Centrifuge-Simulated Spaceflight After Aortic Valve Replacement and Atrial Septal Defect Repair.

INTRODUCTION: Human access to space is expanding rapidly in the commercial environment, with various private companies offering commercial flights to spaceflight participants (SFPs). SFPs are more likely than career astronauts to have medical conditions novel to spaceflight and may not have undergone as rigorous a medical screening process as that used for career astronauts, representing new and unstudied risks in the spaceflight environment. We report participation of a subject with recent median sternotomy for aortic valve replacement and atrial septal defect closure in centrifuge-simulated dynamic phases of orbital and suborbital spaceflight.CASE REPORT: A 40-yr-old man with a history of congenital bicuspid aortic valve and atrial septal defect with successful repair 8 mo prior participated in an ongoing human centrifuge research study. The subject had the opportunity to participate in up to five centrifuge runs in an 8-h period, with profiles simulating commercial spaceflight. Maximum exposures included +4.0 Gz, +4.5 Gx, 6.1 G resultant, and maximum onset rate < 0.5 Gz · s-1 and +1 Gx · s-1. Physiological data acquisition included hemodynamics, electrocardiogram, neurovestibular exams, and postrun questionnaires covering motion sickness, disorientation, and similar. The subject tolerated the physiological aspects of hypergravity well, noting progressive sternal pain with increasing +Gx, ultimately leading him to opt out of the final profile.DISCUSSION: Postcardiothoracic surgery risks to SFPs are largely unknown, especially within 12 mo of a significant surgical procedure. This case provides an approach for risk stratification, preparticipation evaluation, and medical management of a postsurgical patient with significant cardiac history in spaceflight and analog environments.Fernandez WL, Blue RS, Harrison MF, Powers W, Shah R, Auñón-Chancellor S. Centrifuge-simulated spaceflight after aortic valve replacement and atrial septal defect repair. Aerosp Med Hum Perform. 2024; 95(2):123-131.

ST-elevation myocardial infarction after thrombolytic therapy with Tenecteplase for acute ischaemic stroke.

Myocardial infarction (MI) secondary to thrombolytic therapy in the setting of acute ischaemic stroke (AIS) is a rare but severe complication. This phenomenon has been well documented in the past with recombinant tissue-type plasminogen activator, also known as Alteplase. However, there are no documented reports of MI secondary to Tenecteplase (TNKase), an alternative thrombolytic agent rapidly gaining favour in managing AIS. We report a male patient in his 50s who received TNKase for an AIS and subsequently developed an inferolateral ST elevation MI.

Tolerance of Centrifuge-Simulated Commercial Spaceflight in a Subject with Hemophilia A.

INTRODUCTION: With increasing engagement of commercial spaceflight participants in spaceflight activities, the evaluation of individuals with medical conditions not previously characterized in the spaceflight environment is of particular interest. Factors such as acceleration forces experienced during launch, reentry, and landing of spacecraft could pose an altered risk profile in some individuals due to known disease. Bleeding diatheses present a unique concern in the spaceflight environment given hypergravity exposure and, particularly, the potential for injury resulting from transient or impact acceleration.CASE REPORT: A 26-yr-old Caucasian man with severe hemophilia A and no detectable endogenous Factor VIII (FVIII) volunteered for participation in hypergravity exposures simulating spaceflight. His treatment regimen included 50 IU · kg-1 FVIII-Fc fusion protein intravenous administration every 96 h, with supplemental FVIII administration as needed for injury or bleeding. The subject experienced two profiles at the National Aerospace Training and Research Center (NASTAR), with maximum exposure +4.0 Gz, +4.5 Gx, 6.1 G resultant, and maximum onset rate <0.5 Gz · s-1 and +1 Gx · s-1. The subject reported no abnormal events during the profiles other than brief mild vertigo. No petechial hemorrhage, ecchymosis, or other bleeding was noted during or after profiles. Supplemental FVIII was not required before, during, or after exposure.DISCUSSION: Inherited bleeding disorders present several potential concerns that must be evaluated prior to spaceflight participation. Cautious review and management of medical history, adherence and barriers to treatment, duration of spaceflight and longitudinal management concerns, and a thorough and detailed risk/benefit assessment may provide a future pathway for inclusion of individuals with hematological disorders in commercial spaceflight.Reeves IA, Blue RS, Auñon-Chancellor S, Harrison MF, Shah R, Powers WE. Tolerance of centrifuge-simulated commercial spaceflight in a subject with hemophilia A. Aerosp Med Hum Perform. 2023; 94(6):470-474.

A retrospective analysis of normal saline and lactated ringers as resuscitation fluid in sepsis.

Background: The Surviving Sepsis Campaign suggested preferential resuscitation with balanced crystalloids, such as Lactated Ringer's (LR), although the level of recommendation was weak, and the quality of evidence was low. Past studies reported an association of unbalanced solutions, such as normal saline (NS), with increased AKI risks, metabolic acidosis, and prolonged ICU stay, although some of the findings are conflicting. We have compared the outcomes with the preferential use of normal saline vs. ringer's lactate in a cohort of sepsis patients. Method: We performed a retrospective cohort analysis of patients visiting the ED of 19 different Mayo Clinic sites between August 2018 to November 2020 with sepsis and receiving at least 30 mL/kg fluid in the first 6 h. Patients were divided into two cohorts based on the type of resuscitation fluid (LR vs. NS) and propensity-matching was done based on clinical characteristics as well as fluid amount (with 5 ml/kg). Single variable logistic regression (categorical outcomes) and Cox proportional hazards regression models were used to compare the primary and secondary outcomes between the 2 groups. Results: Out of 2022 patients meeting our inclusion criteria; 1,428 (70.6%) received NS, and 594 (29.4%) received LR as the predominant fluid (>30 mL/kg). Patients receiving predominantly NS were more likely to be male and older in age. The LR cohort had a higher BMI, lactate level and incidence of septic shock. Propensity-matched analysis did not show a difference in 30-day and in-hospital mortality rate, mechanical ventilation, oxygen therapy, or CRRT requirement. We did observe longer hospital LOS in the LR group (median 5 vs. 4 days, p = 0.047 and higher requirement for ICU post-admission (OR: 0.70; 95% CI: 0.51-0.96; p = 0.026) in the NS group. However, these did not remain statistically significant after adjustment for multiple testing. Conclusion: In our matched cohort, we did not show any statistically significant difference in mortality rates, hospital LOS, ICU admission after diagnosis, mechanical ventilation, oxygen therapy and RRT between sepsis patients receiving lactated ringers and normal saline as predominant resuscitation fluid. Further large-scale prospective studies are needed to solidify the current guidelines on the use of balanced crystalloids.

Impact of Hospital Safety-Net Burden on Outcomes of In-Hospital Cardiac Arrest in the United States.

High safety-net burden hospitals (HBHs) treating large numbers of uninsured or Medicaid-insured patients have generally been linked to worse clinical outcomes. However, limited data exist on the impact of the hospitals' safety-net burden on in-hospital cardiac arrest (IHCA) outcomes in the United States. OBJECTIVES: To compare the differences in survival to discharge, routine discharge home, and healthcare resource utilization between patients at HBH with those treated at low safety-net burden hospital (LBH). DESIGN SETTING AND PARTICIPANTS: Retrospective cohort study across hospitals in the United States: Hospitalized patients greater than or equal to 18 years that underwent cardiopulmonary resuscitation (CPR) between 2008 and 2018 identified from the Nationwide Inpatient Database. Data analysis was conducted in January 2022. EXPOSURE: IHCA. MAIN OUTCOMES AND MEASURES: The primary outcome is survival to hospital discharge. Other outcomes are routine discharge home among survivors, length of hospital stay, and total hospitalization cost. RESULTS: From 2008 to 2018, an estimated 555,016 patients were hospitalized with IHCA, of which 19.2% occurred at LBH and 55.2% at HBH. Compared with LBH, patients at HBH were younger (62 ± 20 yr vs 67 ± 17 yr) and predominantly in the lowest median household income (< 25th percentile). In multivariate analysis, HBH was associated with lower chances of survival to hospital discharge (adjusted odds ratio [aOR], 0.88; 95% CI, 0.85-0.96) and lower odds of routine discharge (aOR, 0.6; 95% CI, 0.47-0.75), compared with LBH. In addition, IHCA patients at publicly owned hospitals and those with medium and large hospital bed size were less likely to survive to hospital discharge, while patients with median household income greater than 25th percentile had better odds of hospital survival. CONCLUSIONS AND RELEVANCE: Our study suggests that patients who experience IHCA at HBH may have lower rates and odds of in-hospital survival and are less likely to be routinely discharged home after CPR. Median household income and hospital-level characteristics appear to contribute to survival.

Surviving Sepsis Guideline-Directed Fluid Resuscitation: An Assessment of Practice Patterns and Impact on Patient Outcomes.

IMPORTANCE: Aggressive fluid resuscitation remains a cornerstone of the Surviving Sepsis Campaign (SSC) guidelines, but there is growing controversy regarding the recommended 30 mL/kg IV fluid dosage. It is contended that, in selected patients, this volume confers an increased risk of volume overload without either concomitant benefit or strong evidence in support of the recommended IV fluid dosage. OBJECTIVES: Assessment of practice patterns and their impact on patient outcomes following the surviving sepsis guidelines for fluid resuscitation. DESIGN: Large, multisite retrospective cohort study. SETTING AND PARTICIPANTS: The retrospective study included all adult patients who presented to the emergency department at one of 19 different Mayo Clinic sites throughout the Midwest, Southeast, and Southwest from August 2018 to November 2020 with suspected sepsis. MAIN OUTCOMES AND MEASURES: Eight-thousand four-hundred fourteen patients suspected to have sepsis were assessed regarding fluid resuscitation and outcomes among patients receiving 30 mL/kg IV fluid dosing compared with patients who did not. Patient demographics and clinical information were collected via electronic health records. Patients were divided into two cohorts: those who received 0-29.9 mL/kg of IV fluid and those who received 30.0+ mL/kg of IV fluid. Statistical analyses were performed to evaluate the impact of fluid dose on in-hospital death, 30-day mortality, ICU admission after diagnosis, dialysis initiation after diagnosis, ventilator use, vasopressor use, as well as ICU and hospital length of stay. RESULTS: We observed lower in-hospital mortality and 30-day mortality risk in the 30+ mL/kg dosing group. Increased fluid dosage did, however, carry a much greater chance of ICU admission. Most patients (72% after propensity score weighting) in our population received less than 30 mL/kg fluid (based on ideal body weight). CONCLUSIONS AND RELEVANCE: IV fluid dosing for sepsis resuscitation greater than 30 mL/kg was associated with decreased risk of in-hospital mortality, 30-day mortality, and reduced risk of requiring mechanical ventilation. Our data does ultimately seem to support the SSC recommendation.

Massive Pulmonary Embolism Causing Cardiac Arrest Managed with Systemic Thrombolytic Therapy: A Case Report.

BACKGROUND Approximately 290 000 cases of in-hospital cardiac arrest occur annually, the majority of which are due to cardiac or respiratory causes. Cardiac arrest due to acute pulmonary embolism (PE) is associated with a 90% incidence of mortality and, if identified, it can be treated with systemic thrombolytics. Here, we describe a case in which the outcome for such an event was favorable. CASE REPORT A 66-year-old woman was admitted with multiple rib and left ankle fractures due to accidental trauma. Before undergoing orthopedic surgery, she experienced a cardiac arrest with pulseless electrical activity, which was witnessed. She had refractory hypoxia and hypotension following intubation and a brief initial return of spontaneous circulation (ROSC) before a second cardiac arrest. A 100-mg bolus dose of systemic thrombolytic therapy was promptly administered, with rapid achievement of sustained ROSC. The results of a subsequent electrocardiogram, echocardiogram, and computed tomography scan further supported the diagnosis of acute PE with right heart strain. Supportive care in the Intensive Care Unit resulted in full neurological recovery and she was discharged to a physical rehabilitation facility 12 days after her cardiac arrest. CONCLUSIONS Systemic thrombolytic therapy is beneficial for cardiac arrest due to acute PE.

A Case of COVID-19 Re-Infection in a Liver Transplant Patient.

Coronavirus disease 2019 (COVID-19) is an ongoing worldwide pandemic infection. The exact incidence of disease re-infection or recurrence remains unknown. One particular at-risk population includes individuals with solid organ transplantation on immunosuppression. We present a case of COVID-19 re-infection in a chronically immunocompromised liver transplant patient. A 53-year-old female presented to the Emergency Department (ED) with nausea, vomiting, diarrhea, and myalgias. She was found to test positive for COVID-19. Her relevant medical history included liver transplantation on chronic immunosuppression. More recently, she had tested positive for COVID-19 approximately three months prior to this and was hospitalized at that time for encephalopathy and treated with remdesivir and convalescent plasma. She had subsequently recovered with negative COVID-19 testing in the interim. On the ED presentation with presumed re-infection, her disease was deemed to be mild with lack of severe symptoms or pulmonary involvement, and she was discharged with outpatient follow-up for monoclonal antibody infusion therapy. We describe a scenario of presumed COVID-19 re-infection in a liver transplant patient. To our knowledge, this is a rare event and has been reported internationally in only a handful of individuals. We surmise that immunosuppression could offer some protection from the inflammatory cascade of the initial disease process in COVID-19 given the relatively mild disease observed in our patient. On the other hand, a less robust immune response may decrease humoral immunity and leave patients at greater risk of re-infection. Further investigation is necessary to delineate COVID-19 disease re-infection versus relapse, especially in the setting of an immunocompromised state.

A Delayed Case of Pericarditis Following Recovery From COVID-19 Infection.

Pericarditis is a rare cardiac complication of coronavirus 19 (COVID-19) infection. Recent case reports describe severe sequelae of pericarditis, including cardiac tamponade, developing within days of initial COVID-19 symptoms. We present a case of pericarditis with slower onset and milder symptoms, developing over a period of a few weeks in an immunocompetent male who recovered from COVID-19 several months earlier. A 65-year-old male presented to an emergency department several times for one week of worsening chest and neck symptoms, along with fever. He had been symptom-free after a three-day course of cough, myalgias, and fever with positive COVID-19 testing, approximately 70 days earlier. He was ultimately admitted for fever and pericarditis with an associated pericardial effusion and positive PCR testing for COVID-19. Pericarditis should be considered in the differential diagnosis for patients with COVID-19 and unexplained persistent chest symptoms. The possibility of recurrent or atypical latent infection should additionally be considered in the months following the initial COVID-19 infection. Bedside ultrasound may facilitate early diagnosis and management of COVID-19 associated pericarditis.

Outcomes of COVID-19 With the Mayo Clinic Model of Care and Research.

OBJECTIVE: To report the Mayo Clinic experience with coronavirus disease 2019 (COVID-19) related to patient outcomes. METHODS: We conducted a retrospective chart review of patients with COVID-19 diagnosed between March 1, 2020, and July 31, 2020, at any of the Mayo Clinic sites. We abstracted pertinent comorbid conditions such as age, sex, body mass index, Charlson Comorbidity Index variables, and treatments received. Factors associated with hospitalization and mortality were assessed in univariate and multivariate models. RESULTS: A total of 7891 patients with confirmed COVID-19 infection with research authorization on file received care across the Mayo Clinic sites during the study period. Of these, 7217 patients were adults 18 years or older who were analyzed further. A total of 897 (11.4%) patients required hospitalization, and 354 (4.9%) received care in the intensive care unit (ICU). All hospitalized patients were reviewed by a COVID-19 Treatment Review Panel, and 77.5% (695 of 897) of inpatients received a COVID-19-directed therapy. Overall mortality was 1.2% (94 of 7891), with 7.1% (64 of 897) mortality in hospitalized patients and 11.3% (40 of 354) in patients requiring ICU care. CONCLUSION: Mayo Clinic outcomes of patients with COVID-19 infection in the ICU, hospital, and community compare favorably with those reported nationally. This likely reflects the impact of interprofessional multidisciplinary team evaluation, effective leveraging of clinical trials and available treatments, deployment of remote monitoring tools, and maintenance of adequate operating capacity to not require surge adjustments. These best practices can help guide other health care systems with the continuing response to the COVID-19 pandemic.

Incidental Diagnosis of Swyer-James-MacLeod Syndrome in a Military Pilot.

BACKGROUND: Swyer-James-MacLeod syndrome (SJMS) is a specific form of bronchiolitis obliterans that occurs rarely, but represents recognized sequelae of common pediatric respiratory illness, and presents as unilateral hyperlucency on chest imaging. This case study describes such an incidental radiographic finding identified during the assessment of chest wall discomfort in a military pilot.CASE REPORT: A 35-yr-old military pilot presented to his flight surgeon with vague intermittent chest discomfort. Initial evaluation revealed an abnormal chest radiograph with unilateral hyperlucency and mild expiratory airflow limitation on pulmonary function testing. The evaluation also included computed tomography imaging with contrast infusion and echocardiography, though the presenting complaint had resolved. The airman was referred to our clinic for further evaluation and aeromedical recommendations regarding returning to flight duties. He was diagnosed with SJMS and recommended to be returned to flight duties.DISCUSSION: SJMS can be challenging to recognize to the untrained eye. An inflammatory response from viral or bacterial infection in childhood results in dysfunctional growth of the affected region of the lung, causing radiographic asymmetry. Although destruction of the alveoli and emphysema may occur, for most cases, there are minimal clinical sequelae. SJMS is not known to be progressive and is not associated with systemic conditions. The pilot likely had the abnormal chest radiograph at the time of commission and had not experienced any in-flight complications. His chest pain had resolved without intervention and SJMS was determined to be unlikely to impact his flight performance (such as response to supplemental oxygen) or life expectancy.Harrison MF, Cowl CT. Incidental diagnosis of Swyer-James-MacLeod syndrome in a military pilot. Aerosp Med Hum Perform. 2021; 92(4):281285.

Oxygen therapy via a noninvasive helmet: A COVID-19 novelty with potential post-pandemic uses.

COVID-19 has placed a significant strain upon healthcare resources at a global level and refractory hypoxemia is the leading cause of death among COVID-19 patients. The management of limited resources such as mechanical ventilators has remained a contentious issue both at an individual and institutional level since the beginning of the pandemic. As a result, the COVID-19 pandemic has presented challenges to critical care practitioners to find innovative ways to provide supplemental oxygen therapy to their patients. We present a single-center experience: a case series of five COVID-19 infected patients managed with a novel approach to provide supplemental oxygen and positive end-expiration pressure (PEEP) via the helmet. Three of the five patients responded to therapy, did not require intubation, and survived to discharge. The other two patients continued to deteriorate clinically, required endotracheal intubation, and subsequently expired during their hospitalization. We extrapolated our accumulated experience with non-invasive oxygen support by helmet in COVID-19 patients to a non-COVID-19 postoperative patient who underwent sinus surgery and developed hypoxemic respiratory failure also resulting in avoidance of endotracheal intubation. We conclude that oxygen therapy via a helmet is a safe, cost-effective technique to prevent intubation in carefully selected patients with infectious and non-infectious causes of hypoxic respiratory failure. Our positive experience with the system warrants further large-scale study and possible technique refinement.

Decompression Sickness Risk Assessment and Awareness in General Aviation.

INTRODUCTION: Decompression sickness (DCS) can occur during unpressurized flight to altitudes >18,000 ft (FL180; 5486 m). To our knowledge, this has not been studied in general aviation (GA). This knowledge gap may have public health and safety implications because the most popular models of GA aircraft by sales volume are capable of flying >FL180.METHODS: Data from a 1-yr period in a commercial flight tracking database were analyzed to identify flights >FL180 in unpressurized, piston aircraft in the United States. Peak altitude and duration at that altitude were used to calculate DCS risk employing the U.S. Air Force (USAF) Altitude Decompression Sickness Risk Assessment Computer (ADRAC). Registration numbers were cross referenced in publicly available federal databases to identify any events that might be attributable to impairment due to DCS. A web-based survey of practices and associated symptoms was also made available to GA pilots through an online discussion forum.RESULTS: During the data collection period, 1696 flights occurred. The DCS risk was calculated to be 1.9 4.2%. There were 42 responses to the survey. Of these, 25 (59.5%) pilots reported having flown at altitudes >FL180 and 21 (84%) of them reported symptoms possibly attributable to DCS. None sought medical attention. No safety events were identified for any of the aircraft during the study period.CONCLUSION: The risk of DCS in the GA community is not zero. As GA aircraft performance profiles advance and sales increase, this may have significant implications from a public health and safety perspective. Further study is warranted.Harrison MF, Butler WP, Murad MH, Toups GN. Decompression sickness risk assessment and awareness in general aviation. Aerosp Med Hum Perform. 2021; 92(3):138145.

Space Medicine Training in Canada.

INTRODUCTION: Aerospace medicine training is often difficult to obtain outside of military education streams. Undergraduate medical trainees and residents may undertake training opportunities, but often have trouble locating programs and/or receiving credit for their experiences and learning. In many countries, no formal aerospace medicine training program or pathway exists and trainees must search out opportunities on their own. Canada is used as an example of a country which, until recently, had no defined civilian aerospace medicine training program or credentialing pathway. Recent development of a Diploma in Aerospace Medicine certified by the Royal College of Physicians and Surgeons now outlines a series of competencies for trainees and medical professionals seeking advancement in aerospace medicine. Growth of the aviation and aerospace fields will require more training opportunities and more aerospace medicine professionals to support the increased number of aviators and the spacefaring population. This will be particularly important as commercial space companies develop the potential for civilian spaceflight. While few opportunities exist for training, we highlight the major aerospace medicine training opportunities that have been recently available to Canadians. It is our hope that highlighting previous and current opportunities may aid in the development of a formal training program leading to certification in aerospace medicine for Canadians and act as an example for other nations.Sirek A, Samoil K, Harrison MF. Space medicine training in Canada. Aerosp Med Hum Perform. 2019; 90(8):725-729.

The Misunderstood Coagulopathy of Liver Disease: A Review for the Acute Setting.

The international normalized ratio (INR) represents a clinical tool to assess the effectiveness of vitamin-K antagonist therapy. However, it is often used in the acute setting to assess the degree of coagulopathy in patients with hepatic cirrhosis or acute liver failure. This often influences therapeutic decisions about invasive procedures or the need for potentially harmful and unnecessary transfusions of blood product. This may not represent a best-practice or evidence-based approach to patient care. The author performed a review of the literature related to the utility of INR in cirrhotic patients using several scientific search engines. Despite the commonly accepted dogma that an elevated INR in a cirrhotic patient corresponds with an increased hemorrhagic risk during the performance of invasive procedures, the literature does not support this belief. Furthermore, the need for blood-product transfusion prior to an invasive intervention is not supported by the literature, as this practice increases the risk of complications associated with a patient's hospital course. Many publications ranging from case studies to meta-analyses refute this evidence and provide examples of thrombotic events despite elevated INR values. Alternative methods, such as thromboelastogram, represent alternate means of assessing in vivo risk of hemorrhage in patients with acute or chronic liver disease in real-time in the acute setting.

Preflight, In-Flight, and Postflight Imaging of the Cervical and Lumbar Spine in Astronauts.

BACKGROUND: Back pain is a common complaint during spaceflight that is commonly attributed to intervertebral disc swelling in microgravity. Ultrasound (US) represents the only imaging modality on the International Space Station (ISS) to assess its etiology. The present study investigated: 1) The agreement and correlation of spinal US assessments as compared to results of pre- and postflight MRI studies; and 2) the trend in intervertebral disc characteristics over the course of spaceflight to ISS. METHODS: Seven ISS astronauts underwent pre- and postflight US examinations that included anterior disc height and anterior intervertebral angles with comparison to pre- and postflight MRI results. In-flight US images were analyzed for changes in disc height and angle. Statistical analysis included repeated measures ANOVA with Bonferroni post hoc analysis, Bland-Altman plots, and Pearson correlation. RESULTS: Bland-Altman plots revealed significant disagreement between disc heights and angles for MRI and US measurements while significant Pearson correlations were found in MRI and US measurements for lumbar disc height (r2 = 0.83) and angle (r2 = 0.89), but not for cervical disc height (r2 = 0.26) or angle (r2 = 0.02). Changes in anterior intervertebral disc angle-initially increases followed by decreases-were observed in the lumbar and cervical spine over the course of the long-duration mission. The cervical spine demonstrated a loss of total disc height during in-flight assessments (∼0.5 cm). DISCUSSION: Significant disagreement but significant correlation was noted between US and MRI measurements of disc height and angle. Consistency in imaging modality is important for trending measurements and more research related to US technique is required.Harrison MF, Garcia KM, Sargsyan AE, Ebert D, Riascos-Castaneda RF, Dulchavsky SA. Preflight, in-flight, and postflight imaging of the cervical and lumbar spine in astronauts. Aerosp Med Hum Perform. 2018; 89(1):32-40.

Real-time Ultrasound Assessment of Astronaut Spinal Anatomy and Disorders on the International Space Station.

OBJECTIVES: Back pain is one of the most common conditions of astronauts during spaceflight and is hypothesized to be attributed to pathologic anatomic changes. Ultrasound (US) represents the only available imaging modality on the International Space Station, but a formal US protocol for imaging the structures of the spinal column does not exist. This investigation developed a method of acquiring diagnostic-quality images of the anterior lumbar and cervical regions of the spine during long-duration spaceflight. METHODS: Comprehensive spinal US examinations were conducted on 7 long-duration spaceflight astronauts before flight, in flight, and after flight and compared to preflight and postflight magnetic resonance imaging data. In-flight scans were conducted after just-in-time training assisted by remote expert tele-US guidance. RESULTS: Novice users were able to obtain diagnostic-quality spinal images with a 92.5% success rate. Thirty-three anomalous or pathologic findings were identified during the preflight US analysis, and at least 14 new findings or progressions were identified during the postflight US analysis. Common findings included disk desiccation, osteophytes, and qualitative changes in the intervertebral disk height and angle. CONCLUSIONS: Ultrasound has proven efficacy as a portable and versatile diagnostic imaging modality under austere conditions. We demonstrated a potential role for US to evaluate spinal integrity and alterations in the extreme environment of space on the International Space Station. Further investigations should be performed to corroborate this imaging technique and to create a larger database related to in-flight spinal conditions during long-duration spaceflight.

Acute Mountain Sickness Symptom Severity at the South Pole: The Influence of Self-Selected Prophylaxis with Acetazolamide.

INTRODUCTION: Acetazolamide, a carbonic anhydrase inhibitor, remains the only FDA approved pharmaceutical prophylaxis for acute mountain sickness (AMS) though its effectiveness after rapid transport in real world conditions is less clear. METHODS: Over 2 years, 248 healthy adults traveled by airplane from sea level (SL) to the South Pole (ALT, ~3200m) and 226 participants provided Lake Louise Symptom Scores (LLSS) on a daily basis for 1 week; vital signs, blood samples, and urine samples were collected at SL and at ALT. Acetazolamide was available to any participant desiring prophylaxis. Comparisons were made between the acetazolamide with AMS (ACZ/AMS) (n = 42), acetazolamide without AMS (ACZ/No AMS)(n = 49), no acetazolamide with AMS (No ACZ/AMS) (n = 56), and the no acetazolamide without AMS (No ACZ/No AMS) (n = 79) groups. Statistical analysis included Chi-squared and one-way ANOVA with Bonferroni post-hoc tests. Significance was p≤0.05. RESULTS: No significant differences were found for between-group characteristics or incidence of AMS between ACZ and No ACZ groups. ACZ/AMS reported greater LLSS, BMI, and red cell distribution width. ACZ/No AMS had the highest oxygen saturation (O2Sat) at ALT. No significant differences were found in serum electrolyte concentrations or PFT results. DISCUSSION: Acetazolamide during rapid ascent provided no apparent protection from AMS based on LLSS. However, it is unclear if this lack of effect was directly associated with the drug or if perhaps there was some selection bias with individuals taking ACZ more likely to have symptoms or if there may have been more of perceptual phenomenon related to a constellation of side effects.