Anesthetic management and considerations in patients with metabolic syndrome. Risks, challenges, and strategies

 

Nº de DOI: 10.34896/RSI.2026.58.23.001

 

 

AUTHORS

1. Jeniffer Alina Murillo Caicedo. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the University of Guayaquil. (Guayaquil-Ecuador). https://orcid.org/0009-0007-3167-0604
2. Luis David Vinueza Lobato. General Practitioner. Attached to Private Clinics of Ecuador. Graduate of the Catholic University of Cuenca. (Azogues-Ecuador). https://orcid.org/0009-0003-4843-1723
3. Ana Belén Gutiérrez Alvarado. General Practitioner. Attached to the ISTCRE Higher Technological Institute. Graduated from the University of the Americas. (Quito-Ecuador). https://orcid.org/0009-0008-4514-7475
4. María Magdalena Toro Andrade. General Practitioner and Master of Health Management. Attached to the Julius Doefpner General Hospital. Graduate of the Particular Technical University of Loja. (⁠Zamora-Ecuador). https://orcid.org/0009-0007-0080-5393
5. Rosario Del Carmen Gutiérrez Machuca. General Practitioner. Attached to the CETAD Nuevo Renacer Clinic. Graduate of the National University of Loja. (⁠Zamora-Ecuador). https://orcid.org/0009-0007-2821-3218

 

SUMMARY

In addition to the review of clinical guidelines and best evidence, the synthesis provides a framework for limiting complications, including hemodynamic instability, difficult airway, and delayed emergence. In conclusion, the synthesis supports a multidisciplinary, individualized approach including enhanced recovery and goal-directed therapy to improve clinical outcomes in an increasingly common, vulnerable patient population.

KEY WORDS

Metabolic syndrome, anesthesia, obesity, perioperative complications, sleep apnea, anesthetic management, insulin resistance.

RESUMEN

Además de la revisión de las guías clínicas y la mejor evidencia disponible, la síntesis proporciona un marco para limitar las complicaciones, incluyendo inestabilidad hemodinámica, vía aérea difícil y despertar postoperatorio retrasado. En conclusión, la síntesis respalda un enfoque multidisciplinario e individualizado, que incluya recuperación mejorada y terapia dirigida por objetivos, para mejorar los resultados clínicos en una población de pacientes cada vez más común y vulnerable.

PALABRAS CLAVE

Síndrome metabólico, anestesia, obesidad, complicaciones perioperatorias, apnea del sueño, manejo anestésico, resistencia a la insulina.

INTRODUCTION

Metabolic syndrome (MetS) embodies a complex cluster of interrelated physiological, biochemical, clinical, and metabolic factors that significantly increase a person’s risk of cardiovascular disease and type 2 diabetes mellitus (T2DM). In the perioperative environment, MetS creates a multifactorial challenge for the anesthesiologist, as the combination of obesity, hypertension, dyslipidemia, and insulin resistance creates a state of chronic systemic inflammation and diminished physiological reserve. This systematic review provides a synthesis of contemporary evidence relating to anesthetic management of patients with MetS and highlights the pathophysiological issues raised in perioperative risk. Evidence indicates that the pro-inflammatory milieu with adipose tissue dysfunction triggers exaggerated systemic inflammatory responses to surgical injury and increased rates of obstructive sleep apnea (OSA) and diastolic dysfunction requires a unique approach to monitoring and intervention. The review evaluates preoperative risk stratification approaches, recognizing the limitations of traditional parameters like Body Mass Index (BMI), and the need for more complete metabolic mapping. In addition to preoperative risk stratification, the review considers the importance of preoperative optimization, including maintaining glycemic control and stabilization of respiratory comorbidities.

OBJECTIVE

The primary objective of this systematic review is to provide a comprehensive, evidence-based framework for the perioperative management of patients with Metabolic Syndrome.

METHODOLOGY

To provide rigorous and comprehensive evidence collection, systematic search strategy was performed across multiple electronic databases, including PubMed, EMBASE, and Scopus. The search included pre-operative medicine and metabolic research articles published between 2021 and 2025 to reflect the current literature. Key search terms and Boolean operators were utilized, including terms such as «metabolic syndrome AND anesthesia,» «obesity AND perioperative complications,» «obstructive sleep apnea AND anesthetic management,» and «insulin resistance AND surgical outcomes».

The search was designed to obtain high-level evidence, starting with systematic reviews, meta-analysis, clinical practice guidelines, and large prospective cohort studies. In addition to database searching, bibliographies of retrieved articles were manually searched for relevant studies that were missed in the electronic search process. Our approach sought to maintain a wide approach to achieve insight into the intersection of metabolic health and anesthesia across the general surgical population and sub-specialties including bariatric and cardiac surgery.

Study selection was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Studies were eligible if they met the following inclusion criteria: (a) adult patients with metabolic syndrome or the primary components obesity, hypertension, hyperglycemia, and dyslipidemia undergoing anesthesia, (b) the study mentions risks of anesthesia, anesthetic techniques, or anesthetic management in consideration of metabolic syndrome, (c) the study is in peer-reviewed journals published in English.

Studies focusing exclusively on pediatric patients, animal studies, or case reports with limited generalizability were excluded. Titles and abstracts were initially screened to remove duplicates and irrelevant citations. Next, the full text determined eligibility. We placed special consideration to studies of metabolic factors co-occurring such as OSA and obesity to evaluate cardiometabolic risk. The selection process sought to strike a balance between broad reviews of pathophysiology and specific clinical guidelines such as the Chinese guidelines for OSA in 2024.

Data extraction utilized a standardized form to ensure all relevant information was recorded, including the study design, patient demographics, clinical context, primary anesthetic interventions used, and clinical outcomes (i.e., complication rates, recovery times, and metabolic stability measures). For clinical guidelines, the strength of recommendations and the quality of evidence were noted to create a graded perspective relating to management strategies.

Quality assessment was conducted using validated tools that were appropriate for the individual study design, such as AMSTAR-2 for systematic reviews and the Cochrane Risk of Bias tool for randomized controlled trials. In the case of narrative reviews and expert consensus statements, the emphasis was on the degree the authors had synthesized the literature to create a clinically relevant framework. By systematically extracting data and assessing quality, we ensured that the synthesis that followed, was robust and based on reliable and clinically relevent evidence to provide strong recommendations for anesthetic practice within the MetS population.

RESULTS

The prevalence of metabolic syndrome has reached epidemic levels throughout the world as obesity and sedentary lifestyles increase across demographics. Metabolic syndrome, defined by the presence of central obesity, hypertension, impaired fasting glucose, and dyslipidemia, is no longer viewed as collection of discrete risk factors, but a single, comprehensive systemic vulnerability. For the anesthesiologist, MetS is a «perfect storm» of physiological derangements that complicates each stage of care from induction to recovery. The surgical stress response, which includes catecholamines and cortisol, occurs within context of chronic low-grade systemic inflammation, causing hemodynamic instability or complete metabolic collapse.

Obesity, arguably the most significant component of MetS, is a major global health burden, and metabolic-bariatric surgery has become the most effective long-term treatment for obesity¹. However, the synergistic liability of metabolic syndrome extends beyond metabolic-bariatric surgery to patients with that present for various elective and emergent procedures of varying complexity from GI endoscopy to coronary artery bypass grafting. The combined effect of adipose tissue as an endocrinological organ and vascular endothelium creates a state of «pre-primed» inflammation which can lead to more intense inflammatory responses and the systemic inflammatory response syndrome (SIRS) in the immediate post-surgical period.

Moreover, the respiratory repercussions of MetS are substantial. Obstructive sleep apnea (OSA) is notably prevalent in this population, yet it is frequently underdiagnosed in the general surgical population². The combination of abnormal airway anatomy, reduced functional residual capacity (FRC), and the possibility of rapid desaturation creates significant obstacles to airway management and mechanical ventilation. From a cardiovascular standpoint, the presence of MetS influences the burden of myocardial injury, heart failure, venous thromboembolism, and more – especially in high-risk groups such as patients with gynecologic malignancies³.

The growing clinical implications of MetS are undeniable, yet anesthetic management mostly employs fragmented protocols regarding individual comorbidities rather than the syndrome as a whole. In this regard, there is growing need for proper and systematic synthesis of multitasking strategies that can address synergistic risk from MetS. This review will start filling this void by providing comprehensive analyses and regular updates of current evidence on pathophysiological mechanisms, preoperative optimization, and intraoperative strategies – to inform an intended guide for anesthetic care in metabolic patient.

Pathophysiological Implications for Anesthesia:

Cardiovascular Dysfunction and Hemodynamic Instability:

The cardiovascular characteristics of a patient with metabolic syndrome is a complex interaction of both structural and functional abnormalities that place patients at risk of intraoperative hemodynamic instability. Chronic hypertension and insulin resistance contribute to vascular endothelial dysfunction resulting in impaired vasomotor control and sensitive responsiveness to anesthetic induction agents’ vasodilatory effects. This typically presents as profound hypotension when changing the patient from a waking state to an anesthetized state which can threaten organ perfusion.

Furthermore, many patients with MetS are also found to have «heart failure with preserved ejection fraction» (HFpEF) which is primarily caused by left ventricle hypertrophy and diastolic dysfunction. The heart in these patients has limited capacity to handle changes in preload or afterload acutely. Standard liberal fluid resuscitation can lead to pulmonary edema rapidly, as the noncompliant left ventricle requires higher filling pressure to maintain stroke volume, but yet is easily overwhelmed by expanding volume. Evidence from gynecologic oncology populations demonstrates that obesity and metabolic dysfunction increases myocardial injury and heart failure with surgical stress³.

Post-operative atrial fibrillation (POAF) is another issue of concern as it impacts up to 40% of patients after major surgery and is associated with longer hospital stays and greater mortality⁶. Importantly, a chronic inflammatory status in MetS and catecholamine surge during the perioperative period together creates a substrate for cardiac hyperactivity and arrhythmias. Care of these patients must establish a balance of maintaining blood pressure with sufficient perfusion whilst avoiding fluid overload, which can be informed by advanced hemodynamic monitoring to direct vasopressor and fluid therapy.

Respiratory Mechanics and Obstructive Sleep Apnea:

Metabolic syndrome is a «double hit» to the respiratory system, both mechanically and functionally. Centripetal obesity leads to an accumulation of adipose tissue in the chest wall and abdomen to reduce chest wall compliance and push the diaphragm cephalad. This leads to a substantial decrease in functional residual capacity (FRC), often to a level below closing capacity with normal tidal volume breathing. Thus, patients with MetS are prone to atelectasis and V/Q mismatch, leading to rapid arterial desaturation during apnea or hypoventilation.

The MetS population has very high rates of Obstructive Sleep Apnea (OSA), with some ICU based studies estimating OSA in up to 60-70% of critically-ill patients². The pathology of OSA in MetS is also similar to an obesity etiology, especially that of upper airway narrowing from fat deposition in the pharyngeal tissues. Anesthesia induction eliminating upper airway muscle tone contributes to this new area of obstruction, further complicating mask ventilation and tracheal intubation. The 2024 Chinese guidelines identify that OSA not only complicates airway management but leads to organ dysfunction through chronic intermittent hypoxia, which adds to the burden of care².

Furthermore, the interplay between OSA and MetS represents a vicious cycle, chronic hypoxia increases insulin resistance which leads to further weight gain and upper airway inflammation. This is important to the Anesthesiologist as it necessitates comment consideration for the anesthesia plan and the practitioner may bolster pre-oxygenation techniques of high-flow nasal oxygen (HFNO) delivery to maximize «safe apnea time» during induction. Post-operatively these patients remain at increased risk for respiratory depression, particularly with the use of systemic opioids, making the interoperative surveillance frequency extremely careful, requiring re-initiation of CPAP therapy more often than not⁴.

Metabolic Derangements and Pro-inflammatory States:

At the core of metabolic syndrome is chronic, low-grade systemic inflammation mediated by dysfunctional adipose tissue. MetS adipocytes do not store energy, but as active endocrine units that secrete pro-inflammatory cytokines such as Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-a). With this «pre-primed» state of inflammation controlled surgical trauma can be easily converted to exaggerated and excessive systemic inflammatory response.

Insulin resistance, as a character trait in MetS, complicates the metabolic landscape further. Given that surgery elicits a catabolic metabolic state as well as transient insulin resistance in healthy individuals, this process is exacerbated in the MetS patient, leading to significant perioperative hyperglycemia. Hyperglycemia is related to impaired wound healing, surgical site infections, and adverse cardiovascular events. On the other hand the «metabolic crash» that follows surgery is often centered around capillary leak syndrome, the inflammatory landscape increases vascular permeability while also resulting in significant tissue edema and delayed recovery of bowel function (ileus).

The coexistence of Non-Alcoholic Fatty Liver Disease (NAFLD) which also has a high association with MetS impacts the clearance of anesthetic drugs. While a standard liver function test may have normal levels, the altered hepatic blood flow and enzymatic activity of a fatty liver limits the metabolic state of common drugs, increasing the emergence time for sedative agents and extending sedation time, drugs cannot metabolize as expected. It is important to recognize these metabolic factors when determining dosages and the implementation of restrictive glycemic control measures in an effort to limit the systemic impact of metabolic «hangover» post-surgery.

Preoperative Evaluation and Risk Stratification:

Airway and Functional Capacity Assessment:

Preoperative assessment of MetS patients needs to extend beyond a focus on Body Mass Index (BMI), as it does not reflect distribution of adipose tissue or physiological reserve accurately. Airway assessment is foremost, considering anatomical and functional obstruction that can occur. Clinicians should be mindful of specific indicators of difficult airway, including increased neck circumference (>40 cm), limited mobility of a patient’s cervical spine, and a large tongue base⁷. These are superior predictors of a difficult laryngoscopy and airway related incidents than weight. The functional airway also encompasses the patient’s tolerance of being supine without distress to respiration, which is particularly compromised in severe obesity.

Functional capacity assessment is equally important, but can be challenging for most of these individuals due to physical limitations or co-existing osteoarthritis. When standard METS cannot be assessed through history accurately, clinicians may need to rely upon capturing objective markers of cardiopulmonary reserve. The aim is to identify patients at high risk of «cardiorespiratory collapse» under the stress of induction or surgery. Preoperative assessment should include a detailed review of the surgical mortality risk, especially for bariatric procedures, where there is more specific risk scores have been validated⁸.

Interdisciplinary recommendations advocate for input from physical therapists to assess mobility, and nurses to assess early postoperative mobility⁹. This broad view enables the anesthesiologist to evolve from the simple management of crisis to a more proactive approach to risk configuration, applying an anesthetic plan tailored to the individual’s anatomical and functional limitations.

Screening for Undiagnosed Comorbidities:

There lies a distinctly high prevalence of undiagnosed or poorly controlled comorbidity among MetS patient populations presenting for surgery, especially, but not limited, to OSA, and CAD. Because OSA is present in up to 70% of the ICU population and rarely previously diagnosed, all MetS patients should be screened using a universal screening tool, such as the STOP-BANG questionnaire². In the case of a high score, a thorough investigation should be undertaken, or at a minimum, the need for airway management should be expected, along with a high predicted risk of postoperative respiratory issues.

Undetected cardiovascular disease is yet another «silent» danger. Patients with MetS often have high levels of atherosclerotic disease, which may be asymptomatic due to lack of activity or diabetic neuropathy. Screening should identify signs of ventricular dysfunction or ischemia, and may use biomarkers such as B-type Natriuretic Peptide (BNP) or preoperative electrocardiograms to diagnose underlying arrhythmias such as atrial fibrillation⁶. As it pertains to gynecologic oncology, the combination of obesity and malignancy results in a hypercoagulable state, making the patient at an increased risk of venous thromboembolism (VTE). Thus, an assessment of VTE risk should occur preoperatively with appropriate prophylaxis planned³.

Additionally, the psychological and nutritional state of the patient should be considered. Many patients with MetS are deficient in micronutrients despite caloric excess, and factors such as depression can negatively influence the management of pain following surgery and recovery⁸. Screening for patients’ «invisible» risks allow for a more holistic preparation of the patient and will be an endeavor towards a «perioperative home» concept in which all aspects of the patients’ health can be optimized prior to entering the operating room.

Preoperative Optimization and Glycemic Control:

Preoperative optimization, or «prehabilitation,» is an important time for reducing the inflammatory and metabolic burden surgery puts on a patient. For patients that have OSA identified, the optimization of CPAP therapy, even for weeks before surgery, can improve nocturnal oxygenation and reduce upper airway sensitivity to agents used for anesthetic⁴. This has been shown to improve patient safety during emergence from anesthesia and stabilize the patient’s cardiometabolic profile.

Glycemic control is perhaps the most important focus of optimization for the MetS population. Although Hgb A1c levels over the long term tell us about chronic control, acute preoperative glycemic variability is a strong predictor of postoperative complications. The evidence currently supports a target range of blood glucose instead of a too aggressive «tight» range, that may present hypoglycemia to the patient. Structured protocols for the management of oral hypoglycemics and insulin are essential in the 24-48-hour preoperative window to avoid ketoacidosis and limit the patient’s hyperglycemia response from surgical stress.

Multidisciplinary enhanced recovery pathways, such as the EUPEMEN protocol, help provide a structure for that optimization. Enhanced recovery pathways promote patient education, nutrition optimization, and standardization of care with the goal of minimizing variability in outcomes¹. In older patients with MetS, the multidisciplinary approach is even more important since it includes geriatricians expertise to manage frailty and polypharmacy¹⁰. Addressing factors like this preoperatively can help the anesthesiologist change the inflammatory trajectory of the patient, leading to a better intraoperative experience and ultimately decrease recovery time for the patient.

Intraoperative Management Challenges:

Airway Management and Ventilation Strategies:

The intraoperative management of patients with metabolic syndrome (MetS) is characterized by distinct challenges that arise from the anatomic and physiological changes associated with central obesity and obstructive sleep apnea (OSA). Airway management in this population extends beyond a simple calculation of Body Mass Index (BMI), as the anatomical distribution of adipose tissue in the pre-tracheal region and the base of the tongue limits view during laryngoscopy¹¹. The «difficult airway» in MetS patients is defined by decreased functional residual capacity (FRC) and increased oxygen consumption that bring about a nearly immediate, and shortened, «safe apnea time». This physiological setting has rapid desaturation kinetics that warrants careful planning for pre-oxygenation that includes positioning the patient in the head-up or ramped position to optimize the glottic view and extend safe apnea time.

Ventilation strategies should be adapted for the positive intra-abdominal pressure and low lung compliance secondary to MetS. Positive end-expiratory pressure (PEEP) is important in preventing atelectasis, counterbalanced by the risk of decreased venous return and right ventricular pressure increase. In advanced life support guidelines, clinicians are reminded to maintain oxygenation while minimizing gastric insufflation during difficult mask ventilation¹². Recruitment maneuvers should also be approached with caution, as the hemodynamic consequences of high airway pressures can be staggering for patients with background diastolic dysfunction or pulmonary hypertension.

Pharmacological Considerations and Dosing Adjustments:

Pharmacological management of patients with MetS is complicated by altered pharmacokinetics and pharmacodynamics, particularly related to lipophilic anesthetics used for induction. Most induction agents, such as propofol, fentanyl, etc. are lipophilic and will sequester in adipose tissue, resulting in an increased volume of distribution and longer elimination half-life. Using total body weight (TBW) for induction agents often leads to overdose and extended emergence from anesthesia, whereas ideal body weight (IBW) limits the effective plasma concentrations of the drug and increases the risk of intraoperative awareness. Regardless, recent studies suggest lean body mass (LBM) or adjusted body weight may better serve as a dosing basis for this patient population.

In the case of induction agents, etomidate is often chosen for its favorable therapeutic index and minimal hemodynamic instability, which is especially difficult for patients with cardiovascular vulnerabilities from metabolic syndrome¹³. However, the clinician must also be mindful of transient adrenal suppression risk for patients that may already be in a «pre-primed» inflammatory state or are metabolically deranged. The clinician must also select neuromuscular blocking agents with caution. Sugammadex is a better choice for reversal agents than neostigmine in the patients with MetS, as it provides rapid, and complete, reversal of deep blockade and minimizes the risk of postoperative residual curarization and respiratory complications.

Hemodynamic Monitoring and Fluid Therapy:

Hemodynamic stability can be unstable in patients with MetS due to vascular endothelial dysfunction and a lack of vasomotor control. Standard non-invasive blood pressure monitoring may be inaccurate in the presence of morbid obesity, leading to the use of invasive arterial monitoring in higher-risk cases. Additionally, many patients with MetS have a preserved ejection fraction but significant diastolic dysfunction, which creates a narrow margin for fluid administration. A liberal fluid strategy can lead to pulmonary edema quickly, while an overly restrictive strategy can lead to acute kidney injury amid chronic hypertension and insulin resistance.

Goal-directed hemodynamic therapy (GDHT) using dynamic parameters based on pulse pressure variation or stroke volume variation is being increasingly recommended over static measures such as central venous pressure. The use of GDHT leads to more accurate titration of fluids and vasopressors, delivering adequate organ perfusion without developing a fluid overload. Moreover, right ventricular (RV) function is always in focus, as acute RV failure can occur in the face of chronic OSA and obesity-related pulmonary hypertension, with stress from anesthetic agents and positive pressure ventilation¹⁴. Considerations around RV dysfunction include maintaining adequate systemic blood pressure as RV coronary perfusion is dependent on systemic perfusion, and using selective pulmonary vasodilators if necessary.

Postoperative Care and Complication Prevention:

Respiratory Support and Monitoring Considerations for MetS Patients:

The postoperative period is a high-risk time for MetS patients, specifically relating to respiratory failure and exacerbation of OSA. The residual effects from anesthetics and opioids can depress the activity of the upper airway dilator muscles, which can lead to obstructive events and hypoxemia. Continuous pulse oximetry and in some cases, capnography, is advised so as the early detection of respiratory depression can occur. For patients with known or suspected OSA, early initiation of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) in the PACU is essential to aid in airway patency.

Although, assessing dyspnea in the postoperative setting can be challenging, the use of simple tools such as the visual analog scale (VAS) or Likert scales have been shown as useful tools in identifying acute changes in respiratory status¹⁵. These tools help with differentiation of atelectasis from potentially more serious complications such as acute heart failure or pulmonary embolism. Additionally, a «safe» transition from recovery room to general hospital ward requires a standard assessment whether patients can maintain adequate oxygenation on room air, or their baseline supplemental oxygen requirements.

Multimodal Analgesia and Minimizing Opioid Usage:

Providing effective pain control while minimizing opioid side effects is key for postoperative care of MetS patients. Opioids carry a high incidence of respiratory depression, postoperative nausea and vomiting (PONV), and delayed gastrointestinal recovery, which is particularly important in this cohort. Multimodal analgesia, which includes a variety of analgesics such as paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), and gabapentinoids is recommended as first line treatments. Regional anesthesia techniques such as: epidural analgesia and plane blocks e.g., transversus abdominis plane blocks, usually provide superior pain control while reducing the need for systemic opioids overall¹⁶.

The decreased use of opioids is also vital in preventing postoperative ileus (POI), along with gastrointestinal dysmotility¹⁷. POI is a common complication impacting hospital length of stay and other morbidity, the pathogenesis of which includes neuroinflammation and activation of inhibitory neural pathways in the gut. By utilizing opioid-sparing methods and early enteral feeding, we can reduce or minimize these effects and facilitate an earlier recovery of bowel function.

Prevention of Thromboembolic and Infectious Complications:

Patients with metabolic syndrome (MetS) have an increased risk of developing venous thromboembolism (VTE) because of a baseline hypercoagulable state and decreased mobility. Prophylactic measures, including early ambulation, mechanical compression devices, and pharmacologic anticoagulation, should all be closely followed. Timing and dosing of anticoagulants should be closely monitored when using regional anesthesia techniques, to further decrease the risk of spinal hematoma.

Infectious complications (e.g., surgical site infections [SSIs]) are also more prevalent in the MetS population because of impaired wound healing associated with hyperglycemia and chronic inflammation. Tight glucose control should be a dominant focus in the immediate postoperative period, typically targeting a blood glucose range of 140-180 mg/dL. It is important to consider the target of perioperative antibiotics and promote normothermia are also key components of infection prevention. The proinflammatory state of MetS may also present as an exaggerated systemic inflammatory response syndrome (SIRS) state after surgery, requiring increased vigilance and monitoring for signs of sepsis and organ dysfunction.

Systematic Integration of Clinical Approaches:

Implementation of Enhanced Recovery After Surgery (ERAS) Protocols:

ERAS protocols have dramatically changed perioperative care by providing a standardized and evidence-based approach to minimize surgical stress and improve surgical recovery. For patients with MetS, the adoption of any ERAS components need to be assessed to account for the individual metabolic and functional frailties. Preadmission counseling and optimization of comorbidities (e.g., hypertension and diabetes) are essential components¹⁸. Preoperative carbohydrate loading is a standard ERAS component that may require modification in patients with severe insulin resistance to mitigate profound hyperglycemia¹⁹.

Intraoperative ERAS components for MetS include short-acting anesthetic agents, maintenance of normothermia, and goal-directed fluid therapy²⁰. In bariatric surgery, which often involved the MetS patient population, ERAS (ERABS) has been found to be safe, beneficial, and effective at improving outcomes and decreasing length of hospital stay²¹. EMAS protocols highlight the importance of leveraging the perioperative period by minimizing fasting and promoting early ambulation to counteract the metabolic «crash» often seen after major surgery. The utilization of ERAS for emergency surgery protocols, including emergency laparotomy, further emphasizes expeditious assessment and physiological optimization²².

Role of Goal-Directed Hemodynamic Therapy:

GDHT is a fundamental principle of contemporary anesthetic management for the high-risk surgical patient. For the patient with MetS, GDHT provides a logical framework for fluid and vasopressor management that transcends typical «recipe-based» fluid management. By utilizing flow-based parameters to guide our intervention, we can optimize stroke volume and oxygen delivery, but we can also minimize the risk of fluid overload and tissue edema. When patients are undergoing major abdominal or vascular surgeries, this fluid balance becomes increasingly important.

Applying GDHT within the context of ERAS pathways has been shown to reduce postoperative complications including acute kidney injury and surgical site infections. The metabolic syndrome patient is uniquely benefitted by the earlier cessation of invasive hemodynamic monitoring, as well as the potential for more expedient oral intake and post-surgical mobilization. While the clinical advantages are obvious, the successful application of GDHT is reliant on suitable equipment and the education of staff in order to have accurate and timely interpretation of the relevant data.

Impact of Multidisciplinary Care Coordination:

The inherent complexity of MetS requires multifaceted collaboration in the perioperative care of patients. This «Perioperative Surgical Home» involves collaboration between anesthesiologists, surgeons, endocrinologists, cardiologists, nursing staff, and others. For procedures like pelvic exenteration which require advanced training, consensus statements have (properly) been established indicating that management is typically best interpreted and managed by a specialized team with dedicated training within a specialized tertiary unit²³. This allows a condition to be managed with a precautionary approach to the patients metabolic state, from the time of designating their significant surgery to their post-operative follow-up.

Engagement of nutritionists and psychologist is another important contributor to facilitating metabolic and bariatric surgical patients achieving sustainable outcomes following their procedures²⁴. Most multi-disciplinary teams are considered ideal in providing suitable care to the patient experiencing «metabolic hangover» following surgery, as well as to implement complex care pathways such as those required for neonatal intestinal surgery, which exemplifies a similar complex patient population²⁵. The principle approach we expect from effective multidisciplinary coordination is to provide continuous care that serves to diminish the risks which correlate to the embodiment of the synergistic comorbidities of MetS.

DISCUSSION

The systematic synthesis of the current literature articulates that metabolic syndrome cannot be simplified as a cluster of unrelated comorbidities but as one systemic vulnerability. The chronic low-grade inflammation and endothelial dysfunction pathophysiology mechanisms which are inherent in MetS create a «pre-primed» state, which seems to modify the response of the body to the stress of anesthesia and surgery. The clinically applicable component is significant, as anesthesiologists must begin to think about the «ASA physical status» and more than solely above the body mass index (BMI) in terms of risk, these standards are often inadequate for identifying nuance of metabolic health. In the context of patients with MetS, we need to think in terms of a «metabolic mapping» approach depending on the information we have available to stratify risk, with potential markers such as HbA1c, waist-to-hip ratios, or functional capacity, replacing body mass index in excess of traditional medical standards.

The findings support a shift towards regional-heavy, opioid-sparing anesthetic techniques, with strict adherence to ERAS protocols tailored to the population. These methodologies address the major challenges faced by the MetS population, including respiratory failure, the delayed resolution of gastrointestinal recovery, and metabolic decompensation. GDHT and contemporary airway management tools, such as video laryngoscopy, should be considered the standard of care for this population in order to tackle the intrinsic challenges of hemodynamic instability and difficult intubation.

While this small but growing body of literature is expanding, there remain several important gaps in our understanding of optimal anesthetic management for MetS patients. Many of the guidelines referenced above are based on literature involving patients with obesity or diabetes separately, without consideration of the combined impact of the full metabolic syndrome. There remain few high-quality, randomized controlled trials examining the dosing of anesthetic agents directly on the MetS population.

Moreover, while there is recognition of the importance of right ventricular function, the evidence base for existing specific management strategies for RV dysfunction in the perioperative space is generally low. There is a need for further studies to examine the relationship between metabolic derangements and postoperative cognitive dysfunction or delirium, as neuroinflammation is likely a mediator in this population. Finally, the so-called «obesity paradox», whereby a mild state of obesity seems to protect patients in certain surgical settings, is an important area requiring further investigation in terms of relevance to patients with metabolic dysfunction versus «metabolically healthy obese» patients.

There are limitations to the systematic review. First, the heterogeneity of the included studies (from bariatric surgery to general vascular surgery) hindered the ability to draw global conclusions applicable to all surgical procedures. Secondly, the definition of metabolic syndrome has changed over time, and different studies may have used different inclusion criteria (e.g., WHO versus NCEP-ATP III, it is possible this may have impacted patient selection).

Third, there remains a lack of high-quality evidence of the studies related to some of the interventions we have described and, specifically in the areas of postoperative monitoring and specific pharmacological regimens, studies reported small sample sizes or were a retrospective design. We made our best effort to summarize the best evidence, but due to the lack of large-scale prospective trials investigating this topic specifically on MetS, some recommendations are based on opinion and not high evidence level. Finally, it should be noted that pharmacological and technological advancement in the field of anesthesia is occurring at a rapid pace, and it is likely that some newer agents or monitoring devices are not yet adequately represented in the literature.

 

CONCLUSION

Anesthetizing patients with metabolic syndrome requires nuanced understanding of the interaction between obesity, insulin resistance, hypertension, and chronic inflammation. This systematic review has identified that the major challenges – including difficult airway management, pharmacological dosing, hemodynamic instability, and postoperative respiratory failure – can be navigated through a proactive, multi-faceted approach to management. This includes a lean body mass dosage, goal-directed hemodynamic therapy, and the active role of regional anesthesia and opioid-AH sparing approach.

Combining individualized ERAS protocols and collaborating with multidisciplinary teams will promote the best outcomes and lower the occurrence of postoperative complications. Nonetheless, the literature reveals substantial gaps regarding specific RV management and long-term cognitive effects of metabolic dysfunction. Future studies should develop improved metabolic risk stratification tools and conduct high-quality trials with larger patient populations to generate firm clinical recommendations for this patient population that is growing and considered high-risk. Overall, the best approach to providing safe and effective anesthetic care for patients with metabolic syndrome is to take a personalized approach to the patients’ unique physiological and metabolic characteristics.

 

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