“…Of the twenty-six papers nine were performed on healthy subjects [17,20,22,23,25,28,[33][34][35] which accounted for 220 of the total 849 study participants (26%). Pathologies or conditions investigated included; post-operative upper abdominal surgery [15,26], chronic obstructive pulmonary disease (COPD) [13,14,24,29,30], critical care patients [19,32,36,37], post cerebral vascular accident (CVA) [21], spinal cord injury (SCI) [27,31], morbidly obese [16], adolescents with scoliosis [18] and healthy infants [35] (Table 1).…”