Citations

Medical compression garments are used to treat lymphatic disorders or conditions of poor venous return (e.g. orthostatic intolerance). Conventional compression garments, namely elastic compression sleeves and inflatable compression systems, may aid in relief of these conditions but are also limited in usability. Fixed levels of compression in elastic materials may induce challenges in donning/doffing, complicating patient compliance [1]. Compression levels in inflatable systems are customizable, but these garments are also bulky and require a tethered inflation source [2]. We are interested in developing easy-to-don/-doff compression garments using shape memory alloy (SMA) coil actuators that contract with heat from an applied current which can be wrapped around the body to apply compressive forces. More specifically, we use a spring coil formation as described by Holschuh et al. [3]. Further developed in the Wearable Technology Lab at the University of Minnesota, our current SMA compression garment (SMA-CG) design improves upon the work of Duvall et al. [4] presented in previous year’s (2017) Design of Medical Devices Conference, representing a year’s evolution in active compression garment design that integrate actuators made with SMA.

ObjectiveInflammatory back pain (IBP) is often an early manifestation of spondyloarthritis (SpA), but the prognosis of patients with incident IBP is unknown. This study was undertaken to investigate long‐term outcomes in patients with IBP, and predictors of progression to SpA, in a population‐based cohort.MethodsWe conducted a retrospective, longitudinal study using the Rochester Epidemiology Project, a longstanding population‐based cohort of residents of Olmsted County, MN. Patients ages 16–35 years with clinical visits for back pain from 1999 to 2003 were identified, and we screened these patients for the presence of new‐onset IBP and performed medical record reviews to collect data on clinical, laboratory, and imaging features of SpA. Outcomes in these patients were followed up until July 2016. We used survival analysis for competing risks to examine progression to either SpA, a non‐SpA diagnosis, or resolution of back pain. Recursive partitioning was used to identify predictors of progression to SpA.ResultsAmong 5,304 patients with back pain, we identified 124 patients with new‐onset IBP. After a median follow‐up of 13.2 years, IBP had progressed to SpA in 39 patients, 15 patients developed a non‐SpA diagnosis, and 58 patients had resolution of IBP. At 10 years, the probability of having SpA was 30%, while the probability of resolution of IBP was 43%. The most important predictors for progression to SpA were uveitis, male sex, and family history of SpA.ConclusionIn a minority of patients, new‐onset IBP progresses to SpA, while IBP resolves in many. That IBP often resolves may explain the difference between the prevalence of IBP (3–6%) and the prevalence of SpA (0.4–1.3%).

Measurements were made of O2 uptake, CO2 output and CO2 tension of arterial and mixed venous blood and expired alveolar gas in 28 anesthetized and paralyzed dogs ventilated with air at a constant rate. Retention of CO2 was not observed in the lateral decubitus position with either closed or open thorax. Induction of open pneumothorax resulted in an unexplained metabolic alteration characterized by an increase in O2 uptake and CO2 elimination and a decrease in plasma buffer base. Small amounts of CO2 were eliminated from exposed pleura. The left pulmonary artery was occluded (after left thoracotomy) and 1 hour later the left bronchus also was occluded—or the order was reversed. CO2 retention of major degree was observed after initial occlusion of the artery and retention of minor degree after occlusion of the bronchus. During the 2nd hour (after additional occlusion) the previously retained CO2 was eliminated. The results suggest that the ventilatory requirements are not influenced specifically by effects of lateral position, open pneumothorax, or small right-to-left shunts, but rather are determined to a large degree by the metabolic production of CO2 and the degree to which ventilation is distributed to perfused alveoli. Submitted on December 3, 1958

The cardiovascular responses to sympathomimetic agents, the norepinephrine (NE) content in peripheral tissues, and the tissue content and cardiovascular effects of neuropeptide Y (NPY) were examined in anesthetized adult rats with guanethidine-induced sympathectomy (GuSx). We observed blunted pressor responses to tyramine, exaggerated pressor responses to phenylephrine, and markedly reduced NE contents in the atrium, femoral artery, superior cervical ganglion (SCG), and sciatic and vagus nerves. When tyramine responses were corrected for the NE content in the SCG, GuSx rats were similar to controls. A depletion of NPY levels in tissue resulted in an increased sensitivity to the pressor effects of intravenous NPY administration. GuSx, therefore, reproduces findings of postganglionic adrenergic failure in humans. Responses to the administration of sympathomimetic agents may reflect the degree of noradrenergic denervation. NPY may be a potential marker of chronic postganglionic sympathetic denervation in cardiovascular tissue.

The distribution of tidal air and nonshunted blood flow to each lung, the elimination of CO2 from each lung, and Paco2 were measured in ten anesthetized and paralyzed dogs during intermittent positive-pressure breathing in the supine position and before and after thoracotomy in the lateral decubitus position. Ventilation via a divided tracheal airway (Wright-Lategola) at a constant rate and a constant volume (±5%) with 65% oxygen in nitrogen was provided by a Bird ventilator. Reduction of total CO2 elimination and increase of ratio of total physiologic dead space to tidal volume were observed after thoracotomy. Mean percentages of total ventilation and blood flow to, and CO2 elimination from, the right lung were about 58% in the supine position. When the right or left lung became dependent in the lateral decubitus position, its proportional ventilation and CO2 elimination decreased. After thoracotomy was made on the superior nondependent side, further reductions were noted and blood flow to the dependent lung also decreased. Proportional CO2 elimination was more dependent on alveolar ventilation than on the ratio of ventilation to perfusion.

Action potentials of single vagal afferent nerve fibers from slowly adapting pulmonary stretch receptors, transpulmonary pressure and rate of air flow were recorded in anesthetized cats with open thoraxes during varied volumes and rates of inflation and deflation of the lungs. Both discharge frequency and total transpulmonary pressure varied with lung volume and also with its rate and sign of change. Effects of acceleration of volume on discharge frequency were not observed. The receptors provide signals related to the work of breathing.