PubMed · 2333331
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R L DonTigny. 1990. Conservative care.. https://doi.org/10.1093/ptj%2F70.5.324
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PURPOSE: To determine the volume and composition of clot within thrombosed hemodialysis access grafts. MATERIALS AND METHODS: Clots were collected in 22 patients at surgical thrombectomy of polytetrafluoroethylene grafts. Histologic analysis was performed in 10 of these clots plus 21 randomly selected clots from the pathology archives. RESULTS: A small, firm piece of whitish thrombus ("arterial plug") was almost always recovered from the arterial limb of the graft. This plug had a concave surface and ranged from 5 mm to 3 cm in length. The remaining clot was soft, red thrombus. The mean weight of all clots was 3.4 g, and mean volume was 3.2 cm3. Average graft length was 42 cm. Histologically, the arterial plug had a characteristic appearance of densely compacted alternating layers of erythrocytes and fibrin. CONCLUSION: Clot volume in thrombosed dialysis grafts is much less (approximately equal to 25%) than would be expected if the graft were completely filled with thrombus, a finding of significance to mechanical thrombolytic techniques. Resistance of the arterial plug to pulse-spray thrombolysis is likely due to compaction.
The influence of the large arteries and the peripheral load on pressure wave propagation in the human upper limb was investigated in an anatomically realistic multibranched model based on linear transmission theory. To mimic vascular changes seen in life, the viscoelastic properties of large arteries and the peripheral load properties (represented as modified windkessels) were altered as follows: Young's modulus (from 10.9 x 10(6) to 15.3 x 10(6) dyn/cm2) and phase (from 0 to 15 degrees) of the complex elastance, windkessel time constant (from 0 to 0.6 s), and peripheral reflection coefficient (from 0 to 0.95). The relationship between the central aortic and peripheral radial pressure waveforms was analyzed in the time and the frequency domain. Results indicate that the large arterial properties have less influence (peak systolic pressure changed by 3% and peak of transfer function changed by 29%) than the properties of the peripheral load (systolic pressure changed by 14% and peak of transfer function changed by 74%) on the pressure wave propagation in the upper limb.
1. A fundamental question about motor control is related to the nature of the representations used by the nervous system to program the movement. Theoretically, arm displacement can be encoded either in task (extrinsic) or in joint (intrinsic) space. 2. The present study investigated the organization of complex movements consisting of reaching and grasping a cylindrical object presented along different orientations in space. In some trials, object orientation was suddenly modified at movement onset. 3. At a static level, the final limb angles were highly predictable despite the wide range of possible postures allowed by articular redundancy. Moreover, when object orientation was unexpectedly modified at movement onset, the final angular configuration of the limb was identical to that obtained when the object was initially presented along the orientation reached after the perturbation. 4. At a dynamical level, a generalized synergy was observed, and tight correlations were noted between all joint angles implicated in the movement with the exception of elbow flexion. For this joint angle, which did not vary monotonically, strong partial correlations were however observed before and after movement reversal. 5. These results suggest that natural movements are mostly carried out in joint space by postural transitions.