Recent E-mails

Is it correct that the Left diaphragm is more responsible to pull the air to Right chest and Right diaphragm is more responsible to pull the air to Left chest? I was looking for the mechanism of this from PRI textbook and other resources, but could not find the one that makes this clear for me. I would really appreciate if you could explain the mechanism and/or give me some resource to explain that.

There is really no ‘one’ excellent resource to go to that will talk about hemi-diaphragm activity influence on the chest wall uniformly or non-uniformly.  There is no discussion how tidal volume or residual  volume of the lung is influenced by thoracic rotation or hyperinflation more so on one side of the chest wall than the other, even when you review the Scoliosis literature.  However, there is a great deal of information on how ribs are influenced by spinal coupling and directional rotation.  The costal aspect of the diaphragm is responsible for rib external rotation upon diaphragm contraction, while the crural fiber is primarily responsible for dome descension and thoracic lumbar spinal extension.  We have two sets of these muscles and when one rotates to the left with the rib cage or thorax, the ribs on the left are externally rotated with respect to the ribs on the right and the extension of the back at the thoracic lumbar vertebral wall is more extended on the left when compared to the right (Left AIC pattern).  Therefore, the costal and crural fiber on the left is at concentric end range and any respiration that occurs in this pattern will primarily occur with the hemi-diaphragm on the left because of the lengthened state of the crural and costal fiber on the right compared to the left.  Reciprocal breathing in this pattern will more than likely compliment reciprocal thoracic wall expansion on the right, because the costal fiber can pull the ribs up on this side, and the recoil upon exhalation is preserved because of the position the thoracic mediastinums.   Most researchers in pulmonary medicine or in functional performance do not measure tidal volume with individuals in this extreme state of torsion or rotation, either because they do not understand how posture can actually be challenged by these concepts or because it is a very untraditional method that would have a very difficult time being accepted by research reviewers and readers, since they probably would not appreciate the significance of thoracic mechanical expansion or lack of, when considering pulmonary function.  PRI is the only resource you will probably find that postulates these concepts that are scientifically sound because of what already exists in evidenced based research to date on rib mechanics, thoracic function and pulmonary studies.  Patterns of respiration such as the Left AIC or Right BC have not been ever considered to my knowledge.   

Asymmetrical ventilation and perfusion between the right and left lungs occurs in more than half of the children with severe congenital and infantile thoracic scoliosis.  However, the severity of lung function asymmetry does not relate to Cobb angle measurements.  Asymmetry in lung function is influenced by deformity of the chest wall in multiple dimensions, and cannot be ascertained by chest radiographs alone (Redding G. Song K. et al Lung function asymmetry in children with congenital and infantile scoliosis. The Spine Journal, 2008, vol 8,(4) 639-644.).  The last sentence describes it all.  It is very difficult to measure lung or perfusion function unilaterally with an x-ray, or any other pulmonary study method only because of the inability to separate flow from one side of the thorax upon normal non-compensatory postural positions versus compensatory postural positions that become neurologically habitual patterns of the “way” we breathe. 

-Ron Hruska

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