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Bei Patienten mit akuten und chronischen Erkrankungen der Leber ist das perioperative Risiko – insbesondere bei abdominalchirurgischen Eingriffen – signifikant erhoht. Normalerweise besitzt die Leber eine enorme funktionelle Reserve. Bei praoperativ beeintrachtigter Funktion konnen jedoch operations- und anasthesiebedingte Mehrbelastungen zur Dekompensation des Organs fuhren. Ziel muss daher sein, den Patienten mit Erkrankung der Leber zu identifizieren, das Ausmas der Funktionsreserve abzuschatzen und ein Narkoseverfahren zu wahlen, das moglichst wenig mit der Perfusion und Funktion der Leber interferiert.

Typische, klinische Zeichen einer Lebererkrankung sind: (Skleren)ikterus, Foetor hepaticus, „flapping tremor“, „burning feet“, Bauchglatze, Palmarerythem, Spider navi, Umgehungskreislaufe (Caput medusae), Aszites und Muskelatrophie. Bei Patienten mit Leberzirrhose im Endstadium treten neben den Zeichen der Leberinsuffizienz auch funktionelle und strukturelle Veranderungen anderer vitaler Organsysteme auf, die anasthesiologisch relevant sind.

For centuries, mankind has struggled to understand the profound complexity governing the principles of life and the universe. This quest has taken him on scientific journeys far and wide: from the exquisitely simple atomic structure of our DNA to the hellish and chaotic depths of our sun, the energy source for all life on Earth, and beyond. Scientific, artistic, and social discoveries are what drive us as humans, and what distinguish us from all other species with which we share this planet. One of the fundamental questions that still troubles us is how life began on this planet and whether it exists elsewhere in the universe. This deep desire to understand and search for life has taken humans on exploratory journeys to the extremes of our planet: from the depths of our oceans to the heights of our mountains, and from the cold of Antarctica to the darkness of space.

Humans subjected to hostile environments are more prone and vulnerable to infections due to the complex interaction of various stressors. Besides other mechanisms known to induce immune imbalance and suppression as described in this book, this chapter focuses on the still very little known role of hypoxia-triggered immunosuppressive mechanisms in astronauts/cosmonauts e.g. during long-duration space missions. This chapter hence addresses the question of whether stress encountered by astronauts/cosmonauts might trigger neurohumoral effector mechanisms leading to tissue hypoxia thereby causing up-regulation of anti-inflammatory pathways. Such hypoxia signaling-dependent pathways might act additionally to those stimulated by neurohumoral mediators of the stress response even in the absence of hypoxia i.e. under normoxia. Altogether, hypoxic and normoxic pathways of the neurohumoral stress response may synergistically result in immunosuppression.

Health maintenance and disease prevention in astronauts are of high priority during space missions. To achieve this aim, basic science of molecular biology has to be joined with modern noninvasive tools allowing high fidelity research on diagnosing and monitoring of the astronauts’ health status. Experts from biology, medicine, and engineering should merge their expertise to enable additive effects for development and improvement of stress and immune-monitoring tools under extreme environmental conditions. This will hereby ensure not only the success of space mission, especially when leaving the Earth orbit in the future, but also will provide important impetus for many other applications on Earth as well.

Previous chapters have provided some insight into the regulation of immune responses under spaceflight conditions, a unique combination of psychosocial and physical stresses. This multitude of factors affecting almost all components of the immune system could lead to compromised host defense against infections and could have an immediate impact on mission performance. This chapter introduces some strategies that are potentially helpful to mitigate the risk of stress-associated immune dysfunction under conditions of (long-duration) spaceflight.

Exhaled air analyses are an attractive and emerging technology. It is a noninvasive and easy to handle method and may especially be suitable for health monitoring for extended space missions. Based on the current knowledge together with ongoing and future clinical and space-related – earthbound and on the ISS – research, air analyses might become a suitable tool to monitor the adaption of various physiological systems (immune, organs, metabolism) to the stressful condition in space, hereby helping to assess overall health status as well to establish the diagnosis of diseases. As the concentration of volatile organic and inorganic components in exhaled breath is usually found in the low parts per billion of volume range highly sensitive diagnostic platforms are a prerequisite. These requirements are now met by recent technical improvements leading to an increase in the sensitivity of direct mass spectrometric- and gas chromatographic methods. Particular interest is focused to direct mass spectrometric methods as they allow breath-by-breath analyses without evaluation delays. Furthermore, the recent discoveries of close relationships between specific compounds present in exhaled breath and physiological changes feeds the hope of developing possible noninvasive diagnostic and monitoring tools. With these recent progresses the technical cornerstone for exhaled breath gas analyses during space missions has been realized. Current research projects focus on the evaluation of exhaled breath gas compound standard values and the impact of stressors in space akin weightlessness, confinement, nutritional changes, hypoxia, and radiation exposure.

The innate immune system is one of the oldest host defense mechanisms against invading pathogens. Innate immune cells are able to recognise and phagocytose pathogens and activate the adaptive immune system through antigen presenting cells. Humans experience alterations of the innate immune system under many clinical conditions, which can under certain circumstances negatively affect the outcome of disease states. In space, a highly challenging environment for humans to survive in, changes in the innate immune system have been demonstrated but the full picture is still lacking. From initial observations gathered during the Apollo missions it is clear that astronauts become more susceptible to infection as a result of spaceflight. More recent investigations have demonstrated reduced reactive oxygen species generation and phagocytic abilities and attenuated global cellular immune responses. The innate immune pathways investigated in man in space to date have only just scratched the surface of the full antimicrobial mechanisms and armory available to cells of the innate immune system. Although research in humans in space is the gold standard, human spaceflight is a complex mixture of stressors, and is technically and financially challenging. Earth-based scenarios and models such as parabolic flight and head down tilt bed rest mimicking short term zero gravity, and confinement and isolation in hostile environments such as Antarctica, will help to elucidate the effects of specific and individual stressors on innate immunity.

This chapter introduces the main topics of research that have benefited so far from the space environment (reduced gravity, ambient radiation, vacuum, etc.), and provides an outlook for future research development. By convention, it is split into two fields: physical sciences/engineering and life sciences.