Upper and lower rib cage deformation during breathing in quadriplegics

Area of Science:

• Respiratory Mechanics
• Physiology

Background:

• In quadriplegia, the anteroposterior diameter of the rib cage (RC) decreases during inspiration.
• Paradoxical motion of the RC is observed during breathing in individuals with quadriplegia.

Purpose of the Study:

• To further characterize paradoxical RC motion in quadriplegia.
• To determine the extent to which diminished diaphragmatic inspiratory effect on the RC, due to abdominal muscle paralysis, contributes to this motion.

Main Methods:

• Studied upper and lower RC (URC, LRC) displacements in six quadriplegics across various postures.
• Assessed RC motion with and without extrinsic abdominal support, including abdominal compression.
• Investigated thoracic distortability using a cephalad force applied to the RC at the costal margin.

Main Results:

• URC showed the most distortion and did not reach a relaxed configuration during tidal inspiration, even with abdominal compression.
• LRC remained in its relaxed configuration at all studied lung volumes.
• Abdominal compression resulted in diminished RC distortion, attributed to increased diaphragmatic apposition area.

Conclusions:

• Lack of abdominal support does not fully explain RC distortion during spontaneous inspiration in quadriplegics.
• High abdominal pressure diminishes RC distortion, likely by increasing the area of diaphragmatic apposition to the RC.