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Paradoxical movement of the lower ribcage at rest and during exercise in COPD patients

¹ TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy, ² Clinical Sciences Centre, University Hospital Aintree, University of Liverpool, Liverpool, UK, ³ Federal University of Sao Paulo, Sao Paulo, Brazil.

CORRESPONDENCE: A. Aliverti, TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy. Fax: 39 0223999000. E-mail: andrea.aliverti{at}polimi.it

Keywords: Chest wall asynchrony, chronic obstructive pulmonary disease, dyspnoea, exercise, Hoover’s sign

Received: October 26, 2007
Accepted September 9, 2008

Paradoxical inward displacement of the costal margin during inspiration is observed in many chronic obstructive pulmonary disease patients at rest but its importance is unclear.

The current authors studied 20 patients (forced expiratory volume in one second 32.6±11.7, functional residual capacity 186±32% predicted) and 10 healthy controls at rest and during symptom-limited incremental exercise. With optoelectronic plethysmography, the phase shift between pulmonary and abdominal ribcage volumes and the percentage of inspiratory time the ribcage compartments moved in opposite directions were quantified, using control data to define the normal range of movement.

Eight patients showed lower ribcage inspiratory paradox at rest (P+), while 12 patients did not (P-). This was unrelated to resting lung function or exercise tolerance. Total end-expiratory chest wall volume (EEV_cw) increased immediately when exercise began in P+ patients, but later in exercise in P- patients. This difference in EEV_cw was mainly due to a greater increase of end-expiratory pulmonary ribcage volume in P+ patients. During exercise, dyspnoea increased similarly in the two groups, while leg effort increased more markedly in the patients without paradox.

In conclusion, lower ribcage paradox at rest is reproducible and associated with early-onset hyperinflation of the chest wall and predominant dyspnoea at end-exercise. When paradox is absent, the sense of leg effort becomes a more important symptom limiting exercise.