Chronic obstructive pulmonary disease (COPD) and heart disease are often associated. Cardiorespiratory decompensation can be related to fluid overload status with increased LVEDVI, LVEDP, airway resistance and work of breathing. This often requires tracheal intubation with a difficult weaning from mechanical ventilation (MV). The basis to treat an overload status consists of diuretic administration, which has been demonstrated to be able to reduce airway edema and resistance. Loop diuretics can induce tolerance. Their use may be associated with increased morbidity due to deleterious effects, particularly on neurohormonal activation of the renin–angiotensin–aldosterone system with increase of sympathetic renal tone, sodium and water retention, progression of cardiac dysfunction and maintenance of cardiorespiratory decompensation.