Journal of NeuroEngineering and Rehabilitation

those of their able-bodied peers. While no study identi- fied in this review demonstrated the effect of a rehabili- tation program to improve cardiorespiratory capacity of a subject below the levels specified to indicate successful prosthetic use to surpass them, a similar positive out- come was also concluded by Erjavec et al. in a study using the UEE modality [ 20 ] . The multidisciplinary workgroup therefore suggests any patient unable to meet the recommended criteria of either UEE or SLE test should be given the option to complete an exercise pro- gram and re-enter the protocol before being disqualified from prosthetic intervention if desired. Making recommendations for type of exercise regimen is beyond the scope of this review. However, it was pre- viously noted that training on either UEE or SLE modal- ity resulted in fitness gains. It is noted in Vestering et al. [ 26 ] that a combined UEE/SLE modality places a larger cardiopulmonary demand than does UEE alone, so any pre-prosthetic rehabilitation program should incorporate SLE or combined UEE/SLE elements as its basis. Further investigation in this area is needed. The remaining modality in this review after SLE testing with enough evidence to be synthesized is the intermittent UEE test. The conclusions regarding this modality are based on maximum achieved workload in Watts sustained during the test. The work of Erjavec et al. supports the achieved workload of 30 W in the UEE test to correspond to successful prosthetic ambulation in the elderly transfe- moral subject which should assume successful ambulation in the younger and also non-vascular subjects [ 26 ] . How- ever, it should be noted that the literature reports there is greater cardiovascular and ventilatory strain (increased heart rate, blood pressure and respiratory rates) associated with upper extremity exercise compared to lower extremity at any given power output or % exercise intensity [ 27 – 29 ] . The final testing modality included in this review is the rowing machine which was one of the articles mentioned in the systematic review performed by Van Velzen et al. [ 15 ] . Although no causative relationship between achieved workload and aerobic capacity was concluded, it should be noted that 45 W sustained maximum in the rowing machine test was correlated to a cut-off point between those who met criteria of level 2 or level 3 prosthetic ambulator [ 15 ] . It was also found that subjects who achieved this wattage level were less likely to walk with a walker in favor of a higher-level assistive device or inde- pendently [ 15 ] . Further research is needed regarding the use of RM tests in the population of individuals with limb loss to be included in a proposed CPG at this time, al- though initial findings of the modality show promise. Limitations A criticism of this study design may be that the system- atic literature review without meta-analysis should not constitute the basis for a CPG. However, descriptive lit- erature reviews have been used as the basis for clinical practice recommendations in the field of endoskeletal prosthetics as the literature base is currently limited compared to other healthcare fields [ 9 , 11 , 13 ] . Meta-analysis was considered in the early stages of this project, but the heterogeneity of outcome measures in terms of modality, intensity, and continuity limited the clinical meaningfulness of any results. It was also deter- mined that the CPG, which is the primary goal of this project, would not benefit any further from performance of such an analysis except in perceived power. An additional limitation of the review and resultant CPG could be the lack of functional level stratification be- yond basic candidacy at the K1 level. It should be noted the intended purpose of this pathway is only for those in- dividuals with limb loss and suspected comorbid cardio- vascular compromise which may limit prosthetic use who are seeking evaluation for an initial prosthesis or subse- quent prosthesis when other factors including present fit- ness level may render completion of a walking test unsafe or impractical. Testing of this type is not commonly used in the population with LEA and, in practice, most ampu- tee subjects would more commonly be able to perform a walking test or battery such as the amputee mobility pre- dictor. Therefore, it is the lower-functioning patient with multiple comorbidities in the early stages of rehabilitation who would benefit most from an alternative set of criteria for determination of candidacy and functional classifica- tion when access is being limited. A larger review seeking values featured in the results of this review would allow for both the cited limitations of the study to be addressed in the future [ 30 ] . It should be noted that none of the studies identified in this review investigated the effect of an exercise pro- gram to increase cardiovascular capacity from below to above recommended values indicating the predicted suc- cess of ambulation with a prosthesis. Therefore, while the recommendation of such exercise program may be considered medically and clinically reasonable it has not yet been directly studied. It is for this reason that the final EES was also given an evidence grade of E2 indicat- ing support by professional expert opinion. Lastly, none of the articles included in this review in- cluded indirect estimation of VO 2 based on HR. Al- though direct spirometry is the most accurate mode of measuring gas exchange, this equipment is expensive and not often available in general rehabilitation centers which could potentially limit access and delay time to prosthetic fitting. However, a comparison of indirect es- timation of VO 2 to direct measurement in the popula- tion with LEA using the Fick equation or similar validated method could greatly increase access to testing as many physical therapy clinics have at least one of the Klenow et al. Journal of NeuroEngineering and Rehabilitation 2018, 15 (Suppl 1):64 Page 18 of 72