Amplified Inflammatory Response to Sequential Hemorrhage, Resuscitation, and Pulmonary Fat Embolism An Animal Study
ABSTRACT The objective of this study was to assess the role of pulmonary fat embolism caused by intramedullary pressurization of the femoral canal in the development of acute lung injury in the setting of acute hemorrhagic shock and resuscitation.
Thirty New Zealand White rabbits were randomly assigned to one of four groups: (1) nine animals in which hemorrhagic shock was induced by carotid bleeding, resuscitation was performed, and the femoral canal was reamed and pressurized with bone cement to induce fat embolism (hemorrhagic shock and resuscitation/fat embolism [HR/FE] group); (2) six animals in which shock was induced by carotid bleeding, resuscitation was performed, and a sham knee incision was made and closed without drilling, reaming, or pressurization (hemorrhagic shock and resuscitation [HR] group); (3) eight animals in which no hemorrhage or shock was induced but the femoral canal was reamed and pressurized with bone cement to induce fat embolism (fat embolism [FE] group); and (4) seven animals that had a three-hour ventilation period followed by a sham knee incision (control group). The animals were ventilated for four hours following closure. Flow cytometry with use of antibodies against CD45 and CD11b was performed to test neutrophil activation in whole blood. Histological examination of lung specimens was also performed. Plasma and bronchoalveolar lavage fluid were analyzed for monocyte chemotactic peptide-1 and interleukin-8 levels with use of the ELISA (enzyme-linked immunosorbent assay) method.
Three animals in the HR/FE group died immediately after canal pressurization and were excluded. CD11b mean channel fluorescence was significantly elevated, as compared with baseline, only in the HR/FE group at two hours (p = 0.025) and four hours (p = 0.024) after knee closure. Histological analysis showed that only the HR/FE (p < 0.001) and HR (p = 0.010) groups had significantly greater infiltration of alveoli by polymorphonuclear leukocytes as compared with that in the controls. No significant differences in plasma cytokine levels were found between the groups. Only the HR/FE group had significantly higher interleukin-8 (p = 0.020) and monocyte chemotactic peptide-1 (p = 0.004) levels in the bronchoalveolar lavage fluid as compared with those in the controls.
Fat embolism from canal pressurization alone did not activate a pulmonary inflammatory response. The combination of hemorrhagic shock, resuscitation, and fat embolism elicited neutrophil activation, infiltration of alveoli by polymorphonuclear leukocytes, and inflammatory cytokine expression in bronchoalveolar lavage fluid.
Conference Paper: Key Issues and Prospects for Optically Assisted Magnetic Recording[Show abstract] [Hide abstract]
ABSTRACT: A magneto-optical (MO) recording material is a candidate for high-density optically assisted magnetic recording. The relationship between MsHc and microstructure in recording layer is discussed, and it is found that the columnar sturucture is effective for tiny mark recording.Lasers and Electro-Optics, 2005. CLEO/Pacific Rim 2005. Pacific Rim Conference on; 09/2005
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ABSTRACT: To compare the intramedullary pressures developed during reaming of cadaveric femurs with the Synthes Reamer/Irrigator/Aspirator (RIA) reamer and the Zimmer Pressure Sentinel (PS) reamer, controlling for the force and speed of reaming. Fifteen matched pairs of frozen unpreserved femurs were used in the study. Two pressure transducers and two thermocouples were screwed into holes drilled into the femoral shaft. The femurs were stabilized in the vertical position by mechanically attaching them to a custom jig equipped with a load cell to detect the vertical component of force applied to the reamer. Proximally a linear voltage displacement transducer (LVDT) was attached to the reamer to record the continuous position of the reamer. All femurs were reamed to a diameter 2 mm larger than the narrowest point of the canal. Proximal and distal pressures, proximal and distal temperatures, applied vertical force and displacement were measured continuously throughout the reaming process. Maximum and minimum, and average proximal and distal pressures for each reamer were obtained and compared using paired t-tests. Averages were also calculated and compared in the same manner. A p-value of <0.05 was considered statistically significant. The maximum, minimum and average intramedullary pressures during reaming were significantly lower with the RIA system than the PS reamer. In general, the pressures produced by the RIA system were consistently below atmospheric pressure for the majority of the reaming time. This was not true for the PS system. No appreciable temperature changes were observed during any of the trials. The RIA reaming system significantly reduces the intramedullary pressures produced during the reaming process compared to the PS reaming system.Injury 11/2010; 41 Suppl 2:S38-42. DOI:10.1016/S0020-1383(10)70007-3 · 2.46 Impact Factor
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ABSTRACT: Intramedullary reaming of long bones before nail insertion has been known to cause an increase in fat emboli introduction into the bloodstream, which is a potentially fatal phenomenon. The goal of this study was to assess whether the reamer irrigator aspirator (RIA) reamer can reduce fat embolic load compared with the standard AO reamer. Fifteen pigs were prepared using an intravenous catheter inserted into the marginal ear vein for fluid balance and drug administration. One third of the pig's blood volume was withdrawn to simulate hemorrhagic shock. Each animal underwent bilateral retrograde femoral reaming, cementing, and nailing using either an RIA or AO reamer. Assignment of a reamer type to the left or right side was done randomly and allowed for direct comparison of matching femur results. Outcome measures were obtained, namely, pulmonary arterial pressure, mean arterial pressure, partial pressure of arterial oxygen, and cardiac output. Staining techniques were used to ascertain fat emboli counts from lung tissue samples. For mean arterial pressure, partial pressure of arterial oxygen, and cardiac output after cement injection, the RIA reamer group showed statistically higher values than the AO reamer group. In corollary, the RIA showed statistically lower pulmonary arterial pressure levels. No differences were noted at baseline, during hypovolemia, and post resuscitation. With the Student t test, no statistical differences were found between reamers regarding fat emboli counts for both staining methods. With the Mann-Whitney test, the RIA reamer showed statistically fewer emboli (7.0 versus 74.5) (P = 0.02, Z = 2.33) using Oil Red "O" staining. The RIA reamer demonstrated superior results with respect to physiologic measures and fat emboli counts and may provide optimal results compared with the AO reamer.Journal of orthopaedic trauma 02/2012; 26(9):e132-7. DOI:10.1097/BOT.0b013e318238b22b · 1.54 Impact Factor