Right Ventricular Loading by Lung Inflation during Controlled Mechanical Ventilation.

Rationale: The inspiratory rise in transpulmonary pressure during mechanical ventilation increases right ventricular (RV) afterload. One mechanism is that when Palv exceeds left atrial pressure, West zone 1 or 2 (non-zone 3) conditions develop, and Palv becomes the downstream pressure opposing RV ejection. The Vt at which this impact on the right ventricle becomes hemodynamically evident is not well established. Objectives: To determine the magnitude of RV afterload and prevalence of significant non-zone 3 conditions during inspiration across the range of Vt currently prescribed in clinical practice. Methods: In postoperative passively ventilated cardiac surgery patients, we measured right atrial, right ventricle, pulmonary artery, pulmonary artery occlusion pressure, plateau pressure, and esophageal pressure during short periods of controlled ventilation, with Vt increments ranging between 2 and 12 ml/kg predicted body weight (PBW). The inspiratory increase in RV afterload was evaluated hemodynamically and echocardiographically. The prevalence of non-zone 3 conditions was determined using two definitions based on changes in esophageal pressure, pulmonary artery occlusion pressure, and plateau pressure. Measurements and Main Results: Fifty-one patients were studied. There was a linear relationship between Vt, driving pressure, transpulmonary pressure, and the inspiratory increase in the RV isovolumetric contraction pressure. Echocardiographically, increasing Vt was associated with a greater inspiratory increase in markers of afterload and a decrease in stroke volume. Non-zone 3 conditions were present in >50% of subjects at a Vt ⩾ 6 ml/kg PBW. Conclusions: In the Vt range currently prescribed, RV afterload increases with increasing Vt. A mechanical ventilation strategy that limits Vt and driving pressure is cardioprotective.

Migration of an Inferior Vena Cava Tumor Thrombus during Renal Cell Carcinoma Resection.

Approximately 4%-10% of patients with renal cell carcinoma (RCC) have tumoral vascular invasion with resultant thrombi in the renal vein and in the inferior vena cava (IVC). The authors describe an interesting case of IVC tumor thrombus that migrated to the right cardiac chambers during RCC resection. The diagnosis was made by intraoperative transesophageal echocardiography (TEE), which revealed the presence of a free-floating thrombus between the right atrium (RA) and right ventricle (RV). The patient required an urgent sternotomy with cardiopulmonary bypass (CPB) for atrial thrombus removal prior to the completion of the nephrectomy. The patient made a full recovery and was discharged to a rehabilitation facility. These findings illustrate the importance of intraoperative TEE monitoring during nephrectomy and IVC thrombectomy. In this case, TEE allowed for the diagnosis of an unexpected complication necessitating prompt cardiac surgical management.