Anesthetic Management of Unanticipated Subglottic Stenosis in a Patient Undergoing Coronary Artery Bypass Graft Surgery.

A 62-year-old female presented for a scheduled coronary artery bypass graft (CABG) and was found to have an unexpected subglottic stenosis during routine intubation. The case was aborted and six days later, the patient underwent lasering of the stenotic subglottic region and airway balloon dilation. In this case report, causes of subglottic stenosis and surgical/anesthetic management of the condition are discussed. The management of subglottic stenosis in this patient was complicated by concurrent severe coronary artery disease (CAD) involving the left main coronary artery and timing of airway surgery relative to interventions for her CAD. In situations of undiagnosed subglottic stenosis, anesthesiologists should be familiar with airway management based on the location and severity of the stenosis. Close multidisciplinary team management is required for patients who have other complex comorbidities.

Electric field stimulation through a biodegradable polypyrrole-co-polycaprolactone substrate enhances neural cell growth.

Nerve guidance conduits (NGCs) are FDA-approved devices used to bridge gaps across severed nerve cables and help direct axons sprouting from the proximal end toward the distal stump. In this article, we present the development of a novel electrically conductive, biodegradable NGC made from a polypyrrole-block-polycaprolactone (PPy-PCL) copolymer material laminated with poly(lactic-co-glycolic acid) (PLGA). The PPy-PCL has a bulk conductivity ranging 10-20 S/cm and loses 40 wt % after 7 months under physiologic conditions. Dorsal root ganglia (DRG) grown on flat PPy-PCL/PLGA material exposed to direct current electric fields (EF) of 100 mV/cm for 2 h increased axon growth by 13% (± 2%) toward either electrode of a 2-electrode setup, compared with control grown on identical substrates without EF exposure. Alternating current increased axon growth by 21% (±3%) without an observable directional preference, compared with the same control group. The results from this study demonstrate PLGA-coated PPy-PCL is a unique biodegradable material that can deliver substrate EF stimulation to improve axon growth for peripheral nerve repair.

Electric field stimulation through a substrate influences Schwann cell and extracellular matrix structure.

OBJECTIVE: Electric field (EF) stimulation has been used to cue cell growth for tissue engineering applications. In this study, we explore the electrical parameters and extracellular mechanisms that elicit changes in cell behavior when stimulated through the substrate. APPROACH: Rat Schwann cell morphology was compared when exposed to EF through the media or a conductive indium tin oxide substrate. Ionic and structural effects were then analyzed on Matrigel and collagen I, respectively. MAIN RESULTS: When stimulating through media, cells had greater alignment perpendicular to the EF with higher current densities (106 mA cm(-2) at 245 mV mm(-1)), and reached maximum alignment within 8 h. Stimulation through the substrate with EF (up to 110 mV mm(-1)) did not affect Schwann cell orientation, however the EF caused extracellular matrix (ECM) coatings on substrates to peel away, suggesting EF can physically change the ECM. Applying alternating current (ac) 2-1000 Hz signals through the media or substrate both caused cells to flatten and protrude many processes, without preferential alignment. Matrigel exposed to a substrate EF of 10 mV mm(-1) for 2 h had a greater calcium concentration near the cathode, but quickly dissipated when the EF was removed. Schwann cells seeded 7 d after gels were exposed to substrate EF still aligned perpendicular to the EF direction. Microscopy of collagen I exposed to substrate EF shows alignment and bundling of fibrils. SIGNIFICANCE: These findings demonstrate EF exposure can control Schwann cell alignment and morphology, change ECM bulk/surface architecture, and align ECM structures.