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Morris PD, Anderton RA, Marshall-Goebel K, Britton JK, Lee SMC, Smith NP, van de Vosse FN, Ong KM, Newman TA, Taylor DJ, Chico T, Gunn JP, Narracott AJ, Hose DR, Halliday I. Computational modelling of cardiovascular pathophysiology to risk stratify commercial spaceflight. Nat Rev Cardiol 2024:10.1038/s41569-024-01047-5. [PMID: 39030270 DOI: 10.1038/s41569-024-01047-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/30/2024] [Indexed: 07/21/2024]
Abstract
For more than 60 years, humans have travelled into space. Until now, the majority of astronauts have been professional, government agency astronauts selected, in part, for their superlative physical fitness and the absence of disease. Commercial spaceflight is now becoming accessible to members of the public, many of whom would previously have been excluded owing to unsatisfactory fitness or the presence of cardiorespiratory diseases. While data exist on the effects of gravitational and acceleration (G) forces on human physiology, data on the effects of the aerospace environment in unselected members of the public, and particularly in those with clinically significant pathology, are limited. Although short in duration, these high acceleration forces can potentially either impair the experience or, more seriously, pose a risk to health in some individuals. Rather than expose individuals with existing pathology to G forces to collect data, computational modelling might be useful to predict the nature and severity of cardiovascular diseases that are of sufficient risk to restrict access, require modification, or suggest further investigation or training before flight. In this Review, we explore state-of-the-art, zero-dimensional, compartmentalized models of human cardiovascular pathophysiology that can be used to simulate the effects of acceleration forces, homeostatic regulation and ventilation-perfusion matching, using data generated by long-arm centrifuge facilities of the US National Aeronautics and Space Administration and the European Space Agency to risk stratify individuals and help to improve safety in commercial suborbital spaceflight.
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Affiliation(s)
- Paul D Morris
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK.
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
| | - Ryan A Anderton
- Medical Department, Spaceflight, UK Civil Aviation Authority, Gatwick, UK
| | - Karina Marshall-Goebel
- The National Aeronautics and Space Administration (NASA) Johnson Space Center, Houston, TX, USA
| | - Joseph K Britton
- Aerospace Medicine Specialist Wing, Royal Air Force (RAF) Centre of Aerospace Medicine, Henlow, UK
| | - Stuart M C Lee
- KBR, Human Health Countermeasures Element, NASA Johnson Space Center, Houston, TX, USA
| | - Nicolas P Smith
- Victoria University of Wellington, Wellington, New Zealand
- Auckland Bioengineering Institute, Auckland, New Zealand
| | - Frans N van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - Karen M Ong
- Virgin Galactic Medical, Truth or Consequences, NM, USA
| | - Tom A Newman
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Daniel J Taylor
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
| | - Tim Chico
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Julian P Gunn
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Andrew J Narracott
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - D Rod Hose
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - Ian Halliday
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
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Stepanek J, Blue RS, Connolly D. Pulmonary Function in Human Spaceflight. Semin Respir Crit Care Med 2023; 44:696-704. [PMID: 37459884 DOI: 10.1055/s-0043-1770064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Human spaceflight is entering a time of markedly increased activity fueled by collaboration between governmental and private industry entities. This has resulted in successful mission planning for destinations in low Earth orbit, lunar destinations (Artemis program, Gateway station) as well as exploration to Mars. The planned construction of additional commercial space stations will ensure continued low Earth orbit presence and destinations for science but also commercial spaceflight participants. The human in the journey to space is exposed to numerous environmental challenges including increased gravitational forces, microgravity, altered human physiology during adaptation to weightlessness in space, altered ambient pressure, as well as other important stressors contingent on the type of mission and destination. This chapter will cover clinically important aspects relevant to lung function in a normally proceeding mission; emergency scenarios such as decompression, fire, etc., will not be covered as these are beyond the scope of this review. To date, participation in commercial spaceflight by those with pre-existing chronic medical conditions is very limited, and hence, close collaboration between practicing pulmonary specialists and aerospace medicine specialists is of critical importance to guarantee safety, proper clinical management, and hence success in these important endeavors.
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Affiliation(s)
- Jan Stepanek
- Aerospace Medicine Program, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Rebecca S Blue
- Aerospace Medicine Program Aerospace Medicine and Vestibular Research Laboratory (AMVRL), Mayo Clinic, Scottsdale, Arizona
| | - Desmond Connolly
- Human Performance, Air & Space Division, QinetiQ Plc, Farnborough, United Kingdom
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Smith TG, Pollock RD, Britton JK, Green NDC, Hodkinson PD, Mitchell SJ, Stevenson AT. Physiological Effects of Centrifuge-Simulated Suborbital Spaceflight. Aerosp Med Hum Perform 2022; 93:830-839. [PMID: 36757241 DOI: 10.3357/amhp.6153.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND: High-G acceleration experienced during launch and re-entry of suborbital spaceflights may present challenges for older or medically susceptible participants. A detailed understanding of the associated physiological responses would support the development of an evidence-based medical approach to commercial suborbital spaceflight.METHODS: There were 24 healthy subjects recruited into 'younger' (18-44 yr), 'intermediate' (45-64 yr) and 'older' (65-80 yr) age groups. Cardiovascular and respiratory variables were measured continuously during dynamic combinations of +Gx (chest-to-back) and +Gz (head-to-foot) acceleration that simulated suborbital G profiles for spaceplane and rocket/capsule platforms. Measurements were conducted breathing air and breathing 15% oxygen to simulate a cabin pressure altitude of 8000 ft.RESULTS: Suborbital G profiles generated highly dynamic changes in heart rate, blood pressure, and cardiac output. G-induced hypoxemia was observed, with minimum arterial oxygen saturation < 80% in a quarter of subjects. Increased age was associated with greater hypoxemia and reduced cardiac output responses but did not have detrimental cardiovascular effects. ECG changes included recurrent G-induced trigeminy in one individual. Respiratory and visual symptoms were common, with 88% of subjects reporting greyout and 29% reporting blackout. There was one episode of G-induced loss of consciousness (G-LOC).DISCUSSION: Suborbital acceleration profiles are generally well tolerated but are not physiologically inconsequential. Marked hemodynamic effects and transient respiratory compromise could interact with predisposing factors to precipitate adverse cardiopulmonary effects in a minority of participants. Medically susceptible individuals may benefit from expanded preflight centrifuge familiarization that includes targeted physiological evaluation in the form of a 'G challenge test'.Smith TG, Pollock RD, Britton JK, Green NDC, Hodkinson PD, Mitchell SJ, Stevenson AT. Physiological effects of centrifuge-simulated suborbital spaceflight. Aerosp Med Hum Perform. 2022; 93(12):830-839.
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Pollock RD, Hodkinson PD, Smith TG. Oh G: The x, y and z of human physiological responses to acceleration. Exp Physiol 2021; 106:2367-2384. [PMID: 34730860 DOI: 10.1113/ep089712] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/18/2021] [Indexed: 01/06/2023]
Abstract
NEW FINDINGS What is the topic of this review? This review focuses on the main physiological challenges associated with exposure to acceleration in the Gx, Gy and Gz directions and to microgravity. What advances does it highlight? Our current understanding of the physiology of these environments and latest strategies to protect against them are discussed in light of the limited knowledge we have in some of these areas. ABSTRACT The desire to go higher, faster and further has taken us to environments where the accelerations placed on our bodies far exceed or are much lower than that attributable to Earth's gravity. While on the ground, racing drivers of the fastest cars are exposed to high degrees of lateral acceleration (Gy) during cornering. In the air, while within the confines of the lower reaches of Earth's atmosphere, fast jet pilots are routinely exposed to high levels of acceleration in the head-foot direction (Gz). During launch and re-entry of suborbital and orbital spacecraft, astronauts and spaceflight participants are exposed to high levels of chest-back acceleration (Gx), whereas once in space the effects of gravity are all but removed (termed microgravity, μG). Each of these environments has profound effects on the homeostatic mechanisms within the body and can have a serious impact, not only for those with underlying pathology but also for healthy individuals. This review provides an overview of the main challenges associated with these environments and our current understanding of the physiological and pathophysiological adaptations to them. Where relevant, protection strategies are discussed, with the implications of our future exposure to these environments also being considered.
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Affiliation(s)
- Ross D Pollock
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
| | - Peter D Hodkinson
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
| | - Thomas G Smith
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK.,Department of Anaesthesia, Guy's and St Thomas' NHS Foundation Trust, London, UK
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Smith TG, Buckey JC. Anaesthetists and aerospace medicine in a new era of human spaceflight. Anaesthesia 2021; 77:384-388. [PMID: 34496029 DOI: 10.1111/anae.15580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2021] [Indexed: 01/31/2023]
Affiliation(s)
- T G Smith
- Centre for Human and Applied Physiological Sciences, King's College London, UK.,Department of Anaesthesia, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - J C Buckey
- Space Medicine Innovations Laboratory, Geisel School of Medicine, Dartmouth College, Hanover, NH, USA.,Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
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Menden T, Alcaín GB, Stevenson AT, Pollock RD, Tank H, Hodkinson P, Jolley C, Smith TG, Leonhardt S, Walter M. Dynamic lung behavior under high G acceleration monitored with electrical impedance tomography. Physiol Meas 2021; 42. [PMID: 34375953 DOI: 10.1088/1361-6579/ac1c63] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/10/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE During launch and atmospheric re-entry in suborbital space flights, astronauts are exposed to high G-acceleration. These acceleration levels influence gas exchange inside the lung and can potentially lead to hypoxaemia. The distribution of air inside the lung can be monitored by Electrical Impedance Tomography (EIT). This imaging technique might reveal how high gravitational forces affect the dynamic behavior of ventilation and impair gas exchange resulting in hypoxaemia. APPROACH We performed a trial in a long-arm centrifuge with ten participants lying supine while being exposed to +2, +4 and +6\,Gx(chest-to-back acceleration) to study the magnitude of accelerations experienced during suborbital spaceflight. MAIN RESULTS First, the tomographic images revealed that the dorsal region of the lung emptied faster than the ventral region. Second, the ventilated area shifted from dorsal to ventral. Consequently, alveolar pressure in the dorsal area reached the pressure of the upper airways before the ventral area emptied completely. Finally, the upper airways collapsed and the end-expiratory volume increased. This resulted in ventral gas trapping with restricted gas exchange. SIGNIFICANCE At +4xchanges in ventilation distribution varied considerably between subjects potentially due to variation in individual physical conditions. However, at +6\,Gxall participants were affected similarly and the influence of high gravitational conditions was pronounced.
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Affiliation(s)
- Tobias Menden
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Gema B Alcaín
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Alec T Stevenson
- QinetiQ EMEA, Farnborough, Hampshire, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Ross D Pollock
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Henry Tank
- QinetiQ EMEA, Farnborough, Hampshire, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Peter Hodkinson
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Caroline Jolley
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Thomas G Smith
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Steffen Leonhardt
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Marian Walter
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
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