# Enhanced Recovery After Surgery (ERAS) and Multimodal Analgesia

## ERAS Principles

### Philosophy

Enhanced Recovery After Surgery (ERAS) is an evidence-based, multimodal, multidisciplinary approach to perioperative care. The overarching goal is to reduce the surgical stress response, accelerate functional recovery, and shorten hospital length of stay. Achieving these goals requires coordination across surgery, anesthesia, nursing, nutrition, and physiotherapy. First developed for colorectal surgery by Henrik Kehlet in the 1990s, ERAS pathways have since expanded to cover nearly all surgical specialties.

### Core ERAS Elements (Perioperative Phases)

#### Preoperative

The preoperative phase focuses on patient education and expectation setting, carbohydrate loading (a clear carbohydrate drink 2 hours before surgery), minimization of fasting (clear fluids up to 2 hours and solids up to 6 hours before anesthesia), avoidance of routine mechanical bowel preparation, and initiation of preoperative multimodal analgesia (acetaminophen, a gabapentinoid, and celecoxib). Prehabilitation through exercise and nutrition optimization is considered for selected patients. Smoking and alcohol cessation 4-8 weeks before surgery improve outcomes.

#### Intraoperative

Intraoperative elements include goal-directed fluid therapy (avoiding both under- and over-resuscitation), lung-protective ventilation, active warming to maintain normothermia, regional analgesia or neuraxial techniques, minimally invasive surgical approaches when feasible, multimodal PONV prophylaxis, and avoidance of drains, nasogastric tubes, and urinary catheters unless specifically necessary.

#### Postoperative

The postoperative phase emphasizes early oral nutrition (within hours of surgery), early mobilization (out of bed on the day of surgery), multimodal analgesia with opioid minimization, early removal of catheters and drains, standardized discharge criteria, and audit and compliance tracking.

<image>ERAS pathway infographic divided into three columns (preoperative, intraoperative, postoperative) with key interventions listed in each phase. The preoperative column shows patient education, carbohydrate loading, and prehabilitation. The intraoperative column highlights goal-directed fluid therapy, regional anesthesia, normothermia, and lung-protective ventilation. The postoperative column shows early mobilization, multimodal analgesia, early feeding, and standardized discharge criteria. Arrows connect related elements across phases to show continuity of care.</image>

## Multimodal Analgesia Components

### Acetaminophen (Paracetamol)

#### Mechanism

Acetaminophen works through central COX inhibition, serotonergic pathways, and endocannabinoid system modulation. It has a weak peripheral anti-inflammatory effect.

#### Dosing

The oral dose is 1 g every 6 hours, with a maximum of 4 g/day in healthy adults and 2 g/day in patients with liver disease, the elderly, or those with low body weight. The IV dose is 1 g every 6 hours (15 mg/kg in patients under 50 kg). Scheduled dosing is more effective than as-needed administration.

#### Evidence

Acetaminophen provides a modest opioid-sparing effect, reducing morphine consumption by approximately 20-30%. IV formulation has a faster onset than oral, but oral bioavailability is high (approximately 90%), making oral administration preferred when feasible due to cost considerations. Acetaminophen is the foundation of multimodal analgesia and should be used in virtually all patients without contraindication.

### NSAIDs and COX-2 Inhibitors

#### Mechanism

NSAIDs inhibit cyclooxygenase enzymes (COX-1 and COX-2), reducing prostaglandin synthesis. They provide both peripheral anti-inflammatory and central analgesic effects.

#### Common Agents

**Ketorolac** (15-30 mg IV every 6 hours, maximum 5 days) is the most potent perioperative NSAID. **Ibuprofen** (400-600 mg PO every 6 hours) is a common oral option. **Celecoxib** (200-400 mg PO preoperatively) is COX-2 selective and has reduced gastrointestinal and platelet effects. **Diclofenac** (50-75 mg PO/PR every 8-12 hours) is another effective choice.

#### Concerns

NSAIDs may cause renal impairment and should be avoided in patients with CKD, hypovolemia, or concurrent nephrotoxin exposure. Gastrointestinal bleeding risk is lower with COX-2 selective agents. Nonselective NSAIDs impair platelet function, while COX-2 inhibitors spare platelets. The effect on **bone healing** remains controversial: animal data suggests impairment, but clinical evidence in humans is weak and inconsistent. Many orthopedic surgeons still avoid NSAIDs, though ERAS guidelines note that short-term use is reasonable for most fracture fixations and arthroplasty. Cardiovascular risk with COX-2 inhibitors is minimal with short perioperative courses.

### Gabapentinoids (Gabapentin, Pregabalin)

#### Mechanism

Gabapentinoids bind the alpha-2-delta subunit of voltage-gated calcium channels, reducing excitatory neurotransmitter release. They have anti-hyperalgesic, anxiolytic, and opioid-sparing properties.

#### Dosing

Gabapentin is typically given at 300-600 mg preoperatively (with some protocols using 900-1200 mg). Pregabalin is given at 75-150 mg preoperatively.

#### Evidence and Controversy

Earlier meta-analyses showed significant opioid-sparing effects, but more recent high-quality RCTs (including the GABAPENTIN and EPIGAB trials) have shown modest or no clinically meaningful opioid reduction. Side effects are significant, including sedation, dizziness, and visual disturbance in 12-20% of patients. ERAS guidelines have consequently downgraded gabapentinoid recommendations in some pathways. The current consensus is to consider gabapentinoids in patients at high risk for severe postoperative pain or in chronic opioid users, rather than using them routinely in all patients.

### Ketamine

#### Mechanism

Ketamine is an NMDA receptor antagonist with anti-hyperalgesic properties. It prevents central sensitization and provides opioid-sparing analgesia without causing respiratory depression.

#### Dosing

A sub-anesthetic infusion at 0.1-0.3 mg/kg/hr is used intraoperatively, with some protocols extending into the PACU or for 24-48 hours postoperatively. A bolus of 0.25-0.5 mg/kg may be given at induction. Ketamine should be avoided or the dose reduced in patients with uncontrolled hypertension, psychosis, or elevated intracranial pressure.

#### Evidence

Ketamine consistently demonstrates an opioid-sparing effect of 20-40%. It is particularly beneficial in opioid-tolerant patients, chronic pain patients, and those undergoing major surgery. It also reduces opioid-induced hyperalgesia. ERAS guidelines generally support perioperative ketamine as part of the multimodal regimen. Side effects at sub-anesthetic doses are generally mild, including dysphoria, vivid dreams, and nystagmus.

### Dexamethasone

#### Mechanism

Dexamethasone is a glucocorticoid with anti-inflammatory, antiemetic, and analgesic properties. It reduces tissue edema and inflammatory mediator production.

#### Dosing

A dose of 4-8 mg IV at induction serves primarily as an antiemetic. Higher doses (0.1-0.2 mg/kg) may provide additional analgesic benefit.

#### Evidence

Dexamethasone reduces PONV with a number needed to treat of approximately 4. It also reduces postoperative pain scores and opioid consumption and prolongs the duration of peripheral nerve blocks through both perineural and IV routes. Concerns about hyperglycemia are generally transient and manageable. Wound infection risk with a short course appears to be negligible. Adrenal suppression from a single dose is not clinically significant. Dexamethasone is widely included in ERAS protocols.

### IV Lidocaine Infusion

#### Mechanism

Systemic lidocaine provides sodium channel blockade, anti-inflammatory properties, and reduced visceral pain signal transmission.

#### Dosing

A bolus of 1-1.5 mg/kg is given at induction, followed by an infusion at 1-2 mg/kg/hr intraoperatively, with some protocols continuing for 24 hours postoperatively. Patients must be monitored for LAST symptoms.

#### Evidence

The strongest evidence supports IV lidocaine for open abdominal surgery, particularly colorectal procedures, where it reduces pain, opioid consumption, and ileus duration. It may serve as a substitute for thoracic epidural in some ERAS protocols, though it is less effective but carries fewer side effects. Evidence for laparoscopic surgery is less convincing. Contraindications include heart block, severe hepatic dysfunction, and concurrent use of other local anesthetics at high doses.

<image>Multimodal analgesia pyramid diagram showing the layered approach to perioperative pain management. The base layer (used in all patients) contains acetaminophen and NSAIDs. The second layer shows regional anesthesia and local infiltration. The third layer includes ketamine and lidocaine infusions. The fourth layer shows gabapentinoids (with a notation about evolving evidence). The apex shows opioids as rescue, with the goal of minimizing their use. Each layer includes typical dosing and key considerations.</image>

## Regional Anesthesia in ERAS

### Role

Regional anesthesia is a cornerstone of multimodal analgesia in many ERAS pathways, providing superior analgesia with opioid-sparing benefits while facilitating early mobilization, reducing ileus, and improving pulmonary outcomes.

### Technique Selection by Surgery

| Surgery Type | Preferred Regional Technique | Alternative |
|---|---|---|
| Colorectal (open) | Thoracic epidural (T8–T10) | IV lidocaine infusion + TAP block |
| Total knee arthroplasty | Adductor canal block +/- iPACK | Femoral nerve block (less preferred) |
| Total hip arthroplasty | Fascia iliaca block | Lumbar plexus block |
| Thoracic surgery | Paravertebral block | Thoracic epidural |
| Breast surgery | PECS II block | Paravertebral block |
| Cesarean delivery | Intrathecal morphine | TAP block (adjunct) |
| Laparoscopic surgery | TAP block | Wound infiltration |

The optimal regional technique depends on the surgical procedure. **Colorectal surgery** uses thoracic epidural (T8-T10) or IV lidocaine infusion as an alternative, with TAP blocks. **Total knee arthroplasty** uses an adductor canal block with or without an iPACK block. **Total hip arthroplasty** uses a fascia iliaca block or lumbar plexus block. **Thoracic surgery** uses a paravertebral block or thoracic epidural. **Breast surgery** uses a PECS II block or paravertebral block. **Cesarean delivery** uses intrathecal morphine with or without a TAP block. **Laparoscopic surgery** uses a TAP block or wound infiltration.

### Epidural vs. Alternatives in ERAS

Thoracic epidural has traditionally been the gold standard for open abdominal surgery. However, concerns exist about epidural-associated hypotension, urinary retention, motor block limiting mobilization, and a failure rate of 15-30%. Alternative approaches gaining traction include IV lidocaine combined with TAP blocks and wound catheters. Current ERAS guidelines still support thoracic epidural but acknowledge that multimodal alternatives may be equivalent for some procedures, especially with minimally invasive surgery.

## Goal-Directed Fluid Therapy (GDFT) in ERAS

### Principles

Goal-directed fluid therapy aims to avoid both hypovolemia (which causes organ hypoperfusion) and hypervolemia (which causes tissue edema, anastomotic complications, and pulmonary edema). Dynamic parameters such as SVV, PPV, and esophageal Doppler measurements guide fluid bolus decisions. Fluid management should be individualized rather than based on fixed formulae.

### Evidence

Multiple RCTs demonstrate that GDFT reduces complications and length of stay in major abdominal surgery. A typical protocol restricts maintenance fluids to 1-2 mL/kg/hr and administers fluid boluses (250 mL of colloid) based on dynamic parameters (SVV above 12%, or corrected flow time below 350 ms on Doppler). A zero-balance fluid strategy, matching fluid input to measured losses, is the target.

## Measuring ERAS Success

### Outcome Metrics

Key metrics for evaluating ERAS program success include hospital length of stay (the primary outcome in most trials), readmission rate (which should not increase with earlier discharge), postoperative complication rate, patient-reported outcome measures, opioid consumption in total morphine milligram equivalents, time to return of bowel function, and protocol compliance (with a target of over 80% adherence for meaningful benefit).

### Common Barriers

Barriers to successful ERAS implementation include institutional inertia and resistance to change, inconsistent compliance across team members, inadequate patient education, lack of a dedicated ERAS coordinator, and insufficient data tracking and audit infrastructure.

<image>Bar graph comparing outcomes between traditional perioperative care and ERAS protocol implementation for colorectal surgery. The graph shows reductions in: length of stay (8 days to 4-5 days), postoperative ileus duration, total opioid consumption (MME), and complication rates. A secondary axis shows 30-day readmission rates remaining unchanged, addressing the concern that early discharge increases readmissions.</image>

## Clinical Pearls

ERAS is not a single intervention but a bundled pathway; the benefit comes from high compliance with multiple elements simultaneously. Acetaminophen and NSAIDs (or COX-2 inhibitors) should be considered the foundation of multimodal analgesia -- they are cheap, effective, and have a long evidence base. Gabapentinoid enthusiasm has waned; routine preoperative gabapentin is no longer universally recommended due to sedation without consistent opioid-sparing benefit. Sub-anesthetic ketamine is most valuable in opioid-tolerant patients and those undergoing major surgery with expected severe pain. ERAS compliance should be audited regularly because protocols that are not measured tend to degrade over time. The anesthesiologist is a key driver of ERAS success through regional anesthesia, PONV prophylaxis, goal-directed fluid management, and multimodal analgesia.

## References

- Gustafsson UO, Scott MJ, Hubner M, et al. Guidelines for perioperative care in elective colorectal surgery: Enhanced Recovery After Surgery (ERAS) Society recommendations: 2018. *World Journal of Surgery*. 2019;43(3):659-695.
- Kehlet H, Wilmore DW. Evidence-based surgical care and the evolution of fast-track surgery. *Annals of Surgery*. 2008;248(2):189-198.
- Wick EC, Grant MC, Wu CL. Postoperative multimodal analgesia pain management with nonopioid analgesics and techniques: a review. *JAMA Surgery*. 2017;152(7):691-697.
- Fabritius ML, Geisler A, Petersen PL, et al. Gabapentin for postoperative pain management: a systematic review with meta-analysis and trial sequential analysis. *Acta Anaesthesiologica Scandinavica*. 2016;60(9):1188-1208.
- Werawatganon T, Charuluxananan S. Lidocaine for preventing postoperative sore throat (Cochrane Review). *Cochrane Database of Systematic Reviews*. 2017.