Chest wall volumes were divided into six compartments ( left and right of each of pulmonary ribcage -LSB- Vrc , p -RSB- , abdominal ribcage -LSB- Vrc , a -RSB- , and abdomen -LSB- Vab -RSB- ) and phase shift angles ( ) calculated for the asynchrony between Vrc , p and Vrc , a ( RC ) , and between Vrc , a and Vab ( DIA ) .