AT_PO 1.6, ANZCA Fellowship Study Notes
Overview and Context
The traditional model of anaesthetic care, confined to the operating theatre and the immediate perioperative window, is undergoing fundamental transformation. Two complementary frameworks have emerged to address the limitations of fragmented, episodic surgical care: Enhanced Recovery After Surgery (ERAS) and the Perioperative Surgical Home (PSH). Both represent a shift toward coordinated, evidence-based, patient-centred perioperative medicine, and both create expanded professional opportunities for anaesthetists as perioperative physicians.
The impetus for these models arises from several converging pressures: escalating healthcare costs, rising surgical complexity, an opioid epidemic, increasing patient comorbidity, and a healthcare system increasingly focused on value, defined as outcomes achieved per unit cost. These models have demonstrated measurable improvements in outcomes, length of stay (LOS), complication rates, and cost-efficiency across multiple surgical specialties.
Enhanced Recovery After Surgery (ERAS)
Definition and Principles
ERAS protocols are evidence-based, multidisciplinary perioperative care pathways designed to accelerate postoperative convalescence, reduce surgical stress response, minimise complications, and facilitate early functional recovery, without increasing readmission rates.
ERAS represents a paradigm shift: it replaces traditional surgical practices (prolonged fasting, routine bowel preparation, liberal opioid use, routine drains and tubes) with practices validated by high-quality evidence. The fundamental insight is that multiple simultaneous interventions targeting different aspects of the perioperative stress response achieve outcomes that no single intervention can achieve alone.
The concept underpins "fast-track" surgery and involves surgeons, anaesthetists, nurses, physiotherapists, nutritionists, and pharmacists working collaboratively within an integrated pathway.
The Surgical Stress Response: The Central Target
The surgical stress response, mediated by neuroendocrine activation, inflammatory cascades, catecholamine release, and cytokine elaboration, drives postoperative catabolism, ileus, insulin resistance, immunosuppression, and organ dysfunction. ERAS protocols attack this response simultaneously from multiple vectors: attenuating afferent neural signals (regional anaesthesia), minimising the inflammatory trigger (minimally invasive surgery), maintaining metabolic homeostasis (carbohydrate loading, early feeding), and facilitating rapid return of function (early mobilisation, removal of lines and drains).
Critically, good analgesia alone is insufficient to accelerate recovery, because acute pain is only one of many triggers of the injury response. This explains why well-controlled pain with thoracic epidural analgesia (TEA), while providing superior analgesia and earlier return of bowel function, does not consistently shorten LOS or reduce morbidity versus alternative techniques when used within a complete ERAS protocol.
ERAS Protocol Elements
ERAS elements span the full perioperative continuum. The wedge model (Fig. 3.1 in Miller's) illustrates how each phase's interventions influence subsequent phases.
| Phase | Key ERAS Elements |
|---|---|
| Preadmission | Patient education and goal-setting; medical optimisation; nutritional assessment and support; smoking cessation; alcohol cessation counselling |
| Preoperative | Selective (not routine) bowel preparation; preoperative carbohydrate loading; liberalised fasting (clear fluids until 2 hours preoperatively, light solids until 6 hours); PONV risk assessment and prophylaxis; no prolonged NPO |
| Intraoperative | Minimally invasive surgical approach; regional analgesia; opioid-sparing anaesthesia (consider TIVA); goal-directed fluid management; balanced fluid therapy; active temperature management (normothermia); minimise drains and tubes |
| Postoperative | Early removal of drains, tubes, and urinary catheters; early transition from IV to oral fluids and solids; multimodal opioid-sparing analgesia; early mobilisation; structured postdischarge follow-up |
Carbohydrate Loading, Mechanistic Rationale
Preoperative oral carbohydrate drinks (typically a 12.5% carbohydrate solution, 400 mL the evening before and 200 mL 2 hours preoperatively) produce a metabolic anabolic shift with several benefits:
- Perioperative oral carbohydrates raise insulin sensitivity by approximately 50%, reducing postoperative insulin resistance
- Ameliorate gut barrier failure and reduce bacterial translocation risk
- Reduce risk of hyperglycaemic events
- Improve retention of protein and lean body mass
- Support the shift from a catabolic to anabolic metabolic state
The majority of national and international anaesthetic societies now recommend 6-hour fasting for light non-fatty solids and 2-hour fasting for clear fluids (including carbohydrate drinks).
Evidence for ERAS
ERAS has been most extensively evaluated in colorectal surgery, with robust evidence extending to gynaecology, orthopaedics, hepatobiliary, thoracic, vascular, and neurosurgical procedures. Key outcome data include:
| Outcome | Evidence |
|---|---|
| LOS reduction (colorectal) | WMD −2.55 days (95% CI −3.24 to −1.85) |
| Complication rate reduction (colorectal) | RR 0.53 (95% CI 0.44 to 0.64) |
| Nonoperative morbidity reduction (colorectal) | 40-50% reduction |
| LOS reduction (colorectal, absolute) | 2-3 days |
Elements most strongly associated with shorter LOS in colorectal surgery include: laparoscopic approach, increasing protocol compliance, preoperative carbohydrate and fluid loading, and TIVA. Factors reducing complication risk include restrictive perioperative IV fluids, laparoscopic approach, and increasing overall protocol compliance. Independent predictors of early recovery include enforced early oral intake (normal diet by POD 1-3) and early mobilisation.
Importantly, the number of ERAS elements employed matters, protocols in major trials used between 4 and 12 elements (mean 9). Partial compliance yields attenuated benefit; comprehensive, audited implementation is essential.
Multidisciplinary Team Requirements
The most successful ERAS programs include all healthcare and service providers involved in the perioperative course. This is not optional, the multidisciplinary nature is fundamental to the model's success. Without genuine engagement from surgical, nursing, physiotherapy, pharmacy, and nutrition teams alongside anaesthesia, protocols become fragmented and benefits are lost.
Ongoing outcome measurement, audit, and protocol refinement are essential components. When adverse outcomes occur (e.g. acute kidney injury following implementation of restrictive fluid strategies in some colorectal ERAS protocols), the protocol must be reviewed and modified. This iterative approach, collaborative development, implementation, outcomes review, and modification, underpins the value-based healthcare rationale for ERAS.
Perioperative Surgical Home (PSH)
Definition and Conceptual Framework
The Perioperative Surgical Home is a patient-centred, physician-led model of coordinated care that manages the patient from the time of surgical scheduling through the entire perioperative continuum, including the return to primary care. Developed by the American Society of Anesthesiologists (ASA) in collaboration with other medical specialties, the PSH builds on concepts from the Patient-Centred Medical Home (PCMH) model for outpatient chronic disease management.
The PSH is broader in scope than ERAS. Where ERAS provides specific evidence-based protocol elements within the perioperative window, the PSH is an organisational and care coordination model that encompasses the entire patient journey, including scheduling, preoperative assessment, intraoperative and postoperative management, discharge planning, and transition to primary or community care.
Comparison: ERAS vs PSH
| Feature | ERAS | PSH |
|---|---|---|
| Focus | Specific evidence-based perioperative protocol elements | Whole-of-journey care coordination model |
| Timeframe | Perioperative period (preadmission to postdischarge) | Surgical scheduling through return to primary care |
| Lead | Multidisciplinary (no single mandated lead) | Often anaesthesiologist-led, but variable |
| Scope | Procedure-specific protocols | Broader: patient goals, transitions, chronic disease management |
| Outcomes targeted | LOS, complications, cost, recovery speed | Outcomes + patient goals + costs across full continuum |
| Structural requirement | Protocol adherence | Organisational model with defined roles and relationships |
PSH Goals (as proposed by the ASA)
- Identify the patient and proposed surgical plans
- Facilitate communication among surgeons, anaesthesiologists, and other providers to coordinate care
- Provide thorough preoperative assessment and develop a care plan, including management of associated diseases
- Develop and implement evidence-based protocols for clinical care throughout the perioperative period
- Manage clinical care across the continuum
- Measure and publicly report outcomes and performance
The final goal, public reporting, reflects the PSH's alignment with value-based healthcare and the "triple aim" of improving patient experience, improving population health, and reducing per-capita costs.
The Anaesthesiologist as Perioperative Physician
The PSH creates an expanded professional role for anaesthetists, building on their existing expertise in pathophysiology, pharmacology, monitoring, and perioperative risk. In PSH models where the anaesthesiologist assumes primary coordination responsibility, input from hospitalists and medical subspecialists remains essential to address specific clinical needs.
The PSH also has strategic professional implications: the collaborative relationships built under PSH models increase understanding of anaesthesiologists' skills and value within the health system, and critically position anaesthetists in discussions about bundled payment models and distribution of healthcare funding.
Models and Implementation
There is no single mandated PSH model, implementation varies by health system, institutional relationships, and provider interest. Observed benefits from PSH implementation have included:
| Outcome | Reported Effect |
|---|---|
| Surgical cancellations | Reduced |
| Complication rates | Reduced |
| Length of stay | Reduced |
| Readmission rates | Reduced |
Relationship to the Surgical Hospitalist Model
The surgical hospitalist model, where a hospitalist (surgical or medical) manages non-surgical comorbidities perioperatively, freeing surgeons to focus on operative care, is complementary to but distinct from the PSH. The PSH incorporates clear delineation of roles between anaesthesiologist, hospitalist, and intensivist, particularly during transitions of care (e.g. theatre to ICU, ICU to ward, ward to home). Coordination of these transitions is a core PSH function.
Anaesthetic Implications
Role of the Anaesthetist in ERAS
As a consultant anaesthetist, engagement with ERAS should be proactive and informed. Key intraoperative contributions include:
| Domain | Specific Practice |
|---|---|
| Analgesia | Multimodal, opioid-sparing approach; regional techniques (neuraxial, peripheral nerve blocks, wound infiltration); avoid unnecessary TEA where alternatives equivalent within ERAS |
| Anaesthetic technique | Consider TIVA (associated with shorter LOS in ERAS registry data, OR 0.86); opioid-free or opioid-reduced techniques |
| Fluid management | Goal-directed fluid therapy; avoid both liberal and overly restrictive approaches; monitor for AKI with restrictive protocols |
| Temperature | Active normothermia maintenance (forced-air warming, fluid warming); hypothermia impairs coagulation, immune function, and wound healing |
| PONV | Systematic multimodal prophylaxis (risk stratification, combination antiemetics, TIVA); PONV is a major barrier to early oral intake and discharge |
| Fasting | Advocate for and implement liberalised fasting guidelines; ensure carbohydrate loading prescribed preoperatively |
| Lines and tubes | Avoid unnecessary nasogastric tubes, urinary catheters, and drains; plan for early removal when required |
Role of the Anaesthetist in PSH
- Lead or participate in preoperative assessment clinics with a focus on optimisation, not just risk stratification
- Develop and champion evidence-based perioperative protocols collaboratively with surgical teams
- Ensure clear handover documentation and care transitions (theatre → recovery → ward → home)
- Contribute to outcome measurement and protocol audit; be prepared to modify practice based on data
- Engage with postdischarge follow-up pathways; support telemedicine and home-monitoring initiatives increasingly used for postoperative care
Pitfalls and Challenges
| Challenge | Management Approach |
|---|---|
| Partial protocol compliance | Audit compliance; educate all team members; assign protocol champions |
| Fluid management extremes | Goal-directed therapy; monitor urine output and fluid balance; reassess protocol if AKI signals emerge |
| Patient not meeting ERAS criteria (e.g. frailty, complex comorbidity) | Individualise; PSH model accommodates medical optimisation and specialist input |
| Opioid-sparing approach in high-complexity pain | Robust multimodal plan; anaesthesia-led acute pain service involvement |
| Resistance from surgical colleagues | Collaborative protocol development from the outset; share outcome data; emphasise shared goals |
| Defining outcome measures | Incorporate patient-reported outcomes in addition to LOS and complication rates; ERAS outcomes must be meaningful to patients |
Healthcare Economics
ERAS and PSH both represent value-based approaches to perioperative care. Demonstrating value requires measuring outcomes that matter to patients, not just institutional metrics. Future ERAS protocol development must incorporate patient-reported outcome measures (PROMs) to ensure that shorter LOS and fewer complications translate into recovery experiences that patients themselves value.
The PSH model positions anaesthesiology to participate meaningfully in bundled payment models and healthcare funding discussions, a strategic professional opportunity that requires both clinical excellence and outcome data transparency.
Summary
| Concept | Core Message |
|---|---|
| ERAS | Multimodal, evidence-based perioperative protocol targeting the surgical stress response; benefits require multi-element compliance and multidisciplinary engagement |
| PSH | Anaesthesiologist-facilitated, patient-centred care coordination model spanning surgical scheduling to primary care return; broader than ERAS but complementary |
| Anaesthetist's role | Expanded from intraoperative technician to perioperative physician; leadership in both ERAS protocol development and PSH coordination |
| Evidence | Robust for ERAS in colorectal and multiple other surgical populations; PSH evidence accumulating; both models demonstrate reduced LOS, complications, and cost |
| Key insight | Good analgesia alone is insufficient; comprehensive multimodal protocol compliance is required; patient-reported outcomes must be incorporated |
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