Riemannian Geometry Applied to Detection of Respiratory States From EEG Signals: The Basis for a Brain-Ventilator Interface.

GOAL: During mechanical ventilation, patient-ventilator disharmony is frequently observed and may result in increased breathing effort, compromising the patient's comfort and recovery. This circumstance requires clinical intervention and becomes challenging when verbal communication is difficult. In this study, we propose a brain-computer interface (BCI) to automatically and noninvasively detect patient-ventilator disharmony from electroencephalographic (EEG) signals: a brain-ventilator interface (BVI). METHODS: Our framework exploits the cortical activation provoked by the inspiratory compensation when the subject and the ventilator are desynchronized. Use of a one-class approach and Riemannian geometry of EEG covariance matrices allows effective classification of respiratory states. The BVI is validated on nine healthy subjects that performed different respiratory tasks that mimic a patient-ventilator disharmony. RESULTS: Classification performances, in terms of areas under receiver operating characteristic curves, are significantly improved using EEG signals compared to detection based on air flow. Reduction in the number of electrodes that can achieve discrimination can be often desirable (e.g., for portable BCI systems). By using an iterative channel selection technique, the common highest order ranking, we find that a reduced set of electrodes (n = 6) can slightly improve for an intrasubject configuration, and it still provides fairly good performances for a general intersubject setting. CONCLUSION: Results support the discriminant capacity of our approach to identify anomalous respiratory states, by learning from a training set containing only normal respiratory epochs. SIGNIFICANCE: The proposed framework opens the door to BVIs for monitoring patient's breathing comfort and adapting ventilator parameters to patient respiratory needs.

The cortex is in overall control of 'voluntary' eye movement.

The neural circuits that control eye movements are complex and distributed in brainstem, basal ganglia, cerebellum, and multiple areas of cortex. The anatomical function of the substrates implicated in eye movements has been studied for decades in numerous countries, laboratories, and clinics. The modest goal of this brief review is twofold. (1) To present a focused overview of the knowledge about the role of the cerebral cortex in voluntary control of eye movements. (2) To very briefly mention two findings showing that the accepted hierarchy between the frontal and the occipital sensory areas involved in sensory-motor transformation might not be so trivial to reconcile, and to interpret in the context of eye movement command. This presentation has been part of the 44th Cambridge Ophthalmological Symposium, on ocular motility, 3 September 2014 to 5 November 2014.

[Chronic pulmonary artery thrombosis. Therapeutic modality. Apropos of 6 cases]. / Thromboses artérielles pulmonaires chroniques. Modalités thérapeutiques. A propos de 6 observations

Six cases of post-embolic chronic cor pulmonale are presented. All six were treated with thrombolytic agents (4 with streptokinase, 2 with urokinase), and in only one case was improvement maintained at the end of one year. Two patients underwent a disobliterative procedure of the pulmonary artery, together with ligation of the inferior vena cava. One of these operations was unsuccessful, and the other had a successful outcome, as confirmed by objective assessment with angiography, scintigraphy and haemodynamic studies. The literature is reviewed at this stage. It was found that the fibrinolytic agents had some chance of working only if the condition was less than a few months old. One major drawback to surgical disobliteration that cannot be foreseen before operation is the presence of thromboses at the arteriolar level in subjects whose main arteries are already blocked proximally. Nervertheless it is possible to obtain good results by surgery, and the operation is worth attempting in young subjects, given the poor prognosis of the untreated condition.

[Abnormal implantation of a coronary artery in a 53-year-old patient. Surgical correction]. / Implantation anormale d'une artére coronaire chez une malade de 53 ans. Correction chirurgicale

In a 53-years old patient complaining of dyspnoea and angina of effort, the coronary arteriography demonstrated ab abnormal implantation of the pulmonary artery into the left coronary-artery. Correlated with the 39 cases of the adolescent and the adult published in the literature, the case reported has some peculiarities: poorness of the auscultatory signs consisting in a mild apical systolic murmur; electrocardiographic pattern of left complete bundle-branch block; presence of massive calcifications visible by X-ray into the lateral, wall of the left ventricle. Coronary arteriography and catherization made it possible to demonstrate a left-to-right shunt by backward-flow revascularization of the left coronary artery starting from the right coronary artery. A simple suture of the implantation foramen of the abnomal coronary artery resulted in increased pressure into this artery and was followed by disappearance of angina during an observation period of 5 months.