[Analogies between heart and respiratory muscle failure. Importance to clinical practice].
Heart failure is an established diagnosis. Respiratory muscle or ventilatory pump failure, however, is less well known. The latter becomes obvious through hypercapnia, caused by hypoventilation. The respiratory centre tunes into hypercapnea in order to prevent the danger of respiratory muscle overload (hypercapnic ventilatory failure). Hypoventilation will consecutively cause hypoxemia but this will not be responsible for performance limitation. One therefore has to distinguish primary hypoxemia evolving from diseases in the lung parenchyma. Here hypoxemia is the key feature and compensatory hyperventilation usually decreases PaCO2 levels. The cardiac as well as the respiratory pump adapt to an inevitable burden caused by chronic disease. In either case organ muscle mass will increase. If the burden exceeds the range of possible physiological adaptation, compensatory mechanisms will set in that are similar in both instances. During periods of overload either muscle system is mainly fueled by muscular glycogen. In the recovery phase (e. g. during sleep) stores are replenished, which can be recognized by down-regulation of the blood pressure in case of the cardiac pumb or by augmentation of hypercapnia through hypoventilation in case of the respiratory pump. The main function of cardiac and respiratory pump is maintenance of oxygen transport. The human body has developed certain compensatory mechanisms to adapt to insufficient oxygen supply especially during periods of overload. These mechanisms include shift of the oxygen binding curve, expression of respiratory chain isoenzymes capable of producing ATP at lower partial pressures of oxygen and the development of polyglobulia. Medically or pharmacologically the cardiac pump can be unloaded with beta blockers, the respiratory pump by application of inspired oxygen. Newer forms of therapy augment the process of recovery. The heart can be supported through bypass surgery or intravascular pump systems, while respiratory muscles may be supported through elective ventilatory support (mainly non-invasive) in the patient's home. The latter treatment in particular will increase patient endurance and quality of life and decrease mortality. Heart and respiratory pump failure share many common features. Since both take care of oxygen supply to the body, their function and compensatory mechanisms are closely related and linked.
Köhler
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D
Krankenhaus Kloster Grafschaft, Schmallenberg. d.koehler@fkkg.de
D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D006935:Hypercapnia / Q000209:etiology; D007040:Hypoventilation / Q000150:complications / Q000209:etiology; D000860:Hypoxia / Q000175:diagnosis / Q000209:etiology; D010100:Oxygen / Q000378:metabolism; D012121:Respiration, Artificial; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D012132:Respiratory Muscles / Q000503:physiopathology
D010100:Oxygen