Clinical investigations of a CVD diamond detector for radiotherapy dosimetry.

X-ray detectors based on single crystal diamond film made via chemical vapor deposition were investigated to evaluate their performance under clinically relevant conditions for radiotherapy dosimetry. Studies focused on repeatability, dose rate dependence, tissue phantom ratios, output factors and beam profiling. Repeatability experiments revealed a temporary loss in sensitivity due to charge detrapping effects following irradiation, which was modeled to make corrections that improved short-term precision. Dose rate dependence was observed (Fowler fitting parameter Δ = 0.96 ± 0.2) using dose rates up to ~2 Gy min(-1). The detector statistically distinguished (n = 5, P < 0.05) between dose values separated by 7.7 × 10(-3) Gy (1 MU). Depth dose measurements from 1 to 15 cm and output factors using 3 × 3 to 10 × 10 cm2 field sizes compared well with a Farmer ion chamber (<1.3% difference). Output factor measurements indicate encouraging results for fields sizes <4 × 4 cm2. Off-axis measurements showed that perturbation of the beam could be reduced when the detector is used in the edge-on orientation due to its thin-film sandwich configuration and ~200 nm thick Ag contacts. This relatively inexpensive detector has potential to be used for routine dosimetry using conventional radiotherapy instrumentation.

Comparison of natural and synthetic diamond X-ray detectors.

Diamond detectors are particularly well suited for dosimetry applications in radiotherapy for reasons including near-tissue equivalence and high-spatial resolution resulting from small sensitive volumes. However, these detectors have not become commonplace due to high cost and poor availability arising from the need for high-quality diamond. We have fabricated relatively cheap detectors from commercially-available synthetic diamond fabricated using chemical vapour deposition. Here, we present a comparison of one of these detectors with the only commercially-available diamond-based detector (which uses a natural diamond crystal). Parameters such as the energy dependence and linearity of charge with dose were investigated at orthovoltage energies (50-250 kV), and dose-rate dependence of charge at linear accelerator energy (6 MV). The energy dependence of a synthetic diamond detector was similar to that of the natural diamond detector, albeit with slightly less variation across the energy range. Both detectors displayed a linear response with dose (at 100 kV) over the limited dose range used. The sensitivity of the synthetic diamond detector was 302 nC/Gy, compared to 294 nC/Gy measured for the natural diamond detector; however, this was obtained with a bias of 246.50 V compared to a bias of 61.75 V used for the natural diamond detector. The natural diamond detector exhibited a greater dependency on dose-rate than the synthetic diamond detector. Overall, the synthetic diamond detector performed well in comparison to the natural diamond detector.

Prevention of anterior glottic restenosis in a canine model with topical mitomycin-C.

To develop a model for recurrent anterior glottic stenosis and to test the efficacy of topical mitomycin-C in preventing restenosis, we induced anterior glottic stenosis with a CO2 laser in 5 dogs. In 3 dogs, recurrence was established after surgical lysis. Subsequently, the 3 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after a second surgical lysis. In a parallel experiment, the other 2 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after the initial surgical lysis. An anterior glottic web was induced in all 5 dogs with the CO2 laser. The 3 dogs experienced restenosis at the anterior glottis after surgical lysis alone. Mitomycin-C prevented anterior glottic restenosis in 2 of the 3 dogs treated twice and in both of the dogs treated once (p = .02). We conclude that a recurrent stenosis of the anterior glottis may be induced reproducibly in the canine model with the CO2 laser. Application of topical mitomycin-C after lysis of an anterior glottic stenosis produces a statistically significant reduction in the rate of restenosis as compared to surgical lysis alone.

A comparison of scar revision with the free electron and carbon dioxide resurfacing lasers.

Laser scar revision was studied to measure the effects of targeting extracellular matrix protein versus tissue water on scar revision. We compared the free electron laser used at 7.7 microm (the amide III protein absorption band) to the carbon dioxide (CO2) laser and dermabrasion.Nude mice (n = 40) that had rejected skin grafts on their dorsal surface and developed mature scars were used as a model for scar revision. One-half of each scar was revised with either the free electron laser at 7.7 microm (32 to 38 mJ, nonoverlapping pulses delivered with a computerized adjustable pattern generator at 30 Hz, and two to three passes), a 100-microsec CO2 resurfacing laser (500 mJ, 5.0 Hz, and two to five passes), or dermabrasion. The untreated portion of each scar served as an internal control. Evaluation was by measurement of the clinical size of the scar using photography with quantitative computer image analysis to compare the data and histology to evaluate the quality and depth of the scars. The free electron laser at 7.7 microm was significantly better than the CO2 laser and dermabrasion for scar size reduction (p < 0.046 and p < 0.018). The CO2 laser and a highly skilled dermabrader were not statistically significantly different (p < 0.44). The result seen with less skilled dermabraders was significantly worse than all other methods (p < 0.009). The free electron laser at 7.7 microm, which is preferentially absorbed by the proteins of the extracellular matrix, provided better scar reduction than the CO2 resurfacing laser and dermabrasion. Dermabrasion by a skilled operator resulted in improvement similar to the results obtained with the CO2 resurfacing laser, but less skilled operators had significantly poorer results.

Carbon dioxide laser skin resurfacing with a cooled handpiece.

BACKGROUND AND OBJECTIVE: Carbon dioxide (CO(2)) laser skin resurfacing has become an accepted procedure for the rejuvenation of aged and wrinkled facial skin. The benefits of this technique have been limited by the prolonged postoperative erythema, delayed re-epithelialization, and potential changes in pigmentation. We investigated the effects of coupling a pulsed CO(2) laser to a zinc selenide handpiece at various temperatures to cool and conduct heat from the skin surface. We compared the heat conducting handpiece to standard techniques used to determine the effects on epithelial preservation, depth of thermal damage, and new collagen growth. STUDY DESIGN/MATERIALS AND METHODS: The dorsal aspect of piglets was treated with four handpiece arrangements: no thermally conducting window; a zinc selenide thermally conducting window at room temperature; and the zinc selenide thermally conducting window cooled to 10 and 5 degrees C. Intensities were measured to account for reflections from the surface of the handpiece. With the CO(2) laser in scanning mode and a spot size of 1 mm, each handpiece was used at intensities ranging from 8-30 W in one pass. Biopsies for histopathologic analysis and determination of the degree of epithelial damage and the depth of thermal damage were taken on days 0, 2, and 16. RESULTS: All specimens revealed complete re-epithelialization by day 16. The addition of a cooled handpiece did not affect either the amount of epithelial preservation or the depth of thermal damage. CONCLUSIONS: There is no significant advantage in using a cooled or room temperature zinc selenide handpiece for epithelial preservation or decreasing the inflammatory response in CO(2) laser resurfacing.

Comparison of wound healing using the CO2 laser at 10.6 microm and 9.55 microm.

OBJECTIVES/HYPOTHESIS: The wound healing characteristics of incisions made with the short pulsed CO2 laser tuned to 9.55 microm versus the traditional 10.6 microm were investigated. Previous studies have shown that at 9.55 microm, collagen is targeted more selectively than at 10.6 microm, which results in decreased acute thermal injury patterns. This study investigates the difference in wound healing over time between lasers and compares laser incisions with cold knife techniques. STUDY DESIGN: Randomized controlled trial using a porcine model. METHODS: Tissue from 10.6-microm and 9.55-microm incisions of 10 piglets was evaluated with histological analysis and tensiometry at 3, 7, 14, and 21 days postoperatively. A Bonferroni-Dunn corrected analysis of variance analysis at a 95% significance level was used to compare the effect of wavelength. RESULTS: The results demonstrate that although knife incisions are consistently stronger than laser incisions, the 9.55-microm CO2 laser incisions are no stronger than incisions made with the conventional 10.6-microm laser. Furthermore, histological analysis shows no difference in lateral thermal damage between lasers at 3, 7, 14, and 21 days postoperatively. The progression of collagen formation and inflammation does not differ over time. CONCLUSION: This study of wound healing using a porcine model demonstrates that the 9.55-microm CO2 laser does not demonstrate an improvement in wound healing over the traditional 10.6-microm CO2 laser. These results may be secondary to the common explosive vaporization mechanism produced by both lasers in the infrared spectrum.

Quality-of-life assessment in patients with unilateral vocal cord paralysis.

OBJECTIVE: Our objective was to identify the impact of unilateral vocal cord paralysis (UVCP) on an individual's quality of life both before and after thyroplasty. STUDY DESIGN AND SETTING: This was a prospective observational outcome study of consecutive patients presenting to a laryngology clinic with UVCP. Participants received The Medical Outcomes Study Short Form 36-Item Health Survey (SF-36), the Voice Handicap Index (VHI), and the Voice Outcome Survey (VOS). Patients underwent medialization laryngoplasty with silastic, with or without arytenoid adduction. Outcome measures were repeated after surgery. RESULTS: A review of 45 patients at presentation revealed statistically significant reductions in quality of life as measured by each survey. Marked improvements were noted after surgery. CONCLUSIONS: Our preoperative data support a profile of significant general health-related and voice-related limitations caused by UVCP. Patient perceptions improved significantly after the surgical treatment of glottal insufficiency. SIGNIFICANCE: The SF-36, VHI, and VOS provide an important complement to traditional endpoints in the analysis of patients with UVCP.

Cortical bone healing following laser osteotomy using 6.1 microm wavelength.

BACKGROUND AND OBJECTIVE: Use of laser wavelengths in the 6.1 microm (amide I) to 6.45 microm (amide II) regions and a macropulse width of 4.0 microseconds delivered by a computer-controlled delivery system have produced clean, deep cortical bone ablations with minimal collateral thermal injury and no char formation. The purpose of this study was to evaluate the healing of cortical bone following 6.1 microm wavelength laser osteotomy using a 4.0 microsecond pulse, and compare that response to the response of similar osteotomies made with a standard pneumatic surgical bone saw. STUDY DESIGN/MATERIALS AND METHODS: Sixteen mature rabbits were divided equally into 2, 4, 6 and 8-week post-surgical survival groups. A nitrogen driven sagittal bone saw and an FEL generating 6.1 microm wavelength in 4.0 microsecond macropulses of 22.5 +/- 2.5 mJ/pulse directed into a 200 microm diameter spot were used to make 6.6 mm linear cuts into rabbit tibial cortex, and the healing response over time was monitored. Bone saw cuts were made halfway through the thickness of the cortex. Laser cuts were directed by a computer-controlled delivery system, and were either partial or full thickness cortical cuts. Location of the cortical bone cuts (saw or laser, partial or full thickness cut, proximal or distal, medial right or medial left tibia) were randomly assigned. At each predetermined post-surgical time point, rabbits of the appropriate group were euthanized, and the tibias of each subject collected, processed for histologic evaluation, and analyzed by light microscopy. RESULTS: At 2 weeks post-surgery, bone saw cuts showed no evidence of a healing response, while both the partial and full laser cut sites were filled with trabecular bone and primitive bone marrow. By 4 weeks post-surgery, the bone saw cuts showed filling of the defect with trabecular bone and primitive marrow, and an intense osteonal remodeling of the original cortex adjacent to the cuts was evident. All laser cut defects were filled, reactive periosteal bone was being converted to osteons and consolidating, and secondary osteons were appearing in the original cortex. At 6 weeks following surgery, the bone saw defects were filed with a mixture of woven and lamellar bone. All laser defects were filled with lamellar osteons and woven bone, the osteons were remodeling from primary to secondary osteons. By 8 weeks following the surgery, all bone saw and laser cut specimens revealed complete healing. CONCLUSIONS: Histologic evaluation of osteotomy sites made in skeletally mature rabbit tibia using the 6.1 microm wavelength, 4.0 microsecond macropulse FEL, delivered at 6 Hz at the osteotomy site, reveals a healing response which is at least as good as the healing of bone saw osteotomies, and appears to proceed at a faster rate during the first 2-4 weeks following surgery.

Optimizing free electron laser incisions at 6.45 microm with computer-assisted surgical techniques and the utilization of a heat-conducting template.

BACKGROUND AND OBJECTIVE: We sought to optimize laser incisions by evaluating the effects of varying the slit width of a heat-conducting template and the step size with the Computer-Assisted Surgical Techniques (CAST) system on free electron laser (FEL) incisions at 6.45 microm. STUDY DESIGN/MATERIALS AND METHODS: Stainless steel calipers were used as a heat-conducting template on human skin in vitro. The CAST system made the incisions as a series of spot ablations with set step sizes of 50 microm or 1,250 microm. At each step size, incisions were made with or without the calipers, by using varying slit widths. Histologic specimens were analyzed for lateral thermal damage over the entire depth of the incision and over the superficial 150 microm of dermis. RESULTS: Lateral thermal damage over the superficial 150 microm of dermis was most significantly reduced with the calipers at a slit width approximating the FEL's beam diameter (636 microm +/- 100 microm). Also, incisions made with the larger step size (1,250 microm) had significantly less lateral thermal damage over the entire depth of the incision. CONCLUSIONS: The use of a heat-conducting template with an aperture approximating the FEL's beam diameter and larger step size improved FEL incisions at 6.45 microm.

Effect of mitomycin-C on vocal fold healing in a canine model.

For evaluation of the effect of topical mitomycin-C on vocal fold healing and return of function after surgical excision of mucosa, 6 dogs underwent suspension microlaryngoscopy with bilateral microflap excision of vocal fold mucosa. Topical mitomycin-C, a chemotherapeutic agent and a fibroblast inhibitor, was applied randomly to one side, with the contralateral side serving as the control. Laryngeal videostroboscopy (LVS) was performed on each animal before the operation, at 2 weeks, and before sacrifice at 4 weeks. Both functional analysis with LVS and histologic analysis were performed in a blinded fashion to determine the effect of mitomycin-C on healing. Histologic analysis was augmented with computer morphometrics. The LVS revealed diminished mucosal wave vibration in the vocal folds treated with mitomycin-C, as well as a more atrophic appearance to the vibratory surface. The vocal folds treated with mitomycin-C showed fewer fibroblasts and less collagen within the superficial layer of the lamina propria than the control vocal folds (p < .05, Student's t-test, paired analysis). Inflammatory infiltrate was not significantly different between the two sides. Consistent with the known suppression of fibroblast proliferation by mitomycin-C, the treated vocal folds showed less connective tissue response to the surgical injury. In contrast to the reported positive effects of mitomycin-C on tracheal and glottic stenosis, the observed decrease in the healing response in the present study had negative consequences on the vocal fold vibratory pattern.

Percutaneous laser ablation of fetal congenital cystic adenomatoid malformation: too little, too late?

OBJECTIVE: Congenital cystic adenomatoid malformation, type III (CCAM III) lesions are large, bulky tumors which can cause mediastinal shift, prevent normal pulmonary growth, and compress the esophagus, thus leading to complications of nonimmune hydrops, pulmonary hypoplasia and polyhydramnios. Because the mortality rate of untreated fetuses with CCAM and hydrops is high, early delivery or intrauterine resection of the enlarged pulmonary lobe (lobectomy) is indicated; however, open fetal resection of CCAM at less than 30 weeks is associated with perioperative mortality that approaches 40%, as well as the usual maternal and fetal morbidity of open fetal surgery. As an alternative, percutaneous laser ablation of a CCAM III lesion with hydrops was attempted. METHODS: A 30-year-old G3 P1011 with CCAM III in the left fetal hemithorax developed mediastinal shift, hydrops and polyhydramnios at 23 weeks' gestation. After pregnancy termination and open fetal resection were declined, an 18-gauge needle was placed into the fetal tumor percutaneously under real-time ultrasonographic guidance, using sterile technique with light sedation. A cleaved 400-microm Nd:YAG laser fiber was passed through the needle lumen, and using a power setting of 15 W, a total of 2,943 J of laser energy was delivered in pulses of 1.0 s at 0.2-second intervals over two sessions one week apart. RESULTS: Although tumor size decreased, the hydrops worsened and fetal death occurred. CONCLUSIONS: The fetus with CCAM complicated by hydrops is already so compromised by the advanced state of the disease that insufficient time is available for necrotic tissue reabsorption after minimally invasive therapy with laser energy. Until earlier markers for intervention are determined, percutaneous laser debulking of CCAM is unlikely to be successful.

Noninvasive fluorescent identification of bacteria causing acute otitis media in a chinchilla model.

OBJECTIVES: To evaluate a noninvasive method of bacterial identification via fluorescence spectroscopy in the setting of acute otitis media in a chinchilla model. STUDY DESIGN: Prospective. METHODS: For each chinchilla, transbullar inoculation with Streptococcus pneumoniae, Haemophilus influenzae, or Staphylococcus aureus was performed bilaterally and clinical infection was determined by otoscopy. An optical fiber coupled to a spectrofluorometer allowed for the delivery of an excitation wavelength to the inflamed tympanic membrane and the acquisition of the resulting emission signal. Sequential emission spectra obtained over a range of excitation wavelengths were assembled by a computer algorithm, and a single, three-dimensional plot was created for each test ear. Similarly, plots from the healthy external auditory canal (EAC) were also recorded. Twelve animals were used to establish a library of four reference plots representing the three bacteria and the EAC. Of the 24 ears available for study, 10 were excluded from analysis because of lack of clinical infection or presence of tympanic membrane perforation with purulent drainage. From four additional animals, four samples from ears infected with the above bacteria and three samples of the EAC served as unknowns. The unknown plots were analyzed by an investigator blinded to their identity. RESULTS: Using a multiple correlation of the unknown to the reference plots, seven of seven samples were correctly identified. CONCLUSIONS: We were able to establish a prototype method for the noninvasive identification of a limited library of pathogens in a chinchilla model of acute otitis media.

Comparative histology and vibration of the vocal folds: implications for experimental studies in microlaryngeal surgery.

OBJECTIVES/HYPOTHESIS: To determine the most suitable animal model for experimental studies on vocal fold surgery and function by a histological comparison of the microflap surgical plane and laryngeal videostroboscopy (LVS) in different species of animals. A second goal was to determine how the layered vocal fold structure in humans and three different animal species affects surgical dissection within the lamina propria. STUDY DESIGN: Prospective laboratory. METHODS: Three larynges each from dogs, monkeys, and pigs were compared with three ex vivo human larynges. Microflap surgery was performed on one vocal fold from each larynx. Both the operated and nonoperated vocal folds were examined histologically using stains specific for elastin, mature collagen, and ground substance. Based on the histological results, LVS was performed on two dogs and two pigs after first performing a tracheotomy for ventilation and airflow through the glottis. Arytenoid adduction sutures were placed to facilitate vocal fold adduction. RESULTS: The distributions of the collagen and elastin fibers were found to differ among the species with concentrations varying within species. Unlike the human vocal fold, which has a higher elastin concentration in the deeper layers of the lamina propria, both the pig and the dog had a thin band of elastin concentrated just deep to the basement membrane zone in the superficial layer. Just deep to this thin band, the collagen and the elastin were less concentrated. The monkey vocal fold had a very thin mucosal layer with less elastin throughout the mucosa. The microflap dissections in each of the dog, pig, and human vocal folds were similar, being located within that portion of the superficial lamina propria where the elastin and mature collagen are less concentrated. The microflap plane in the monkey vocal fold was more deeply located near the vocalis fibers. Despite the differences in elastin concentration, the microflap plane in both the dog and the pig was found to be similar to that in humans. The dog anatomy was much more suitable for microsuspension laryngoscopy and stroboscopic examination. The dog vocal folds vibrated in a similar fashion to human vocal folds with mucosal waves and vertical phase differences, features not seen in the pig vocal folds. CONCLUSIONS: Based on both the histological and stroboscopic results, the dog was believed to be a more suitable animal model for studies on vocal fold surgery, acknowledging that no animal's laryngeal anatomy is identical to that of the human. The dog LVS model presented allows for longitudinal laryngeal studies requiring repeated examinations at multiple time periods with histological correlation applied at sacrifice.

Effects of thermal conducting media on the skin surface during laser irradiation.

OBJECTIVES: To investigate the effects of thermally conductive, optically transparent media placed on skin during treatment with the flashlamp excited dye laser (FEDL). The use of higher energy densities to treat persistent cutaneous vascular lesions may result in a decrease in the number of treatment sessions. However, increased fluences can cause complications of scarring, hyperpigmentation, infection, skin texture changes, or hypopigmentation. The thermally conductive media should assist in dissipating surface thermal energy and thereby protect the skin from the complications. STUDY DESIGN: This was a prospective laboratory study using an animal model. The results were verified in a prospective, pilot, human-use trial. METHODS: The threshold for acute skin damage and measurements of the thermal transients were made using a rabbit model. The threshold for purpura was noted with and without the use of a sapphire as a thermal conductor. The thermal transients were measured with small thermocouples placed subcutaneously. On a human subject, purpura intensities were photographed and measured using computer morphometrics after treatment with the FEDL and skin surface protection with air, glass, sapphire, and diamond as conductive media. RESULTS: With the interposition of the sapphire thermal conductor during the FEDL treatment, excessive temperature increases of the epidermis were prevented during the laser pulse compared with glass and controls. Both sapphire and diamond resulted in decreased purpuric intensities with the applications of equivalent fluences. Wound recovery time for the purpura was decreased by approximately half a day when any of the surface conductors were used. CONCLUSIONS: The decreased transient temperature and decrease in purpura seen with the use of sapphire and diamond protecting the epidermis during treatment with the FEDL should result in fewer untoward effects during treatment of vascular lesions and facilitate their management.

Wound healing and collagen thermal damage in 7.5-microsec pulsed CO(2) laser skin incisions.

BACKGROUND AND OBJECTIVE: Wound-healing delays caused by lateral thermal damage to tissue remain a drawback of CO(2) surgical lasers. This study compares the thermal damage and wound-healing properties of a 7.5-micros pulsed CO(2) laser with scalpel and continuous wave (CW) CO(2) laser incisions. STUDY DESIGN/MATERIALS AND METHODS: We created incisions on the dorsal pelts of rats with a 7.5-micros pulsed CO(2) laser at 5-, 10-, or 15-Hz repetition rate, a conventional CW laser, or scalpel. Animals were euthanized at postoperative days 3, 7, 14, 21, and 80. Tissue was harvested and analyzed histologically and for wound tensile strength. In addition, tissue was harvested acutely and analyzed for acute thermal injury lateral to the incisions. RESULTS: Incisions made with the pulsed laser had significantly higher tensile strength and histologic rankings than did CW laser incisions at days 3-21, producing 118 microm of thermal damage to tissue as compared with 333 microm for CW laser. Pulsed laser incisions were not statistically different than scalpel incisions at days 3-14 of healing. Mathematical modeling showed the pulsed laser to produce a wound healing delay of 1.0 day by tensiometry and 1.9 days by histology, compared with 3.2 days by tensiometry and 6.0 days by histology for CW laser. There were no significant differences in wound healing when the pulsed laser was used at repetition rates of 5-15 Hz. CONCLUSIONS: Using a 7.5-micros pulse duration, CO(2) laser incisions healed at a rate similar to scalpel incisions and reduced the wound-healing delay seen with typical surgical CO(2) lasers.

Comparison of cortical bone ablations by using infrared laser wavelengths 2.9 to 9.2 microm.

BACKGROUND AND OBJECTIVE: The purpose of this study was to compare the ablation of cortical bone at wavelengths across the near and midinfrared region. STUDY DESIGN/MATERIALS AND METHODS: An free electron laser generating 4-micros macropulses at specific wavelengths between 2.9 and 9.2 microm was used to ablate cortical bone. The same pulse intensity, repetition rate, radiant exposure, number of pulses, and delivery was used for each wavelength. Tissue removal, collateral thermal injury, and morphologic characteristics of the ablation sites were measured by light and scanning electron microscopy, and compared with the infrared absorption characteristics of cortical bone. RESULTS: Within the parameters used, bone ablation was found to be wavelength dependent. Incisions were deepest where protein has strong absorption, and were most shallow where mineral is a strong absorber. No char was observed on ablation surfaces where 3.0, and 5.9-6.45 microm wavelengths were used. CONCLUSIONS: The use of wavelengths in the 6.1-microm amide I to 6.45-microm amide II region, with the pulse characteristics described, were the most efficient for cutting cortical bone and produced less collateral thermal injury than cutting with a surgical bone saw. This study confirms previous observations that the ablation mechanism below plasma threshold is consistent with an explosive process driven by internal vaporization of water in a confined space and demonstrates that ablation is enhanced by using wavelengths that target the protein matrix of cortical bone.

Osteoplastic flap for obliteration of the frontal sinus: five years' experience.

The objective of this retrospective study was to evaluate the osteoplastic flap (OPF) for the obliteration of the frontal sinus in this current era of endoscopic management of frontal sinus disease. A review of consecutive OPF procedures (n = 43) performed by the senior author (J.A.D.) from 1992 to 1997 was carried out. Data were gathered regarding chief symptom, medical history, previous sinus surgery, endoscopic findings in the office and at surgery, CT scan findings, and follow-up results (mean 19.4 months). Previous endoscopic management of frontal sinus disease had failed in 24% of patients; 97% had eventual resolution of frontal sinusitis with OPF. After OPF, 63% also had improvement or resolution of disease in other paranasal sinuses. Statistically significant, positive correlations (P < 0.05) were noted between the resolution of frontal sinusitis and improved or resolved pain, as well as the resolution of frontal sinusitis and improved or resolved infections in other paranasal sinuses. In 1998 OPF remains the standard for treating frontal sinus disease refractory to other methods. OPF can decrease the pain associated with frontal sinus infections and has a positive impact on inflammatory disease in other paranasal sinuses.

Inhibition of subglottic stenosis with mitomycin-C in the canine model.

The objective of this randomized, prospective study was to study the efficacy of topical mitomycin-C in the inhibition of subglottic stenosis in a canine model. Subglottic stenosis was elicited with the carbon dioxide laser in 10 mongrel dogs. Radial incision and serial dilation of the subglottic airway were then carried out. The animals were randomized to receive a topical solution of 1% mitomycin-C to the dilated area for a 5-minute duration or no further treatment. Weekly direct microlaryngoscopy and photodocumentation were performed during the 6-week study. Airway distress developed in 4 of the 5 control dogs, requiring early sacrifice, while all treatment group animals survived the duration of the study (p < or = .006). Morphometric analysis of the subglottic photographs confirmed a greater than 100% increase in the percentage of relative airway at sacrifice in the treatment group (p < or = .049). A statistically significant (p < or = .015) decrease in collagen formation in the subglottic scar of dogs treated with topical mitomycin-C was documented. Mitomycin-C favorably altered the clinical progression of subglottic stenosis, improved quantified airway patency, and reduced the amount of subglottic collagen formation in the canine model.

Radiofrequency tissue ablation of the inferior turbinates using a thermocouple feedback electrode.

OBJECTIVE: The objective of this clinical trial was to assess the safety and efficacy of radiofrequency (RF) tissue ablation of the inferior turbinates in the treatment of nasal obstruction using an RF energy delivery system with a thermocouple feedback electrode. METHODS: A prospective, nonrandomized study of 11 patients (mean age, 47+/-12 y) with chronic nasal obstruction was conducted. Using patient-based visual analogue scales (VAS), symptom parameters were assessed. These included degree of nasal obstruction, frequency of nasal obstruction, and pain. Physician assessment of nasal obstruction was also collected by the principal investigator. Follow-up was conducted at 24 hours, 1 week, 4 weeks, 8 weeks, and 1 year. ANOVA was carried out to determine statistically significant differences in the data. Data were fit to a regression model, and confidence intervals were determined from a 95% confidence level. RESULTS: In patient-assessed degree of nasal obstruction, statistical significance was seen among baseline and 4 weeks, 8 weeks, and 1 year (P<.001, P<.0001, and P<.0008, respectively). There was no difference between 8 weeks and 1 year (P<.15). The data appeared to follow an exponential decay to a constant value. The pretreatment baseline average degree of obstruction was 7.5+/-0.5 on a scale of 0 to 10. The degree of obstruction after 8 weeks was 2.7+/-0.6. The time constant for this change was 21 days to reach 90% of the final value. At 1 year, degree of obstruction was 3.3+/-0.7. For frequency of nasal obstruction, statistical significance was seen among baseline and 4 weeks, 8 weeks, and 1 year (P<.0001, P<.0001, and P<.0001, respectively). There was no difference between 8 weeks and 1 year (P<.15). The pretreatment baseline average frequency of obstruction was 7.8+/-0.5. The remaining frequency of obstruction after 8 weeks was 2.9+/-0.6. The time constant was 18 days. At 1 year, frequency of obstruction was 3.3+/-0.6. Physician assessment of nasal obstruction revealed statistical significance among baseline and 4 weeks, and baseline and 8 weeks (P<.0055 and P<.0056, respectively). There was no difference between 4 weeks and 8 weeks (P<.24). The average initial obstruction was 83%+/-4%. The remaining obstruction after 8 weeks was 58% +/-5%. The time constant was 14 days. Mild pain was reported by 55% of patients during the procedure; the remaining 45% reported no pain. Only one patient required pain medication consisting of acetaminophen after the procedure. There were no significant complications. CONCLUSIONS: Degree and frequency of nasal obstruction, as reported by patients, decreased following RF tissue ablation of the inferior turbinates. This improvement in symptoms was still evident after 1 year (P<.001). Physician assessment of obstruction also correlated with patient reports for the initial 8-week study period. The procedure was safe and well tolerated. Thermocouples within the active electrode provided additional feedback to the operating surgeon allowing the use of relatively lower tissue temperatures, power, and energy as compared with traditional techniques. These results support the need for continued research to evaluate this modality as a treatment for chronic nasal obstruction.

Analysis of a critical pathway in osteoplastic flap for frontal sinus obliteration.

OBJECTIVES: A critical pathway was applied to patients undergoing osteoplastic flap (OPF) for frontal sinus obliteration to determine whether efficiency could be improved. STUDY DESIGN: A retrospective review of consecutive OPF procedures (n = 51) performed between 1992 and July 1997 was conducted. METHODS: The patient groups were subdivided into those who underwent OPF alone and those who had endoscopic sinus procedures performed in addition to OPF. Comparisons were made between the precritical pathway and post-critical pathway groups, specifically noting operative time, total operating room (OR) time, estimated blood loss (EBL), length of hospital stay, and costs. We used a critical pathway that was developed for endoscopic sinus procedures at our institution through a multidisciplinary team approach. Preoperative evaluation and testing, intraoperative equipment and medications, and postoperative care including follow-up clinic visits were all standardized. An unpaired, two-tailed Student t test was used to evaluate the data. RESULTS: Statistically significant (P<.05) reductions in operative times, total OR time, EBL, and length of hospital stay were observed in the post-critical pathway group who underwent endoscopic sinus procedures as well as OPF. Costs to the OR were reduced 29% and 15% for OPF and for OPF with endoscopic surgery, respectively. Patient costs were reduced 5% and 4% in these groups, respectively. CONCLUSIONS: With implementation of effective critical pathways, significant decreases in length of stay are seen, and cost reductions can be realized through the improved efficiency, shortened OR times, and decreases in redundancy of ordering materials.