Background: A low cardiac output state can complicate the postoperative course of patients undergoing Fontan-type operations and tetralogy of Fallot repair.
Methods and results: We investigated the effect of negative-pressure ventilation on cardiac output in 11 children in the early postoperative period after right heart surgery. All patients were initially ventilated with volume-cycled intermittent positive-pressure ventilation, and negative-pressure ventilation was delivered with the Hayek external high-frequency oscillator. Cardiac output was calculated by the direct Fick method, oxygen consumption being measured by respiratory mass spectrometry. Cardiac output was measured during intermittent positive-pressure ventilation and after 15 minutes of negative-pressure ventilation. Negative-pressure ventilation improved the cardiac output by a mean of 46% (P = .005). Heart rate did not change, and stroke volume increased by a mean of 48.5% (P = .005). Mixed venous saturation increased by 4.6% (P < .02), and consequently arteriovenous oxygen content difference fell significantly (P = .01). The systemic and pulmonary vascular resistances were reduced significantly during negative-pressure ventilation (P < .05 and P < .03, respectively).
Conclusions: Negative-pressure ventilation improves cardiac output in children after total cavopulmonary connection and tetralogy of Fallot repair and may prove to be an important therapeutic option in children with the low cardiac output state.