Fundamentals of Anesthesiology for Spaceflight

During future space exploration missions, the risk of medical events requiring surgery is significant, and will likely rely on anesthetic techniques. Available options during spaceflight include local, regional (nerve block) and general anesthesia. No actual invasive anesthesia was ever performed on humans in space or immediately after landing, and the safe delivery of such advanced medical care in this context is challenging. In the first section of this review, Human adaptation to the space environment is detailed, with a focus on the cardiovascular system, along with a discussion regarding which medical conditions may arise. The second part of the study focuses on discussing the extensive list of challenges associated with delivering an anesthetic procedure in space or on a foreign planetary surface. They schematically fall into two categories: missing technologies (generation of intravenous fluid, specific medical equipment, preservation of drugs…) and missing knowledge (human physiology in partial gravity, use of vasopressors, cardiovascular tolerance of general anesthesia and blood loss, choice of the most appropriate anesthetic technique, medical training). Future space exploration mis¬sions will push back the limits of human expe¬rience in maintaining health and performance of crew members in extreme settings. After more than five decades of research, our understanding of human physiology in weightlessness is advanced. Despite a number of challenges, the safe delivery of an anesthetic procedure on previously healthy individuals and given our current knowledge and technologies remains risky but could be possible even by non-anesthesiologists, and should not represent a showstopper for future space exploration missions.