Residency · Residency · Anesthesiology

Preoperative Optimization: Anemia, Frailty, and Prehabilitation

Introduction

The preoperative period represents a critical window of opportunity to optimize modifiable risk factors and improve surgical outcomes. Three areas have gained particular attention in perioperative medicine: anemia management, frailty assessment, and prehabilitation programs. These concepts align with the principles of Enhanced Recovery After Surgery (ERAS) and Patient Blood Management (PBM), shifting the paradigm from reactive treatment to proactive optimization.

Preoperative Anemia

Epidemiology and Impact

Preoperative anemia is present in 30 to 40% of patients undergoing major surgery. Even mild anemia (hemoglobin 10 to 12 g/dL) is independently associated with increased 30-day mortality, morbidity, ICU admission, and length of stay. Anemia also increases the likelihood of allogenic blood transfusion, which itself carries independent risks including infections, transfusion reactions, immunomodulation, and increased mortality.

Etiology in the Surgical Population

Iron deficiency anemia (IDA) is the most common cause, accounting for up to 60% of cases and often being multifactorial in origin. Anemia of chronic disease or inflammation involves cytokine-mediated iron sequestration and is common in cancer, autoimmune disease, and chronic kidney disease. Vitamin B12 and folate deficiency causes macrocytic anemia and should be checked in elderly and malnourished patients. Chronic kidney disease leads to anemia through decreased erythropoietin production. Blood loss from GI bleeding, menorrhagia, or prior surgery is another frequent contributor.

Diagnostic Workup

A CBC with indices provides the MCV to classify anemia as microcytic, normocytic, or macrocytic. Iron studies including ferritin, transferrin saturation (TSAT), serum iron, and total iron binding capacity (TIBC) are essential. Iron deficiency anemia is indicated by a ferritin less than 30 ng/mL or TSAT less than 20%, while functional iron deficiency in inflammatory states is suggested by a ferritin of 30 to 100 ng/mL with TSAT less than 20%. A reticulocyte count assesses marrow response. B12 and folate levels are checked if the anemia is macrocytic. CRP helps distinguish iron deficiency from anemia of chronic disease. Renal function is assessed for CKD-related anemia.

Treatment Strategies

Oral iron with ferrous sulfate 200 mg (65 mg elemental iron) daily or every other day has efficacy limited by GI side effects and a slow response of 4 to 6 weeks for a meaningful hemoglobin increase. IV iron such as ferric carboxymaltose (750 to 1000 mg), iron sucrose, or ferric derisomaltose is preferred when surgery is within 2 to 6 weeks or when oral iron is ineffective or not tolerated; it can raise hemoglobin by 1 to 2 g/dL in 2 to 4 weeks. Erythropoiesis-stimulating agents (ESAs) should be considered in CKD-related anemia or when combined with iron therapy, targeting a hemoglobin of 10 to 12 g/dL while avoiding higher targets due to thromboembolic risk. B12 and folate supplementation is provided when deficiency is identified. Ideally, anemia should be identified and treated 4 to 8 weeks before elective surgery.

Frailty

Definition and Relevance

Frailty is a state of decreased physiologic reserve and increased vulnerability to stressors, distinct from age, disability, or specific comorbidities. Frail patients have a 2 to 3 fold increase in postoperative mortality, major complications, prolonged hospitalization, ICU admission, and discharge to skilled nursing facilities. Frailty prevalence increases with age but is present in 10 to 20% of patients over 65 years and can occur at any age.

Assessment Tools

The Fried Phenotype Model uses five criteria: unintentional weight loss, exhaustion, low physical activity, slow gait speed, and weak grip strength. A score of 3 to 5 criteria indicates frailty, while 1 to 2 criteria indicates pre-frailty. The Clinical Frailty Scale (CFS) is a 9-point pictographic scale ranging from very fit to terminally ill, with a score of 5 or higher indicating frailty; it is quick, practical, and widely used in preoperative clinics. The Modified Frailty Index (mFI) is based on NSQIP variables and consists of an 11-item checklist. The Edmonton Frail Scale is a 17-point scale assessing cognition, function, mood, continence, nutrition, social support, medications, and functional performance. The Timed Up and Go (TUG) test measures the time to rise from a chair, walk 3 meters, return, and sit down, with a time greater than 15 seconds suggesting functional limitation.

Integration into Surgical Decision-Making

Frailty assessment should be part of the preoperative evaluation for all patients over 65 years and for younger patients with suspected frailty. Frailty scoring helps inform shared decision-making about surgical risk, goals of care, and the appropriateness of intervention. Frail patients benefit from targeted prehabilitation, multidisciplinary optimization, and enhanced postoperative care pathways.

Prehabilitation

Concept

Prehabilitation refers to structured preoperative interventions designed to enhance functional capacity and physiologic reserve before surgery. It is based on the principle that a patient with greater baseline reserve will tolerate surgical stress better and recover faster. Multimodal prehabilitation addresses exercise, nutrition, and psychological well-being.

Components

Exercise Prehabilitation

Aerobic training with walking, cycling, or swimming programs 3 to 5 times per week for 4 to 8 weeks preoperatively forms the foundation. Resistance training for upper and lower extremity strengthening is particularly important for sarcopenic and frail patients. Inspiratory muscle training (IMT) has been shown to reduce postoperative pulmonary complications in thoracic and upper abdominal surgery. The target is to improve cardiopulmonary fitness measured by VO2 peak or 6-minute walk distance. Meta-analyses show reduced postoperative complications, shorter length of stay, and faster functional recovery with exercise prehabilitation.

Nutritional Optimization

Screening for malnutrition involves checking albumin (less than 3.0 g/dL), unintentional weight loss greater than 10%, BMI less than 18.5, or subjective global assessment. Protein supplementation targets 1.2 to 1.5 g/kg/day with emphasis on leucine-rich sources. Immunonutrition supplements containing arginine, omega-3 fatty acids, and nucleotides for 5 to 7 days preoperatively may reduce infectious complications, with evidence strongest in GI cancer surgery. Carbohydrate loading with clear carbohydrate drinks 2 to 3 hours preoperatively reduces insulin resistance and improves recovery, which is standard in ERAS protocols. Micronutrient deficiencies in vitamin D, B12, and iron should be corrected as identified.

Psychological Preparation

Preoperative anxiety is associated with higher pain scores, greater opioid consumption, and delayed recovery. Cognitive behavioral techniques including relaxation, guided imagery, and mindfulness-based stress reduction can help mitigate these effects. Smoking cessation ideally occurs 4 to 8 weeks before surgery, though even 48 hours of abstinence reduces carbon monoxide and improves oxygen-carrying capacity. Alcohol reduction with 4 weeks of abstinence reduces surgical complications in heavy drinkers.

Patient Blood Management (PBM)

Three Pillars of PBM

The first pillar is optimizing erythropoiesis by treating preoperative anemia with iron, ESAs, and B12 or folate. The second pillar is minimizing blood loss through meticulous surgical technique, cell salvage, antifibrinolytics (tranexamic acid), point-of-care coagulation testing, and normothermia. The third pillar is optimizing anemia tolerance by using restrictive transfusion thresholds (hemoglobin 7 g/dL for most patients), maximizing oxygen delivery, and tolerating lower hemoglobin when safe.

Evidence for PBM

PBM programs reduce allogenic transfusion rates by 30 to 50%, decrease mortality, shorten length of stay, and lower infection rates. The PREVENTT trial demonstrated that preoperative IV iron reduces transfusion requirements in anemic patients undergoing major abdominal surgery, though the hemoglobin response was modest in short preoperative windows.

Perioperative Medicine Clinics

Multidisciplinary preoperative assessment clinics enable early identification and management of anemia, frailty, malnutrition, and deconditioning. The ideal timeline involves assessment 4 to 8 weeks before surgery to allow meaningful optimization. The team includes anesthesiologists, internists or hospitalists, nutritionists, physical therapists, social workers, and pharmacists. Structured preoperative pathways reduce day-of-surgery cancellations, improve outcomes, and enhance patient experience.

Key Clinical Pearls

Preoperative anemia should be treated, not tolerated, and IV iron is the preferred treatment when surgery is within 2 to 6 weeks. Frailty is a stronger predictor of postoperative outcomes than age or ASA status, and all patients over 65 should be assessed with a validated tool such as the Clinical Frailty Scale. Multimodal prehabilitation combining exercise, nutrition, and psychological preparation is more effective than any single intervention. Even 2 to 4 weeks of prehabilitation before major surgery can produce measurable improvements in functional capacity. Patient Blood Management is not about withholding transfusions; it is about optimizing the patient before surgery so that transfusions are less likely to be needed.

References

1. Muñoz M, Acheson AG, Bisbe E, et al. An international consensus statement on the management of postoperative anaemia after major surgical procedures. Anaesthesia. 2018;73(11):1418-1431.
2. Lin HS, Watts JN, Peel NM, Hubbard RE. Frailty and post-operative outcomes in older surgical patients: a systematic review. BMC Geriatr. 2016;16(1):157.
3. Minnella EM, Bousquet-Dion G, Awasthi R, et al. Multimodal prehabilitation improves functional capacity before and after colorectal surgery for cancer: a five-year research experience. Acta Oncol. 2017;56(2):295-300.
4. Richards T, Baikady RR, Clevenger B, et al. Preoperative intravenous iron to treat anaemia before major abdominal surgery (PREVENTT): a randomised, double-blind, controlled trial. Lancet. 2020;396(10259):1353-1361.

Read this lecture as Markdown