Preoperative Cardiopulmonary Evaluation Algorithm
All patients undergoing surgery should first undergo cardiac risk stratification followed by pulmonary function assessment, with testing reserved only for those whose results will change perioperative management. 1
Step 1: Initial Cardiac Risk Assessment
Obtain a preoperative ECG on all patients undergoing lung resection or high-risk surgery. 1 For other surgeries, ECG is indicated for high-risk procedures, intermediate-risk procedures with at least one cardiac risk factor, or patients with known cardiovascular disease. 2
Stratify Cardiac Risk Using Clinical Predictors:
Major Risk Factors (require formal cardiology consultation): 1
- Unstable coronary syndromes or recent MI with evidence of ischemic risk
- Unstable or severe angina (Canadian Cardiovascular Society grades 3-4)
- Decompensated heart failure
- Significant arrhythmias (high-grade AV block, symptomatic ventricular arrhythmias, uncontrolled supraventricular arrhythmias)
- Severe valvular disease
Intermediate Risk Factors: 1
- Mild angina (grades 1-2)
- Prior MI based on history or pathological Q waves
- Compensated or prior heart failure
- Diabetes mellitus
Minor Risk Factors: 1
- Advanced age
- Abnormal ECG (LVH, LBBB, ST-T abnormalities)
- Rhythm other than sinus
- Low functional capacity (unable to climb one flight of stairs)
- History of stroke
- Uncontrolled hypertension
Cardiac Management Based on Risk:
Major Risk: Formal cardiology assessment and multidisciplinary discussion required. 1 Patients with significant coronary lesions on angiography should be considered for revascularization before lung resection, though routine prophylactic revascularization does not reduce procedural risk and delays cancer treatment. 3, 4
Intermediate Risk with good functional capacity (can comfortably walk up one flight of stairs): No further cardiac testing needed. 1 These patients are not at greater than average risk.
Intermediate Risk with poor functional capacity: Obtain ECG-monitored exercise test and echocardiogram, discuss with cardiologist. 1
Minor Risk with single factor: Not at greater than average risk. 1 However, multiple cardiovascular risk factors warrant careful evaluation.
Special Cardiac Considerations:
Recent MI: Do not operate within 6 weeks of myocardial infarction. 1 Any patient with MI within 6 months requires cardiology consultation. 1
Audible cardiac murmur: Obtain echocardiogram. 1
Previous stroke/TIA/carotid bruits: Assess with carotid Doppler studies. 1 Patients with stenosis >70% require vascular surgery or stroke medicine consultation before proceeding. 1
Routine echocardiography: Not recommended unless clinically indicated. 1 However, it may be considered in patients with previously documented LV dysfunction if no assessment within one year. 1
Stress testing: Only consider for patients at elevated risk with poor functional capacity (<4 METs, unable to climb 2 flights of stairs) if results will change management. 1, 4 Do not perform routine stress testing or angiography unless results will alter perioperative approach. 2
Step 2: Pulmonary Function Assessment
Measure FEV1 and DLCO in all patients and calculate predicted postoperative (PPO) values. 1
Calculate PPO Values:
For pneumonectomy: Use quantitative perfusion scan. 1
- PPO = preoperative value × (1 - fraction of total perfusion for resected lung)
For lobectomy: Use segmental counting method. 1
- PPO = preoperative value × (1 - y/z), where y = functional segments removed, z = total functional segments
Risk Stratification Based on PPO Values:
Low Risk (PPO FEV1 >60% AND PPO DLCO >60%): Expected mortality <1%. 1 Major anatomic resections can be safely performed. 1
Moderate Risk (PPO FEV1 OR PPO DLCO between 30-60%): Proceed to exercise testing. 1
High Risk (PPO FEV1 <30% OR PPO DLCO <30%): Proceed to cardiopulmonary exercise testing. 1 Expected mortality may exceed 10% for major resections. 1
Alternative Risk Stratification (if PPO not calculated):
Average Risk: Estimated postoperative FEV1 >40% predicted AND estimated postoperative TLCO >40% predicted AND oxygen saturation >90% on room air. 1
High Risk: Estimated postoperative FEV1 <40% predicted AND estimated postoperative TLCO <40% predicted. 1
Uncertain Risk: All other combinations require exercise testing. 1
Arterial Blood Gas Considerations:
Preoperative hypercapnia (PaCO2 >45 mmHg): Not an independent risk factor for increased perioperative complications and should not be used as an exclusion criterion. 1
Preoperative hypoxemia (oxygen saturation <90%): Associated with increased risk of postoperative complications. 1
Step 3: Exercise Testing (When Indicated)
Low-Technology Screening Tests:
Shuttle walk test (preferred): More reproducible and better correlation with VO2 peak than six-minute walk. 1
- High risk: <25 shuttles (250 m) OR desaturation >4% during test. 1
- Satisfactory performance: ≥25 shuttles indicates moderate risk, no further testing needed. 1
Stair climbing test: Height reached <22 m indicates high risk. 1 However, this test lacks standardization. 1
Formal Cardiopulmonary Exercise Testing (CPET):
Indications for CPET: 1
- PPO FEV1 or PPO DLCO <30%
- Unsatisfactory performance on low-technology exercise test (shuttle walk <400 m or stair climb <22 m)
- High-risk cardiac evaluation but deemed stable to proceed
CPET Risk Stratification: 1
- Low risk: VO2 peak >20 mL/kg/min or >75% predicted
- Moderate risk: VO2 peak 10-20 mL/kg/min
- High risk: VO2 peak <10 mL/kg/min or <35% predicted
VO2 peak >15 mL/kg/min: Associated with no appreciable increase in perioperative mortality and complications. 1
Important Caveat on CPET:
For general noncardiac surgery (not lung resection), cardiopulmonary exercise testing may be considered for elevated-risk procedures when functional capacity is unknown, though evidence is limited. 1 The anaerobic threshold of approximately 10 mL O2/kg/min is the optimal discrimination point for perioperative cardiovascular complications. 1
Critical Testing Principles
Do not order routine preoperative testing batteries. 2 This increases costs, delays surgery, and rarely changes management. 2
Do not perform routine preoperative spirometry or chest radiography. 2 These tests do not reduce complications and should only be obtained when results will change management. 2, 5, 6
Chest radiography indications: Only for patients at risk of postoperative pulmonary complications if results would change perioperative management, or for patients with acute cardiopulmonary symptoms requiring evaluation. 2
Laboratory testing: Order selectively based on clinical indication (electrolytes, creatinine, glucose, CBC, coagulation studies, urinalysis as appropriate). 2
Common Pitfalls to Avoid
Do not deny surgery based solely on pulmonary function tests if the surgical indication is compelling. 5 Procedure-related risk factors are more important than patient-related factors for predicting pulmonary events. 5
Do not use composite cardiopulmonary risk indices as primary decision tools. 1, 7 The multifactorial cardiopulmonary risk index and its components are inadequate predictors of complications after thoracic surgery in general populations. 7
Do not dismiss surgery based solely on age. 2 Fully evaluate cardiopulmonary fitness without age prejudice, considering tumor stage, life expectancy, performance status, and comorbidities. 2
Do not start new beta-blockers perioperatively. 3, 4 High-dose beta-blockers (e.g., 100 mg metoprolol succinate) administered 2-4 hours before surgery increase stroke risk (1.0% vs 0.5%, p=0.005) and mortality (3.1% vs 2.3%, p=0.03). 4 However, continue existing beta-blockers in patients already taking them. 3
Do not routinely use low-dose aspirin perioperatively. 4 It does not decrease cardiovascular events but does increase surgical bleeding. 4
High-Risk Patient Counseling
For patients with high risk (mortality >10% for major resections): Counsel about alternative surgical options (minor resections, minimally invasive surgery) or nonsurgical options. 1 Considerable risk of severe cardiopulmonary morbidity and residual functional loss is expected. 1