No abstract

The pattern of thoracoabdominal motion during quiet breathing correlates with BASFI, and its response to anti-TNFalpha treatment is large. This variable may be an appropriate target for evaluating potential usefulness in monitoring thoracic spine involvement and response to treatment in AS.

We tested the hypothesis that the pattern of chest wall configuration during speech production correlates with the pattern of chest wall motion during resting breathing. Twenty-one men (age 40 +/- 8 years) with ankylosing spondylitis and varied degrees of ribcage involvement participated in the study. None of the patients had an obvious speech abnormality. Ribcage and abdominal displacements during quiet breathing and during reading were measured with a respiratory plethysmograph. Measurements were taken in the sitting and standing body positions. In each body position, ribcage or abdominal displacements during quiet breathing correlated with the corresponding chest wall displacements recorded during reading (P < 0.001). In addition, linear regression analysis showed that the slope of the chest wall motion loop during quiet breathing correlated with the ratio of ribcage to abdomen contribution to lung volume displacement during reading (r = 0.78, P < 0.001 for sitting and r = 0.64, P = 0.002 for standing position). The slopes of the regression lines did not differ between the sitting and standing body position (P > 0.05). We conclude that the relative contribution of the ribcage and abdomen to lung volume displacement during speech production correlates with the relative ribcage and abdomen contribution to tidal volume during quiet breathing; our data support the notion that the pattern of chest wall configuration during quiet breathing largely predicts the pattern of ribcage and abdomen displacement during speech.

In individuals with advanced AS, the abdomen is the primary contributor to volume displacement. In the absence of speech impairment in participants with AS, the data show the capacity of the abdomen to compensate for the decreased compliance of the rib cage.