Evaluation of embolic protection devices for fat emboli prevention

Patients with acutely treated femoral shaft fractures with reamed intramedullary nailing are at risk for acute respiratory distress syndrome due to liberation of bone marrow fat particles that travel to the lung and cause damage to the parenchyma. The purpose of this study was to demonstrate: (1) the ability of clinically applicable embolic protection devices to capture such particles; (2) how such a device affects cardiopulmonary function after reamed intramedullary nailing; and (3) evaluation of lung pathology to determine whether filtration affects pulmonary embolic load.

A total of 12 canines were anesthetized, and hemodynamic monitoring was established. Carotid embolic protection devices were introduced into the iliac vein, and ipsilateral intramedullary reaming and nailing was performed. Cardiopulmonary parameters were recorded at timed intervals up to 60 minutes after the procedure. The control group (n = 4) was compared with groups treated with Accunet (n = 4) and Spider (n = 4) filters. A blinded histopathological review was performed on lung specimens to determine the average number of emboli per section and to measure the area (mm(2)) of embolic load by digital image analysis.

Gross inspection of the embolic protection devices showed the presence of bone marrow debris. A significant change was observed in pH levels (control = -0.052, filters = +0.005; P < .05) within the 60 minutes after intramedullary nailing. Serum bicarbonate (meq/dL) values were noted to have similar changes of -2.7 and -1.8 at 10 and 60 minutes, whereas the experimental group was +0.6 and +0.8 at the same time intervals (P =.01 and .0004, respectively). Pulmonary measurements for pO2 and oxygen saturation were analogous to the serum parameters with decreases in the control group in comparison with the filter groups. The mean numbers of emboli and area measurements of embolic load were significantly reduced in the filter group (all P < .01).

Embolic protection devices were effective in capturing embolic debris from reamed intramedullary nailing of lower extremity long bones and demonstrated a protective effect on pulmonary function and significantly decreased the number and size of emboli in the lung. Based on these findings, patients with long bone fractures at risk for pulmonary complications and acute respiratory distress syndrome could benefit from the placement of embolic protection devices prior to intramedullary fixation. While this study utilized filtration devices designed for carotid embolic protection, further study is warranted to determine optimal filter design in this setting.