Perioperative Management Protocols: Enhanced Recovery After Surgery

Introduction

Enhanced recovery after surgery (ERAS) represented a paradigm shift in the perioperative care of the surgical patient when it was first implemented in the 1990s, initially in the field of colorectal surgery, and has subsequently been adopted by multiple other specialties. By applying multimodal and interdisciplinary care using specialty and procedure-specific evidence-based protocols across all perioperative phases, ERAS aims to mitigate the physiological stress of surgery and maintain homeostatic balance, ultimately improving clinical and health economic outcomes. Although there is ample evidence for its clinical and cost-effectiveness in other surgical specialties, the adoption of ERAS in spinal surgery remains in its infancy, and data on its efficacy are scant. In this chapter, we briefly review the history of ERAS as well as the physiological principles underpinning it, followed by a discussion on the emerging need for ERAS in spinal surgery, including the potential synergy with minimally invasive surgical (MIS) techniques. We then detail the specific phases and elements of ERAS, including sharing our experience at the University of Miami, followed by reviewing the most current literature. We conclude by discussing possible future directions of ERAS in spinal surgery.

Brief History of Enhanced Recovery After Surgery in Other Surgical Specialties

The conception of ERAS has for the most part been credited to Kehlet and colleagues in the 1990s, and was first trialed in Denmark in elective abdominal surgery by adopting an integrative approach to maintaining balance in vital perioperative parameters rather than addressing singular variables. Initially dubbed fast-track surgery, with the primary goal of reducing length of stay (LOS), ERAS has subsequently evolved in both language and approach to optimize the entire perioperative patient experience, championed internationally by the field of colorectal surgery, with numerous randomized controlled trials demonstrating improved pain control and patient satisfaction, as well as reductions in LOS, hospital costs, and complications, including postoperative ileus. ERAS subsequently disseminated throughout other general surgical specialties, with a recent metaanalysis of 10 randomized controlled trials on noncolorectal abdominal surgery demonstrating an average cost reduction of $5109 US dollars, attributed to the combined effect of reduced LOS without increasing complication or readmission rates. Common elements initially included preoperative education, rationalization of bowel preparation, multimodal analgesia including epidural techniques, and early enteral nutrition and mobilization, and evolved to also target the postoperative systemic inflammatory response by using selective anesthetic agents, goal-directed fluid therapy, and MIS techniques.

The original ERAS study group was formed in London in 2001, and was later rebranded the ERAS society. The first set of guidelines on perioperative care in elective colorectal surgery was formulated in 2005, advocating a multidisciplinary, multimodal, and evidence-based approach. The recognition of the importance of continual audit and data-driven quality improvement has since seen these guidelines undergo several iterations. Extensive research has been conducted into the metabolic aspects of perioperative nutrition and inflammation, such as the effects of preoperative carbohydrate loading and the roles of specific hormones and amino acids, including in physiologically vulnerable oncology patients. Over the past decade or so, the ERAS movement has spread across almost the entire surgical spectrum, including cardiac bypass, hip arthroplasty, carotid endarterectomy, and mastectomy, and throughout most industrialized countries. There is now an annual ERAS world congress, and several subsidiary societies assisting institutions with protocol implementation. There have been in excess of 3000 PubMed-listed publications on ERAS over the past 10 years alone.

Physiological Foundation for Enhanced Recovery After Surgery

The aim of the ERAS paradigm is to minimize the physiological, psychological, and social stress that surgery places upon each patient. Some of the principal stressors incurred by patients undergoing spinal surgery include the general anesthetic, extensive iatrogenic collateral tissue destruction and potential blood loss, significant postoperative pain, and possible neurological dysfunction, leading to a stress response mediated by metabolic derangements and activation of the inflammatory cascade with liberation of cytokines, complement, and arachidonic acid. This response is often amplified by the suboptimal functional status and comorbidities of the patient, as well as the development of perioperative complications. The subsequent failure of normal homeostatic mechanisms could in part explain the often unexpected end-organ dysfunction and poor clinical outcomes observed, despite advances in surgical and anesthetic technique. By supporting this homeostatic balance through specific evidence-based interventions, it is postulated that adverse effects, such as postoperative catabolism, immunological dysfunction, free radical production, and hypercoagulability, are minimized. Hyperglycemia and insulin insensitivity are often considered biochemical surrogates of these physiological perturbations, with the ERAS paradigm in turn dampening this response and reducing fluctuations seen in traditional care ( Fig. 79.1 ).

Perioperative variables that modulate the aforementioned stress response can be broadly categorized based on the specific perioperative phase, that is, preoperative comorbidities, intraoperative surgical and anesthetic stress, fluid balance and thermoregulation, and postoperative pain, immobility, malnutrition, and complications. These are often compounded by the frailty of the patient and declining physiological reserve, as well as overt epidemics such as smoking and obesity, and covert ones such as osteoporosis and narcotic use disorders. It is these individual stressors and modulators that components of a comprehensive ERAS program aim to mitigate. To whom responsibility for these interventions should fall in spinal surgery remains unclear, especially given they are largely considered outside the scope of traditional roles of surgeon and anesthesiologist, leading to an emerging need for dedicated spinal ERAS programs and teams.

Need for Enhanced Recovery After Surgery Programs in Spinal Surgery

There are several reasons why there is an emerging need for the adoption of ERAS strategies in spinal surgery. Firstly, with an ageing global population and the elderly being the fastest-growing demographic in industrialized countries, the need for a strategy to minimize the physiological impact of surgery cannot be understated. There is no doubt that elderly patients may benefit from spinal surgery, including those over the age of 85 years. However, inherent frailty and accumulation of comorbidities have often led surgeons and anesthesiologists alike to hold pessimistic views on complex surgery in this population. Although comorbidities undoubtedly contribute to complications, there is emerging evidence challenging their relative contributions to overall LOS. For example, Adogwa et al. demonstrated in a study of nearly 3800 patients from the American College of Surgeons National Surgical Quality Improvement Program who experienced extended LOS (>5 days) following one- or two-level lumbar fusion that the majority (75%) did not experience a postoperative complication, and only a minority had a comorbidity traditionally associated with prolonged hospitalization (24% had diabetes, 7% emphysema, 2% stroke, and <1% had significant cardiac disease and renal failure, respectively), suggesting that at least some of the variability in LOS may arise from surgical and institutional idiosyncrasies, and therefore is potentially actionable via ERAS protocols.

Secondly, the increasing burden of disease caused by spinal pathology needs to be equaled by efforts to increase effectiveness and efficiency of perioperative care. The World Health Organization estimated that low back pain affects approximately two-thirds of people in industrialized countries at some point in their lives. Epidemiological studies have ranked low back pain as the second commonest cause of disability in adults in the United States, and number one in Years Lived with Disability based on the Global Burden of Disease study published in 2010, consuming nearly 10% of total healthcare costs in the United States, exceeding $100 billion. In addition, the number of lumbar fusion procedures performed in the United States has increased exponentially from 60 per 100,000 population in 2004 to 80 per 100,000 in 2015, based on analysis of the National Inpatient Sample, with the fastest increases seen in the over-65 age group, whereas the cost per case has trebled from approximately $30,000 in 1998 to over $90,000 in 2008. This is in direct competition with escalating costs of healthcare overall and increasing focus on cost reduction. Furthermore, hospitals themselves have come under growing financial pressure as reimbursement models have shifted toward value-based healthcare with bundled payments and diagnosis-related groups, leading to pressures to reduce LOS and hospitalization costs without increasing complications or readmissions. Although ERAS programs in spinal surgery remain in their relative infancy compared with other surgical specialties, early results do suggest that LOS and overall costs may be reduced while maintaining stable rates of complications and readmissions.

Thirdly, there is a general need to change public perceptions towards spinal surgery itself. Lumbar fusions and complex spinal reconstructions are ranked among the most painful of all surgical procedures. Pain intensity and protracted recovery, perceived barriers to access, cursory approach of providers, and unmet needs have led to generally negative connotations of spinal surgery and spinal care in the community. ^. Furthermore, despite being the most commonly performed spinal surgical procedure, there remains conflicting level I evidence in the medical literature regarding the efficacy of lumbar fusion, ^, and its acceptance among the medical profession is far from universal.

To this end, minimally invasive surgery (MIS) has become an established option in carefully selected patients in spinal surgery, and in many ways has revolutionized spinal care. There is now ample evidence that MIS techniques are associated with reduced blood loss, LOS, and complications, including infections, ^, as well as reduced collateral damage to paraspinal musculature, ^, duration of postoperative narcotic use, and interval to return to work, without compromising clinical outcomes or radiological fusion rates. Wang et al. demonstrated in over 6000 patients in a United States–based national database that MIS spinal surgery was associated with a cost saving of $2106 in two-level interbody fusion when compared with open surgery, largely attributable to reduced LOS (3.4 vs. 4 days), operating room, pharmacy, and laboratory costs, as well as outliers requiring prolonged hospitalization. However, reductions in surgical invasiveness form only one aspect of an overarching need to minimize total perioperative physiological perturbation. Furthermore, MIS techniques are only applicable to selected patient pathologies, with open spinal surgery remaining a widely practiced and often more suitable option. The interplay between MIS and ERAS will undoubtedly continue to evolve, and is grounded in surgical history, (i.e., laparoscopic techniques preceded) and have become a critical component of ERAS in abdominal surgery. MIS not only naturally lends itself to the intraoperative phase of an ERAS strategy, it is also currently the only viable option that might act synergistically with, for example, an awake anesthetic strategy to mitigate the physiological stress incurred by a general anesthetic—an important consideration particularly in the elderly and infirm. Ultimately, the combination of MIS techniques within an overarching and iterative ERAS strategy may help eventually overcome both the negative public perception towards spinal fusion and the relative paucity of level I evidence for its efficacy.

Furthermore, the largely unregulated prescription of opioids to date has led to a generation of narcotic misuse and dependency, with prescription drug abuse the fastest growing drug problem in the United States. Since 2003, more overdose deaths have involved narcotics than heroin and cocaine combined. Increasing recognition of this growing epidemic by government and regulatory authorities has led to sweeping legislation limiting narcotic prescriptions. Narcotics have been a mainstay in the treatment of postoperative pain in spinal surgery due to the intensity of pain and the lack of effective alternatives, often leading to longer-term use and potential dependency. In addition, patients with chronic pain and spinal pathology are some of the highest consumers of narcotics. All of these factors have led to an urgent need for alternative and multimodal analgesia strategies, which form a vital cog in any ERAS protocol, with emerging evidence for alternatives such as gabapentinoids and long-acting liposomal bupivacaine local anesthetic (LA). Furthermore, reduction via ERAS strategies in overall physiological disruption, including tissue destruction through MIS techniques, would likely complement these opioid-sparing strategies.

The widespread uptake of ERAS will undoubtedly face challenges, particularly at the inception stage, similar to those faced by MIS spinal surgery, including the general inertia to change established practices, societal and cultural influence, and need to compare with, if not surpass, existing standards of care. Unlike MIS spinal surgery and the financial incentivization of industry to support its adoption and advancement, the adoption of ERAS is likely to require leadership from surgeons, anesthesiologists, and other providers within the hospital system. Unlike specific techniques, technologies, or interventions, individual ERAS elements may be difficult to reproduce, study, and disseminate. The initial labor intensiveness and learning curve would hopefully in the long term be offset by reduced LOS and hospital costs, and ultimately improved patient outcomes, a goal already achieved and replicated by our general surgical colleagues.

Critics may argue ERAS simply represents an attempt to brand existing protocols and quality improvement projects within institutions to facilitate day surgery and faster discharge. However, individual policies and practices at an institutional level do not possess the strength and external validity of evidence-based ERAS programs, particularly as interdisciplinary, multiinstitutional, and international dissemination and collaborations occur, societies mature, guidelines are formulated, and language is standardized. Having a common language improves communication, standardizes variables used in audit and research, and may facilitate a concerted effort in a common cause. Furthermore, many of the individual elements of ERAS programs, such as preoperative assessment clinics, multimodal analgesia and postoperative pain rounds, and multidisciplinary allied health already exist within institutions, albeit lacking the coordination and protocolization of ERAS.

Phases of Enhanced Recovery After Surgery in Spinal Surgery

ERAS strategies aim to minimize not just the physiological stress of surgery, but also its psychosocial impact by ensuring a seamless transition between different phases of a patient’s journey, which has traditionally been fragmented, with different teams responsible for singular aspects of care. Surgeons and anesthesiologists often focus their attention on the intraoperative aspects of care, whereas complications often manifest as a result of the culmination of multiple, often neglected and preventable, microevents with origins in the preoperative phase, and continue postoperatively. It is these three phases of a patient’s journey, (i.e., pre-, intra-, and postoperative), into which individual elements of an ERAS model can be categorized, analogous in some ways to steps in a recipe or pieces of a puzzle. See Fig. 79.2 for a pictorial depiction of the ERAS cycle.