Three-dimensional ballistocardiography and respiratory motion in sustained microgravity.

BACKGROUND: We measured the three-dimensional ballistocardiogram (BCG) in a free-floating subject in sustained microgravity during spaceflight to test the usefulness of such measurements for future non-invasive monitoring of cardiac function, and to examine the effects of respiratory movement on the BCG in three axes. METHODS: Acceleration was measured using a three-axis accelerometer fastened to the lumbar region of the subject while simultaneous recordings of ECG, and respiratory motion via impedance plethysmography were also made. Data were recorded during a 146-s period of inactivity on the part of the subject during which time there was no contact with the spacecraft. RESULTS: Total body motion due to respiratory activity was consistent with that calculated from the known action of the diaphragm and conservation of momentum. The accelerations due to cardiac activity, ensemble averaged over the R-R interval, were greatest along the head-to-foot axis. Maximum amplitude of the HIJK complex of the BCG generated by ventricular ejection was greatest in the head to foot axis (approximately 70 x 10(-3) m x s(-2)), but there were also substantial accelerations along the dorsoventral axis of up to 43 10(-3) m x s(-2), that are not measured interrestrial two-dimensional studies. The amplitude of the BCG was strongly affected by lung volume, with accelerations being reduced 50 to 70% between end-inspiration and end-expiration. CONCLUSIONS: These data suggest a greatly reduced transmission of the cardiac motion to the body at end-expiration (FRC) than at higher lung volumes. The BCG might be further developed as a non-invasive means of monitoring parameters such as stroke volume in microgravity.

Telemetry as a new concept in long term monitoring of SIDS-risk infant.

Sudden Infant Death Syndrome (SIDS) is the most frequent cause of infant death within the period of 2 to 12 months in western countries. It has been found that a suit similar to that worn by the astronauts during the execution of experiments on the Spacelab Mission D-2 is a very simple and useful means to carry the sensors required to monitor vital signs of babies at risk. A small baby-suit has been developed with the same technology used for the Spacelab Mission. The baby s suit is equipped with similar sensors to record thoracic and abdominal respiratory movements as its big -space travel brother-. This is a typical example of a successful technology transfer from medical aerospace activities into fields of daily clinical routine. In addition to the above described sensors, ECG-electrodes were integrated, as well as sensors to record vascular oxygen saturation and the corresponding pulse curve, and the baby s movements. All these vital signs are registered by a medical monitor, and permanently stored and automatically analysed online. In case of a life-threatening situation the system alerts simultaneously the personal at hospital and the parents at home. The requisite software algorithms have been developed by DLR in Cooperation with the pediatricians of the Pediatric Hospital in Köln-Porz, Cologne. When the system registers an alteration of the parameters above described -as a signal of a change in the baby s health condition- all vital signs are transfered in real-time to the supervising hospital via radio data transmission devices, mobile phone or a fixed network phone. The parents are also alerted by the device, and they can carry out the necessary reanimation procedures in case of an emergency. Parents will be trained in such actions when newborns must to be monitored. But nevertheless, they are guided and tele-assisted by an expert via telephone during the action. A clinical field trial, that will start in December 1999 at the Pediatric Hospital in Köln-Porz, Cologne, will evaluate the benefits of teleprotection by home monitoring of SIDS risk-babies.

Telemedicine for the International Space Station.

The medical care for the integrated crew of the International Space Station (ISS) will require close co-operation between the partner agencies in the areas of selection, medical surveillance, countermeasures, and handling of acute medical problems. Based on a commonly accepted policy of shared care and responsibilities medical guidelines, procedures, and standards for medical data and communication need to be harmonised under the responsibility of the Multilateral Medical Operations Panel (MMOP). A supporting telemedical network connecting the partners on an organisational and technical level will facilitate the harmonisation process and provide new tools for effective co-operation between medical professionals. Earth bound projects with similar application areas can profit from and contribute to this development and need to be considered for efficient implementation and exploitation.

Health care in remote areas.

Migration from space medicine toward telemedicine services is described by potential application areas in highly populated and remote areas of Europe. Special emphasis is laid upon links between mobile patient monitoring and health care in remote areas. Pilot projects are described for home (mobile) monitoring of newborn infants endangered by sudden infant death (SID) and adults suffering from sleep apnoea. Health care in remote areas is described by the "TeleClinic-project" which will link national nodes for telemedicine services in several European states for the mobile European citizen. Another project describes the future potential of robotics for semiautonomous ultrasound diagnostics and for realtime interaction of remote experts with diagnostics and therapy.

MUSC information system ARIADNE: a consistent tool for support of experiment planning, execution and scientific evaluation of microgravity-experiments.

One of the main tasks of DLR-MUSC (Microgravity User Support Center) is to accompany an experiment's complete life-cycle, thus supporting the investigators. This task starts with the preparation of experiments, continues with their execution and finally leads to the evaluation of the respective measurement results. A computer-based information system facilitates these tasks. Considerable effort has been taken in order to make a detailed as well as modular design--as a result the system can now be applied for any mission. ARIADNE mainly supports three phases, all using the same consistent database. 1. The first phase of experiment preparation is supported by--the acquisition and maintenance of general and basic data by user entries into the database, and the support of the integration of partially similar experiment proposals into a timeline as planned which is composed by activities. 2. The support during experiment execution consists of--real-time data acquisition and control (i.e. on-line database generation and display after processing) including experiment monitoring, enabling of fast replanning. 3. The support ARIADNE provides for experiment evaluation includes--the selection of series of measurements belonging to the specified experiment (parts), further processing and evaluation of the collected data, which must partly be done in real-time and partly post-mission and, creation of back-up's of the processing results. The ARIADNE database consists of a relational ORACLE-part (for numerical and character data), a bibliographic part, a program-library, and a realtime-part (BAPAS). The open design of ARIADNE allows interfaces to stored special data (such as graphics, images, archives) as well as several interfaces to other systems, such as CUIS, MARS-MDB, EXPRES, etc.

Cardiovascular effect of sparteine in anaesthetized dogs with and without blockade of cardiac autonomic nerves.

L-Sparteine sulfate (sparteine, 3 mg/kg) was injected intravenously over 3 min in 12 anaesthetized dogs in order to evaluate the inotropic effect of this antiarrhythmic drug on the heart in intact organisms. There was a discrete decline in left ventricular dP/dtmax which was transient within 9 min. No influence could be detected on right ventricular pressure rise velocity. Aortic pressure increased by about 15% and a parallel increase in left ventricular enddiastolic pressure was observed. Heart rate was slightly diminished. Pharmacological blockade of cardiac autonomic nerves did not influence considerably the effect of sparteine. Pretreatment with captopril and phentolamine did not abolish the vasoconstrictive property which was also present in a reserpine pretreated dog. Sparteine shows no pronounced inotropic effect in the heart in situ. It increases arterial blood pressure by direct vascular constriction.