The presence of congestive heart failure can complicate the management of patients who undergo mechanical ventilation. Mechanical ventilation by itself affects the pathophysiology of congestive heart failure by decreasing both the venous return to the heart and cardiac afterload, both of which are well described. In addition, there are other ventilator cardiopulmonary interactions that are less well studied, but may also palliate the severity of heart failure. Withdrawal of mechanical ventilation during weaning reverses the beneficial effects on congestive heart failure of the ventilator. In patients with a low cardiac reserve, it can precipitate myocardial ischemia and worsen heart failure. Patients with poor left ventricular reserve may thus fail weaning attempts despite adequate lung mechanics. Aggressive treatment tailored to the severity of congestive heart failure can facilitate weaning from mechanical ventilation. Monitoring during weaning should be focused on clinical, biochemical, and imaging data that collectively represent the earliest indicators of decompensating heart failure. Treatment strategies include protocol driven weaning and increasing use of noninvasive positive pressure breathing after extubation.O ptimal gas exchange and oxygen delivery are quintessential in successful outcomes in patients with major organ dysfunction in critical care. Strategies to optimize gas exchange have included an array of treatment options including invasive, and lately, noninvasive positive pressure ventilation to support the lungs. Adequate oxygen delivery on the other hand focuses on the cardiovascular system. Optimization of pulmonary function in this scenario requires a clear understanding of the pathophysiology of the respiratory system in congestive heart failure (CHF). The pump function of the heart is deranged in CHF leading to far-reaching consequences on respiratory physiology and oxygen transport. Mechanical ventilation has been used as a temporizing modality to support ventilation when the pump function of the heart is being optimized in CHF. Mechanical ventilation itself in turn impacts respiratory physiology and the pump function of the heart. These effects of mechanical ventilation are lost when the patient is weaned off the ventilator. Successful weaning from mechanical ventilation in CHF is then dependent on an understanding of the pathophysiologic changes in pulmonary and cardiac function in these patients in addition to their vital interactions with mechanical ventilation. 1,2 Not uncommonly, the pulmonologist or the critical care physician is called upon to assist with management of patients with significant baseline derangement of both organ systems. The presence of CHF has been associated with a failure to wean from mechanical ventilation. 3,4 The pathologic changes affecting gas exchange and oxygen transport during CHF are detailed in the subsequent sections. The effect of mechanical ventilation on gas exchange and oxygen transport in patients with CHF is further described. The understanding...