Evaluation of a Graphical Anesthesia Drug Display for Space Travel

As the frequency and duration of space travel increase, the potential need for emergency medical care in space grows, and with it the need for patient monitoring devices supporting therapeutic treatment. Providing emergency care to an injured astronaut may necessitate immediate surgery. During such events, the timely administration of anesthetic agents will need to be performed by someone who is not a formally trained anesthesiologist. The availability of usable real-time displays of intravenous anesthetic concentrations and effects could significantly enhance intraoperative clinical decision-making both in space and on earth. The effectiveness of the real-time anesthesia display on the management of total intravenous anesthesia was determined by 31 anesthesiologists participating in a simulation study. In the presence of the anesthesia drug display, clinicians maintained physiologic indicators such as blood pressure and heart rate closer to baseline levels. Participants also reported an increase in perceived performance when using the drug display. The results indicate that surgeries on earth and in orbit would benefit from the implementation of this display

Pulmonary Metaphor Design and Anesthesia Simulation Testing

Medical decision making is a crucial process to successfully treat a critical medical emergency. During an unexpected medical event, astronauts, like anesthesiologists, must react quickly in a complex environment. Tools, such as the pulmonary metaphor display, were created to aid the medical caregiver\u27s decision making process. The pulmonary metaphor display is designed to help the caregiver collect and integrate pulmonary data to provide a more accurate, quicker diagnosis and treatment. The following outline anesthesiology simulation study will provide the data to prove that the pulmonary metaphor display is beneficial to medical decision making

Development and Evaluation of a Noninvasive Hemoglobinometer

Measurement of hemoglobin concentration is among the most common clinical procedures. It is necessary in screening for anemia and is a means of providing a general assessment of physical well-being. Current methods for measuring hemoglobin concentration are invasive, requiring blood access. This paper describes a novel technique for measuring hemoglobin concentration noninvasively. The method takes advantage of the unique optical properties of hemoglobin to make the measurement. A vascularized tissue bed is transilluminated with a narrow linewidth optical source at an isobestic wavelength of oxy- and deoxy-hemoglobin. The transmitted light intensity is measured as the tissue is compressed, which causes an increase in the transmitted optical signal by forcing blood out of the optical path. The Lambert-Beer Law, modified to include optical scattering by tissue, provides the basic principle upon which the technique is based. The theory is discussed and an experimental prototype device is described. Preliminary analysis of experimental results shows a correlation between measurements obtained using the noninvasive tissue compression/transillumination method and hemoglobin concentrations measured by a clinical (invasive) hemoglobinometer. However, noise in the data are cause for concern, and may limit the clinical utility of the technique. Possible explanations for the variability in experimental results are given, along with suggestions for possible improvements to the device and technique

Monitoring breathing via signal strength in wireless networks

Abstract—This paper shows experimentally that standard wireless networks which measure received signal strength (RSS) can be used to reliably detect human breathing and estimate the breathing rate, an application we call “BreathTaking”. We show that although an individual link cannot reliably detect breathing, the collective spectral content of a network of devices reliably indicates the presence and rate of breathing. We present a maximum likelihood estimator (MLE) of breathing rate, amplitude, and phase, which uses the RSS data from many links simultaneously. We show experimental results which demonstrate that reliable detection and frequency estimation is possible with 30 seconds of data, within 0.3 breaths per minute (bpm) RMS error. Use of directional antennas is shown to improve robustness to motion near the network.

A desflurane and fentanyl dosing regimen for wake-up testing during scoliosis surgery: Implications for the time-course of emergence from anesthesia

The Stagnara wake-up test assesses neurological deficits during scoliosis surgery, and response surface interaction models for opioids and inhaled agents predicts anesthetic drug effects. We hypothesized that there is an optimal desflurane–fentanyl dosing regimen that can provide a faster and more predictable wake-up time, while also ensuring adequate analgesia during wake-up testing. Methods: Twenty-three American Society of Anesthesiologists Class I–II scoliosis patients who received desflurane–fentanyl anesthetic regimens were enrolled in this posthoc study, and their intraoperative drug administration data were collected retrospectively. Desflurane and fentanyl effect site concentrations were calculated using pharmacokinetic models, and converted to equivalent remifentanil–sevoflurane concentrations. Results: Results were fitted into Greco models for predicting the probability of an Observers Assessment of Alertness/Sedation score of <2. At time of wake-up, the models correctly predicted the probability that patients would respond to voice prompts and prodding was approximately 50%. The probability of pain intensity was distributed between 50% and 95%, indicating a low degree of pain at emergence. When comparing subgroups defined by calculated effect-site fentanyl concentrations, the wake-up time in the intermediate concentration group was significantly shorter than that in the high concentration group (p = 0.024). Conclusion: This study provides evidence that desflurane–fentanyl-based anesthesia is conducive to rapid emergence followed by an immediate neurological evaluation. Intermediate fentanyl effect-site concentrations (1–2 ng/mL) at time of wake-up were associated with good balance between rapid emergence and adequate analgesia. Furthermore, we believe that generalizing response surface models to a variety of inhalation agent-opioid combinations using simple relative potency relationships is possible and practical