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Biomedical subjects

L Vogt

Publications and source records attributed to L Vogt.

82 records · Page 5Linked to original sources
PubMed1979

[Effect of dihydroergotamine on pulmonary perfusion in acceleration stress (author's transl)].

An orthostatic circulatory load of varying degree (1-4 G) can be simulated by means of a human centrifuge. This results in a partial shifting of the intrathoracic blood volume into the capacity vessels of the lower extremity. In the pulmonary region, this is associated with a decrease in perfusion from the apical to the basal segments, which can be demonstrated by double nuclide perfusion scintigraphy. The degree of change in pulmonary perfusion was determined quantitatively in 26 volunteers by perfusion scintigraphy before and during acceleration, and the influence of dihydroergotamine (Dihydergot) was studied. The results show that the redistribution of the polmonary blood volume into the lower parts of the body can be largely prevented by Dihydergot. Pulmonary perfusion remains almost unchanged, compared with the initial value, up to an acceleration stress of 3 G, following intravenous injection of 0.5 mg dihydroergotamine. After oral administration (6 mg/d over 12 days), this applies to 1 and 2 G. Hence, dihydroergotamine represents, so to say, a "pharmacological anti-G suit".

Acceleration↗
PubMed1978

Model of the supine human body and its reactions to external forces.

Mechanical impedance and vibration transmissibility measurements were conducted on supine humans using sinusoidal vibrations. The frequencies tested were 1-20 Hz with a constant acceleration amplitude of 0.3 G. The tests were repeated with 4.54 kg pure mass placed on each segment. Both results were used to calculate a multi-degree-of-freedom lumped parameter model. The nonlinear reactions of the body are revealed by comparing the model parameters under "no load" and "load" conditions. When the results are compared with impedance measurements conducted under sustained acceleration, it becomes obvious that the thorax, due to its anatomical design, reacts differently from the remaining body parts.

Abdomen↗
PubMedDate not supplied

[Sensomotor function while wearing lumbar support ortheses].

AIM: Flexible lumbar corsets should contribute to an improved active and passive stabilisation of the lumbar spine. In the present study, the effects of flexible corsets on sensory-motor abilities have been investigated. METHODS: 24 healthy subjects (m = 10, f = 14, 26.7 years) performed angle- and force-reproduction tasks with and without wearing a flexible corset. The subjects tried to reproduce trunk flexion angles of 20 degrees und 40 degrees as well as forces of 33% and 66% of the maximum strength of the back extensor muscles. Additionally, muscular reactions were measured during destabilizing stimuli. RESULTS: No significant differences were found for the reproduction tasks. When wearing the corset, the left erector spinae muscles showed a delayed onset (+15 ms, p < 0.05), and the obliquus abdominis reached maximal activity more rapidly (-18 ms, p < 0.05). In the preinnervation phase the obliquus abdominis (-33%, p < 0.01), in the eccentric phase the erector spinae (-27%, p < 0.05) and the right obliquus abdominis (-46%, p < 0.05) and in the concentric phase the right obliquus abdominis (-35%, p < 0.01) and the rectus abdominis (-32%, p < 0.05) showed lower activities. CONCLUSION: The reduced muscle activities with destabilizing stimuli can be interpreted as the result of an improved passive stabilisation of the lumbar region by wearing a flexible corset.

Adult↗
PubMedDate not supplied

[Gait disorders - assessment and rehabilitation supported by movement analysis].

AIM: The present paper validates the use of two-dimensional pelvis and thorax translation data for the assessment of gait disturbances and evaluates the effects of a real-time visual feedback system based on thoracic spine kinematics for gait rehabilitation. METHODS: To validate the use of two-dimensional gait kinematics, vertical and horizontal displacements of pelvis (S1) and thorax (T12) markers of the twelve healthy individuals (25.9 +/- 2.7 years) were recorded during two gait perturbations: a brace constraining the knee to 30 degrees of flexure and a shoe lift of 3 cm. To investigate the effects of verbal instructions and additional real-time visual feedback on vertical and medial-lateral pelvis and trunk movements, gait kinematics were recorded during three randomized trials (verbal instruction, real-time visual kinematic feedback, free walking). RESULTS: Gait deviations did result in significant (p < 0.05) increases of horizontal and vertical trunk pelvis movements. Significant (p < 0.05) reductions in oscillation amplitudes were noted when verbal cues and visual information were received. However, the major decrease occurred during real-time visual feedback. CONCLUSION: Asymmetric limping, similar to gait disorders of individuals with hip pathologies, could be detected and described by two-dimensional thorax and pelvis translation data. It could be speculated that gait disorders may be addressed by real-time kinematic feedback training.

Adult↗
PubMedDate not supplied

Lumbar corsets: their effect on three-dimensional kinematics of the pelvis.

Lumbar corsets have been recommended for low back pain patients as a way of stabilizing the lumbar region, facilitating flexion movements, and reducing pain. However, little is known about how these devices affect lumbar motion. To determine the degree of changes in the lumbar region, our approach was to quantify three-dimensional kinematic data of the pelvis in harness-supported treadmill walking. Twelve healthy subjects (age=32+/-11.8 years) walked on a motorized treadmill at 4.5 km/h with and without wearing a lumbar corset. Three external markers overlying the sacrum were tracked by three ultrasound microphones, determining a local coordinate system, to obtain pelvic motions in the frontal, sagittal, and transverse planes. Raw kinematic data were low-pass filtered and normalized relative to the right heel strike. Mean values for net angular displacements of the pelvis were calculated for each plane within the 5th and 95th percentile. The Student's t-test demonstrated significant differences (P<0.001) between the corset/no-corset conditions in the frontal plane. An average 40% decrease in the relative pelvis up- and downward movement occurred in the frontal plane (4.1 degrees+/-2.9 degrees vs. 7.1 degrees+/-3.3 degrees). The analysis revealed no significant differences of net angular displacements in the sagittal (2.9 degrees+/-1.4 vs. 3.4 degrees+/-1.7 degrees) and the transverse planes (4.4 degrees+/-2.6 degrees vs. 4.3 degrees+/-2.1 degrees).

Adult↗