Stress Metabolism Adaptation & Critical Illness: Mervyn Singer

In this podcast, Mervyn Singer talks about the link between stress and multiple organ failure. Often, the organs involved in multi-organ failure show no signs of structural damage or cell damage that would indicate these organs might be under stress. Stress might cause functional damage rather than structural damage. Stress is a normal coping mechanism which helps to deal with the various stressors we encounter. These mechanisms include changes in behaviour, as well as autonomic and hormonal modulation of various systems. These include inflammatory, immune, cardiovascular, respiratory and metabolic systems. Human bodies are not designed to cope with the stresses of prolonged life. These stresses include old age, co-morbidities, prolonged critical illness, modern lifesaving drugs, and organ support. Mervyn discusses the evolution of various theories associated with stress. Walter Cannon discovered acute stress response in 1915 when he noticed the manifestation of nervous exhaustion as physical illness in soldiers of World War I. Furthermore, Hans Seyle described the general adaptation syndrome in 1936, stating that when in distress, the physiological systems are functionally compromised. Moreover, Takotsubo identified cardiomyopathy in the early 90s in Japan – in this condition heart failure occurs due to emotional stress. Ultimately, Sterling and Eyer defined Allostasis in 1988 as "staying the same by being different." The body goes into allostatic overload when exposed to extreme stress conditions. Type 1 allostatic overload of stress causes the organism to switch off in order to regain energy balance. Hibernation, estivation, anoxia, and dormancy are all example of allostatic response to stress. Myocardial hibernation is an example of an allostatic response in humans. Multiple markers identify poor prognosis in stressed patients. Energy and metabolism are directly proportional to each other and a reduced level of either or both can be seen in critically stressed patients.  An ICU patient is under multiple stressors. These include physiological, pharmacological, environmental, and psychological stress, all of which lead to chronic critical illnesses. Thus, multiple organ failure may be an allostatic response to the prolonged stress faced by an ICU patient. Mervyn ends the podcast by suggesting multiple pharmacological and non-pharmacological methods to de-stress the patients.  

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