On-orbit prospective echocardiography on International Space Station crew.

OBJECTIVES: A prospective trial of echocardiography was conducted on six crew members onboard the International Space Station. The main objective was to determine the efficacy of remotely guided tele-echocardiography, including just-in-time e-training methods and determine what is "space normal" echocardiographic data. METHODS: Each crew member operator (n = 6) had 2-hour preflight training. Baseline echocardiographic data were collected 55-167 days preflight. Similar equipment was used in each 60-minute in-flight session (mean microgravity exposure--114 days [34--190]). On-orbit ultrasound (US) operators used an e-learning system within 24 hours of these sessions. Expert assistance was provided using US video downlink and two-way voice. Testing was repeated 5-16 days after landing. Separate ANOVA was used on each echocardiographic variable (n = 33). Within each ANOVA, three tests were made: (a) effect of mission phase (preflight, in-flight, postflight); (b) effect of echo technician (two technicians independently analyzed the data); (c) interaction between mission phase and technician. RESULTS: Eleven rejections of the null hypothesis (mission phase or technician or both had no effect) were found that could be considered for possible follow up. Of these, eight rejections were for significant technician effects, not space flight. Three rejections of the null hypothesis (aortic valve time velocity integral, mitral E-wave velocity, and heart rate) were attributable to space flight but determine to not be clinically significant. No rejections were due to the interaction between technician and space flight. CONCLUSION: Thus, we found no consistent clinically significant effects of long-duration space flight on echocardiographic variables of the given group of subjects.

Sonography for determining the optic nerve sheath diameter with increasing intracranial pressure in a porcine model.

OBJECTIVES: This study investigated whether it is feasible to use sonography to monitor changes in the optic nerve sheath diameter in a porcine model. METHODS: A fiber-optic intracranial pressure transducer was surgically placed through the frontal sinus directly into the brain parenchyma of adult Yorkshire pigs (n = 5). A second bolt was placed on the contralateral side for intraparenchymal fluid infusion. Optic nerve sheath diameter measurements were acquired by each of 2 ultrasound operators around the leading edge of the nerve, 3 to 5 mm distal from the origin of the optic nerve. To induce a change in diameter, intracranial pressure was manipulated by injecting normal saline into the intraparenchymal infusion catheter located in the symmetric contralateral position as the pressure-monitoring probe. RESULTS: Data from 1 pig were unusable because of a cerebrospinal fluid leak into the sinus and orbital fissure. Saline aliquots of 1 to 10 mL were able to generate intracranial pressures typically starting from 10 to 15 mm Hg and increasing to 75 to 90 mm Hg, which eventually evoked a Cushing response. Fluid injection was controlled to increase pressures by 60 mm Hg over a 15- to 20-minute period. Regression analysis of all animals showed that the optic nerve sheath diameter increased by 0.0034 mm/mm Hg of intracranial pressure; however, this slope ranged from 0.0025 to 0.0046, depending on the animal measured. There was no discernible effect of the ultrasound operator on the slope; however, measurements made by 1 operator were consistently higher than the others by about 8% of the overall diameter range. CONCLUSIONS: These results suggest that the use of the optic nerve sheath diameter to noninvasively confirm acute changes in intracranial pressure over 1 hour is feasible in a porcine model. We recommend that this method be validated in humans using direct intracranial pressure measurement where possible to confirm it as a screening tool for acute and chronically increased diameters secondary to elevated pressure in clinical settings.

Ultrasonographic evaluation of sinusitis during microgravity in a novel animal model.

OBJECTIVES: To develop an animal model of rhinosinusitis in microgravity, to characterize the behavior of intracavitary fluid in microgravity, and to assess the accuracy of ultrasonographic (US) diagnosis in microgravity. DESIGN: An animal model of acute sinusitis was developed in anesthetized swine by creating a window into a frontal sinus to allow unilateral catheter placement and injection of fluid. We performed US examinations in normal and microgravity environments on control and sinusitis conditions and recorded these for later interpretation. SETTING: Henry Ford Hospital and the National Aeronautics and Space Administration (NASA) Microgravity Research Facility in Houston, Texas. SUBJECTS: Ground (normal-gravity) experiments were conducted on anesthetized swine (n = 4) at Henry Ford Hospital before the microgravity experiments (n = 4) conducted in the NASA Microgravity Research Facility. MAIN OUTCOME MEASURE: Ultrasound visualization of fluid cavity. RESULTS: Results of bilateral US examinations before fluid injection demonstrated typical air-filled sinuses. After unilateral injection of 1 mL of fluid, a consistent air-fluid interface was observed on the catheterized side at ground conditions. Microgravity conditions caused the rapid (<10-second) dissolution of the air-fluid interface, associated with uniform dispersion of the fluid to the walls of the sinus. The air-fluid interface reformed on return to normal gravity. CONCLUSIONS: The US appearance of fluid in nasal sinuses during microgravity is characterized in the large animal model. On the introduction of microgravity, the typical air-fluid interface disassociates, and fluid lining the sinus can be observed. Such fluid behavior can be used to develop diagnostic criteria for acute bacterial rhinosinusitis in the microgravity environment.

Battling fire and ice: remote guidance ultrasound to diagnose injury on the International Space Station and the ice rink.

BACKGROUND: National Aeronautical and Space and Administration (NASA) researchers have optimized training methods that allow minimally trained, non-physician operators to obtain diagnostic ultrasound (US) images for medical diagnosis including musculoskeletal injury. We hypothesize that these techniques could be expanded to non-expert operators including National Hockey League (NHL) and Olympic athletic trainers to diagnose musculoskeletal injuries in athletes. METHODS: NHL and Olympic athletic trainers received a brief course on musculoskeletal US. Remote guidance musculoskeletal examinations were conducted by athletic trainers, consisting of hockey groin hernia, knee, ankle, elbow, or shoulder evaluations. US images were transmitted to remote experts for interpretation. RESULTS: Groin, knee, ankle, elbow, or shoulder images were obtained on 32 athletes; all real-time US video stream and still capture images were considered adequate for diagnostic interpretation. CONCLUSIONS: This experience suggests that US can be expanded for use in locations without a high level of on-site expertise. A non-physician with minimal training can perform complex, diagnostic-quality examinations when directed by a remote-based expert.

Evaluation of shoulder integrity in space: first report of musculoskeletal US on the International Space Station.

Investigative procedures were approved by Henry Ford Human Investigation Committee and NASA Johnson Space Center Committee for Protection of Human Subjects. Informed consent was obtained. Authors evaluated ability of nonphysician crewmember to obtain diagnostic-quality musculoskeletal ultrasonographic (US) data of the shoulder by following a just-in-time training algorithm and using real-time remote guidance aboard the International Space Station (ISS). ISS Expedition-9 crewmembers attended a 2.5-hour didactic and hands-on US training session 4 months before launch. Aboard the ISS, they completed a 1-hour computer-based Onboard Proficiency Enhancement program 7 days before examination. Crewmembers did not receive specific training in shoulder anatomy or shoulder US techniques. Evaluation of astronaut shoulder integrity was done by using a Human Research Facility US system. Crew used special positioning techniques for subject and operator to facilitate US in microgravity environment. Common anatomic reference points aided initial probe placement. Real-time US video of shoulder was transmitted to remote experienced sonologists in Telescience Center at Johnson Space Center. Probe manipulation and equipment adjustments were guided with verbal commands from remote sonologists to astronaut operators to complete rotator cuff evaluation. Comprehensive US of crewmember's shoulder included transverse and longitudinal images of biceps and supraspinatus tendons and articular cartilage surface. Total examination time required to guide astronaut operator to acquire necessary images was approximately 15 minutes. Multiple arm and probe positions were used to acquire dynamic video images that were of excellent quality to allow evaluation of shoulder integrity. Postsession download and analysis of high-fidelity US images collected onboard demonstrated additional anatomic detail that could be used to exclude subtle injury. Musculoskeletal US can be performed in space by minimally trained operators by using remote guidance. This technique can be used to evaluate shoulder integrity in symptomatic crewmembers after strenuous extravehicular activities or to monitor microgravity-associated changes in musculoskeletal anatomy. Just-in-time training, combined with remote experienced physician guidance, may provide a useful approach to complex medical tasks performed by nonexperienced personnel in a variety of remote settings, including current and future space programs.

Sonographic detection of pneumothorax and hemothorax in microgravity.

INTRODUCTION: An intrathoracic injury may be disastrous to a crew-member aboard the International Space Station (ISS) if the diagnosis is missed or delayed. Symptomatic or clinically suspicious thoracic trauma is treated as a surgical emergency on Earth, usually with immediate stabilization and rapid transport to a facility that is able to deliver the appropriate medical care. A similar approach is planned for the ISS; however, an unnecessary evacuation would cause a significant mission impact and an exorbitant expense. HYPOTHESIS: The use of ultrasound imaging for the detection of pneumothorax and hemothorax in microgravity is both possible and practical. METHODS: Sonography was performed on anesthetized pigs in a ground-based laboratory (n = 4) and microgravity conditions (0 G) during parabolic flight (n = 4). Aliquots of air (50-500 ml) or saline (10-200 ml) were introduced into the pleural space to simulate pneumothorax and hemothorax, respectively. RESULTS: The presence of "lung sliding" excluded pnemothorax. In microgravity, a loss of "lung sliding" was noted simultaneously in the anterior and posterior sonographic windows after 100 ml of air was introduced into the chest, indicating pneumothorax. The presence of the fluid layer in simulated hemothorax was noted in the anterior and posterior sonographic windows after 50 ml of fluid was injected into the pleural space. During the microgravity phase, the intrapleural fluid rapidly redistributed so that it could be detected using either anterior or posterior sonographic windows. CONCLUSION: Modest to severe pneumothorax and hemothorax can be diagnosed using ultrasound in microgravity.