Hardware Design Improvements to the Major Constituent Analyzer

The Major Constituent Analyzer (MCA) onboard the International Space Station (ISS) is designed to monitor the major constituents of the ISS's internal atmosphere. This mass spectrometer based system is an integral part of the Environmental Control and Life Support System (ECLSS) and is a primary tool for the management of ISS atmosphere composition. As a part of NASA Change Request CR10773A, several alterations to the hardware have been made to accommodate improved MCA logistics. First, the ORU 08 verification gas assembly has been modified to allow the verification gas cylinder to be installed on orbit. The verification gas is an essential MCA consumable that requires periodic replenishment. Designing the cylinder for subassembly transport reduces the size and weight of the maintained item for launch. The redesign of the ORU 08 assembly includes a redesigned housing, cylinder mounting apparatus, and pneumatic connection. The second hardware change is a redesigned wiring harness for the ORU 02 analyzer. The ORU 02 electrical connector interface was damaged in a previous on-orbit installation, and this necessitated the development of a temporary fix while a more permanent solution was developed. The new wiring harness design includes flexible cable as well as indexing fasteners and guide-pins, and provides better accessibility during the on-orbit maintenance operation. This presentation will describe the hardware improvements being implemented for MCA as well as the expected improvement to logistics and maintenance

Improving stamina and mobility with preop walking in surgical patients with frailty traits -OASIS IV: randomized clinical trial study protocol

BACKGROUND: Frail older surgical patients face more than a two-fold increase in postoperative complications, including myocardial infarction, deep vein thrombosis, pulmonary embolism, pneumonia, ileus, and others. Many of these complications occur because of postoperative loss of stamina and poor mobility. Preoperative exercise may better prepare these vulnerable patients for surgery. We present the protocol for our ongoing randomized trial to assess the impact of a preoperative walking intervention with remote coaching and pedometer on outcomes of stamina (six-minute walk distance- 6MWD) and mobility (postoperative steps) in older adults with frailty traits. METHODS: We will be conducting a randomized clinical trial with a total of 120 patients permitting up to a 33% rate of attrition, to reach a final sample size of 80 (with 40 patients for each study arm). We will include patients who are age 60 or higher, score 4 or greater on the Edmonton Frailty Scale assessment, and will be undergoing a surgical operation that requires a 2 or more night hospital stay to be eligible for our trial. Using block randomization stratified on baseline 6MWD, we will assign patients to wear a pedometer. At the end of three baseline days, an athletic trainer (AT) will provide a daily step count goal reflecting a 10-20% increase from baseline. Subsequently, the AT will call weekly to further titrate the goal or calls more frequently if the patient is not meeting the prescribed goal. Controls will receive general walking advice. Our main outcome is change in 6MWD on postoperative day (POD) 2/3 vs. baseline. We will also collect 6MWD approximately 4 weeks after surgery and daily in-hospital steps. CONCLUSION: If changes in a 6MWD and step counts are significantly higher for the intervention group, we believe this will confirm our hypothesis that the intervention leads to decreased loss of stamina and mobility. Once confirmed, we anticipate expanding to multiple centers to assess the interventional impact on clinical endpoints. TRIAL REGISTRATION: The randomized clinical trial was registered on clinicaltrials.gov under the identifier NCT03892187 on March 27, 2019

Commentaries on viewpoint : physiology and fast marathons

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When coronary arteries need systolic pressure: surgical considerations

OBJECTIVES: Patients with pulmonary atresia and intact ventricular septum (PA-IVS) may have coronary sinusoids connected to a hypertensive right ventricle. Coronary perfusion may then completely depend on the right ventricular systolic pressure wave; decompression of the right ventricle can be deleterious in these patients. This study was set to investigate the treatment strategies and outcomes of patients with coronary sinusoids. METHODS: National multicentre retrospective analysis over 15 years (1985-2010) in a population of ∼10.2 million people. All patients with PA-IVS and coronary sinusoids were identified from local databases. All angiograms, echocardiograms, surgical reports and outcome data were reviewed. RESULTS: Thirty patients were identified. Right ventricular-dependent coronary circulation was present in nine patients (30%). A systemic-to-pulmonary artery shunt was created in 23 patients (77%) at a median age of 13.0 days (range: 1-479). A bidirectional Glenn was performed in 20 children at a median age of 7.8 months (range: 2.1-112.9) and 11 children proceeded to a Fontan repair at a median age of 3.6 years (range: 2.1-19.6). Pulmonary valve perforation and angioplasty were performed in six children and in three a simultaneous decompression procedure was also done. Ten patients died (33%). Four died at the time of systemic-to-pulmonary artery shunt and three during the bidirectional Glenn shunt. In all these patients myocardial ischaemia was reported. CONCLUSIONS: Mortality in PA-IVS with sinusoids is high. Right ventricular coronary dependence may lead to early death if the right ventricular systolic pressure wave is interrupted. Adequate understanding of the underlying pathology and pathophysiology is essential before attempting any procedure in this subgroup of children

When coronary arteries need systolic pressure: surgical considerations

OBJECTIVES: Patients with pulmonary atresia and intact ventricular septum (PA-IVS) may have coronary sinusoids connected to a hypertensive right ventricle. Coronary perfusion may then completely depend on the right ventricular systolic pressure wave; decompression of the right ventricle can be deleterious in these patients. This study was set to investigate the treatment strategies and outcomes of patients with coronary sinusoids. METHODS: National multicentre retrospective analysis over 15 years (1985-2010) in a population of ∼10.2 million people. All patients with PA-IVS and coronary sinusoids were identified from local databases. All angiograms, echocardiograms, surgical reports and outcome data were reviewed. RESULTS: Thirty patients were identified. Right ventricular-dependent coronary circulation was present in nine patients (30%). A systemic-to-pulmonary artery shunt was created in 23 patients (77%) at a median age of 13.0 days (range: 1-479). A bidirectional Glenn was performed in 20 children at a median age of 7.8 months (range: 2.1-112.9) and 11 children proceeded to a Fontan repair at a median age of 3.6 years (range: 2.1-19.6). Pulmonary valve perforation and angioplasty were performed in six children and in three a simultaneous decompression procedure was also done. Ten patients died (33%). Four died at the time of systemic-to-pulmonary artery shunt and three during the bidirectional Glenn shunt. In all these patients myocardial ischaemia was reported. CONCLUSIONS: Mortality in PA-IVS with sinusoids is high. Right ventricular coronary dependence may lead to early death if the right ventricular systolic pressure wave is interrupted. Adequate understanding of the underlying pathology and pathophysiology is essential before attempting any procedure in this subgroup of children.status: publishe

The effect of bosentan in patients with a failing Fontan circulation.

OBJECTIVES: To investigate the effect of bosentan in patients with a failing Fontan circulation. DESIGN: A multicentric open label, non-controlled study. SETTING: 5 tertiary care centres for congenital cardiology.PatientsWe included 10 patients with a failing Fontan circulation. Their median age at inclusion was 12.12 years, with a range from 4.41 to 33,41 years. The median interval between the Fontan operation and inclusion was 7.84 years, with a range from 1.96 to 12,18 years. Participants received half the usual dose of bosentan for 4 weeks, and then the full dose for a further 12 weeks.Main measures of outcomesWe assessed saturations of oxygen at rest and during exercise, using a 6 minutes walk test, at baseline, and during and after 16 weeks of treatment. At each visit, we assessed blood chemistry and hepatic function, and asked the patients to complete a questionnaire concerning quality of life. All medical events and possible side effects were recorded. RESULTS: Of the cohort, 1 patient withdrew. The changes in saturations of oxygen, exercise performance, and scores for the questionnaire did not reach statistical significance for the whole group. We noted, nonetheless, that saturations of oxygen and/or exercise capacity improved in 5 of the patients. This was further confirmed when those patients deteriorated again when the drug was discontinued. CONCLUSIONS: Our study failed to show significant improvement after 3 months of treatment with bosentan in a small group of patients with failing Fontan circulations. Some individuals, nonetheless, did improve. When planning larger trials, it would be better to identify those patients who might potentially benefit from the treatment prior to commencing the trial