inspiratory impedance threshold valve
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inspiratory impedance threshold valve,
A valve placed between a patient's airway and his or her source of respiratory gas, e.g., ambient air or, in the case of critically ill patients, a ventilator or bag-valve mask. It lowers tracheal and intrathoracic pressure and as a result increases blood pressure and blood flow to the brain and coronary arteries. It is used in cardiopulmonary resuscitation and advanced cardiac life support to support the circulation in the absence of volume resuscitation. It can also be used to prevent hypotension and syncope in patients with hypovolemia or reduced stroke volumes. The device works by allowing air to escape during chest compressions but not to re-enter the lungs until pressure is > -10 cm H2O. This negative intrathoracic pressure increases venous return.Synonym: inspiratory impedance threshold device