Alexandre Moreau-Gaudry

A Generic Three-Dimensional Static Force Distribution Basis for a Medical Needle Inserted into Soft Tissue

In this paper, the static interaction forces between a medical needle and soft tissue during CT (Computerized Tomography) guided insertion are studied. More precisely a set of linearly independent elements describing the forces (a basis) is identified. This forms a generic basis from which any forces that act on a static needle (that is not fixed at its base and that is inserted into human tissue) can be described accurately. To achieve this purpose, the same needle was inserted 62 times into fresh porcine shoulder tissue and CT scans were acquired after each push to determine the final trajectory of the needle. From this set of trajectories, a generic static force basis was determined by using static Beam, B-spline theories and Principal Component Analysis (PCA). This generic basis was first validated on theoretical simulations and then on 20 different needles inserted into in vivo human tissues during real clinical interventions. Such a basis could be of use to highlight the forces acting all along the length of a needle inserted into a complex tissue and enables models of needle deflection to be developed. These models could be used in the development of automated robot assisted and/or image guided strategies for needle steering.

Distinguishing surgical behavior by sequential pattern discovery

OBJECTIVE Each surgical procedure is unique due to patients and also surgeons particularities. In this study, we propose a new approach to distinguish surgical behaviors between surgical sites, levels of expertise and individual surgeons thanks to a pattern discovery method. METHODS The developed approach aims to distinguish surgical behaviors based on shared longest frequent sequential patterns between surgical process models. To allow clustering, we propose a new metric called SLFSP. The approach is validated by comparison with a clustering method using Dynamic Time Warping as a metric to characterize the similarity between surgical process models. RESULTS Our method outperformed the existing approach. It was able to make a perfect distinction between surgical sites (accuracy of 100%). We reached an accuracy superior to 90% and 85% for distinguishing levels of expertise and individual surgeons. CONCLUSION Clustering based on shared longest frequent sequential patterns outperformed the previous study based on time analysis. SIGNIFICANCE The proposed method shows the feasibility of comparing surgical process models, not only by their duration but also by their structure of activities. Furthermore, patterns may show risky behaviors, which could be an interesting information for surgical training to prevent adverse events.

An innovative technique to control bleeding with vacuum device

Bleeding is one of the major problems during surgery as well as in cases of accidental vascular injury. Control of bleeding can be life threatening in two surgical circumstances: when the wound is difficult to expose, and when the tissue too fragile to suture. Following more than 100 animal tests, we developed an innovative vacuum-based suction device, which enables us to address this challenge. We set up a proof-of-concept protocol in humans and report here our first clinical experience.

Analyse spectrale par transformée de Fourier du flux sanguin cutané dans la sclérodermie systémique

OBJECTIVES Endothelial dysfunction is an early event and a critical step in the pathogenesis of systemic sclerosis. Accurate and sensitive tests are needed to correctly assess the degree of microvascular endothelial dysfunction. Spectral analysis of skin blood flow contains a characteristic low frequency reported to be associated with endothelial function in healthy subjects. We hypothesized that the relative amplitude of the oscillation recorded for this low frequency spectrum (0.008 to 0.021 Hz) would be less pronounced in patients with systemic sclerosis than in healthy subjects and in patients with primary Raynauds phenomenon. PATIENTS AND METHOD Twenty-one patients with systemic sclerosis, twenty patients with primary Raynaud phenomenon and eleven healthy subjects were enrolled. Skin perfusion was recorded at rest for 30 minutes using laser Doppler flowmetry on the pad of the left third left. Fourier transform spectral analysis was applied to obtain the mean amplitude of the cutaneous blood perfusion signal of the total spectrum from 0.008 to 1.6 Hz and the mean amplitude of each characteristic frequency in the laser Doppler flowmeter blood flow oscillations. RESULTS The relative amplitudes of each characteristic frequency in the laser Doppler flowmeter blood flow oscillations were not statistically different in the three groups, particularly for frequency spectrum from 0.008 Hz to 0.021 Hz. CONCLUSION Fourier transform spectral analysis of baseline cutaneous blood flow does not provide significant information. Further studies are required, perhaps using wavelet spectral analysis or stimulated conditions.

Haemostasis of a right ventricle-gunshot wound using a novel haemostatic vacuum device

Heart wounds are frequently fatal. The haemorrhage from a right ventricle-gunshot wound in a male patient was successfully controlled using a novel haemostatic vacuum device. This case report shows how this simple, quick and efficient method can be used to control critical bleedings.

Extraction of substernal goitre using an innovative vacuum device

The extraction by cervicotomy of substernal goitres may be impossible and sometimes requires the enlargement of the thoracic inlet with at least a sternal-split. We present the extraction of a posterior mediastinal substernal goitre with the application of an innovative vacuum-based suction device, previously used for the control of bleeding from the heart and great vessels in clinical and experimental conditions.