CPT code 94150 describes a pulmonary function test that measures total vital capacity—the maximum volume of gas a patient can exhale after full inspiration. Nationally, this measurement is a standard component of respiratory assessment used to evaluate lung volumes and distinguish between restrictive and obstructive patterns, supporting diagnosis and management of pulmonary conditions. The code is relevant across outpatient clinics, pulmonary laboratories, and hospital outpatient departments where spirometric and lung volume testing is performed. Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context, common sites of service, and expected billing considerations. The publication also summarizes payer coverage patterns and typical modifiers encountered for this service where available, and contextualizes the code within pulmonary diagnostic workflows. Data not available in the input where payer-specific rates, ICD-10 pairings, and related codes would normally be detailed.