Pre-Operative Evaluation and Optimization

Medical School · Year 4 · Subinternship Surgery · includes a quiz and discussion video

Pre-Operative Evaluation and Optimization

Year 4: Sub-Internship Surgery

Learning Objectives

By the end of this seminar, students will be able to:

Perform comprehensive pre-operative assessment including history, physical examination, and functional capacity evaluation
Risk stratify surgical patients using cardiac risk indices and pulmonary risk factors
Apply evidence-based guidelines for pre-operative testing and avoid unnecessary studies
Manage peri-operative medications including anticoagulation bridging and diabetes adjustments
Optimize patients with chronic diseases before elective surgery and recognize conditions requiring delay
Execute day-of-surgery protocols including consent verification, site marking, and surgical time-out

Section I: Pre-Operative Assessment Framework

The pre-operative history establishes the foundation for risk assessment and surgical planning. The current illness must be understood in sufficient detail to confirm surgical indication and timing, as some conditions allow optimization while others demand urgent intervention. Prior surgical history receives particular attention, including previous operations, complications such as bleeding or infection, and anesthetic issues including difficult intubation or adverse reactions. A complete medication list identifies drugs requiring perioperative adjustment, particularly anticoagulants, antiplatelet agents, and insulin. Allergies must be documented precisely, distinguishing true allergic reactions from intolerances, with particular attention to latex sensitivity and contrast reactions.

Social history directly impacts surgical outcomes and planning. Tobacco use affects wound healing, pulmonary function, and anesthetic risk, making documentation of pack-years and current status essential. Alcohol consumption, especially heavy or dependent use, predicts withdrawal risk requiring prophylaxis and monitoring. Illicit drug use affects anesthetic requirements and may suggest underlying infectious risk. Living situation and support system influence discharge planning, as patients without adequate home support may require rehabilitation or extended hospitalization. Functional status, assessed by activities of daily living and exercise tolerance, predicts recovery trajectory and perioperative risk.

The physical examination focuses on findings that impact anesthetic safety and surgical planning. Airway assessment includes mouth opening, Mallampati score, thyromental distance, neck mobility, and dentition, as these predict difficult intubation. Cardiovascular examination evaluates heart sounds for murmurs suggesting valvular disease, jugular venous pressure indicating volume status and right heart function, and peripheral edema suggesting heart failure. Pulmonary examination documents baseline breath sounds and any evidence of active respiratory disease. The abdominal examination is relevant to the planned procedure, including prior incisions, hernias, and organomegaly. Vascular assessment notes peripheral pulses and bruits.

Functional capacity provides crucial prognostic information that guides the extent of cardiac evaluation required. Measured in metabolic equivalents (METs), functional capacity correlates with ability to increase cardiac output to meet surgical stress. Activities equivalent to one to four METs include self-care activities and walking one to two blocks on level ground. Four to seven METs corresponds to climbing a flight of stairs or walking uphill. Seven to ten METs includes heavy housework or moderate recreational sports. Greater than ten METs reflects vigorous athletic activity. Patients unable to achieve four METs face higher surgical risk and may require additional cardiac testing before proceeding with non-emergent surgery.

Section II: Cardiac Risk Assessment

The Revised Cardiac Risk Index (RCRI) provides a validated, evidence-based approach to predicting major adverse cardiac events (MACE) in patients undergoing non-cardiac surgery. Six independent predictors of cardiac risk comprise the index: high-risk surgery including intraperitoneal, intrathoracic, or suprainguinal vascular procedures; history of ischemic heart disease including prior myocardial infarction, positive stress test, ongoing angina, nitrate use, or pathologic Q waves; history of heart failure; history of cerebrovascular disease including stroke or transient ischemic attack; diabetes mellitus requiring insulin treatment; and renal insufficiency with creatinine greater than two milligrams per deciliter. Each factor present adds one point to the score.

The RCRI score translates into predicted risk of major adverse cardiac events including myocardial infarction, pulmonary edema, ventricular fibrillation, cardiac arrest, and complete heart block. A score of zero predicts a 0.4 percent risk of MACE, making additional testing rarely indicated. One risk factor predicts 0.9 percent risk, still relatively low. Two factors increase risk to 6.6 percent, and three or more factors predict 11 percent or higher risk, levels at which additional evaluation and optimization often improve outcomes. These quantified risks facilitate informed discussions with patients and guide decisions about testing and timing.

Determining when cardiac testing adds value requires weighing pretest probability, test characteristics, and potential to change management. Emergency surgery proceeds without delay regardless of cardiac risk, as the benefit of avoiding surgical emergency outweighs cardiac risk. Active cardiac conditions including acute coronary syndrome, decompensated heart failure, significant arrhythmias, and severe valvular disease warrant delay and treatment before elective surgery. For patients with stable coronary artery disease, additional testing rarely changes management, as revascularization before non-cardiac surgery has not shown benefit. Testing is most useful when patients with elevated risk factors also demonstrate poor functional capacity, as normal results may allow proceeding with surgery and abnormal results prompt optimization.

Cardiology consultation adds value when active cardiac conditions require management or when testing results require subspecialty interpretation. Recent myocardial infarction within sixty days represents high risk and benefits from cardiology guidance on timing and optimization. Unstable or new angina requires evaluation and treatment before elective surgery. Decompensated heart failure must be optimized, with cardiology guiding diuresis and afterload reduction. Significant arrhythmias may require rate control, rhythm management, or device considerations. Severe valvular disease, particularly aortic stenosis, significantly increases operative risk and may require intervention before non-cardiac surgery.

Section III: Pulmonary Risk Assessment

Patient-related risk factors for pulmonary complications significantly impact postoperative morbidity and mortality. Chronic obstructive pulmonary disease represents the strongest patient-related predictor, particularly when poorly controlled or requiring recent hospitalization. Active smoking impairs mucociliary clearance and increases secretions, though cessation even four to eight weeks before surgery reduces risk. Obstructive sleep apnea creates unique risks related to airway management, opioid sensitivity, and postoperative monitoring requirements. Obesity impairs respiratory mechanics and predisposes to atelectasis. Poor functional status, reflected by ASA class II or greater, independently predicts pulmonary complications. Advanced age correlates with decreased physiologic reserve and impaired cough.

Procedure-related factors often exceed patient factors in determining pulmonary complication risk. Aortic surgery carries the highest pulmonary risk among non-thoracic procedures. Thoracic surgery directly impacts pulmonary function through lung manipulation, pain limiting breathing, and potential parenchymal resection. Upper abdominal surgery, particularly when requiring large incisions, significantly impairs diaphragmatic function and deep breathing. Lower abdominal surgery carries moderate risk, generally less than upper abdominal procedures. Peripheral and extremity surgery presents the lowest pulmonary risk when regional anesthesia is possible. Duration of surgery independently predicts complications, with procedures exceeding three hours carrying substantially higher risk.

Pre-operative pulmonary testing should be indication-based rather than routine. Spirometry is not indicated for routine preoperative evaluation, even in patients with known lung disease, unless results would change management. Consider spirometry for dyspnea of unclear etiology when results might reveal unexpected pathology. Chest radiograph is not routinely indicated but appropriate for new respiratory symptoms or physical examination abnormalities. Arterial blood gas analysis establishes baseline for patients with severe COPD when postoperative ventilation decisions may be needed. Sleep studies identify undiagnosed obstructive sleep apnea when history suggests risk, allowing appropriate monitoring arrangements.

Risk reduction strategies target modifiable factors before surgery and optimize management of chronic disease. Smoking cessation ideally begins eight or more weeks before surgery, though even brief abstinence provides some benefit. COPD optimization includes ensuring appropriate bronchodilator therapy, treating any active exacerbation, and considering short-term corticosteroids when significant bronchospasm exists. Patient education about incentive spirometry before surgery improves postoperative compliance and effectiveness. Laparoscopic approaches, when surgically appropriate, reduce pulmonary complications compared to open surgery. Regional anesthesia, when feasible, reduces respiratory depression risk and improves cough and deep breathing compared to general anesthesia with systemic opioids.

Section IV: Medication Management

Medications to continue through the perioperative period include those whose discontinuation poses greater risk than continuation. Beta-blockers should be continued in patients already taking them chronically, as withdrawal increases cardiac risk. Statins continue perioperatively and may provide benefit through pleiotropic effects beyond lipid lowering. Aspirin continues in patients with coronary stents, as the risk of stent thrombosis outweighs most bleeding risks; however, this decision should be individualized and discussed with the surgical team. Thyroid hormone, essential for normal metabolism, continues on the morning of surgery with a sip of water. Proton pump inhibitors and histamine blockers reduce aspiration risk and continue perioperatively. Anti-epileptic medications prevent seizures and should not be interrupted.

Medications requiring discontinuation before surgery include those that increase bleeding risk or interact adversely with anesthesia. Warfarin stops five days before surgery to allow INR normalization. Direct oral anticoagulants (DOACs) stop twenty-four to forty-eight hours before surgery depending on renal function and specific agent. Aspirin in patients without cardiac indications stops seven days before surgery. Clopidogrel and other P2Y12 inhibitors stop five to seven days before to allow platelet function recovery. Metformin stops the day of surgery to prevent lactic acidosis in the setting of contrast exposure or hypoperfusion. NSAIDs stop three to seven days before to reduce bleeding risk. ACE inhibitors and ARBs stop the morning of surgery to reduce intraoperative hypotension risk.

Anticoagulation bridging decisions balance thromboembolic risk against bleeding risk. Low-risk patients, including those with atrial fibrillation without prior stroke and low CHA2DS2-VASc scores, generally require no bridging. Moderate-risk patients require individualized decisions weighing the specific surgery's bleeding risk against thromboembolic risk. High-risk patients, including those with mechanical heart valves, especially mitral, recent venous thromboembolism within three months, or atrial fibrillation with prior stroke, typically require bridging with low-molecular-weight heparin or unfractionated heparin. The typical bridging protocol stops warfarin five days before surgery, starts bridging three days before surgery, holds bridging twenty-four hours before surgery, and resumes bridging when hemostasis is secure.

Diabetes medication management prevents both hypoglycemia and severe hyperglycemia during the perioperative period. Metformin holds on the day of surgery and resumes when the patient is eating and renal function is stable. Sulfonylureas and other insulin secretagogues hold on the day of surgery to prevent hypoglycemia while NPO. Sodium-glucose cotransporter-2 (SGLT2) inhibitors stop three to four days before surgery due to euglycemic diabetic ketoacidosis risk. Basal insulin typically continues at fifty to seventy-five percent of the usual dose to prevent ketoacidosis. Bolus insulin holds when the patient is NPO. Glucose monitoring increases perioperatively with correction insulin as needed, targeting levels below one hundred eighty milligrams per deciliter.

Section V: Pre-Operative Testing

Evidence-based test selection avoids unnecessary studies while ensuring important abnormalities are detected. The principle of indication-based testing means ordering studies only when clinical factors suggest potential abnormality and when results would change management. Repeating recent normal studies wastes resources and delays surgery without benefit. History and physical examination findings should guide testing; routine panels based solely on age or scheduled surgery type often fail to improve outcomes. Acknowledging the time and cost burden of testing encourages thoughtful orders that respect patient resources and system efficiency.

Common preoperative laboratory studies have specific indications based on patient and surgical factors. Complete blood count is indicated for major surgery with anticipated blood loss, known anemia, or conditions affecting blood counts. Basic metabolic panel is appropriate for patients with renal disease, diabetes, diuretic use, ACE inhibitor therapy, or electrolyte disorders. Coagulation studies including PT, PTT, and INR are indicated for patients on anticoagulation, those with liver disease, or those with bleeding history. Type and screen is ordered when transfusion possibility exists, with type and crossmatch when transfusion is likely. Hemoglobin A1c assesses recent glucose control in diabetic patients and may influence surgical timing. Pregnancy testing is indicated for all women of reproductive age.

Pre-operative imaging and cardiac testing follows clinical indication rather than routine ordering. Chest radiograph is not routinely indicated and should be reserved for new or unexplained pulmonary symptoms or physical examination abnormalities. Electrocardiogram is appropriate for patients with known coronary artery disease, significant arrhythmia, structural heart disease, or symptoms suggesting cardiac disease. Echocardiography is indicated for new or worsening symptoms of heart failure or valvular disease, not for routine assessment. Stress testing is reserved for patients with poor functional capacity undergoing high-risk surgery when results would change management by prompting optimization or procedure modification.

Age alone does not determine testing requirements; comorbidities and surgical factors guide decisions. Healthy patients under forty years typically require no routine testing for low-risk surgery. Patients aged forty to sixty may require electrocardiogram if cardiac risk factors are present. Patients over sixty commonly receive ECG, complete blood count, and basic metabolic panel, though evidence for routine testing is limited even in this age group. Regardless of age, testing should be driven by clinical factors identified in history and physical examination. The reflex ordering of comprehensive panels for all surgical patients contradicts evidence-based principles and increases costs without improving outcomes.

Section VI: Special Populations

Elderly patients require assessment beyond chronological age to identify those at increased surgical risk. Frailty screening using validated tools predicts adverse outcomes better than age alone and identifies patients who may benefit from prehabilitation or modified surgical approaches. Cognitive assessment establishes baseline function and identifies patients at high risk for postoperative delirium, allowing preventive measures. Polypharmacy review identifies medications that can be discontinued or adjusted to reduce interactions and adverse effects. Goals of care discussions before surgery ensure that the planned procedure aligns with patient values and that complications can be managed consistent with preferences. Functional status assessment predicts recovery trajectory and discharge needs.

Renal disease creates specific perioperative considerations requiring attention. Dialysis timing around surgery coordinates with the surgical team to optimize volume and electrolyte status, with dialysis typically performed the day before surgery. Electrolyte abnormalities, particularly hyperkalemia, must be corrected before proceeding. Contrast exposure should be minimized and accompanied by appropriate hydration when unavoidable. Medication dosing requires adjustment for altered clearance, with particular attention to opioids and antibiotics. Vascular access preservation protects dialysis fistulas and grafts from blood pressure measurements, venipuncture, and intravenous line placement in the affected extremity.

Liver disease significantly impacts surgical risk, particularly when advanced. The Model for End-Stage Liver Disease (MELD) score, calculated from bilirubin, creatinine, and INR, predicts mortality after abdominal surgery and guides decisions about proceeding. Coagulopathy may require fresh frozen plasma or vitamin K before surgery, though correction may be incomplete in advanced disease. Hypoalbuminemia impairs wound healing and predicts complications. Hepatic encephalopathy indicates decompensated disease and significantly increases operative risk. Elective surgery is often contraindicated in Child-Pugh class B and C cirrhosis, with decisions requiring careful risk-benefit discussion.

Pregnancy creates unique considerations balancing maternal and fetal wellbeing. The second trimester represents the safest period for necessary surgery, after organogenesis is complete but before the risk of preterm labor significantly increases. Fetal monitoring before and after surgery follows obstetric guidance based on gestational age and viability. Left lateral positioning during surgery prevents aortocaval compression from the gravid uterus after approximately twenty weeks. Medication choices must consider teratogenicity, with anesthesia providers experienced in obstetric anesthesia ensuring safe drug selection. Regional anesthesia offers advantages when appropriate for the procedure, reducing fetal drug exposure.

Section VII: Specific Procedure Considerations

Abdominal surgery preparation addresses the unique requirements of procedures involving the gastrointestinal tract. Bowel preparation, when indicated for colon surgery, follows protocol-driven mechanical and antibiotic regimens shown to reduce surgical site infection. Deep venous thrombosis prophylaxis planning considers the extended operative times and postoperative immobility inherent to major abdominal procedures. Prophylactic antibiotics, selected based on flora encountered during the specific procedure, must be timed for administration within sixty minutes of incision. Nasogastric tube placement, when indicated for decompression, should be discussed and planned preoperatively. Urinary catheter duration planning balances the need for output monitoring against catheter-associated infection risk.

Vascular surgery patients often carry the highest perioperative cardiac risk and require thorough optimization. Cardiac risk assessment recognizes that suprainguinal vascular procedures constitute high-risk surgery on the RCRI, and these patients frequently have concomitant coronary artery disease. Renal protection strategies include hydration before and after contrast exposure and minimizing contrast volume during angiography. Anticoagulation management considers both the indication for surgery and the risk of graft or stent thrombosis. Baseline imaging establishes graft surveillance reference points. Patients with recent coronary stenting require careful coordination regarding dual antiplatelet therapy continuation.

Thoracic surgery requires specific attention to pulmonary function and reserve. Pulmonary function testing before lung resection predicts postoperative function and identifies patients at high risk for respiratory failure. Predicted postoperative FEV1 greater than forty percent of expected suggests acceptable risk, while lower values require additional evaluation. Split lung function testing using ventilation-perfusion scanning determines the contribution of the lung being resected and refines postoperative predictions. Cardiac stress testing evaluates coronary disease risk, which is common in patients with smoking histories. Nutritional optimization improves healing and resistance to pulmonary complications.

Emergency surgery limits preoperative optimization but does not eliminate basic safety measures. Minimizing delay appropriately prioritizes the life-threatening condition being treated over complete optimization. Essential assessment includes basic vital signs, point-of-care testing for hemoglobin and coagulation when bleeding is present, and focused history for allergy and critical medications. Active resuscitation with fluid, blood, and vasopressors continues during the evaluation period. Risk communication with patients or surrogate decision-makers honestly conveys the urgency and elevated risk of emergency operation. Documentation records what assessment was possible and why optimization was not feasible.

Section VIII: NPO Guidelines

Standard fasting guidelines balance aspiration risk against patient comfort and physiologic preparation. Clear liquids, including water, clear juice without pulp, black coffee, and tea, may be consumed until two hours before anesthesia induction. Breast milk for infants may continue until four hours before surgery. Formula, non-human milk, and light meals such as toast require six hours of fasting. Full meals, particularly those containing fat or fried foods, require eight hours for gastric emptying. These evidence-based intervals represent minimum fasting periods; longer fasting does not provide additional benefit and may cause unnecessary dehydration and discomfort.

Enhanced recovery after surgery (ERAS) protocols challenge traditional prolonged fasting practices. Carbohydrate loading with clear carbohydrate-rich drinks two to three hours before surgery reduces insulin resistance, preserves lean body mass, and improves patient comfort. Shorter fasting periods than traditional overnight NPO reduce preoperative dehydration and do not increase aspiration risk in appropriately selected patients. Oral hydration with clear fluids up to two hours before surgery maintains volume status. Early postoperative feeding, rather than waiting for flatus or bowel sounds, accelerates recovery without increasing complications. These principles, supported by substantial evidence, improve outcomes while challenging long-standing but unsupported traditions.

Aspiration risk assessment identifies patients requiring modified approaches despite standard guidelines. Gastroesophageal reflux disease increases aspiration risk and may warrant rapid sequence induction regardless of fasting duration. Obesity increases intra-abdominal pressure and reduces lower esophageal sphincter competence. Pregnancy causes delayed gastric emptying and increased aspiration risk, particularly in later trimesters. Diabetes mellitus with gastroparesis results in unpredictable gastric emptying and retained food despite prolonged fasting. Opioid use delays gastric emptying and may necessitate longer fasting or additional precautions. These factors inform anesthesia planning even when standard fasting has been observed.

Special situations require individualized NPO management. Diabetic patients require careful insulin adjustment alongside fasting to prevent hypoglycemia or severe hyperglycemia. Dehydrated patients benefit from intravenous fluid administration during the fasting period, particularly if arriving from emergency settings. Emergency surgery accepts unavoidable aspiration risk while taking precautions such as rapid sequence induction and suction availability. Pediatric patients follow age-appropriate fasting guidelines that differ from adult intervals. Patients with feeding tubes may require longer fasting periods depending on formula type and tube position. Communication of NPO guidelines should include specific times and permitted substances to prevent confusion.

Section IX: Consent and Documentation

Informed consent requires more than a signature; it represents a communication process ensuring patient understanding and voluntary agreement. The procedure must be explained in understandable terms, including its name and what will be done. The indication explains why surgery is recommended over other options. Risks must be specific to the procedure and quantified when possible, not merely listing generic complications. Benefits describe the expected outcome in realistic terms. Alternatives, including non-surgical management, must be presented fairly. The patient must have opportunity to ask questions and receive understandable answers before deciding.

Common surgical risks should be discussed with all patients, with additional procedure-specific risks added as relevant. Bleeding occurs with any surgery and may require transfusion. Infection risk varies by wound class and patient factors but exists for all procedures. Deep venous thrombosis and pulmonary embolism risk accompanies surgery and immobility. Anesthesia risks include airway complications, cardiovascular events, and adverse reactions. Procedure-specific risks such as nerve injury, adjacent organ damage, or failure to achieve surgical goals must be individualized. For laparoscopic procedures, the possibility of conversion to open surgery should be discussed.

Surgical site marking prevents wrong-site surgery and constitutes a required safety practice. All procedures involving laterality, including those on paired organs or extremities, require marking the operative site. Spine surgery requires marking the operative level. Skin lesions should be marked before preparation obscures landmarks. Patient participation in marking, when possible, confirms agreement and involves the patient in safety. The surgical time-out, performed after positioning and before incision, verifies that the site marked matches the consent, imaging, and team understanding.

The preoperative note documents the assessment, risk evaluation, and planning that justify proceeding with surgery. A brief history of present illness focuses on the surgical indication and relevant clinical course. Pertinent past medical and surgical history highlights factors affecting surgical risk. The current medication list notes perioperative adjustments made. Allergies are prominently documented. Physical examination findings relevant to surgery and anesthesia are recorded. Laboratory and imaging results are reviewed and documented, with abnormalities addressed. The assessment summarizes the indication, patient fitness, and planned procedure. Confirmation that informed consent has been obtained completes the documentation.

Section X: Day of Surgery Preparation

The preoperative checklist provides systematic verification of surgical readiness. Consent documentation must be complete and accurate, matching the planned procedure including laterality and approach. NPO status is confirmed with the patient, identifying any lapses that might increase aspiration risk. Site marking is verified as present and correct for applicable procedures. Laboratory results are reviewed, with any new abnormalities addressed before proceeding. Blood product availability is confirmed when transfusion is anticipated. Prophylactic antibiotics are ordered with appropriate timing instructions. DVT prophylaxis measures, whether sequential compression devices, heparin, or both, are ordered for the perioperative period.

The preoperative holding area visit allows final verification and patient support. Patient identity is confirmed using two identifiers, typically name and date of birth or medical record number. The consent is reviewed verbally with the patient to confirm continued agreement and accurate procedure description. Any interval changes in condition, new symptoms, or new concerns are identified and communicated to the team. Questions from the patient or family are answered, and anxiety is addressed with reassurance and information. Working intravenous access is confirmed. Communication with the anesthesia team ensures shared understanding of patient factors and concerns.

The surgical time-out represents the final safety check before incision and requires participation from all team members. Patient identity is verbally confirmed by the team. The correct procedure is verified against the consent and the operative schedule. The operative site is confirmed as marked and matching all documentation. The consent form is verified as signed and accurate. Prophylactic antibiotic administration is confirmed, including timing within the appropriate window. Blood product availability is confirmed for cases with transfusion potential. Relevant imaging is displayed and verified as belonging to the correct patient. Any specific safety concerns, such as allergies or equipment needs, are communicated.

Troubleshooting common day-of-surgery problems prevents delays and cancellations. Abnormal laboratory values discovered on the day of surgery require team discussion regarding the need for correction versus proceeding; many minor abnormalities do not warrant delay. New symptoms reported by the patient need evaluation; minor symptoms often do not prevent surgery, while acute illness may necessitate postponement. Missing consent requires completion before proceeding; the patient must have adequate time and mental clarity to provide valid consent. Medication errors, such as failure to hold anticoagulants, require evaluation of bleeding risk and possible surgical delay. Patient anxiety may respond to reassurance, information, or anxiolytic premedication.

Summary

Pre-operative evaluation systematically assesses surgical candidates to identify risk factors, optimize modifiable conditions, and ensure safe perioperative care. The comprehensive assessment includes history with attention to surgical and anesthetic factors, physical examination emphasizing airway and cardiopulmonary status, and functional capacity evaluation using metabolic equivalents. Cardiac risk stratification using the RCRI guides decisions about additional testing, which is reserved for patients with elevated risk and poor functional capacity undergoing significant surgery. Pulmonary risk factors include COPD, smoking, obesity, and procedure-related factors, with optimization including smoking cessation and disease management. Medication management requires continuing beta-blockers and statins while holding anticoagulants according to drug-specific timelines, with bridging reserved for high thromboembolic risk. Pre-operative testing follows clinical indication rather than routine ordering, avoiding unnecessary studies that delay surgery without improving outcomes. Special populations including elderly, renal disease, liver disease, and pregnancy patients require individualized assessment addressing their specific risks. NPO guidelines balance aspiration prevention with evidence supporting shorter fasting intervals and carbohydrate loading in ERAS protocols. Informed consent represents a communication process ensuring patient understanding, while documentation captures assessment and planning. Day-of-surgery protocols include systematic checklists, holding area verification, and surgical time-out to prevent errors.

Key Terms

ASA Class: American Society of Anesthesiologists physical status classification ranging from I (healthy) through VI (brain dead organ donor), with E suffix indicating emergency surgery.

RCRI (Revised Cardiac Risk Index): Validated six-factor scoring system predicting major adverse cardiac events after non-cardiac surgery based on surgical type, cardiac history, diabetes, and renal function.

METs (Metabolic Equivalents): Measure of functional capacity where one MET equals resting oxygen consumption; activities are classified by MET level, with less than four METs indicating elevated surgical risk.

MACE (Major Adverse Cardiac Event): Composite outcome including myocardial infarction, cardiac arrest, heart failure, and significant arrhythmia occurring in the perioperative period.

NPO (Nil Per Os): Medical abbreviation meaning nothing by mouth, used to designate fasting status before procedures requiring anesthesia or sedation.

Bridging: Temporary use of short-acting anticoagulant during the period when long-acting anticoagulation is held for surgery, employed in patients with high thromboembolic risk.

Time Out: Standardized pre-procedure pause in which all team members verify patient identity, procedure, site, consent, and safety measures before surgical incision.

Enhanced Recovery (ERAS): Evidence-based perioperative care protocols designed to reduce surgical stress response and accelerate recovery through optimized anesthesia, pain control, nutrition, and mobilization.

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