Ashot E. Sargsyan

Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts after Long-duration Space Flight

PURPOSE To describe the history, clinical findings, and possible etiologies of ophthalmic findings discovered in 7 astronauts after long-duration space flight, and document vision changes in approximately 300 additional astronauts. DESIGN Retrospective, observational examination of ophthalmic findings in 7 astronauts and analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts. PARTICIPANTS Seven astronauts with ophthalmic anomalies upon return from long-duration space missions to the International Space Station and 300 additional astronauts who completed postflight questionnaires regarding in-flight vision changes. METHODS Before and after long-duration space flight, all 7 subjects underwent complete eye examinations, including cycloplegic and/or manifest refraction and fundus photography. Six underwent postmission optical coherence tomography (OCT) and magnetic resonance imaging (MRI); 4 had lumbar punctures (LP). Approximately 300 astronauts were queried regarding visual changes during space missions. MAIN OUTCOME MEASURES Refractive change, fundus photograph examination, retina OCT, orbital MRI, LP opening pressures, and examination of visual acuity data. RESULTS After 6 months of space flight, 7 astronauts had ophthalmic findings, consisting of disc edema in 5, globe flattening in 5, choroidal folds in 5, cotton wool spots (CWS) in 3, nerve fiber layer thickening by OCT in 6, and decreased near vision in 6 astronauts. Five of 7 with near vision complaints had a hyperopic shift ≥+0.50 diopters (D) between pre/postmission spherical equivalent refraction in 1 or both eyes (range, +0.50 to +1.75 D). These 5 showed globe flattening on MRI. Lumbar punctures performed in the 4 with disc edema documented opening pressures of 22, 21, 28, and 28.5 cm H(2)O performed 60, 19, 12, and 57 days postmission, respectively. The 300 postflight questionnaires documented that approximately 29% and 60% of astronauts on short and long-duration missions, respectively, experienced a degradation in distant and near visual acuity. Some of these vision changes remain unresolved years after flight. CONCLUSIONS We hypothesize that the optic nerve and ocular changes we describe may result from cephalad fluid shifts brought about by prolonged microgravity exposure. The findings we report may represent parts of a spectrum of ocular and cerebral responses to extended microgravity exposure. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Goal-directed ultrasound in the detection of long-bone fractures

BACKGROUND New portable ultrasound (US) systems are capable of detecting fractures in the remote setting. However, the accuracy of ultrasound by physicians with minimal ultrasound training is unknown. METHODS After one hour of standardized training, physicians with minimal US experience clinically evaluated patients presenting with pain and trauma to the upper arm or leg. The investigators then performed a long-bone US evaluation, recording their impression of fracture presence or absence. Results of the examination were compared with routine plain or computer aided radiography (CT). RESULTS 58 patients were examined. The sensitivity and specificity of US were 92.9% and 83.3%, and of the physical examination were 78.6% and 90.0%, respectively. US provided improved sensitivity with less specificity compared with physical examination in the detection of fractures in long bones. CONCLUSION Ultrasound scans by minimally trained clinicians may be used to rule out a long-bone fracture in patients with a medium to low probability of fracture.

FAST at MACH 20: Clinical ultrasound aboard the International Space Station

BACKGROUND Focused assessment with sonography for trauma (FAST) examination has been proved accurate for diagnosing trauma when performed by nonradiologist physicians. Recent reports have suggested that nonphysicians also may be able to perform the FAST examination reliably. A multipurpose ultrasound system is installed on the International Space Station as a component of the Human Research Facility. Nonphysician crew members aboard the International Space Station receive modest training in hardware operation, sonographic techniques, and remotely guided scanning. This report documents the first FAST examination conducted in space, as part of the sustained effort to maintain the highest possible level of available medical care during long-duration space flight. METHODS An International Space Station crew member with minimal sonography training was remotely guided through a FAST examination by an ultrasound imaging expert from Mission Control Center using private real-time two-way audio and a private space-to-ground video downlink (7.5 frames/second). There was a 2-second satellite delay for both video and audio. To facilitate the real-time telemedical ultrasound examination, identical reference cards showing topologic reference points and hardware controls were available to both the crew member and the ground-based expert. RESULTS A FAST examination, including four standard abdominal windows, was completed in approximately 5.5 minutes. Following commands from the Mission Control Center-based expert, the crew member acquired all target images without difficulty. The anatomic content and fidelity of the ultrasound video were excellent and would allow clinical decision making. CONCLUSIONS It is possible to conduct a remotely guided FAST examination with excellent clinical results and speed, even with a significantly reduced video frame rate and a 2-second communication latency. A wider application of trauma ultrasound applications for remote medicine on earth appears to be possible and warranted.

Orbital and Intracranial Effects of Microgravity: Findings at 3-T MR Imaging

PURPOSE To identify intraorbital and intracranial abnormalities in astronauts previously exposed to microgravity by using quantitative and qualitative magnetic resonance (MR) techniques. MATERIALS AND METHODS The institutional review board approved this HIPAA-compliant, retrospective review and waived the requirement for informed consent. Twenty-seven astronauts (mean age ± standard deviation, 48 years ± 4.5) underwent 3-T MR imaging with use of thin-section, three-dimensional, axial T2-weighted orbital and conventional brain sequences. Eight astronauts underwent repeat imaging after an additional mission in space. Optic nerve sheath diameter (ONSD) and optic nerve diameter (OND) were quantified in the retrolaminar optic nerve. OND and central optic nerve T2 hyperintensity were quantified at mid orbit. Qualitative analysis of the optic nerve sheath, optic disc, posterior globe, and pituitary gland morphology was performed and correlated for association with intracranial evidence of hydrocephalus, vasogenic edema, central venous thrombosis, and/or mass lesion. Statistical analyses included the paired t test, Mann-Whitney nonparametric test for group comparisons, Cronbach α coefficient for reproducibility, and Pearson correlation coefficient. RESULTS All astronauts had previous exposure to microgravity and, thus, control data were not available for comparison. The ONSD and OND ranged from 4.7 to 10.8 mm (mean, 6.2 mm ± 1.1) and from 2.4 to 4.5 mm (mean, 3.0 mm ± 0.5), respectively. Posterior globe flattening was seen in seven of the 27 astronauts (26%), optic nerve protrusion in four (15%), and moderate concavity of the pituitary dome with posterior stalk deviation in three (11%) without additional intracranial abnormalities. Retrolaminar OND increased linearly relative to ONSD (r = 0.797, Pearson correlation). A central area of T2 hyperintensity was identifiable in 26 of the 27 astronauts (96%) and increased in diameter in association with kinking of the optic nerve sheath. CONCLUSION Exposure to microgravity can result in a spectrum of intraorbital and intracranial findings similar to those in idiopathic intracranial hypertension.

Ocular examination for trauma; clinical ultrasound aboard the International Space Station

Background:Ultrasound imaging is a successful modality in a broad variety of diagnostic applications including trauma. Ultrasound has been shown to be accurate when performed by non-radiologist physicians; recent reports have suggested that non-physicians can perform limited ultrasound examinations.

Optic disc edema in an astronaut after repeat long-duration space flight

Background: A number of ophthalmic findings including optic disc edema, globe flattening, and choroidal folds have been observed in several astronauts after long-duration space flights. The authors report the first astronaut with previously documented postflight ophthalmic abnormalities who developed new pathological changes after a repeat long-duration mission. Methods: A case study of an astronaut with 2 long-duration (6 months) exposures to microgravity. Before and after his first long-duration space flight, he underwent complete eye examination, including fundus photography. Before and after his second flight, 9 years later, he underwent fundus photography, optical coherence tomography, ocular ultrasonography, and brain magnetic resonance imaging, as well as in-flight fundus photography and ultrasound. Results: After his first long-duration mission, the astronaut was documented to have eye findings limited to unilateral choroidal folds and a single cotton wool spot. During a subsequent 6-month mission, he developed more widespread choroidal folds and new onset of optic disc edema in the same eye. Conclusion: Microgravity-induced anatomical changes that occurred during the first mission may have set the stage for recurrent or additional changes when the astronaut was subjected to physiological stress of repeat space flight.

Focused assessment with sonography for trauma in weightlessness: a feasibility study

BACKGROUND The Focused Assessment with Sonography for Trauma (FAST) examines for fluid in gravitationally dependent regions. There is no prior experience with this technique in weightlessness, such as on the International Space Station, where sonography is currently the only diagnostic imaging tool. STUDY DESIGN A ground-based (1 g) porcine model for sonography was developed. We examined both the feasibility and the comparative performance of the FAST examination in parabolic flight. Sonographic detection and fluid behavior were evaluated in four animals during alternating weightlessness (0 g) and hypergravity (1.8 g) periods. During flight, boluses of fluid were incrementally introduced into the peritoneal cavity. Standardized sonographic windows were recorded. Postflight, the video recordings were divided into 169 20-second segments for subsequent interpretation by 12 blinded ultrasonography experts. Reviewers first decided whether a video segment was of sufficient diagnostic quality to analyze (determinate). Determinate segments were then analyzed as containing or not containing fluid. A probit regression model compared the probability of a positive fluid diagnosis to actual fluid levels (0 to 500 mL) under both 0-g and 1.8-g conditions. RESULTS The in-flight sonographers found real-time scanning and interpretation technically similar to that of terrestrial conditions, as long as restraint was maintained. On blinded review, 80% of the recorded ultrasound segments were considered determinate. The best sensitivity for diagnosis in 0 g was found to be from the subhepatic space, with probability of a positive fluid diagnosis ranging from 9% (no fluid) to 51% (500 mL fluid). CONCLUSIONS The FAST examination is technically feasible in weightlessness, and merits operational consideration for clinical contingencies in space.

Persistent Asymmetric Optic Disc Swelling After Long-Duration Space Flight: Implications for Pathogenesis.

Background: Several ophthalmic findings including optic disc swelling, globe flattening and choroidal folds have been observed in astronauts following long-duration space flight. The authors now report asymmetric choroidal expansion, disc swelling and optic disc morphologic changes in a 45-year-old astronaut which occurred during long-duration space flight and persisted following his space mission. Methods: Case study of ocular findings in an astronaut documented during and after a long-duration space flight of approximately 6 months. Before, during and after his spaceflight, he underwent complete eye examination, including fundus photography, ultrasound, and optical coherence tomography. Results: We documented asymmetric choroidal expansion inflight that largely resolved by 30 days postflight, asymmetric disc swelling observed inflight that persisted for over 180 days postflight, asymmetric optic disc morphologic changes documented inflight by OCT that persisted for 630 days postflight and asymmetric globe flattening that began inflight and continued 660 days postflight. Lumbar puncture opening pressures obtained at 7 and 365 days post-mission were 22 and 16 cm H20 respectively. Conclusion: The persistent asymmetric findings noted above, coupled with the lumbar puncture opening pressures, suggest that prolonged microgravity exposure may have produced asymmetric pressure changes within the perioptic subarachnoid space.

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. (Echocardiography 2011;28:491‐501)

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

This study investigated whether it is feasible to use sonography to monitor changes in the optic nerve sheath diameter in a porcine model.