Chest wall kinematics and Hoover's sign

Area of Science:

• Pulmonary Physiology
• Respiratory Mechanics

Background:

• Hoover's sign, indicative of rib cage distortion, has not been previously quantified by volume displacement.
• The relationship between Hoover's sign and hyperinflation in obstructive lung disease remains unclear.

Purpose of the Study:

• To quantify Hoover's sign in terms of chest wall volume displacement.
• To investigate the independence of Hoover's sign and hyperinflation in stable obstructed patients.

Main Methods:

• Twenty stable patients with obstructive lung disease were assessed.
• Patients were categorized based on the presence or absence of Hoover's sign during quiet breathing.
• Optoelectronic plethysmography was used to measure chest wall and compartment volumes (upper rib cage, lower rib cage, abdomen).

Main Results:

• Volumes of the upper rib cage, lower rib cage, and abdomen, as a percentage of total chest wall volume, were similar between groups.
• Tidal volume of the chest wall, upper rib cage, lower rib cage, their ratio, and abdomen quantified Hoover's sign.
• Quantification of Hoover's sign did not correlate with the degree of hyperinflation.

Conclusions:

• Rib cage distortion (Hoover's sign) and hyperinflation are independent parameters.
• These independent factors define the functional condition of patients with obstructive lung disease.