Cardiorespiratory responses to negative pressure ventilation after tetralogy of fallot repair: A hemodynamic tool for patients with a low-output state

OBJECTIVES We hypothesized that a period of cuirass negative pressure venti lation (NPV) would augment the cardiac output of patients in the early post operative period after complete correction of tetralogy of Fallot (TOF). BACKGROUND Diastolic right ventricular dysfunction can lead to a low-output state in an important minority of patients after TOF repair. In these pati ents, the diastolic pulmonary arterial flow, which characterizes restrictiv e right ventricular physiology, and on which the cardiac output is so depen dent, is highly sensitive to changes in intrathoracic pressure. METHODS The effects of NPV on pulmonary blood flow were investigated in 23 intubated children who were initially ventilated using intermittent positiv e pressure ventilation after TOF repair. Eight patients had restrictive rig ht ventricular physiology. All children received a 15-min period of NPV, an d eight received a prolonged period (45 min) of NPV. RESULTS A brief period of NPV increased pulmonary blood flow by 39%, and th e improvement further continued if the study period was extended, with a to tal increase of 67% after 45 min. Patients with restrictive physiology had a somewhat delayed response to NPV, but the ultimate increase during an ext ended period of NPV was greater in restrictive patients (84%) than nonrestr ictive patients (50%). CONCLUSIONS By manipulating important cardiopulmonary interactions, NPV imp roves the cardiac output of patients after TOF repair, and has a role as a hemodynamic tool in the management of the low-output state in selected case s. (C) 1999 by the American College of Cardiology.