CARDIOPULMONARY EXERCISE TESTING: A COMPREHENSIVE REVIEW OF PROTOCOLS, CLINICAL APPLICATIONS, AND LIMITATIONS

Аннотация

Cardiopulmonary exercise testing (CPET) is a vital tool for evaluating symptoms, disease severity, prognosis, and therapeutic responses in patients with cardiopulmonary diseases. By assessing theintegrated function of cardiovascular, pulmonary, musculoskeletal, nervous, and hematological systems during exertion, CPET provides objective data that complement resting diagnostics. This review outlines key CPET variables, protocols, and clinical indications, emphasizing its role in diagnosing unexplained dyspnea, guiding exercise prescriptions, and managing heart failure. Limitations, including sex-based differences and theimpact of obesity, are also discussed. Introduction: Symptoms of cardiopulmonary diseases often manifest during physical activity, making CPET a unique diagnostic modality. Unlike resting evaluations (e.g., echocardiography, spirometry), CPET captures dynamic physiological responses, offering insights into oxygen transport and utilization. This review synthesizes evidence on CPET’s utility in diverse populations, from athletes to patients with heart failure, and highlights gaps incurrent standards. Methods: A narrative review was conducted using peer-reviewed literature on CPET protocols, clinical applications, and limitations. Data sources included PubMed, NEJM Evidence, and consensus guidelines. Key themes were organized into sections on protocols, functional assessment, and special populations. Results: 1. CPET Protocols Modalities: Treadmill testing is preferred for simulating daily activities, while cycle ergometry suits patients with gait limitations. VO\(_2\) max values are 5–11% lower on ergometers due to reduced muscle engagement. Protocols: The Bruce protocol’s variable increments may obscure results. Alternatives like the modified Astrand (2% grade increase/2 min) or Ellestad (speed-focused) protocols yield comparable VO\(_2\) max but differ in secondary parameters (e.g., heart rate). VO\(_2\) Max Criteria: Indirect markers (plateau in VO\(_2\), RER >1.1, maximal HR, RPE) are commonly used, though repeatingtests at higher workloads remains thegold standard. 2. Clinical Applications: Functional Assessment: CPET distinguishes cardiac, pulmonary, and peripheral limitations in unexplained dyspnea. Exercise Prescription: Ventilatory threshold defines sustainable exercise intensity. Heart Failure: HFrEF: VO\(_2\) peak ≤14 mL/kg/min (≤12 mL/kg/min on beta-blockers) indicates transplant referral. V\(_E\)/VCO\(_2\) slope >34 predicts hospitalization risk. HFpEF: CPET diagnoses early- stage disease via abnormal PCWP during exercise, though peripheral limitations (e.g., reduced skeletal muscle perfusion) often contribute. 3. Limitations: Sex Differences: VO\(_2\) max norms, derived predominantly from men, underestimate women’s capacity due to lower muscle mass and hemoglobin. Obesity: Scaling VO\(_2\) to total body mass penalizes obese individuals; fat-free mass adjustments 98,7:ROTCAFTCAPMI .SECNEICSLACIDEM,5202,yaM,5emuloV gro.srehsilbupcimedaca.www may better reflect fitness. Medications: Beta-blockers reduce VO\(_2\) max, necessitating reliance on alternative metrics. Peripheral Factors: Endothelial dysfunction, reduced capillary density, or orthopedic injuries may limit exercise capacity independently of cardiopulmonary function. Discussion: CPET’s integrative approach enhances diagnostic precision and personalized care. However, standardization challenges persist, particularly for women, obese patients, and those with congenital heart disease. Future research should address: Sex-specific VO\(_2\) max criteria. The prognostic value of fat-free mass-adjusted metrics. CPET’s role inemerging HFpEF phenotypes. Conclusion: CPET is indispensable for evaluating exercise intolerance and guiding therapeutic decisions. Its multivariate data capture systemic interactions often missed by statictests,though methodological refinements are needed tooptimizeequity and accuracy.