Objective: To assess a new technique for the detection of free pleural fluid.
Design: 118 consecutive inpatients with radiologic evidence of free pleural fluid and a control group of 175 randomly selected inpatients were examined over a three-year period in a prospective blind study by auscultatory percussion (AP) for evidence of pleural effusion. The cutoff in the percussion note by AP is strikingly loud and sharp at the fluid level and allows precise delineation of even minimal amounts of pleural fluid. The fluid level was measured in reference to the last rib. The criterion for detection of pleural effusion by AP was a demonstrable horizontal fluid level at the sound cutoff across the posterior hemithorax above the last rib that shifted with lateral tilt.
Setting: A general medical and surgical university-affiliated teaching Veterans Affairs hospital.
Patients/participants: All inpatients were eligible. Ready availability of examiners was essential. Rotating third- and fourth-year medical students, residents, and senior staff members participated.
Interventions: None.
Major results: 113 of the 118 patients with radiologic evidence of pleural effusion had a distinct horizontal fluid level above the last rib that shifted with lateral tilt (sensitivity = 95.8%). None of the 175 control patients examined at random showed evidence of pleural effusion by AP examination, which was confirmed by chest radiography (specificity = 100%). Nine of the 175 patients without radiologic evidence of pleural effusion had elevated diaphragms that simulated a fluid level in the examination by AP. Each of the nine patients, however, had no shift in the level with lateral tilt. Subpulmonic effusions were readily displaced and identified by this method of AP.
Conclusions: Examination by AP is highly sensitive and specific for the detection of free pleural fluid, even in the presence of obesity, thickened pleura, lung masses, pneumonia, and associated lung disease. The examination correlates closely with standard and lateral decubitus chest radiography. Pleural effusion unsuspected by conventional means of physical examination and undetectable by standard chest radiography can readily be detected by the method of AP. The examination is easy to do and is particularly suited to enhance detection of pleural effusion. As little as 50 mL of free pleural fluid can be detected.