic approach is encouraged to reduce high-dose opioid usage, such as the use of regular paracetamol, non-steroidal anti-inflammatory agents and regional anaesthesia to improve post-operative mobilisation and recovery.

There is little evidence to support one anaesthetic technique over another, but generally, the principles of ERAS pathways are to use short-acting anaesthetic agents and analgesics. For example, the use of fentanyl perioperatively instead of morphine.

Post-operative nausea and vomiting (PONV) still remains one of the most debilitating side effects for patients postoperatively. The ERAS guidelines recommend risk stratification for PONV using the Apfel scoring system.

Each of these risk factors scores one point: female, non-smoker, previous PONV or use of opioids perioperatively. Two risk factors are classed as moderate risk, and 3 are high risk.

ERAS recommendations are for the use of dexamethasone at induction or a 5HT-3 receptor antagonist, such as ondansetron, at the end of surgery for moderate risk. For high-risk patients, it is recommended that two or more anti-emetics should be provided, plus the use of total intravenous anaesthesia.

Table 1. Table showing PONV risk (%) using Apfel score.

Risk factor score PONV risk (%)
0 10
1 20
2 40
3 60
4 80

Intraoperative fluid administration should be goal-directed to prevent overhydration, which may be harmful and result in impaired healing and slow recovery of gastrointestinal function.

Fluid maintenance with 1-3ml/kg/hr of crystalloid is sufficient for low-risk patients. An oesophageal Doppler cardiac monitor is used to guide fluid administration in high-risk patients to maintain cardiac output without fluid overload.


Early enteral feeding helps to reduce the need for intravenous fluid administration and postoperative ileus after surgery. Adequate nutrition is vital to help with wound healing, improve muscle strength for mobilisation and reduce infection risks.

Patients should be encouraged to mobilise early to improve respiratory function, reduce skeletal muscle loss and increase oxygen delivery to tissues.

It is recommended that patients should sit out of bed for 2 hours on the day of surgery and 6 hours a day until discharge. Ideally, involving the physiotherapy team further improves patient care and recovery. The best recovery can be achieved by ensuring that patients are being counselled to take part in ownership with the engagement of the whole multidisciplinary team in the postoperative rehabilitation pathway.

Multimodal analgesia should be continued in the postoperative period to avoid excessive use of opioids, which in turn can cause ileus, respiratory depression and sedation. Drains and urinary catheters placed intraoperatively should be removed as early as possible.

Key points

  • The ERAS pathway highlights the importance of partnership between clinicians and patients in providing the best perioperative outcomes.
  • The requisites for a successful ERAS program include patient education and a dedicated multidisciplinary team approach.


Dr Amarjeet Patil

Consultant anaesthetist


Dr Chris Jefferies


  1. Fawcett, W. J., Mythen, M. G., & Scott, M. J. (2021). Enhanced recovery: Joining the dots. British Journal of Anaesthesia, 126(4), 751–755. https://doi.org/10.1016/j.bja.2020.12.027
  2. Day, A., Fawcett, W. J., Scott, M. J. P., & Rockall, T. A. (2012). Fast-track surgery and the elderly. British Journal of Anaesthesia, 109(1), 124. https://doi.org/10.1093/bja/aes196


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