Vocal Fremitus
The test where a patient phonates while the examiner palpates the chest is called vocal fremitus (VF).
Definition and Technique
Vocal fremitus refers to the palpable vibrations transmitted through the chest wall when a patient speaks 1. During this examination:
- The examiner places their hands on the patient's chest wall
- The patient is asked to repeat words or phrases (typically "ninety-nine" or similar resonant phrases)
- The examiner feels for the transmission of vocal vibrations through the chest wall 1
Clinical Significance
Vocal fremitus is an established component of the standard physical examination of the respiratory system 1. The technique helps detect:
- Increased fremitus: Occurs with pulmonary consolidation (pneumonia) or masses, where solid tissue conducts vibrations more effectively 2, 3
- Decreased fremitus: Suggests pleural effusion, pneumothorax, or airway obstruction, where fluid or air dampens vibration transmission 3
Diagnostic Accuracy
In a study of 278 patients with respiratory symptoms, vocal fremitus demonstrated:
- Excellent inter-observer reliability (kappa 0.84-0.89) 3
- Asymmetric findings were independently predictive of pleural effusion (OR 5.22,95% CI 2.06-13.23) 3
- When combined with other physical signs like percussion, the diagnostic accuracy improved substantially (ROC curve area 0.88) 3
Related Examination Techniques
Vocal resonance (VR) is the auscultatory equivalent, where the examiner listens rather than palpates for transmitted vocal sounds 1, 4. This includes:
- Bronchophony (increased vocal transmission)
- Egophony (E-to-A changes)
- Whispering pectoriloquy 4
Mechanism
Sound transmission through the respiratory system occurs primarily via wave propagation through the parenchymal porous structure rather than through free gas 5. This explains why consolidation (which increases tissue density) enhances fremitus transmission 5, 2.