Thomas Robey

Characterization of a Sudden Expansion Flow Chamber to Study the Response of Endothelium to Flow Recirculation

In order to simulate regions of flow separation observed in vivo, a conventional parallel plate flow chamber was modified to produce an asymmetric sudden expansion. The flow field was visualized using light reflecting particles and the size of the recirculation zone was measured by image analysis of the particles. Finite element numerical solutions of the two and three-dimensional forms of the Navier-Stokes equation were used to determine the wall shear stress distribution and predict the location of reattachment. For two different size expansions, numerical estimates of the reattachment point along the centerline of the flow chamber agreed well with experimental values for Reynolds numbers below 473. Even at a Reynolds number of 473, the flow could be approximated as two-dimensional for 80 percent of the chamber width. Peak shear stresses in the recirculation zone as high as 80 dyne/cm2 and shear stress gradients of 2500 (dyne/cm2)/cm were produced. As an application of this flow chamber, subconfluent bovine aortic endothelial cell shape and orientation were examined in the zone of recirculation during a 24 h exposure to flow at a Reynolds number of 267. After 24 h, gradients in cell orientation and shape were observed within the recirculation zone. At the location of reattachment, where the wall shear stress was zero but the shear stress gradients were large, cells plated at low density were still aligned with the direction of flow. No preferred orientation was observed at the gasket edge where the wall shear stress and shear stress gradients were zero. At higher cell densities, no alignment was observed at the separation point.(ABSTRACT TRUNCATED AT 250 WORDS)

Biodegradable External Tracheal Stents and Their Use in a Rabbit Tracheal Reconstruction Model

Objectives/Hypothesis To design and develop an e‐ternal biodegradable tracheal stent for use in airway reconstructive surgery.

Recovery of vocal fold immobility following isolated patent ductus arteriosus ligation

OBJECTIVE Identify laryngoscopic and functional outcomes of infants with vocal fold immobility (VFI) following patent ductus arteriosus (PDA) ligation and identify predictors of recovery. METHODS Retrospective review of patients with VFI following PDA ligation from 2001 to 2012 at a single institution. Inclusion criteria were: (1) PDA ligation as only cardiac surgical procedure; (2) left VFI documented by laryngoscopy; (3) minimum follow up 120 days, with at least 2 laryngoscopies performed. Resolution of VFI was determined at follow-up laryngoscopy. Univariate logistic regression models were used to identify variables associated with VFI recovery. RESULTS 66 subjects were included with median follow up of 3.0 (± 2.1) years. The mean gestational age was 24.5 ± 1.4 weeks, mean birth weight 673 ± 167 g, and mean age at procedure was 18.6 ± 14.3 days. Patients presented with respiratory symptoms (39%), dysphonia (78%) and dysphagia (55%). Resolution of VFI was observed in 2/66 (3%) patients. Recovery was documented at 20 days and 11 months respectively. Respiratory symptoms, dysphagia, and dysphonia persisted at last follow up in 11%, 47%, and 20% of patients. CONCLUSIONS VFI associated with ligation of the ductus arteriosus has a low rate of recovery. Clinical symptoms frequently persist, and as such regular follow-up by otolaryngologists to mitigate morbidity is indicated.

Factors associated with tracheotomy and decannulation in pediatric bilateral vocal fold immobility.

OBJECTIVE Describe the natural history of all-cause bilateral vocal fold immobility (BVFI) in pediatric patients and analyze factors associated with tracheotomy and subsequent decannulation. METHODS This is a retrospective review of all patients diagnosed with complete or partial BVFI at a metropolitan private pediatric otolaryngology practice between 2001 and 2012. Records were reviewed for data on demographics, etiologies, vocal fold position, and BVFI resolution. Patients requiring tracheotomy were further investigated for tracheotomy duration and associated complications and procedures. RESULTS One hundred two patients were included, with a median (range) follow-up of 32.9 (0.3-124.2) months. Of these, 68.6% required tracheotomy. Tracheotomies were more likely in those with concomitant airway disease (p = 0.005) and paramedian vocal fold position compared to lateral position (p = 0.02). Among patients requiring tracheotomy, 64.3% underwent decannulation during follow up. Decannulation was more likely in those who demonstrated VFI resolution (p = 0.002) and those with idiopathic compared to neurogenic etiologies (p = 0.003). Median duration of cannulation was 30.6 (0.5-297.3) months. The most common tracheotomy-related complication requiring medical attention was tracheal and stomal granuloma formation (77.1%), while the most frequent associated procedures included granuloma excision (47.1%) and airway reconstruction (31.4%). Of those who avoided tracheotomy, 40.6% did not demonstrate BVFI resolution during median follow up of 13.4 (0.6-44.4) months. CONCLUSIONS Most pediatric BVFI patients require tracheotomy, with the majority of those undergoing eventual decannulation. A better understanding of the factors associated with tracheotomy and subsequent decannulation improves the otolaryngologists ability to counsel parents and caregivers of children with BVFI.

Vocal Fold Immobility due to Birth Trauma: A Systematic Review and Pooled Analysis

Objectives To describe the present understanding of birth trauma–related vocal fold immobility and quantitatively compare it with idiopathic congenital vocal fold immobility to explore whether it is a discrete entity. Data Sources PubMed, Ovid, and Cochrane databases. Review Methods English-language, observational, or experimental studies involving infants with idiopathic congenital or birth trauma–related vocal fold immobility were included. Data from these studies were pooled with our institution’s vocal fold immobility database, with the resultant idiopathic congenital and birth trauma cohorts compared regarding patterns and outcomes of immobility. Results The search returned 288 articles, with 24 meeting inclusion criteria. Of studies reviewing all-cause immobility, 8 of 9 (88.9%) identified birth trauma as an etiology, although birth trauma definitions and proposed mechanisms of immobility varied. The study subjects, combined with our institution’s database, yielded 188 idiopathic congenital and 113 birth trauma cases. Compared with idiopathic congenital cases, birth trauma cases had a higher proportion of unilateral immobility (72 of 113 [63.7%] vs 52 of 188 [27.7%], P < .001) and rate of resolution (41 of 51 [80.4%] vs 91 of 159 [57.2%], P = .003). Resolution occurred in 24 of 26 (91.3%) unilateral and 17 of 25 (68.0%) bilateral birth trauma cases and in 30 of 40 (75.0%) unilateral and 59 of 109 (54.1%) bilateral idiopathic congenital cases (P = .11 and .20, respectively). Conclusion While the definition and mechanism of birth trauma–related vocal fold immobility warrant further investigation, these findings suggest that it is distinct from idiopathic congenital vocal fold immobility, with a unique presentation and potentially more favorable outcomes. This can inform counseling and management for infants with otherwise unexplained immobility but known birth trauma.

Vocal fold paralysis in preterm infants: prevalence and analysis of risk factors

Objective:To calculate the prevalence of vocal fold paralysis (VFP) in preterm (<37 weeks of gestation) infants at a single neonatal intensive care unit (NICU) and identify risk factors for the development of VFP.Study Design:This is a case control study of all surviving preterm infants admitted to the NICU at Children’s Hospital of Wisconsin from 2006 to 2012, comparing those with and without VFP. Multivariate analysis was performed to identify significant risk factors for VFP.Results:Of the 2083 patients included, 73 (3.5%) had VFP, including 18% of those at <26 weeks of gestation. On multivariate analyses, VFP was associated with patent ductus arteriosus (PDA) ligation (P<0.001, odds ratio (OR) 15.9, 95% confidence interval (CI) 8.9 to 28.1), history of invasive ventilation (P=0.008, OR 4.5, 95% CI 1.5 to 13.6) and black vs non-black race (P=0.001, OR 2.5, 95% CI 1.5 to 4.3).Conclusion:Given the prevalence of VFP and its associated morbidity, efforts to decrease PDA ligation and invasive ventilation in preterm infants are warranted.

Self-directed Learning in Otolaryngology Residents’ Preparation for Surgical Cases: A Survey and Literature Review Examining Study Habits and Resource Utilization

Objectives: To characterize the nature of surgical preparation among otolaryngology residents nationwide, determine the self-rated effectiveness and efficiency of case preparation practices, and identify potential means for educational improvement. Methods: A survey examining the study objectives was developed and distributed to otolaryngology residents nationwide. Survey response data were submitted to descriptive analysis and comparative analyses between junior and senior residents. Literature regarding case preparation among otolaryngology residents was reviewed. Results: Among 108 resident respondents, the most commonly used resources included textbooks (86.1%), surgical education websites (74.1%), and surgical atlases (66.7%). Time was the primary limitation (cited by 84.3%) and convenience the predominant factor influencing resource selection (92.5%). On a 5-point Likert scale, mean scores regarding effectiveness and efficiency of case preparation were 3.53 ± 0.68 and 3.19 ± 0.88, respectively. Senior residents compared to junior residents were more likely to rate their preparation as effective (3.75 ± 0.54 vs 3.40 ± 0.72, P = .008) and efficient (3.45 ± 0.85 vs 3.03 ± 0.86, P = .02). Conclusion: Otolaryngology residents do not consistently rate their case preparation as effective or efficient. While there appears to be progress in self-directed learning throughout residency, room for improvement remains, with potential avenues for such improvement explored here.

Trends in Pediatric Otolaryngology Disparities Research

Objectives To describe trends in disparities research within pediatric otolaryngology as evidenced by major meeting presentations and to compare observed trends with those in the realm of patient safety and quality improvement (PSQI). Study Design Retrospective review of presentations at national otolaryngology meetings. Setting Online review of meeting programs. Subjects and Methods Meeting programs from the American Society of Pediatric Otolaryngology, Triological Society, American Academy of Otolaryngology—Head and Neck Surgery Foundation, and Society for Ear, Nose and Throat Advances in Children from 2003 to 2016 were manually searched for pediatric oral and poster presentations addressing disparities and socioeconomic determinants of health, as well as PSQI. Presentation frequency was compared between categories and within each category over time. Results Of 11,311 total presentations, 3078 were related to the pediatric population, and 1945 (63.2%) of those were oral presentations. Disparities-related presentations increased from 0 in 2003 to 17 in 2016. From 2003 to 2009, 9 of 656 (1.4%) presentations involved disparities, as opposed to 70 of 2422 (2.9%) from 2010 to 2016 (P = .03). The proportion of presentations regarding PSQI also increased: from 42 of 656 (6.4%) in 2003-2009 to 221 of 2422 (9.1%) in 2010-2016 (P = .01). PSQI presentations remain more common than disparities presentations (9.1% vs 2.9%, P < .001). Conclusion Health care disparities are increasingly addressed in pediatric otolaryngology meeting presentations. Compared with the well-established realm of PSQI, disparities research remains nascent but is gaining attention. Health care reform and quality improvement efforts should recognize the role of socioeconomic factors and include strategies for addressing disparities.

Healthcare disparities in pediatric otolaryngology: A systematic review: Disparities in Pediatric Otolaryngology

Multiple studies have reported healthcare disparities in particular settings and conditions within pediatric otolaryngology, but a systematic examination of the breadth of the problem within the field is lacking. This studys objectives are to synthesize the available evidence regarding healthcare disparities in pediatric otolaryngology, highlight recurrent themes with respect to etiologies and manifestations, and demonstrate potential impacts from patient and provider standpoints.