Analysis of arterial flowmotion in spinal cord injured and elderly subjects in an area at risk for the development of pressure sores

Flowmotion (blood flow changes due to vasomotion) in the skin over a risk area for pressure sores, the sacrum, and a non-risk area, the gluteus muscle, was evaluated by laser Doppler fluxmetry during resting conditions and post-occlusive reactive hyperaemia (PRH) response. Measurements were made in healthy younger subjects and in two risk groups for pressure sores-spinal cord injured (SCI) and the elderly. The SCI were divided into two subgroups, one with and one without distinct flowmotion seen on the original recordings over the sacrum. The Prony spectral line estimation (PSLE) method was used to determine the power spectrum of the flowmotion activity. During the PRH, flowmotion frequencies were found in two separated bands, 5.4-6.6 cpm (cycles min-1) and 7.8-9.0 cpm. In the subgroup without distinct flowmotion, the PSLE method found flowmotion frequencies similar to the other groups. During the PRH, the flowmotion power pattern over the sacrum was similar within all groups, but the power was extremely low in one subgroup of SCI subjects. To conclude, flowmotion (vasomotion) was present in the two skin areas and increased during the PRH response, reaching a maximum within 50 s. This study shows that the flowmotion frequencies might be locally driven, whereas the power might be centrally mediated. Disturbances in microcirculatory flowmotion can be a part of the mechanisms leading to skin ischaemia and pressure sores. A new method has been developed for analysing differences in flowmotion behaviour such that statistical comparisons can be made.

Improvements in tests of long-range charge independence

The procedure used to determine the pionnucleon coupling constant g(2) from multi-energy fits to nucleon-nucleon (N-N) scattering data has been shortened without a material loss of accuracy. The g(2) presetting effect is discussed in connection with the limited accuracy of g(2) determinations in general and the possibilities of the "optimized polynomial expansions". The desirability of the Yale graded introduction of one-pion exchange (OPE)-to-"searched" transition energies (E(tr)) is brought out. Corrections for virtual discontinuities in phase-shift-energy dependence at the E(tr) decreased the violation of long-range charge independence (LRCI). The effect of two-pion exchange (TPE) has been calculated on the ps theory as approximately 1 for go(2)(p-p) - go(2)(n-p), go(2) = g(2)/[unk]c; a result consistent with LRCI. Searching all phase parameters including g(2) for both isospin values I in g(2) determinations from n-p data, but with fixed I = 1 non-OPE phases as deduced from p-p data in the base search with frozen g(2), the OPE effect of the neutral pion, pi degrees , was separated from that of the charged pion, pi(c). The g(2) for pi(c) in n-p scattering is determined with much better statistical accuracy than that for pi degrees . The overall n-p value of g(2) is nearly equal to that for pi(c). The results suggest that the distinction between p-p and n-p values of g(2), if present, is in first approximation that arising from the difference between pi degrees -N and pi(c)-N couplings. Some limitations on the validity of the conclusions are mentioned.