Christian Otto

Into Thin Air: Extreme Ultrasound on Mt Everest

Abstract Objective.—Mountaineers face a variety of health risks at altitude including pulmonary edema; portable ultrasound may be used to diagnose high altitude pulmonary edema. This report tests the functionality of electronic equipment in a hypobaric test environment and the ability of remotely guided nonexperts to use ultrasound to evaluate respiratory status on Mt Everest. Methods.—Two ultrasound devices and associated video equipment were tested in a cooled (4°C–5°C) hypobaric chamber to 27 000 feet (8230 m) before travel to Mt Everest. The ultrasound system was connected via satellite phone to a video streaming device and portable computer to stream video through the Internet for remote guidance of a novice user by an expert. Pulmonary interstitial fluid was quantified by the presence of “comet tail” artifacts. Results.—There was no notable degradation in equipment performance in cold, hypobaric conditions; ultrasound confirmation of increased comet tails was noted in the chamber despite oxygen supplementation and the very brief exposure. Two pulmonary surveys of asymptomatic participants were completed by novice operators within 25 minutes on Mt Everest. The remote expert was able to guide and identify comet tails suggestive of intermediate pulmonary interstitial fluid. Image quality was excellent. Conclusions.—The tested ultrasound devices functioned nominally in cold, hypobaric conditions; acute changes in lung fluid content were noted in these conditions despite normoxia. We successfully used a satellite telemedical connection with a remote expert to guide thoracic ultrasound examinations at Advanced Base Camp on Mt Everest. Coupling portable ultrasound with remote expert guidance telemedicine provides a robust diagnostic capability in austere locations.

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.

Why a One-Way Ticket to Mars May Result in One-Way Directional Glymphatic Flow to the Eye: Response

We greatly appreciate the opportunity to respond to the comments of Dr. Wostyn et al. Their theory focuses on a glymphatic flow imbalance mechanism at the optic nerve head that may, at least partially, explain the development of optic disc swelling in astronauts during long-duration space flight. Th