A Novel Macroscale Acoustic Device for Blood Filtration.

Retransfusion of a patient's own shed blood during cardiac surgery is attractive since it reduces the need for allogeneic transfusion, minimizes cost, and decreases transfusion related morbidity. Evidence suggests that lipid micro-emboli associated with the retransfusion of the shed blood are the predominant causes of the neurocognitive disorders. We have developed a novel acoustophoretic filtration system that can remove lipids from blood at clinically relevant flow rates. Unlike other acoustophoretic separation systems, this ultrasound technology works at the macroscale, and is therefore able to process larger flow rates than typical micro-electromechanical system (MEMS) scale acoustophoretic separation devices. In this work, we have first demonstrated the systematic design of the acoustic device and its optimization, followed by examining the feasibility of the device to filter lipids from the system. Then, we demonstrate the effects of the acoustic waves on the shed blood; examining hemolysis using both haptoglobin formation and lactate dehydrogenase release, as well as the potential of platelet aggregation or inflammatory cascade activation. Finally, in a porcine surgical model, we determined the potential viability of acoustic trapping as a blood filtration technology, as the animal responded to redelivered blood by increasing both systemic and mean arterial blood pressure.

Loop-anchor purse-string closure of gastrotomy in NOTES(R) procedures: survival studies in a porcine model.

INTRODUCTION: Transgastric NOTES(®) procedures remain without a simple method to close the gastrotomy. In four survival swine studies, we have tested a novel gastric closure device: the loop-anchor purse-string (LAPS) closure system. METHODS: In four anesthetized pigs, an endoscopic gastrotomy was performed. Four loop anchors were arrayed in a 2-cm square pattern around the gastrotomy. The endoscope was passed into the abdominal cavity, and the gastrotomy was cinched closed. RESULTS: Procedure times ranged from 50-180 minutes. Three pigs survived 14 days. One animal was sacrificed early due to signs of sepsis. Another animal developed fevers and was treated with antibiotics. At necropsy, there were no abscesses, including in the septic animal. Histologic examination revealed evidence of healing in all animals. DISCUSSION: The LAPS system holds promise with early success in an animal model. Future human studies are needed to determine viability as a human visceral closure device.

Feasibility of using near-infrared spectroscopy to diagnose testicular torsion: an experimental study in sheep.

STUDY OBJECTIVE: To assess whether near-infrared spectroscopy can detect testicular hypoxia in a sheep model of testicular torsion within 6 hours of experimental torsion. METHODS: This was a randomized, controlled, nonblinded study. Trans-scrotal, near-infrared, spectroscopy-derived testicular tissue saturation of oxygen values were obtained from the posterior hemiscrota of 6 anesthetized sheep at baseline and every 15 minutes for 6 hours after either experimental-side, 720-degree, unilateral, medial testicular torsion and orchidopexy or control-side sham procedure with orchidopexy and then for 75 minutes after reduction of torsion and pexy. Color Doppler ultrasonography was performed every 30 minutes to confirm loss of vascular flow on the experimental side, return of flow after torsion reduction, and preserved flow on the control side. RESULTS: Near infrared spectroscopy detected a prompt, sustained reduction in testicular tissue saturation of oxygen after experimental torsion. Further, it documented a rapid return of these values to pretorsion levels after reduction of torsion. Experimental-side testicular tissue saturation of oxygen fell from a median value of 59% (interquartile range [IQR] 57% to 69%) at baseline to 14% (IQR 11% to 29%) at 2.5 hours of torsion, and postreduction values were approximately 70%. Control-side testicular tissue saturation of oxygen values increased from a median value of 67% (IQR 59% to 68%) at baseline to 77% (IQR 77% to 94%) at 2.5 hours and remained at approximately 80% for the entire protocol. The difference in median testicular tissue saturation of oxygen between experimental and control sides, using the Friedman test, was found to be significant (P=.017). CONCLUSION: This study demonstrates the feasibility, in a sheep model, of using near-infrared spectroscopy for the noninvasive diagnosis of testicular torsion and for quantification of reperfusion after torsion reduction. The applicability of these findings, from an animal model using complete torsion, to the clinical setting remains to be established.