Unilateral decrease in vesicular murmur

Specialty: Respiratory.

• unilateral hypoventilation
• decreased breath sounds in one hemithorax

Why it occurs

• Massive pleural effusion (the fluid accumulated in the pleural space acts as a physical acoustic barrier that prevents the transmission of noise generated in the lung to the chest wall)
• Tension or spontaneous pneumothorax (the presence of free air in the pleural cavity collapses the lung and prevents its ventilation, abolishing the transmission of vesicular murmur)
• Complete obstruction of a main bronchus due to neoplasia, mucus plug or foreign body (completely prevents the entry of air into the entire lung or corresponding lobe, selectively abolishing auscultatory sounds)
• Complete lobar or pulmonary atelectasis due to selective intubation (the endotracheal tube inadvertently advances towards the right main bronchus, leaving the left lung without ventilation)
• Pachypleuritis or fibrothorax (extreme thickening and calcification of the pleura that limits lung expansion and dampens sound transmission).

Initial workup

Urgent chest x-ray; Bedside pleuropulmonary ultrasound (immediate evaluation of absent pleural sliding and lung point for pneumothorax, or visualization of effusion); Computed tomography (CT) of the chest; Emergency flexible bronchoscopy; Analytical arterial blood gas.

Standard management

• There are no first-line drugs for the mechanical abolition of noise; immediate physical intervention required — needle decompression in the second intercostal space midclavicular line if there is tension pneumothorax, or placement of a chest tube of appropriate caliber
• Salbutamol (nebulized if associated with reactive bronchospasm).