Michael Scholtes

Quantification of nasal respiratory flow by tracheal sound analysis

By now the pneumotachograph is the gold standard for quantitative measurement of the respiratory flow. However, for continuous quantitative monitoring of airflow or measuring flow within non-invasive ventilated patients an ideal solution is still missing. In this study we made an attempt to detect the nasal breathing with our newly developed system of measurement. This method allows the detection of nasal airflow by means of a sensor, which is placed on the trachea. In 20 pulmonary healthy male subjects the airflow was measured by a pneumotachograph. At the same time tracheal breathing sounds were recorded by a sensor placed paralaryngeal. Using a newly developed analysis system, tracheal breathing sounds can be transformed and the real respiratory flow curve can be calculated. For inspiration, as well as expiration, the estimated airflow showed a highly significant correlation (pearson correlation coefficient, r = 0.89 up to 0.92 with p< 0.01). The presented method is still being tested but has the potential to be applicable in polysomnography.

Integrating a Usability Engineering Process into a Consisting Risk Management

Abstract The complexity of medical devices and its user interactions increases. A growing number of incident reports are assumed to be associated primarily with user errors. This development is tackled through current modifications in standards, such as ISO 13485:2016 and legislations, such as the Medical Device Regulation. Both intensify the focus on use errors significantly. The aim of this paper was the development of a process orientated approach integrating usability engineering into a consisting risk management based on a classic V-model. An appropriate procedure was worked out. For each development step, risk and usability activities were cumulated. Thus, the present paper might help medical device manufacturers to reflect their risk management and usability management processes to find synergies. Prospectively, a step-by-step guide for the integration of risk management and usability engineering based on this approach should be developed.

Evaluation of an app-based stress protocol

Abstract Stress is a major influence on the quality of life in our fast-moving society. This paper describes a standardized and contemporary protocol that is capable of inducing moderate psychological stress in a laboratory setting. Furthermore, it evaluates its effects on physiological biomarkers. The protocol called “THM-Stresstest” mainly consists of a rest period (30 min), an app-based stress test under the surveillance of an audience (4 min) and a regeneration period (32 min). We investigated 12 subjects to evaluate the developed protocol. We could show significant changes in heart rate variability, electromyography, electro dermal activity and salivary cortisol and α-amylase. From this data we conclude that the THM-Stresstest can serve as a psychobiological tool for provoking responses in the cardiovascular-, the endocrine and exocrine system as well as the sympathetic part of the central nervous system.

Bestimmung der hyperkapnischen Atemantwort bei Patienten mit COPD

Previous studies showed a reduced hypercapnic ventilatory response (HCVR) in patients with COPD. However, the association between HCVR and COPD GOLD stages is unknown. The measurement of the HCVR is a methodological option to test the function of the breathing feedback cycle. The aim of this feasibility study was to present a new automatic and standardized device (MATAM) to measure and interpret the HCVR. This device determines if exposure to CO2 leads to an adequate increase in breathing frequency and tidal volume. Recordings are performed in a closed system that allows selective changes of each gas component. The minute ventilation (AMV) under hypercapnic stimulation is plotted against the end-tidal CO2 (ETCO2). The HCVR is defined as the linear regression line.28 patients (18 male; 10 female) with COPD GOLD stages 0 to IV were studied. The patients had a mean age of 57 ± 14 (standard deviation) years and a mean BMI of 32 ± 9 kg/m(2). We could show that the HCVR measurement in patients with COPD using MATAM was feasible. Patients with more severe COPD stages had a significantly more reduced HCVR. This could be an indication of reduced chemosensitivity due to a worsening of blood values (pH and pCO2) which affect the central chemoreceptors in the long term. Further studies will be needed to validate the MATAM device for healthy individuals and other patient groups, and for the investigation of standard values.

Bestimmung der Atemstromstärke mithilfe des ThorAKUSTIK-Verfahrens bei Mund- und Nasenatmung

BACKGROUND Respiratory flow detection with the aim of detecting sleep-related breathing disorders plays a major role in polysomnography. Due to the fact that pneumotachographs are too bulky and not suitable for measurements during sleep, the ThorAKUSTIK system has been developed. By attaching a noise sensor right next to larynx, it determines the respiratory flow in an acoustic way. METHODS The ThorAKUSTIK system as well as a pneumotachograph were applied simultaneously. The correlation between those two methods has been calculated. PATIENTS We investigated twenty male subjects. All of them were non-smokers. RESULTS The ThorAKUSTIK-System showed a highly positive correlation (r = 0.89 to 0.91; p < 0.01) and was able to measure the respiratory flow in a reliable way. CONCLUSIONS The ThorAKUSTIK-System allows a long-term live monitoring and has the potential to be used in several clinical departments. Larger studies are necessary to verify the application in the clinical routine.