Mechanical Ventilation in Specific Disorders

In myocardial ischemia, the goal of mechanical ventilation is to decrease the work of breathing and thereby the oxygen demands of the respiratory muscles. When the work of breathing is high, as much as 40% of the cardiac output can be diverted to the respiratory muscles69: myocardial ischemia will worsen, and a positive feedback cycle is established (Fig. 9.1). Ventilating patients with strategies that unload the respiratory muscles can be expected to improve myocardial perfusion and break the vicious cycle.