Do we have the guts to go? The abdominal compartment, intra-abdominal hypertension, the human microbiome and exploration class space missions.

Humans are destined to explore space, yet critical illness and injury may be catastrophically limiting for extraterrestrial travel. Humans are superorganisms living in symbiosis with their microbiomes, whose genetic diversity dwarfs that of humans. Symbiosis is critical and imbalances are associated with disease, occurring within hours of serious illness and injury. There are many characteristics of space flight that negatively influence the microbiome, especially deep space itself, with its increased radiation and absence of gravity. Prolonged weightlessness causes many physiologic changes that are detrimental; some resemble aging and will adversely affect the ability to tolerate critical illness or injury and subsequent treatment. Critical illness-induced intra-abdominal hypertension (IAH) may induce malperfusion of both the viscera and microbiome, with potentially catastrophic effects. Evidence from animal models confirms profound IAH effects on the gut, namely ischemia and disruption of barrier function, mechanistically linking IAH to resultant organ dysfunction. Therefore, a pathologic dysbiome, space-induced immune dysfunction and a diminished cardiorespiratory reserve with exacerbated susceptibility to IAH, imply that a space-deconditioned astronaut will be vulnerable to IAH-induced gut malperfusion. This sets the stage for severe gut ischemia and massive biomediator generation in an astronaut with reduced cardiorespiratory/immunological capacity. Fortunately, experiments in weightless analogue environments suggest that IAH may be ameliorated by conformational abdominal wall changes and a resetting of thoracoabdominal mechanics. Thus, review of the interactions of physiologic changes with prolonged weightlessness and IAH is required to identify appropriate questions for planning exploration class space surgical care.

L'humanité est à l'aube d'une nouvelle ère d'exploration spatiale, mais le risque de maladies et blessures graves pourrait restreindre de manière catastrophique le potentiel des voyages dans l'espace. L'être humain est un superorganisme vivant en symbiose avec son microbiote, dont la diversité génétique éclipse celle de l'hôte. Cette symbiose est essentielle : tout déséquilibre est associé à une dégradation de l'état de santé dans les heures suivant l'occurrence d'une blessure ou d'une maladie grave. Bon nombre de caractéristiques propres au vol spatial ont des répercussions négatives sur le microbiote; l'espace lointain présente des dangers particuliers en raison de l'exposition accrue au rayonnement et de l'absence de gravité. L'exposition prolongée à l'apesanteur cause une myriade de changements physiologiques nuisant à la santé. Certains ressemblent à des processus de vieillissement et réduiront la capacité à tolérer une blessure ou une maladie grave et son traitement. L'hypertension intra-abdominale (HIA) causée par une maladie grave peut réduire la perfusion des viscères et du microbiote, ce qui peut avoir des conséquences catastrophiques. Des études sur modèle animal ont confirmé les effets profondément délétères de l'HIA sur les intestins par l'apparition d'une ischémie et une altération de la barrière intestinale; cette découverte permettrait d'établir un lien mécanistique entre l'HIA et la défaillance d'organes résultante. Par conséquent, une dysbiose pathologique, associée à un dysfonctionnement immunitaire en apesanteur et à une réduction de la réserve cardiorespiratoire accompagnée d'une exacerbation de la susceptibilité à l'HIA, pourrait signifier qu'un astronaute exposé à l'effet déconditionnant de l'apesanteur serait vulnérable aux problèmes de perfusion de l'intestin découlant de l'HIA. Ce problème pourrait à son tour mener à une ischémie intestinale grave et à une production massive de biomédiateurs chez un astronaute présentant déjà une capacité cardiorespiratoire et immunitaire réduite. Heureusement, des expériences dans des environnements simulant l'apesanteur semblent indiquer que les effets de l'HIA pourraient être contrés par des changements conformationnels de la paroi abdominale et un rétablissement de la mécanique thoracoabdominale. Par conséquent, un examen des interactions des changements physiologiques associés à un état d'apesanteur prolongé et à l'HIA est requis pour déterminer les questions à poser afin de planifier adéquatement les soins chirurgicaux en contexte d'exploration spatiale.

MR-derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity.

PURPOSE: To quantify the change in cerebral spinal fluid (CSF) production rate and maximum systolic velocity in astronauts before and after exposure to microgravity and identify any physiologic trend and/or risk factor related to intracranial hypertension. MATERIALS AND METHODS: Following Institutional Review Board (IRB) approval, with waiver of informed consent, a retrospective review of 27 astronauts imaged at 3T was done. Qualitative analysis was performed on T2 -weighted axial images through the orbits for degree of flattening of the posterior globe according to the following grades: 0 = none, 1 = mild, 2 = moderate, and 3 = severe. One grade level change postflight was considered significant for exposure to intracranial hypertension. CSF production rate and maximum systolic velocity was calculated from cine phase-contrast magnetic resonance imaging and compared to seven healthy controls. RESULTS: Fourteen astronauts were studied. The preflight CSF production rate in astronauts was similar to controls (P = 0.83). Six astronauts with significant posterior globe flattening demonstrated a 70% increase in CSF production rate postflight compared to baseline (P = 0.01). There was a significant increase in CSF maximum systolic velocity in the subgroup without posterior globe flattening (P = 0.01). CONCLUSION: The increased postflight CSF production rate in astronauts with positive flattening is compatible with the hypothesis of microgravity-induced intracranial hypertension inferring downregulation in CSF production in microgravity that is upregulated upon return to normal gravity. Increased postflight CSF maximum systolic velocity in astronauts with negative flattening suggests increased craniospinal compliance and a potential negative risk factor to microgravity-induced intracranial hypertension.

Enabling the mission through trans-atlantic remote mentored musculoskeletal ultrasound: case report of a portable hand-carried tele-ultrasound system for medical relief missions.

Modern medical practice has become extremely dependent upon diagnostic imaging technologies to confirm the results of clinical examination and to guide the response to therapies. Of the various diagnostic imaging techniques, ultrasound is the most portable modality and one that is repeatable, dynamic, relatively cheap, and safe as long as the imaging provided is accurately interpreted. It is, however, the most user-dependent, a characteristic that has prompted the development of remote guidance techniques, wherein remote experts guide distant users through the use of information technologies. Medical mission work often brings specialist physicians to less developed locations, where they wish to provide the highest levels of care but are often bereft of diagnostic imaging resources on which they depend. Furthermore, if these personnel become ill or injured, their own care received may not be to the standard they have left at home. We herein report the utilization of a compact hand-carried remote tele-ultrasound system that allowed real-time diagnosis and follow-up of an acutely torn adductor muscle by a team of ultrasonographers, surgeons, and physicians. The patient was one of the mission surgeons who was guided to self-image. The virtual network of supporting experts was located across North America, whereas the patient was in Lome, Togo, West Africa. The system consisted of a hand-carried ultrasound, the output of which was digitized and streamed to the experts within standard voice-over-Internet-protocol software with an embedded simultaneous videocamera image of the ultrasonographer's hands using a customized graphical user interface. The practical concept of a virtual tele-ultrasound support network was illustrated through the clinical guidance of multiple physicians, including National Aeronautics and Space Administration Medical Operations remote guiders, Olympic team-associated surgeons, and ultrasound-focused emergentologists.

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.

Just-in-time cost-effective off-the-shelf remote telementoring of paramedical personnel in bedside lung sonography-a technical case study.

PURPOSE: Remote telementored ultrasound (RTMUS) is a new discipline that allows a remote expert to guide variably experienced clinical responders through focused ultrasound examinations. We used the examination of the pleural spaces after tube thoracostomy (TT) removal by a nurse with no prior ultrasound experience as an illustrative but highly accurate example of the technique using a simple cost-effective system. MATERIALS AND METHODS: The image outputs of a handheld ultrasound machine and a head-mounted Web camera were input into a customized graphical user interface and streamed over a freely available voice over Internet protocol system that allowed two-way audio and visual communication between the novice examiner and the remote expert. The bedside nurse was then guided to examine the anterior chest of a patient who had recently had bilateral TTs removed. The team sought to determine the presence or absence of any recurrent pneumothoraces using the standard criteria for the ultrasound diagnosis of post-removal pneumothorax (PTXs). An upright chest radiograph (CXR) was obtained immediately after the RTMUS examination. RESULTS: The RTMUS system enabled the novice user to learn how to hold the ultrasound probe, where to place it on the chest, and thereafter to diagnose a subtle unilateral PTX characterized as "tiny" on the subsequent formal CXR report. CONCLUSIONS: As ultrasound has almost limitless clinical utility, using simple but advanced informatics and communication technologies has potential to improve worldwide healthcare delivery. RTMUS could be used both to enhance the information content as well as to digitally document important physiologic findings in any clinical encounter wherever a portable ultrasound and Internet connectivity are available.

Estimating outcomes of astronauts with myocardial infarction in exploration class space missions.

INTRODUCTION: We estimate likelihood of presenting rhythms and survival to hospital discharge outcome after acute cardiac ischemia with arrhythmia and/or myocardial infarction (AMI) during long-duration space missions (LDSM) using selected terrestrial cohorts in medical literature. Medical scenarios were risk-stratified by coronary artery calcium score (CAC) and Framingham risk factors (FRF). METHODS: AMI with and without sudden cardiac arrest (SCA) likelihoods and clinically significant rhythm scenarios and associated outcomes in "astronaut-like" cohorts were derived from two prospective trials identified by an evidence-based literature review. Results are presented using an event sequence diagram and event time line. The association of increasing CAC scores and FRF with AMI and SCA outcomes was calculated. RESULTS: Low AMI likelihoods are estimated in individuals with CAC scores of zero or < 100 and a low number of FRF. Survival rate to hospital discharge after out of hospital SCA in a large urban environment study was 5.2%. EMS-witnessed ventricular tachycardia and/or ventricular fibrillation survival rate of 37.5% represents < 1% of all urban out of hospital AMI, and these patients have a high proportion of known ischemic cardiovascular and pulmonary disease "disqualifying for spaceflight." DISCUSSION: Multiple factors may be expected to delay or defeat rapid access to "chain of survival" resources during LDSM, lowering survival rates below urban levels of 5.2%. Low CAC and FRF reflect lower risk for AMI events. Zero CAC was associated with the lowest risk of AMI after 3.5 yr of follow-up. Quantifiable incidence and outcome characterization suggests AMI in LDSM outcomes will be relatively independent of in-flight medical resources.

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.

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.

Electrical Shock Hazard Severity Estimation During Extravehicular Activity for the International Space Station.

INTRODUCTION: Research has shown that astronauts performing extravehicular activities may be exposed, under certain conditions, to undesired electrical hazards. This study used computer models to determine whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation.METHODS: A multiresolution variant of the admittance method along with a magnetic resonance image millimeter resolution model of a male human body were used to calculate the following: 1) induced electric fields; 2) resistance between contact areas in a Extravehicular Mobility Unit spacesuit; 3) currents induced in the human body; 4) the physiological effects of these electrical exposures; and 5) the risk to the crew during extravehicular activities.RESULTS: Using typical EMU shock exposure conditions, with a 15V source, the current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions during a spacewalk in the charged ionospheric plasma of space, astronauts could experience possibly harmful involuntary motor response and sensory pain nerve activation.Hamilton DR. Electrical shock hazard severity estimation during extravehicular activity for the International Space Station. Aerosp Med Hum Perform. 2021; 92(4):231239.

Houston's medical disaster response to Hurricane Katrina: part 2: transitioning from emergency evacuee care to community health care.

After Hurricane Katrina hit the Gulf Coast on August 29, 2005, thousands of ill and injured evacuees were transported to Houston, TX. Houston's regional disaster plan was quickly implemented, leading to the activation of the Regional Hospital Preparedness Council's Catastrophic Medical Operations Center and the rapid construction of a 65-examination-room medical facility within the Reliant Center. A plan for triage of arriving evacuees was quickly developed and the Astrodome/Reliant Center Complex mega-shelter was created. Herein, we discuss major elements of the regional disaster response, including regional coordination, triage and emergency medical service transfers into the region's medical centers, medical care in population shelters, and community health challenges.

Houston's medical disaster response to Hurricane Katrina: part 1: the initial medical response from Trauma Service Area Q.

After Hurricane Katrina hit the Gulf Coast on August 29, 2005, thousands of ill and injured evacuees were transported to Houston, TX. Houston's regional disaster plan was quickly implemented, leading to the activation of the Regional Hospital Preparedness Council's Catastrophic Medical Operations Center and the rapid construction of a 65-examination-room medical facility within the Reliant Center. A plan for triage of arriving evacuees was quickly developed and the Astrodome/Reliant Center Complex mega-shelter was created. Herein, we discuss major elements of the regional disaster response, including regional coordination, triage and emergency medical service transfers into the region's medical centers, medical care in population shelters, and community health challenges.

Ultrasound evaluation of sinus fluid levels in swine during microgravity conditions.

BACKGROUND: Acute rhinosinusitis is a common problem that could occur in space secondary to absence of gravity-dependent drainage or odontogenic or external sources of infection. The purpose of this study was to determine the efficacy of ultrasound to determine sinus fluid distribution levels in swine and to assess the accuracy of ultrasound in the animal during normal and microgravity conditions. METHODS: Anesthetized swine had a catheter placed through a frontal bone window to allow aliquots of a viscous solution to be injected at 1 G (N = 4) or during brief microgravity parabolic flights (N = 4). Ultrasound examinations were performed with a high frequency probe during baseline and fluid-induced conditions. RESULTS: There was a consistent air-fluid level interface seen on ultrasound examination with the injection of 1 ml of fluid during 1-G conditions. Microgravity conditions caused the rapid (< 10 s) dissolution of the air-fluid level associated with dispersion of the fluid to the walIs of the sinus cavity in a uniform fashion. The air-fluid interface was recreated with return to 1 G. CONCLUSIONS: Ultrasound is a reliable diagnostic test for assessing fluid levels; these experiments demonstrate the technique can be used during microgravity conditions with attention to altered fluid behavior in the absence of gravity.

Hypothetical Case of Pancreatitis During a Long Duration Lunar Mission.

INTRODUCTION: This peer-reviewed hypothetical case was written to help the readership understand the challenges of dealing with quite common yet very debilitating diseases during space missions. This scenario is based on a real case of an astronaut who had previously flown in space and developed acute pancreatitis after being dehydrated from wilderness survival training. Many astronauts experience life threatening illness and injury before and after flight and, as space missions become longer and more remote, it is only a matter of time before these events occur during a mission. Future exploration space mission planners need to anticipate that these common catastrophic medical events will occur.CASE REPORT: You are a flight surgeon working on console at Mission Control during a long duration lunar mission. You have completed extensive space, military, and civilian aerospace medical training to address almost any anticipated medical event and can summon advice from medical experts located around the world. One crewmember is a 37-yr-old man who just completed an 8-h moonwalk and now describes a constant 7/10 dull epigastric pain with radiation around the left flank to his back. His pain is getting progressively worse and he is presently sitting with his trunk flexed and knees drawn up in extreme distress. Working with the flight director, you must decide in the next 12 h whether to recommend the multibillion-dollar mission be aborted and have the crew return to Earth immediately to save your patient.Hamilton DR, McBeth PB, Greene MR, Kirkpatrick AW, Ball CG. Hypothetical case of pancreatitis during a long duration lunar mission. Aerosp Med Hum Perform. 2019; 90(6):570-578.

The clinical and technical evaluation of a remote telementored telesonography system during the acute resuscitation and transfer of the injured patient.

BACKGROUND: Ultrasound (US) has an ever increasing scope in the evaluation of trauma, but relies greatly on operator experience. NASA has refined telesongraphy (TS) protocols for traumatic injury, especially in reference to mentoring inexperienced users. We hypothesized that such TS might benefit remote terrestrial caregivers. We thus explored using real-time US and video communication between a remote (Banff) and central (Calgary) site during acute trauma resuscitations. METHODS: A existing internet link, allowing bidirectional videoconferencing and unidirectional US transmission was used between the Banff and Calgary ERs. Protocols to direct or observe an extended focused assessment with sonography for trauma (EFAST) were adapted from NASA algorithms. A call rota was established. Technical feasibility was ascertained through review of completed checklists. Involved personnel were interviewed with a semistructured interview. RESULTS: In addition to three normal volunteers, 20 acute clinical examinations were completed. Technical challenges requiring solution included initiating US; audio and video communications; image freezing; and US transmission delays. FAST exams were completed in all cases and EFASTs in 14. The critical anatomic features of a diagnostic examination were identified in 98% of all FAST exams and a 100% of all EFASTs that were attempted. Enhancement of clinical care included confirmation of five cases of hemoperitoneum and two pneumothoraces (PTXs), as well as educational benefits. Remote personnel were appreciative of the remote direction particularly when instructions were given sequentially in simple, nontechnical language. CONCLUSIONS: The remote real-time guidance or observation of an EFAST using TS appears feasible. Most technical problems were quickly overcome. Further evaluation of this approach and technology is warranted in more remote settings with less experienced personnel.

Ultrasound detection of simulated intra-ocular foreign bodies by minimally trained personnel.

PURPOSE: To test the ability of non-expert ultrasound operators of divergent backgrounds to detect the presence, size, location, and composition of foreign bodies in an ocular model. METHODS: High school students (N = 10) and NASA astronauts (N = 4) completed a brief ultrasound training session which focused on basic ultrasound principles and the detection of foreign bodies. The operators used portable ultrasound devices to detect foreign objects of varying location, size (0.5-2 mm), and material (glass, plastic, metal) in a gelatinous ocular model. Operator findings were compared to known foreign object parameters and ultrasound experts (N = 2) to determine accuracy across and between groups. RESULTS: Ultrasound had high sensitivity (astronauts 85%, students 87%, and experts 100%) and specificity (astronauts 81%, students 83%, and experts 95%) for the detection of foreign bodies. All user groups were able to accurately detect the presence of foreign bodies in this model (astronauts 84%, students 81%, and experts 97%). Astronaut and student sensitivity results for material (64% vs. 48%), size (60% vs. 46%), and position (77% vs. 64%) were not statistically different. Experts' results for material (85%), size (90%), and position (98%) were higher; however, the small sample size precluded statistical conclusions. CONCLUSIONS: Ultrasound can be used by operators with varying training to detect the presence, location, and composition of intraocular foreign bodies with high sensitivity, specificity, and accuracy.

Human health and performance for long-duration spaceflight.

Future long-duration spaceflights are now being planned to the Moon and Mars as a part of the "Vision for Space Exploration" program initiated by NASA in 2004. This report describes the design reference missions for the International Space Station, Lunar Base, and eventually a Mars Expedition. There is a need to develop more stringent preflight medical screening for crewmembers to minimize risk factors for diseases which cannot be effectively treated in flight. Since funding for space life sciences research and development has been eliminated to fund program development, these missions will be enabled by countermeasures much like those currently in use aboard the International Space Station. Artificial gravity using centrifugation in a rotating spacecraft has been suggested repeatedly as a "universal countermeasure" against deconditioning in microgravity and could be an option if other countermeasures are found to be ineffective. However, the greatest medical unknown in interplanetary flight may be the effects of radiation exposure. In addition, a Mars expedition would lead to a far greater level of isolation and psychological stress than any space mission attempted previously; because of this, psychiatric decompensation remains a risk. Historically, mortality and morbidity related to illness and injury have accounted for more failures and delays in new exploration than have defective transportation systems. The medical care system on a future Mars expedition will need to be autonomous and self-sufficient due to the extremely long separation from definitive medical care. This capability could be expanded by the presence of a physician in the crew and including simple, low-technology surgical capability.

Percutaneous bladder catheterization in microgravity.

INTRODUCTION: Urinary obstruction (UO) or failure to void has been observed during several episodes of short-duration spaceflight, necessitating bladder catheterization. It should be considered a possible medical condition in long-duration space missions as well. Antiemetics used early in space flight add to the risk and severity of voiding problems, along with the sensory and psychological peculiarities of voiding without gravity and in the unusual setting of a spacecraft. Urolithiasis due to the above-normal calcium excretion increases the risk of UO in long duration space missions. Finally, the individual risk of UO is higher against the background of preexisting conditions such as benign prostatic hyperplasia (BPH) or urethral stricture. Both acute retention and ureteral obstruction are associated with substantial patient distress, and carry a risk of urosepsis and/or acute renal failure. If UO in orbital flight is unresolved or complicated, it would likely result in crew emergency return from orbit. Exploration missions, however, may require means for definitive treatment of urinary tract obstruction. This study documents successful ultrasound-guided percutaneous catheterization of the urinary bladder in microgravity. A porcine model of urethral occlusion was used. The results demonstrate an additional capability from our previous investigations describing endoscopic catheterization and stenting of the ureters in microgravity conditions. METHODS: In an anesthetized porcine model, a Foley catheter was placed in the bladder and clamped after instillation of 200 ml of colored liquid. The bladder was visualized and then drained under ultrasound guidance through suprapubic puncture, employing a 10.3 F pigtail catheter with introducer. The procedural elements were conducted only during microgravity portions of the parabolic flight. RESULTS: Ultrasound imaging was used to successfully perform image-guided percutaneous puncture through the anterior bladder wall with the catheter, without injury to adjacent organs. The percutaneous catheter was able to successfully drain the bladder in microgravity conditions. CONCLUSIONS: Percutaneous bladder catheterization and drainage can be successfully performed in weightless conditions under ultrasound guidance. Ultrasound provides a low-power, portable means to safely conduct minimally invasive procedures in pertinent organs and tissues. Percutaneous bladder catheterization is a standard procedure when luminal bladder catheterization is not possible; this technique can be successfully modified for use in space medicine applications.

Breast cancer and spaceflight: risk and management.

Spaceflight exposes astronauts to a host of environmental factors which could increase their risk for cancer. Epidemiological studies have shown an increased incidence of breast cancer in female commercial flight attendants, with occupational risk factors as one of the proposed mechanisms for the higher incidence in this cohort. Since female astronauts are exposed to similar occupational conditions as flight attendants, they too may be at an increased risk for breast cancer. With the planning of exploration class missions to the Moon and to Mars it is important to assess and minimize the risk for breast malignancy, and to have a well-defined protocol for the diagnosis and treatment of a breast mass discovered during a mission. Risk factors for development of breast cancer in the female astronaut include ionizing radiation, disrupted melatonin homeostasis secondary to circadian shifting, chemical exposure, and changes in immune function. Preflight, in-flight, and postflight screening and management modalities include imaging and fine needle aspiration (FNA). Employing such a strategy may provide a viable management approach in the case of a newly diagnosed breast mass inflight.