The interest in, and the need for effective measures to be used in screening, diagnosis, and the follow-up of skeletal pathologies is growing markedly. This paper proposes a completely new and non-invasive technique allowing the study of the human tibia bone marrow (BM) haemodynamics with a time resolution of 1 s. The technique, based on near infrared spectroscopy, is sensitive enough to allow the detection of BM blood volume and/or oxygen saturation changes during orthostatic variations imposed by a tilt bed. An increase in the slope of the bed of 15 degrees is sufficient to detect this phenomenon. The ability to study the possible presence of a neural control of BM haemodynamics is also discussed. No other existing technique currently allows one to obtain the proposed results and this approach might open up a new field of study related to human BM physiology.
"In another study it has been shown that the physiological parameters (hemoglobin concentration and oxygen saturation) can change in the rigid bone (Binzoni et al 2006), the constant RBC count in latter work (Binzoni et al 2013) has been explained by differentiating fast and slow changes. In slow changes, like response to cuff inflation, that we have observed in this study or in response to changes in the bed angle, reported by Binzoni et al (2006), the interstitial fluid had some extra time to diffuse away from the bone. In this way, this volume can be replaced by blood (dilating vessels) and an increase in THC occurs. "
[Show abstract][Hide abstract] ABSTRACT: The cardiac cycle related pulsatile behavior of the absorption and scattering coefficients of diffuse light and the corresponding alterations in hemoglobin concentrations in the human patella was studied. The pulsations in scattering is considerably smaller than absorption. The difference in amplitude of absorption coefficient pulsations for different wavelengths was translated to pulsations in oxygenated and deoxygenated hemoglobin, which leads to strong pulsations in the total hemoglobin concentration and oxygen saturation. The physiological origin of the observed signals was confirmed by applying a thigh-cuff. Moreover, we have investigated the optical and physiological properties of the patella bone and their changes in response to arterial cuff occlusion.
"In the same work, it has also been shown that blood oxygen saturation is higher in bone marrow and it remains constant as a function of age while it decreases is muscle. In another study, it was found that the vascular volume (tibia bone/bone marrow) increases when the subject is submitted to an orthostatic stress (tilt bed) and that an arterio-venous reflex might be present during the tilt as it normally happens in skeletal muscle (Binzoni et al 2006). On the other hand, Näslund et al (2006) have shown by photoplethysmography (using near-infrared wavelength) that it is possible to observe blood pulsations in human patellar trabecular bone. "
[Show abstract][Hide abstract] ABSTRACT: Laser-Doppler flowmetry (LDF) is an outstanding tool to monitor blood flow in a continuous and non-invasive way. In this work, we study LDF at large interoptode spacing applied to a human bone model (i.e. tibia diaphysis). To that aim, we first performed an extensive set of Monte Carlo (MC) simulations for 10 and 25 mm interoptode spacing. Second, we have assembled a dedicated LDF instrumentation based on an optimized industrial avalanche photo-detector. We performed LDF experimental measurements on human muscle using well-known physiological protocols, which confirmed the reliability of our instrumentation and the relevance of the LDF algorithms tested with the MC simulations. In a second set, we repeated the measurements on human tibia diaphysis. Again, the experiments corroborate the MC simulations and demonstrate the effectiveness of LDF to monitor blood perfusion in bone. The proposed technique has great potential for non-invasive neuro-vascular studies since it will certainly help to reveal the mechanisms underlying the interaction between bone/bone marrow, the circulatory system and the nervous system.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.