Alexander T. Hillel

Applications of robotics for laryngeal surgery.

The authors present the clinical application of robotics to laryngeal surgery in terms of enhancement of surgical precision and performance of other minimally invasive procedures not feasible with current instrumentation. Presented in this article are comparisons of human arm with robotic arm in terms of degrees of freedom and discussion of surgeries and outcomes with use of the robotic arm. Robotic equipment for laryngeal surgery has the potential to overcome many of the limitations of endolaryngeal procedures by improving optics, increasing instrument degrees of freedom, and modulating tremor. Outside of laryngology, a multi-armed robotic system would have utility in microvascular surgery, procedures at the base of the skull, sinus surgery, and single-port gastrointestinal and thoracic access surgery.

Photoactivated Composite Biomaterial for Soft Tissue Restoration in Rodents and in Humans

Photoactivated composite poly(ethylene glycol)–hyaluronic acid biomaterials demonstrate enhanced physicochemical properties for facial soft tissue reconstruction. Photogenic Polymers Can Fix the Flaws Some people just love the spotlight; apparently, some polymers do too. Here, Hillel et al. introduce a class of composite polymers that react favorably to light by crosslinking within minutes. These polymers, composed of synthetic poly(ethylene glycol) (PEG) and natural hyaluronic acid (HA), have been developed for reconstructing facial soft tissue. Deformities in craniofacial soft tissue are a clinical challenge because even small defects can have a major impact on a person’s social behavior and psychological well-being. Hillel and colleagues created a polymeric composite that can be injected into the damaged site, massaged into shape, and then crosslinked in situ with light. A transdermal light exposure method would allow clinicians to inject a liquid polymer, rather than surgically inserting already-polymerized material. First, the authors designed an array of light-emitting diodes to penetrate up to 4 mm of human skin (both light and dark) without any painful side effects. A 2-min exposure to light was enough to crosslink the PEG-HA material under the skin. Next, the polymer was tailored to closely match the elastic properties of native soft tissues, such as human fat. Various amounts of PEG and concentrations of HA were tested, with the authors arriving at an optimal combination of 100 mg PEG and 24 mg/ml HA. When polymerized subcutaneously in rats, the PEG-HA implants were able to maintain near their original volume for up to 491 days, whereas control HA injections were completely resorbed. Notably, these HA-based materials were partially reversible with the addition of the enzyme hyaluronidase. To translate this material to the clinic, Hillel et al. then tested the PEG-HA composites in humans. The polymer was injected into the intradermal space in the abdomen of three patients scheduled to undergo abdominoplasty surgery. Similar to the rodent studies, the PEG-HA material persisted for 12 weeks, whereas the control HA injections lost their shape. An inflammatory response was observed surrounding the injections. It is clear that this new photo-friendly polymer and transdermal crosslinking method will be clinically useful for soft tissue reconstruction—perhaps even encouraging more people to put their best faces forward in the spotlight. Soft tissue reconstruction often requires multiple surgical procedures that can result in scars and disfiguration. Facial soft tissue reconstruction represents a clinical challenge because even subtle deformities can severely affect an individual’s social and psychological function. We therefore developed a biosynthetic soft tissue replacement composed of poly(ethylene glycol) (PEG) and hyaluronic acid (HA) that can be injected and photocrosslinked in situ with transdermal light exposure. Modulating the ratio of synthetic to biological polymer allowed us to tune implant elasticity and volume persistence. In a small-animal model, implanted photocrosslinked PEG-HA showed a dose-dependent relationship between increasing PEG concentration and enhanced implant volume persistence. In direct comparison with commercial HA injections, the PEG-HA implants maintained significantly greater average volumes and heights. Reversibility of the implant volume was achieved with hyaluronidase injection. Pilot clinical testing in human patients confirmed the feasibility of the transdermal photocrosslinking approach for implantation in abdomen soft tissue, although an inflammatory response was observed surrounding some of the materials.

Engineering Musculoskeletal Tissues with Human Embryonic Germ Cell Derivatives

The cells derived from differentiating embryoid bodies of human embryonic germ (hEG) cells express a broad spectrum of gene markers and have been induced toward ecto‐ and endodermal lineages. We describe here in vitro and in vivo differentiation of hEG‐derived cells (LVEC line) toward mesenchymal tissues. The LVEC cells express many surface marker proteins characteristic of mesenchymal stem cells and differentiated into cartilage, bone, and fat. Homogenous hyaline cartilage was generated from cells after 63 population doublings. In vivo results demonstrate cell survival, differentiation, and tissue formation. The high proliferative capacity of hEG‐derived cells and their ability to differentiate and form three‐dimensional mesenchymal tissues without teratoma formation underscores their significant potential for regenerative medicine. The adopted coculture system also provides new insights into how a microenvironment comprised of extracellular and cellular components may be harnessed to generate hierarchically complex tissues from pluripotent cells. STEM CELLS 2010;28:765–774

Difficult Airway Response Team: A Novel Quality Improvement Program for Managing Hospital-Wide Airway Emergencies

BACKGROUND:Difficult airway cases can quickly become emergencies, increasing the risk of life-threatening complications or death. Emergency airway management outside the operating room is particularly challenging. METHODS:We developed a quality improvement program—the Difficult Airway Response Team (DART)—to improve emergency airway management outside the operating room. DART was implemented by a team of anesthesiologists, otolaryngologists, trauma surgeons, emergency medicine physicians, and risk managers in 2005 at The Johns Hopkins Hospital in Baltimore, Maryland. The DART program had 3 core components: operations, safety, and education. The operations component focused on developing a multidisciplinary difficult airway response team, standardizing the emergency response process, and deploying difficult airway equipment carts throughout the hospital. The safety component focused on real-time monitoring of DART activations and learning from past DART events to continuously improve system-level performance. This objective entailed monitoring the paging system, reporting difficult airway events and DART activations to a Web-based registry, and using in situ simulations to identify and mitigate defects in the emergency airway management process. The educational component included development of a multispecialty difficult airway curriculum encompassing case-based lectures, simulation, and team building/communication to ensure consistency of care. Educational materials were also developed for non-DART staff and patients to inform them about the needs of patients with difficult airways and ensure continuity of care with other providers after discharge. RESULTS:Between July 2008 and June 2013, DART managed 360 adult difficult airway events comprising 8% of all code activations. Predisposing patient factors included body mass index >40, history of head and neck tumor, prior difficult intubation, cervical spine injury, airway edema, airway bleeding, and previous or current tracheostomy. Twenty-three patients (6%) required emergent surgical airways. Sixty-two patients (17%) were stabilized and transported to the operating room for definitive airway management. There were no airway management–related deaths, sentinel events, or malpractice claims in adult patients managed by DART. Five in situ simulations conducted in the first program year improved DART’s teamwork, communication, and response times and increased the functionality of the difficult airway carts. Over the 5-year period, we conducted 18 airway courses, through which >200 providers were trained. CONCLUSIONS:DART is a comprehensive program for improving difficult airway management. Future studies will examine the comparative effectiveness of the DART program and evaluate how DART has impacted patient outcomes, operational efficiency, and costs of care.

Selective versus comprehensive neck dissection after chemoradiation for advanced oropharyngeal squamous cell carcinoma

OBJECTIVE: To determine whether a comprehensive neck dissection (CND) or a selective neck dissection (SND) is indicated as planned post–primary chemoradiation treatment (CRT) for patients with advanced oropharyngeal squamous cell carcinoma (OPSCC). STUDY DESIGN: Case series with chart review. SETTING: A community teaching hospital. SUBJECTS: Patients with advanced OPSCC who received a uniform CRT protocol at Greater Baltimore Medical Center (GBMC). METHODS: Medical records of patients treated with primary CRT for locoregionally advanced OPSCC at GBMC between 2001 and 2007 were reviewed. All patients received 7000 to 7500, 6000, and 5000 cGy to primary disease sites, involved cervical lymphatics, and uninvolved cervical and supraclavicular lymphatics, respectively, with concomitant cisplatin (12 mg/m2/1 h) and 5-fluorouracil (600 mg/m2/20 h) given on days one through five and 29 through 33. RESULTS: Seventy-six patients received CRT, and 41 met the criteria for neck dissection. Forty-eight neck dissections were performed (34 unilateral and 7 bilateral), of which 23 (48%) were CNDs and 25 (52%) were SNDs. Residual carcinoma was found in six (26%) of the CND and five (20%) of the SND heminecks. The CND group had six (26%) complications, whereas the SND group had two (8%). CONCLUSION: The high rate of residual disease demonstrated in this study supports the need for post-CRT neck dissection. Although complication rates were not significantly different between the two groups, the trend in this study indicates that SND results in less morbidity. The presumed reduced morbidity and equivalent regional control rate suggest that SND is an appropriate surgical option for OPSCC patients after primary CRT.

Characterization of human mesenchymal stem cell-engineered cartilage: analysis of its ultrastructure, cell density and chondrocyte phenotype compared to native adult and fetal cartilage.

The production of engineered cartilage from mesenchymal stem cells is a rapidly developing field. Potential applications include the treatment of degenerative joint disease as well as the treatment of traumatic and surgical bone injury. Prior to clinical application, however, further characterization of the morphology, ultrastructure, biocompatibility, and performance of the engineered tissue is warranted. To achieve this, human mesenchymal stem cells (hMSCs) were grown in vitro in pellet culture for 3 weeks in chondrogenic medium conditions. The resultant engineered cartilage was compared to native adult and fetal tissue. Routine histology, special stains, and ultrastructural and quantitative histomorphometric analyses were performed. The engineered tissue demonstrated a similar chondrocyte phenotype, collagen fibril appearance, and matrix distribution when compared to native cartilage. By histomorphometric analysis, the cell density of the engineered cartilage was between that of native fetal and adult cartilage. The cell-to-matrix ratio and cellular area fraction of engineered cartilage samples was significantly greater than in adult samples, but indistinguishable from fetal cartilage samples, supporting the hypothesis that hMSC-engineered cartilage regeneration may mimic fetal cartilage development.

Disease homogeneity and treatment heterogeneity in idiopathic subglottic stenosis

Idiopathic subglottic stenosis (iSGS) is a rare and potentially life‐threatening disease marked by recurrent and progressive airway obstruction frequently requiring repeated surgery to stabilize the airway. Unknown etiology and low disease prevalence have limited the ability to characterize the natural history of iSGS and resulted in variability in surgical management. It is uncertain how this variation relates to clinical outcomes.

Evolution of endoscopic surgical therapy for Zenker's diverticulum

Zenkers diverticulum is a rare anatomic defect that physicians have confronted for almost 250 years. Its location at the interface of the pharynx, neck, and mediastinum makes surgical access difficult and risks severe morbidity. Minimally invasive endoscopic surgical repair of Zenkers diverticulum has been attempted for more than a century as an alternative to reduce morbidity of an open transcervical approach. However, limitations due to available antibiotics, instrumentation, and laryngoscopes, as well as a general discomfort with a sutureless closure of the mucosal excision, have delayed widespread adoption of minimally invasive repair until the last 10 to 15 years. This manuscript will detail the historical evolution of endoscopic surgical therapy for Zenkers diverticulum and highlight the work of two otolaryngologists, Chevalier Jackson and Gosta Dohlman, who were critical in advancing the surgical technique and reducing morbidity. Lastly, this manuscript will analyze the delay in widespread application of endoscopic surgical repair of Zenkers diverticulum. Laryngoscope, 119:39–44, 2009

A novel role for otolaryngologists in the multidisciplinary difficult airway response team

The Difficult Airway Response Team (DART) was implemented in July 2008 to address emergent difficult airway situations. The main objective of this study was to highlight the unique role and skill set that otolaryngologists bring and their impact on patient outcomes.

Utilization of a standardized tracheostomy capping and decannulation protocol to improve patient safety

To develop and assess the feasibility of a new standardized protocol to guide tracheostomy decannulation.