Hemodynamic effects of 1:2 ECG-coupled jet ventilation in the dog. A comparison with other modes.

In 16 closed-chest dogs the hemodynamics of ECG-coupled jet ventilation (JV) with frequencies of 1:1 (one breath for each cardiac systole) and 1:2 (one breath for every other cardiac systole) were compared to noncoupled JV and intermittent positive-pressure ventilation (IPPV). Cardiac output was similar during 1:2 coupling (1.6 +/- 0.2 L/min) and IPPV (1.6 +/- 0.2 L/min) but decreased during 1:1 coupling (1.2 +/- 0.2 L/min) and noncoupled JV (1.3 +/- 0.2 L/min), p less than 0.05. During 1:2 coupling and IPPV, systemic arterial and transmural left atrial pressures were increased, and pulmonary artery, pericardial, and right atrial pressures were decreased in comparison to the other JV modes. Pulmonary blood volume was preserved during 1:2 coupling but decreased during 1:1 coupling and noncoupled JV. Coupling at 1:2 preserves output by maintaining left ventricular preload via a decrease in right atrial pressure and subsequent maintenance of systemic venous return.