Balloon occlusion of the right main bronchus in an ovine model provides sufficient time for emergent interventions in massive pulmonary embolism.

PURPOSE Massive pulmonary embolism (PE) causes hemodynamic compromise and is associated with a high rate of mortality. We sought to create a model of massive PE and to determine whether occlusion of the right main bronchus could mitigate the physiological effects of massive PE in this model. MATERIALS AND METHODS We used 27 female sheep to generate a model of massive PE by either autologous blood clot injection (n=18) or detachable balloon release (n=9) into the right main pulmonary artery. Four sheep were excluded after blood clot injection, as they did not exhibit adequate declines in blood oxygen saturation (SaO(2)). Nine of the sheep that received autologous blood clot and nine that received detachable balloons went on to treatment with right main bronchus occlusion. The control group (n=5) received the autologous blood clot, but no occlusion of the right main bronchus. All sheep underwent continuous monitoring of pulmonary arterial mean pressure (PAMP), SaO(2), arterial partial pressure of oxygen (PaO(2)), and arterial partial pressure of carbon dioxide. RESULTS Twenty-three sheep (85%) subjected to PE demonstrated immediate tachycardia, tachypnea, and decline in SaO(2) of at least 25% within 30 min. After right main bronchus occlusion, 18 sheep (100%) survived for the length of the experiment and exhibited persistently higher SaO(2) and PaO(2) levels, as well as decreased PAMP compared with the controls. In the control group, two out of five sheep died within 30 min, and the three surviving subjects demonstrated significantly decreased SaO(2) and PaO(2) levels. CONCLUSION Occlusion of the right main bronchus in an ovine model of massive PE effectively extends life and provides favorable physiological parameters to allow emergent interventions.