Hemorheological Approach to Improve Perfusion of Red Blood Cells with Reduced Deformability Using Drag-Reducing Polymer (In Vitro Study).

Drag-reducing polymers (DRPs) are nontoxic water-soluble blood additives that have been shown to beneficially alter hemodynamics when delivered intravenously in nanomolar concentrations. This study examines the ability of DRPs to alter the traffic of mixtures of normal and less-deformable red blood cells (RBCs) through branched microchannels and is intended to support and expand upon previous experiments within straight capillary tubes to promote DRPs for future clinical use. Branched polydimethylsiloxane microchannels were perfused with a mixture of normal bovine RBCs also containing heat-treated less-deformable RBCs at a hematocrit of 30% with 10 ppm of the DRP poly(ethylene oxide) (MW 4M Da). Suspensions were driven by syringe pump, collected at outlets, and RBC dimensions measured while subject to shear stress to determine the proportion of healthy RBCs in each sample. DRPs eliminated evidence of the plasma skimming phenomena and significantly increased the pressure drop across microchannels. Further, DRPs were found to cause an increase in the proportion of healthy RBCs exiting the branch outlet from -8.5 ± 2.5% (control groups) to +12.1 ± 5.4% (n = 6, p = 0.02). These results suggest DRP additives may be used to improve the perfusion of less-deformable RBCs in vivo and indicates their potential for future clinical use.

Comprehensive Diagnosis and Surgical Management of Cushing Disease: Two-Dimensional Angiographic and Operative Video.

Cushing disease (CD), or hypercortisolemia secondary to an adrenocorticotropic hormone-secreting (ACTH-secreting) pituitary adenoma, is the most common etiology of noniatrogenic Cushing syndrome.1 The diagnostic algorithm employed in the patient with suspected CD is complex and includes consideration for inferior petrosal sinus sampling (IPSS).2,3 When workup is consistent with CD, extracapsular resection of the ACTH-secreting pituitary adenoma through the endonasal corridor is the preferred operative strategy.4 In this publication, we discuss the case of a 26-year-old woman who presented with 9 months of weight gain (Video 1). Initial labs, including low- and high-dose dexamethasone suppression tests, were consistent with CD. Findings on dynamic magnetic resonance imaging were suggestive of a left 2-mm microadenoma. IPSS confirmed central origin of hypercortisolemia and was indicative of a left-sided focus. The patient was taken to the operating room for endoscopic endonasal approach for extracapsular resection of left-sided, ACTH-secreting microadenoma. Following surgery, the patient required glucocorticoid supplementation after her cortisol levels decreased to 2 ug/dL the evening of surgery. Subsequent laboratory analysis has been consistent with hormonal cure.5,6 The accompanying video manuscript describes 1) preoperative diagnostic evaluation of the patient with suspected CD, 2) indications for and techniques of IPSS, 3) nuances of endoscopic transsphenoidal surgical management, and 4) relevant considerations in postoperative care. Of note, full patient consent for photography and/or recording of other forms of video/imaging was obtained in the preoperative period.7-10.