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Biomedical subjects

James A Burns

Publications and source records attributed to James A Burns.

11 recordsLinked to original sources
PubMed2007

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

OBJECTIVES: Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. STUDY DESIGN: The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. METHODS: Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. RESULTS: Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). CONCLUSIONS: This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Animals↗
PubMed2006

Office-based 532-nm pulsed KTP laser treatment of glottal papillomatosis and dysplasia.

OBJECTIVES: Treatment of glottal papillomatosis and dysplasia was mirror-guided and done in surgeons' offices in the 19th century. It migrated to the operating room in the 20th century to accommodate direct laryngoscopic surgery, which required assistants to administer anesthesia and procedural support. The primary treatment goals, which are disease regression and voice restoration and/or maintenance, are tempered by the morbidity of general anesthesia and potential treatment-induced vocal deterioration. To obviate general anesthesia, office-based laser laryngeal surgery was first done in 2001 with the 585-nm pulsed dye laser (PDL), because it employs a fiber delivery system and its energy is selectively absorbed by oxyhemoglobin. Since then, this new angiolytic laser treatment paradigm has become a mainstay of management for many surgeons; however, there are a number of shortcomings of the PDL. To further develop this concept and address the limitations of the PDL, we used a 532-nm pulsed potassium titanyl phosphate (KTP) laser. METHODS: A prospective assessment was performed on 48 patients in 72 cases of recurrent glottal dysplasia (36) or papillomatosis (36). All individuals had previously undergone microlaryngoscopic management with histopathologic evaluation. RESULTS: Two dysplasia patients did not tolerate the procedure. Of the treatable dysplasia cases, there was follow-up in 29 of 34. Disease regression was at least 75% in 18 of 29 cases (62%), 50% to 75% in 7 of 29 (24%), and 25% to 50% in the remaining 4 of 29 (14%). Papilloma patients returned for treatment when symptoms recurred, so disease regression could not be assessed accurately. Similar to data obtained with the PDL, these data confirmed that dysplastic mucosa could normalize without resection. CONCLUSIONS: Our observations revealed that the 532-nm pulsed KTP laser provided enhanced performance over the PDL laser in a number of ways. The ability to use smaller glass fibers precluded mechanical trauma to the channels of the flexible laryngoscopes and allowed for improved suctioning of secretions. Oxyhemoglobin absorbs energy better at 532 nm than at 585 nm, and the KTP laser can be delivered through a longer pulse width. These factors provide enhanced hemostasis and improved intralesional energy absorbance. Finally, unlike the PDL, the KTP laser is a solid-state laser and is not prone to mechanical failure.

Ambulatory Surgical Procedures↗
PubMed2006

Comparison of a flexible laryngoscope with calibrated sizing function to intraoperative measurements.

OBJECTIVES: The objectives were to assess the clinical performance and accuracy of a prototype fiberoptic transnasal laryngeal endoscope with an auxiliary optical system that allows images to be spatially calibrated. METHODS: A novel fiberoptic endoscope was developed that projects green laser beams across the field of view from a separate optical channel. According to the location of the spots in the field of view, the images can be calibrated with a software routine. To assess its performance, we compared measurements of 14 lesions imaged with the calibrated endoscope and during microlaryngoscopy, where a calibration instrument was placed next to the lesions. Four clinicians measured lesion length, width, and area from the collected images. RESULTS: The calibrated endoscope performed as well as current flexible fiberoptic laryngoscopes in terms of image quality and patient comfort. For lesions with well-defined borders, the error ranged from 14% to 23% for length, from 20% to 30% for width, and from 33% to 50% for area across observers. Factors contributing to larger errors in some subjects were identified. CONCLUSIONS: The calibrated endoscope is capable of providing useful sizing information for laryngeal structures, and these measures correspond quite well to more direct measurements in the operating room. Objective sizing of laryngeal lesions is complicated by subjective judgments of lesion boundaries, which can be indistinct in many cases.

Adult↗
PubMed2006

Office-based and microlaryngeal applications of a fiber-based thulium laser.

OBJECTIVES: The carbon dioxide (CO2) laser is the premier dissecting instrument for hemostatic cutting and ablation during endolaryngeal surgery. However, microlaryngeal tangential dissection and office-based photoablation have been limited by the lack of a fiber-based delivery system. To address this limitation, a new laser was designed, which is a diode-pumped solid-state laser with a thulium-doped yttrium-aluminum-garnet laser rod. It produces a continuous-wave beam with a wavelength of 2013 nm and a target chromophore of water. This new laser functions similarly to a CO2 laser with the benefit of being delivered through a small glass fiber (0.365 to 0.550 mm). METHODS: A prospective pilot trial was done in 74 cases to explore applications of the new thulium laser. Thirty-two procedures were done with the laser used as an ablating instrument and topical anesthesia through a flexible laryngoscope (papillomatosis, 20; microinvasive carcinoma, 6; benign supraglottic lesions, 3; edema, 2; granuloma, (1). Forty-two procedures were done with the laser used as a cutting or ablating instrument for microlaryngeal dissection and general anesthesia. These included 27 partial laryngeal resections (supraglottis, 15; glottis, 10; subglottis, (2) and 8 posterior glottic laryngoplasties. The laser was also used as an ablative instrument during microlaryngoscopy in 7 cases. RESULTS: The thulium laser was used effectively in all cases, under both local and general anesthesia. In microlaryngeal dissection, electrocautery was not needed to control bleeding, even during cutting in the highly vascular paraglottic space. No complications related to the use of the thulium laser were experienced in any case. CONCLUSIONS: Because of the fiber-based delivery system, the 2013-nm continuous-wave thulium laser shows substantial promise for tangential dissection during microlaryngoscopy and soft tissue photoablation during office-based flexible laryngoscopy. Hemostasis was judged to be superior to experiences with the CO2 laser. In this pilot study, performing en bloc laryngeal cancer resection procedures was facilitated by use of the thulium laser.

Adult↗
PubMed2005

Imaging the mucosa of the human vocal fold with optical coherence tomography.

OBJECTIVES: Discerning the layered microstructure of the vocal folds is critical for effective phonomicrosurgery. Optical coherence tomography (OCT), a noncontact, noninvasive technology that provides cross-sectional images by means of backscattered light, offers the potential for delineating these layers in vivo. METHODS: The glottal mucosa of 3 human cadaver larynges was imaged with conventional OCT and polarization-sensitive OCT (PS-OCT). Images were obtained through the epithelium and lamina propria. RESULTS: Although the superficial layer of the lamina propria appeared quite homogeneous, the outer surface of the superficial lamina propria was correlated with an increase in backscatter with OCT. The superficial lamina propria and vocal ligament were correlated with a marked increase in tissue birefringence with PS-OCT. CONCLUSIONS: This preliminary study demonstrates the capacity of OCT and PS-OCT for visualizing the layered microstructure of the vocal fold mucosa. We believe that these imaging techniques will have applications in the exploration of solutions to vocal fold scarring and in imaging vocal fold disorders in the clinic and operating room.

Cadaver↗
PubMed2004

Rise and fall of the Beringian steppe bison.

The widespread extinctions of large mammals at the end of the Pleistocene epoch have often been attributed to the depredations of humans; here we present genetic evidence that questions this assumption. We used ancient DNA and Bayesian techniques to reconstruct a detailed genetic history of bison throughout the late Pleistocene and Holocene epochs. Our analyses depict a large diverse population living throughout Beringia until around 37,000 years before the present, when the population's genetic diversity began to decline dramatically. The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, whereas archaeological evidence does not support the presence of large populations of humans in Eastern Beringia until more than 15,000 years later.

Alaska↗
PubMed2004

Technique of en block laser endoscopic frontolateral laryngectomy for glottic cancer.

During the last 30 years, there has been expansion of the role of endoscopic partial laryngectomy procedures since Jako, Strong, and Vaughan explored the possibilities of CO2 laser microlaryngeal procedures. Despite the fact that a number of investigators have verified the validity of endolaryngeal laser resection of mid-sized glottic cancer, there are many who are unfamiliar with the technique and others who are uncomfortable with sectioning the tumor to facilitate its resection. In the past 3 years, 15 patients underwent successful en block resection of mid-sized glottic cancer (T1b 2, T2b 11, T3 2). Because en block resection is more consistent with open oncologic approaches, this method should widen the acceptance of this approach in selected lesions. The nuances of en block endoscopic frontolateral laryngectomy are presented with the hope that more surgeons will adopt this philosophy as an aspect of their armamentarium.

Glottis↗
PubMed2004

Suspension laryngoscopy revisited.

Every critical advancement in direct laryngoscopic surgical technique has enhanced its precision. Among the most notable was Killian's seminal description of suspension laryngoscopy 90 years ago, which allowed for bimanual direct laryngoscopic surgery. Because of the technical difficulties encountered while performing suspension laryngoscopy, Brünings and Seiffert designed fulcrum laryngoscope holder-stabilizers for spatula laryngoscopes from Killian's original instrument design. Their devices, which were easier to use and better tolerated by patients, were supported from the laryngeal cartilage framework or chest wall. Laryngoscope holder-stabilizers were retrofitted to tubular laryngoscope specula in the 1940s and 1950s, whereupon they became very popular. Suspension laryngoscopy should have become more common subsequent to the introduction of general endotracheal anesthesia with paralysis in the 1960s. However, laryngoscope holder-stabilizers were entrenched as the device preferred by most, and they remain so today. This entrenchment occurred despite the fact that suspension laryngoscopy allows for positioning a larger examining speculum, which in turn allows for enhanced exposure and endolaryngeal procedural precision. The applied vector forces on the mandible, maxilla, oral cavity, pharynx, and larynx associated with suspension laryngoscopy are preferable to those associated with holder-stabilizers. A prospective assessment of 120 cases revealed effective use of suspension laryngoscopy in all. We believe that only a minority of surgeons has actually seen true suspension laryngoscopy and that its merits are worthy of reexamination.

History, 19th Century↗
PubMed2004

Office-based treatment of glottal dysplasia and papillomatosis with the 585-nm pulsed dye laser and local anesthesia.

Treatment of glottal papillomatosis and dysplasia was mirror-guided and performed in surgeons' offices in the 19th century. It migrated to the operating room in the 20th century to accommodate direct laryngoscopic surgery, which required assistants to administer anesthesia and procedural support. Presently, the primary treatment goals, which are disease regression and voice restoration or maintenance, are tempered by the morbidity of general anesthesia and potential treatment-induced vocal deterioration. In fact, general anesthesia has been appropriately considered to be an acceptable source of morbidity for the promise of a precise procedure, which usually ensures airway safety and an optimal vocal outcome. However, patients with recurrent glottal papillomatosis and keratosis with dysplasia are typically monitored with various degrees of watchful waiting until there is a subjective judgment (on the part of the patient and surgeon) that the disease is more of a liability than is the procedure to treat it. Innovations in the 585-nm pulsed dye laser delivery system have allowed for its use in the clinic with local anesthesia through the working channel of a flexible fiberoptic laryngoscope. A prospective assessment was done on 51 patients in 82 cases of recurrent glottal papillomatosis (30) and dysplasia (52). All individuals had previously undergone microlaryngoscopic management with histopathologic evaluation. Five procedures could not be completed because of impaired exposure (2) or discomfort (3). Of those patients who could be treated, there was at least a 50% disease involution in 68 of 77 cases (88%) and 25% to 50% disease regression in the remaining 9 (12%). Patient self-assessment of the voice revealed that 34 of 77 were improved, 39 were unchanged, 4 were slightly worse, and none were substantially worse. These data confirm that diseased mucosa can be normalized without resection or substantial loss of vocal function. The putative mechanisms, which vary according to the fluence (energy) delivered by the laser, are photoangiolysis of sublesional microcirculation. denaturing of epithelial basement membrane linking proteins, and cellular destruction. Furthermore, this relatively safe, effective technique allowed for treatment of many patients (in a clinic setting) in whom classic surgery-related morbidity would have often delayed intervention.

Adult↗