Characterization of submucosal lesions using optical coherence tomography in the rabbit subglottis.

OBJECTIVE: To evaluate the efficacy of optical coherence tomography in differentiating between several simulated subglottic lesions, using an ex vivo rabbit laryngotracheal model. DESIGN: Laryngotracheal complexes were harvested from euthanized rabbits and divided into the following 4 groups: (1) control, (2) submucosal collagen injection (simulating scar formation), (3) dehydration and rehydration (simulating edema), and (4) repeated intubation trauma. The subglottic region was imaged using optical coherence tomography. Images were later correlated with conventional histologic findings. RESULTS: The epithelium, basement membrane, lamina propria, perichondrium, and cartilage (cricoid and tracheal) were clearly imaged. In group 2, an increase in the thickness of the lamina propria was observed, in addition to a characteristic optical pattern of the injected collagen. Dehydration (in group 3) produced a visible reduction in the thickness of the lamina propria, while rehydration of the same specimen with distilled water revealed a significant increase in submucosal swelling. Repeated intubation (in group 4) resulted in tissue edema that was seen as wavy heterogeneous thickening of the lamina propria. Edema produced by repeated intubation or distilled water immersion was easily differentiated from native and collagen-injected tissues. CONCLUSION: Optical coherence tomography successfully identifies the microstructure layers of the subglottis and can differentiate between edema and increased collagen deposition in the rabbit model.

A novel laryngoscope instrument stabilizer for operative microlaryngoscopy.

OBJECTIVE: To evaluate and optimize the design of a removable and inexpensive internal stabilization device to reduce the effect of intention tremor during laryngeal microsurgery. STUDY DESIGN AND SETTING: In this laboratory investigation, stabilizers were designed and constructed to allow a nonobstructing view of the surgical field, permit simple insertion and removal, and accommodate microsurgical instruments. Prototype stabilizers were tested by using a Dedo laryngoscope, a measurement grid, and video recording equipment, which recorded instrument tremor within the magnified operative field for later analysis. Physicians also rated instrument stability, mobility, visualization, and ease of use on a survey form. RESULTS: Instrument tremor was reduced approximately 90%, with little obstruction of view of the surgical field. Instrument range of motion was reduced but improved rapidly as the stabilizer bar was moved further from the tip of the laryngoscope. CONCLUSIONS: Use of a stabilization device in the laryngoscope lumen reduces instrument tremor and has the potential to improve surgical performance during laryngeal microsurgery. EBM RATING: B-3.

Congenital lobar emphysema: an otolaryngologic perspective.

Congenital lobar emphysema (CLE) is an uncommon but potentially life threatening pulmonary abnormality affecting infants. Patients often present within the first 6 months of life with recurrent respiratory distress as a result of hyperinflation of the affected pulmonary lobe, and resultant near total collapse of normal lung parenchyma. We present a case of a 2-month-old infant with recurrent admissions for respiratory distress.

Predicting survival of lung transplantation candidates with idiopathic interstitial pneumonia: does PaO(2) predict survival?

OBJECTIVE: To find a parameter that would discriminate between the patients with idiopathic interstitial pneumonia who survived to undergo transplantation and those who died while waiting to undergo transplantation. METHODS: A retrospective review was performed of all lung transplant referrals for idiopathic interstitial pneumonia that were listed with United Network for Organ Sharing at the University of California San Diego from January 1990 to February 1999. Of the 331 patients who were listed, 48 met the eligibility criteria. Patient demographics, radiographic studies, pathology reports, and the results of resting and exercise cardiopulmonary function tests were recorded from each patient's chart. Patients were divided into the following two groups: those patients who survived until transplantation and those still waiting were classified as "alive"; and those patients who died before undergoing transplantation were classified as "deceased." RESULTS: Forty-three of 48 patients had a pathologic diagnosis. The cohort included 25 patients with usual interstitial pneumonitis, 3 patients with nonspecific interstitial pneumonitis, 1 patient with desquamative interstitial pneumonitis, and 14 patients with interstitial lung disease of unknown etiology. The only significant difference between the two groups was resting PaO(2) (p = 0.035). A stepwise multivariate analysis demonstrated that PaO(2) and FEV(1)/FVC ratio were significantly associated with survival (hazards ratio, 1.06; confidence interval, 0.99 to 1.13; p = 0.019). CONCLUSIONS: A survival analysis using PaO(2) and FEV(1)/FVC ratio values proved to be statistically significant, but a prospective trial is needed to determine the clinical relevance of these parameters for predicting survival in patients with idiopathic interstitial pneumonia.

A cost-benefit analysis and method of creating high-quality posters for a low cost.

OBJECTIVE: To introduce the results of a cost-benefit analysis comparing an office-based low-cost technique for producing research posters versus conventional methods. STUDY DESIGN: Cost-benefit analysis. METHODS: The average cost for manufacturing a 4' x 6' poster using university-based and commercial reprographic centers (from 10 different institutions and cities) was determined through a phone survey. The total number of posters (1248) presented at the American Academy of Otolaryngology-Head and Neck Surgery Annual Meeting from 1995 through 1999 was used to calculate and subsequently compare the total cost of generating posters using conventional versus our low-cost method. A detailed description of this technique (low-cost) is also offered. RESULTS: The total printing costs for this meeting using the commercial or university-based services was $294,000 and $268,000 versus approximately $11,000 with our method. Esthetically, our technique is satisfactory and difficult to distinguish from standard methods from the typical poster-viewing distance. CONCLUSIONS: Given the current medical economic environment, the cost disparity between conventional and "low-cost" poster production, the esthetic acceptability of both, and the relative (compared with oral presentations) lack of scientific impact, we propose that the present technique is an extremely pragmatic option for poster production.

Radiofrequency cartilage reshaping: efficacy, biophysical measurements, and tissue viability.

OBJECTIVES: To assess the feasibility of reshaping cartilage using radiofrequency (RF) heating, and to examine the effects of this process on tissue biophysical properties (optical and thermal) and cellular viability. METHODS: Mechanically deformed porcine septal cartilage was reshaped using 2 RF-generating devices. We performed dynamic measurements of tissue thermal and optical properties while heating cartilage with one of these devices. Cellular viability was assessed immediately and 7 days after treatment. RESULTS: A characteristic change in the diffuse transmittance of light through the cartilage occurred during heating. Change in transmittance has been shown to accompany the onset of stress relaxation in cartilage. Peak radiometric surface temperature during heating was 88.6 degrees C. Specimens retained their user-specified curved shape for the observed period of 14 days. Chondrocyte viability in RF-heated tissue was 19% and 14% of that in untreated control specimens at days 0 and 7 after treatment, respectively. CONCLUSIONS: Radiofrequency heating has been shown to effectively reshape cartilage while maintaining cellular viability, illustrating a novel application for a widely used technology.

Long-term in vivo stability of rabbit nasal septal cartilage following laser cartilage reshaping: a pilot investigation.

BACKGROUND AND OBJECTIVES: To evaluate the long-term effect of laser cartilage reshaping on rabbit nasal septal cartilage viability and mechanical integrity in an in vivo model. STUDY DESIGN/MATERIALS AND METHODS: In vivo animal investigation. Rabbit septal cartilage specimens were laser (Nd:YAG, lambda = 1.32 mum, spot size 5.4-mm diameter, 10 W, 10 seconds, 50 Hz PPR) reshaped and subsequently reimplanted into an interscapular subcutaneous pocket. Specimens were harvested at 8 and 12 months and evaluated using photography, flow cytometry, and histology. RESULTS: Grossly, specimens showed alteration in the physical integrity with varying degrees of tissue resorption. The non-irradiated control specimens demonstrated significantly increased stiffness. Histologically, there was marked depletion of the extracellular matrix and an overall reduction in tissue mass in laser irradiated tissues. However, flow cytometry data identified viable chondrocytes in laser-irradiated specimens that were identical to those observed in controls. CONCLUSIONS: Study results demonstrate that the rabbit nasal septal cartilage model can be effectively used to study laser reshaping, however alternative recipient sites with perichondrial lining, such as the pinna, may provide a more realistic physiologic environment for reshaped graft tissue. The dosimetry used in this pilot study likely led to significant thermal injury. Study results underscore the importance of elucidating the optimal laser dosimetry required to initiate permanent shape change while minimizing thermal damage.

Lasers in pediatric airway surgery: current and future clinical applications.

BACKGROUND AND OBJECTIVES: The smaller anatomy and limited access to instrumentation pose a challenge to the pediatric airway surgeon. The enhanced precision and ability to photocoagulate tissue while operating with the laser enhances the surgeon's ability to successfully treat unique pediatric conditions. STUDY DESIGN/MATERIALS AND METHODS: A comprehensive literature review was performed using the Medline (1995-2004) database. RESULTS: Due to its shallow tissue penetration and thermal effect, the carbon dioxide (CO2) laser is generally considered the laser of choice for pediatric airway applications. The potential for increased scarring and damage to underlying tissue caused by the greater penetration depth and thermal effect of the Nd:YAG and potassium-titanyl-phosphate (KTP) lasers preclude their widespread use in this population. CONCLUSIONS: In this review, we will discuss the clinical applications of lasers in pediatric airway surgery, the current state of the art, where the current technology is deficient, and the potential applications of novel laser systems.