George Z. Cheng

Three-dimensional Printing and 3D Slicer: Powerful Tools in Understanding and Treating Structural Lung Disease.

Recent advances in the three-dimensional (3D) printing industry have enabled clinicians to explore the use of 3D printing in preprocedural planning, biomedical tissue modeling, and direct implantable device manufacturing. Despite the increased adoption of rapid prototyping and additive manufacturing techniques in the health-care field, many physicians lack the technical skill set to use this exciting and useful technology. Additionally, the growth in the 3D printing sector brings an ever-increasing number of 3D printers and printable materials. Therefore, it is important for clinicians to keep abreast of this rapidly developing field in order to benefit. In this Ahead of the Curve, we review the history of 3D printing from its inception to the most recent biomedical applications. Additionally, we will address some of the major barriers to wider adoption of the technology in the medical field. Finally, we will provide an initial guide to 3D modeling and printing by demonstrating how to design a personalized airway prosthesis via 3D Slicer. We hope this information will reduce the barriers to use and increase clinician participation in the 3D printing health-care sector.

Concurrent Intrapleural Instillation of Tissue Plasminogen Activator and DNase for Pleural Infection. A Single-Center Experience

RATIONALE Treatment of pleural infection with instillation of intrapleural tissue plasminogen activator (tPA) and human recombinant DNase (DNase) has been proven to decrease the length of hospital stay, decrease surgical referral, and improve drainage. The optimal dosage, administration, timing, and frequency of the regimen remain unclear. It is unknown if the two drugs can be administered immediately one after the other (referred to as concurrent) instead of instilling them separately with a 1- to -2-hour interval in between. OBJECTIVES To assess the safety and efficacy of concurrent instillation of intrapleural tPA/DNase guided by radiographic and clinical response in patients with pleural infection. METHODS We conducted a retrospective cohort study. Consecutive patients with pleural infection who received concurrent tPA/DNase were included. The initiation and number of doses of tPA/DNase therapy were based on pleural fluid drainage, clinical response, and radiographic findings. MEASUREMENTS AND MAIN RESULTS Seventy-three patients received concurrent tPA/DNase therapy. Treatment was successful in 90.4% of them; 80.8% were effectively treated with fewer than six doses of therapy (median, 2; interquartile range [IQR], 1-3.5); and 71.2% received their first dose of tPA/DNase within 24 hours after chest tube insertion. The median hospital stay from the first dose of tPA/DNase to discharge was 7 days (IQR, 5-11 d). The volume of pleural fluid drained increased from a median of 295 ml (IQR, 97.5-520 ml) 24 hours before treatment to a median of 1,102 ml (IQR, 627-2,200 ml) 72 hours following therapy (P < 0.001). Nonfatal pleural bleeding occurred in 5.4%, 15.1% had chest pain, and 2.7% died as a result of pleural infection. CONCLUSIONS This cohort study shows that early administration of concurrent tPA/DNase in patients with pleural infection is relatively safe and effective. Given the high cost of therapy, it is feasible to guide therapy on the basis of clinical and radiographic response.

Tunneled Pleural Catheter Placement with and without Talc Poudrage for Treatment of Pleural Effusions Due to Congestive Heart Failure

RATIONALE There is a paucity of evidence regarding the role of tunneled pleural catheters in pleural effusions caused by congestive heart failure that is refractory to medical management. OBJECTIVES The aim of this study was to assess the feasibility of tunneled pleural catheter drainage for treatment of refractory pleural effusions associated with congestive heart failure, either when used alone or with concomitant talc pleurodesis performed during thoracoscopy. METHODS This was a retrospective cohort study. We identified patients with congestive heart failure and recurrent symptomatic pleural effusions who were treated between 2005 and 2015 by placement of a tunneled pleural catheter. Patients underwent either thoracoscopy followed by talc poudrage and pleural catheter placement (group 1) or catheter insertion alone (group 2). MEASUREMENTS AND MAIN RESULTS Forthy-three catheters were inserted in 36 patients, with 15 placed in group 1 and 28 in group 2. Successful pleurodesis was seen in 80% in group 1 and 25% in group 2. The median time of catheter placement was 11.5 days in group 1 and 66 days in group 2. There was a significant decrease in hospital admissions and pleural interventions after catheter placement compared with before insertion (P < 0.05). CONCLUSIONS This single-center, retrospective study demonstrated the feasibility of catheter placement used alone or with talc poudrage for the treatment of refractory pleural effusions associated with congestive heart failure. The addition of talc poudrage might increase the pleurodesis rate and reduce the days to catheter removal in highly selected patients. Prospective studies on a larger number of patients are warranted to verify the safety and efficacy of this intervention.

3D Printing and Personalized Airway Stents

In recent years, the 3D printing industry has undergone rapid development. Clinicians and researchers have begun to apply this technology in procedural planning, tissue engineering, and device manufacturing. Rapid prototyping and additive manufacturing techniques in the healthcare field have already yielded very exciting results and point to a bright future involving these technologies. This is especially true in pulmonology. 3D printing industry growth is accompanied by increased availability of 3D printers and printable materials, which offers exciting arrays of possible applications. In this review, we present a brief history of 3D printing and its applications in the medical field with a focus on pulmonology. Additionally, we describe a methodology on how to 3D model and print personalized airway prosthesis via 3D Slicer and a commercial 3D printer. We hope this will help to stimulate additional innovation and application of 3D printing in medicine.

Three-dimensional Modeled T-tube Design and Insertion in a Patient With Tracheal Dehiscence

A 68-year-old man with recurrent medullary thyroid cancer underwent cervical tracheal resection and reconstruction. His course was complicated by tracheal anastomotic dehiscence, right carotid blowout, and ultimately cervical tracheoplasty with AlloDerm. Given the complex vascular interventions and upper-airway anatomy, a custom-designed Montgomery T-tube was designed for him. Three-dimensional digital reconstruction of his upper airways was obtained from a CT scan. The T-tube was designed and fabricated based on the digital trachea model and was subsequently placed successfully. Follow-up CT scan and bronchoscopy confirmed placement and revealed no granulation tissue at 4 weeks. The patient was discharged to home with the ability to phonate. To our knowledge, this is the first demonstration of three-dimensional modeling of an upper-airway defect with subsequent T-tube design using engineering software. The success of this case demonstrates a possible avenue for personalized airway prosthesis design and manufacturing in the future.

Safety and Efficacy of Tissue Plasminogen Activator and DNase for Complicated Pleural Effusions Secondary to Abdominal Pathology

Rationale: Exudative pleural effusions may arise secondary to inflammation of intra‐abdominal structures. Pleural space loculations can complicate these effusions, preventing adequate chest tube drainage and leading to consideration of surgical intervention. Previous studies have demonstrated that intrapleural administration of tissue plasminogen activator (tPA) combined with human recombinant DNase can improve fluid drainage and reduce surgery for patients with loculated parapneumonic effusions; however, the efficacy of this treatment has not been evaluated for complicated pleural effusions attributed to intra‐abdominal inflammation. Objectives: We assessed the safety and efficacy of tPA/DNase for 17 pleural effusions associated with nonmalignant intra‐abdominal pathology that did not drain adequately after placement of one or more chest tubes. Methods: Efficacy was measured by comparing post‐ to pretreatment fluid drainage rates, volumetric assessment of pleural fluid on radiographic images before and after treatment, and clinical improvement, including the need for surgical intervention. Symptomatic relief was assessed using the Borg scale for breathlessness. Measurements and Main Results: After a median of two doses of tPA/DNase, 23.5% of patients had chest pain and none had pleural bleeding. The volume of pleural fluid drained increased from a median of 325 ml to 890 ml per 24 hours after therapy (P = 0.018). The area of pleural space opacity on chest radiographs decreased from a median of 42.8‐17.8% of the hemithorax (P = 0.001). tPA/DNase reduced the pleural fluid volume on chest computed tomographic imaging from a median of 294.4 ml to 116.1 ml. Borg scores improved from a median of 3 (interquartile range = 1‐6) to 0 (interquartile range = 0‐2) after therapy (P = 0.001). The median duration of chest tube placement and hospital stay were 4 and 11 days, respectively. Two patients required surgical intervention for lung entrapment. Overall, treatment was considered successful for 88.2% of patients. Conclusions: This retrospective case series suggests that intrapleural tPA/DNase can be safe and effective for patients with complicated pleural effusions attributed to abdominal pathology that do not drain adequately after chest tube placement. Additional studies are needed to determine whether the combination of tPA and DNase is more effective than tPA for this indication.

Use of Self-expanding Metallic Airway Stents in Tracheobronchomalacia.

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Evaluation of rigid bronchoscopy-guided percutaneous dilational tracheostomy. A pilot study.

RATIONALE Rigid bronchoscopy-guided (RBG) percutaneous tracheostomy has been used in patients with morbid obesity, prior neck surgery, distorted airway anatomy, and uncorrected coagulopathy where standard percutaneous dilational tracheostomy (PDT) is relatively contraindicated. OBJECTIVES This study aims to describe a standardized approach to incorporate RBG-PDT in clinical practice. METHODS AND MEASUREMENTS Retrospective case series of patients who underwent RBG-PDT from 2008 to 2012 at Beth Israel Deaconess Medical Center. Patient medical records were reviewed for demographics, comorbid conditions, American Society of Anesthesiologists classification, indication for tracheostomy, duration of procedure, and periprocedural complications. MAIN RESULTS A total of 35 patients underwent RBG-PDT, including 24 men, with a mean age of 66 years (±11 yr; range, 42-88 yr). The mean body mass index was 34 kg/m(2). The mean procedure time was 32 (±10) minutes, with a median of 33 minutes. The most common indication for tracheostomy was failure to wean from mechanical ventilation, followed by tracheal stenosis and tracheobronchomalacia. The most common indications for RBG-PDT were complex airway, obesity, and coagulopathy. There were no periprocedural complications of consequence, or mortality associated with the procedure. CONCLUSIONS RBG-PDT is safe and effective in a population of high-risk patients who are otherwise not considered good candidates for standard PDT.

Surface tension-assisted additive manufacturing

The proliferation of computer-aided design and additive manufacturing enables on-demand fabrication of complex, three-dimensional structures. However, combining the versatility of cell-laden hydrogels within the 3D printing process remains a challenge. Herein, we describe a facile and versatile method that integrates polymer networks (including hydrogels) with 3D-printed mechanical supports to fabricate multicomponent (bio)materials. The approach exploits surface tension to coat fenestrated surfaces with suspended liquid films that can be transformed into solid films. The operating parameters for the process are determined using a physical model, and complex geometric structures are successfully fabricated. We engineer, by tailoring the window geometry, scaffolds with anisotropic mechanical properties that compress longitudinally (~30% strain) without damaging the hydrogel coating. Finally, the process is amenable to high cell density encapsulation and co-culture. Viability (>95%) was maintained 28 days after encapsulation. This general approach can generate biocompatible, macroscale devices with structural integrity and anisotropic mechanical properties.Integrating cell-laden hydrogels effectively into the 3D printing process is a challenge in the creation of tissue engineering scaffolds. Here, the authors describe an additive manufacturing technique to combine polymer and cell-containing networks with 3D-printed mechanical supports.

Postradiofrequency ablation inflammatory pseudotumor associated with pulmonary venoocclusive disease: case report and review of the literature.

Radiofrequency ablation of pulmonary veins is a common therapeutic intervention for atrial fibrillation. Pulmonary vein stenosis and venoocclusive disease are recognized complications, but the spectrum of pathologies postablation have not been previously reviewed. A recent case at our hospital showed a left hilar soft tissue mass in association with superior pulmonary vein stenosis in a patient 4 years postablation. On resection, this proved to be an inflammatory pseudotumor composed of myofibroblasts in an organizing pneumonia-type pattern with adjacent dendriform ossifications. Pulmonary venoocclusive change was a prominent feature. Literature on the histopathology of postradiofrequency ablation complications is limited. The severity of vascular pathology appears to increase with the postablation interval. Although pulmonary vascular changes are the most common late finding, fibroinflammatory changes including pulmonary pseudotumor formation, attributable to thermal injury, should be considered in the differential diagnosis of these cases.