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Respiratory system
Current Anaesthesia & Critical Care (2003) 14, 57
c 2003 ElsevierLtd. All rights reserved. doi:10.1016/S0953-7112(03)00033- 4
EDITORIAL
Respiratory system In the beginning was a primaeval soup but in that soup something stirred. Aeons later cellular organisms were individual islands of life nurturing, protecting and propagating their simple gene pool. Intracellular systems evolved to produce energy. Soon colonies of cells existed as co-operatives and as such worked together to fulf|l their aspirations and ambitions which were predominantly devoted to the success and survival of the gene pool. More sophisticated behaviour lends advantages but necessitates sophisticated infrastructure an important aspect of which is energy supply. A far more eff|cient energy production method was elaborated based on oxygen as a super fuel and the mitochondrion and its components as the engine. With enhanced fuel supplies, colony growth was facilitated and the structures became more sophisticated and larger, the consequence of which was that the mitochondrion became further removed from its fuel supplies so methods had to be developed for delivery. In the modern mammal the heart lungs and cardiovascular system are there to provide and deliver an abundance of substrates. They are there to supply the mitochondria which are there to serve the gene pool. Is this relevant ? In modern medicine, it is easy to be focused on organ systems and their problems almost in isolation and particularly in critical care the management may be so focused on the problems of a single organ that the rest of the organism is insidiously lost. In reality, many of the problems of the heart and lungs are problems because they are failing to subserve their primary functionFthe support of the mitochondria and in turn the gene pool. It is all about dragging oxygen in, delivering it to where it is needed and then removing the waste products. The
classif|cation of respiratory failure reflects this concept. Type I is hypoxaemic respiratory failure or oxygenation failure and type II is hypercapnic or ventilatory failure. The f|rst relates to the pathway by which oxygen is dragged to the mitochondrion, the latter to the pump that works the system, in this case the mechanics of breathing mechanisms. In this edition, the f|rst chapter reminds us of the pivotal role of the mitochondrion and the physiology of the oxygen cascade although a better analogy might be the oxygen whirlpool. Acute lung injury and its problems is classical type I respiratory failure while asthma potentially involves both I and II and COAD predominantly type II. One of the major advances in our understanding of critical care management is the realization that positive pressure ventilation which was the basis of the roots of our speciality may not be a totally benign and benevolent intervention. There appears to be an increasing body of evidence that suggests that barotrauma is more prevalent than was previously thought and that part of the mechanism might be inflammatory in nature. Hence, a section on the new modes of ventilation which in themselves are not novel but rather the philosophy and rationale behind their application is new. This edition seeks to update or at least to cogently reiterate some of the more common areas of respiratory management. We hope you f|nd it both interesting and helpful. N. Soni Department of Anaesthesia, Chelsea & Westminster Hospitals, 369 Fulham Road, London SW10 9NH, UK
c 2003 ElsevierLtd. All rights reserved. doi:10.1016/S0953-7112(03)00033- 4
EDITORIAL
Respiratory system In the beginning was a primaeval soup but in that soup something stirred. Aeons later cellular organisms were individual islands of life nurturing, protecting and propagating their simple gene pool. Intracellular systems evolved to produce energy. Soon colonies of cells existed as co-operatives and as such worked together to fulf|l their aspirations and ambitions which were predominantly devoted to the success and survival of the gene pool. More sophisticated behaviour lends advantages but necessitates sophisticated infrastructure an important aspect of which is energy supply. A far more eff|cient energy production method was elaborated based on oxygen as a super fuel and the mitochondrion and its components as the engine. With enhanced fuel supplies, colony growth was facilitated and the structures became more sophisticated and larger, the consequence of which was that the mitochondrion became further removed from its fuel supplies so methods had to be developed for delivery. In the modern mammal the heart lungs and cardiovascular system are there to provide and deliver an abundance of substrates. They are there to supply the mitochondria which are there to serve the gene pool. Is this relevant ? In modern medicine, it is easy to be focused on organ systems and their problems almost in isolation and particularly in critical care the management may be so focused on the problems of a single organ that the rest of the organism is insidiously lost. In reality, many of the problems of the heart and lungs are problems because they are failing to subserve their primary functionFthe support of the mitochondria and in turn the gene pool. It is all about dragging oxygen in, delivering it to where it is needed and then removing the waste products. The
classif|cation of respiratory failure reflects this concept. Type I is hypoxaemic respiratory failure or oxygenation failure and type II is hypercapnic or ventilatory failure. The f|rst relates to the pathway by which oxygen is dragged to the mitochondrion, the latter to the pump that works the system, in this case the mechanics of breathing mechanisms. In this edition, the f|rst chapter reminds us of the pivotal role of the mitochondrion and the physiology of the oxygen cascade although a better analogy might be the oxygen whirlpool. Acute lung injury and its problems is classical type I respiratory failure while asthma potentially involves both I and II and COAD predominantly type II. One of the major advances in our understanding of critical care management is the realization that positive pressure ventilation which was the basis of the roots of our speciality may not be a totally benign and benevolent intervention. There appears to be an increasing body of evidence that suggests that barotrauma is more prevalent than was previously thought and that part of the mechanism might be inflammatory in nature. Hence, a section on the new modes of ventilation which in themselves are not novel but rather the philosophy and rationale behind their application is new. This edition seeks to update or at least to cogently reiterate some of the more common areas of respiratory management. We hope you f|nd it both interesting and helpful. N. Soni Department of Anaesthesia, Chelsea & Westminster Hospitals, 369 Fulham Road, London SW10 9NH, UK