A mathematical model for breath gas analysis of volatile organic compounds with special emphasis on acetone

Recommended standardized procedures for determining exhaled lower respiratory nitric oxide and nasal nitric oxide have been developed by task forces of the European Respiratory Society and the American Thoracic Society. These recommendations have paved the way for the measurement of nitric oxide to become a diagnostic tool for specific clinical applications. It would be desirable to develop similar guidelines for the sampling of other trace gases in exhaled breath, especially volatile organic compounds (VOCs) which reflect ongoing metabolism. The concentrations of water-soluble, blood-borne substances in exhaled breath are influenced by: (i) breathing patterns affecting gas exchange in the conducting airways; (ii) the concentrations in the tracheo-bronchial lining fluid; (iii) the alveolar and systemic concentrations of the compound. The classical Farhi equation takes only the alveolar concentrations into account. Real-time measurements of acetone in end-tidal breath under an ergometer challenge show characteristics which cannot be explained within the Farhi setting. Here we develop a compartment model that reliably captures these profiles and is capable of relating breath to the systemic concentrations of acetone. By comparison with experimental data it is inferred that the major part of variability in breath acetone concentrations (e.g., in response to moderate exercise or altered breathing patterns) can be attributed to airway gas exchange, with minimal changes of the underlying blood and tissue concentrations. Moreover, it is deduced that measured end-tidal breath concentrations of acetone determined during resting conditions and free breathing will be rather poor indicators for endogenous levels. Particularly, the current formulation includes the classical Farhi and the Scheid series inhomogeneity model as special limiting cases.Comment: 38 page

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Nervenarzt

We performed a prospective study on 208 patients with neurogenic dysphagia who were consecutively admitted for swallowing therapy over a 3-year period. The most frequent etiology was stroke (48%). Videofluoroscopic and/or fiber optic endoscopic evaluation of swallowing were performed in 204 patients. Swallowing therapy was comprised of restitution methods, compensation, and adaptation, each of which was applied in more than 80% of the patients. Mean duration of swallowing therapy was 2 months (full oral patients 1 month, patients dependent on tube feeding or tracheostomy 2.5 and 3.5 months, respectively). Fifty-five percent of the patients initially dependent on tube feeding were full oral feeders after swallowing therapy. A target variable reflecting functional feeding status showed significant improvement after swallowing therapy,also in patients with a disease duration of more than half a year, ruling out spontaneous recovery as a sole explanation of amelioration. The following variables were the main contributors to outcome prediction: functional feeding status, Barthel index, duration of disease, and degree of aspiration as shown by endosco

Schluckstörungen bei neurologischen Patienten : eine prospektive Studie zu Diagnostik, Störungsmustern, Therapie u. Outcome

We performed a prospective study on 208 patients with neurogenic dysphagia who were consecutively admitted for swallowing therapy over a 3-year period. The most frequent etiology was stroke (48%). Videofluoroscopic and/or fiber optic endoscopic evaluation of swallowing were performed in 204 patients. Swallowing therapy was comprised of restitution methods, compensation, and adaptation, each of which was applied in more than 80% of the patients. Mean duration of swallowing therapy was 2 months (full oral patients 1 month, patients dependent on tube feeding or tracheostomy 2.5 and 3.5 months, respectively). Fifty-five percent of the patients initially dependent on tube feeding were full oral feeders after swallowing therapy. A target variable reflecting functional feeding status showed significant improvement after swallowing therapy,also in patients with a disease duration of more than half a year, ruling out spontaneous recovery as a sole explanation of amelioration. The following variables were the main contributors to outcome prediction: functional feeding status, Barthel index, duration of disease, and degree of aspiration as shown by endosco