ABSTRACT
BACKGROUND AND OBJECTIVE: The purpose of this study was to develop a feedback control system for the pulsed holmium:YAG medical laser that enhances tissue selectivity and safety by discriminating between soft and hard biological tissue such as urinary and biliary calculi and bone. STUDY DESIGN/MATERIALS AND METHODS: The ability to discriminate is achieved by monitoring prompt laser-induced visible/NIR photoemissions via retrograde transmission over the laser delivery fiber in conjunction with a developed detection algorithm. RESULTS: Experimental data are presented for a system that employs this discrimination scheme with an electro-optic shutter for rapid intrapulse feedback control of holmium laser-based lithotripsy procedures. The results demonstrate the feasibility of a lithotriptor that can deliver 1 J per pulse to calculi yet limit errant discharges to surrounding urinary tract tissue to < or = 0.1 J. CONCLUSION: Based on animal tissue safety data, the laser margin of safety is improved by an order of magnitude.
Subject(s)
Lithotripsy, Laser/instrumentation , Algorithms , Animals , Equipment Design , Feasibility Studies , Feedback , Female , Humans , In Vitro Techniques , Lithotripsy, Laser/methods , RabbitsABSTRACT
We performed a cross-sectional study of 705 textile workers in two cotton mills and one silk mill in Shanghai, People's Republic of China, to assess small airway function among cotton textile workers and to compare the FEV1 to the FEF25-75 in detecting airflow obstruction in these workers. All workers had at least 2 years of work experience. Environmental sampling was performed with vertical elutriators and revealed that in the cotton mills mean elutriated dust levels were 1.07 +/- 0.23 mg/m3 in mill 1 and 1.01 mg/m3 +/- 0.24 mg/m3 in mill 2. Mean endotoxin levels were 332 +/- 83 ng/m3 in mill 1 and 101 +/- 46 ng/m3 in mill 2. No differences were found in preshift FEV1 or FEF25-75 between cotton and silk workers. Cotton workers had significantly greater declines than silk workers in FEV1 across a workshift, but not in FEF25-75. These acute changes in FEV1 were noted in both byssinotic and nonbyssinotic workers. Although cotton dust may affect both large and small airways, spirometric measures of small airway function (e.g., FEF25-75) add little to the FEV1 and FVC in detecting airflow limitation in cotton dust-exposed workers.
Subject(s)
Gossypium , Insect Proteins , Lung Diseases/physiopathology , Occupational Exposure/adverse effects , Adult , Bronchitis/epidemiology , Bronchitis/etiology , Byssinosis/epidemiology , Byssinosis/etiology , China/epidemiology , Chronic Disease , Cohort Studies , Cough/epidemiology , Cough/etiology , Cross-Sectional Studies , Female , Forced Expiratory Flow Rates/physiology , Forced Expiratory Volume/physiology , Humans , Lung Diseases/epidemiology , Lung Diseases/etiology , Male , Middle Aged , Proteins , Silk , Textile IndustryABSTRACT
Deficits in FEV1 and FVC have been shown to correlate with the presence of occupationally related obstructive and restrictive lung disease, but significant changes do not occur in the two parameters until these diseases are already well established. The current understanding of the relationship between small airways testing and the subsequent development of COPD is reviewed. Various methods for evaluating peripheral airways are discussed, with emphasis on applicability in the field, reliability and reproducibility, and technical aspects of testing.
Subject(s)
Lung Diseases, Obstructive/diagnosis , Occupational Diseases/diagnosis , Respiratory Function Tests/standards , Humans , Lung Diseases, Obstructive/epidemiology , Mass Screening/methods , Mass Screening/standards , Occupational Diseases/epidemiology , Reference Values , Reproducibility of Results , Respiratory Function Tests/methods , Sensitivity and SpecificityABSTRACT
A Navy helicopter pilot was found to have a suprasellar mass during evaluation for primary infertility and mildly elevated prolactin level. Extensive evaluation revealed no other abnormalities. After 1 year of followup without radiographic tumor enlargement, he was returned to flying duties with continuing medical monitoring. Aeromedical considerations for tumors in the juxtasellar region are reviewed, including neuroendocrine disorders, neuro-ophthalmologic defects, and neurological impairment. The impact of improved diagnostic capabilities on aeromedical disposition is discussed.
Subject(s)
Aerospace Medicine , Hypothalamic Neoplasms/diagnosis , Sella Turcica/pathology , Adult , Aircraft , Bromocriptine/administration & dosage , Diagnosis, Differential , Humans , Hyperprolactinemia/drug therapy , Hyperprolactinemia/etiology , Hypothalamic Neoplasms/physiopathology , Magnetic Resonance Imaging , Male , Sella Turcica/physiopathologyABSTRACT
An endoscope-compatible, optical fiber system has been developed which can be used to obtain laser-induced fluorescence spectra of mucosal abnormalities during endoscopy in real time. The results of our previous in vitro studies have suggested that laser-induced fluorescence tissue spectra are sufficiently unique that they can be used to accurately diagnose mucosal abnormalities in some systems. To test this hypothesis in vivo, laser-induced fluorescence spectra were obtained during colonoscopy from 31 colonic adenomas, 4 hyperplastic polyps, and 32 examples of normal mucosa in 20 patients. The resulting spectra could be used to correctly differentiate adenomas from normal colonic mucosa and hyperplastic polyps in 97% of the specimens studied with the resulting sensitivity, specificity, and positive predictive value of 100%, 97%, and 94%, respectively. These results, although preliminary in nature, suggest that laser-induced fluorescence spectra can be used in the recognition and differential diagnosis of mucosal abnormalities at endoscopy.
Subject(s)
Adenoma/diagnosis , Intestinal Neoplasms/diagnosis , Intestinal Polyps/diagnosis , Intestines/pathology , Lasers , Spectrometry, Fluorescence/methods , Colonoscopy , Diagnosis, Differential , HumansABSTRACT
Removal of intravascular atherosclerotic obstructions by laser irradiation has gained the attention of many investigators, but has proven to be considerably more difficult to accomplish than initially envisioned. We tested, in an animal model, an argon ion laser delivery system that permits control of (1) laser power, (2) exposure time, and (3) laser beam spot size. The study was conducted on surgically, induced focal fibrous plaques in the carotid arteries of nine dogs. Plaque removal, vessel patency, and healing were evaluated angiographically and by light and electron microscopy at intervals up to 60 days after treatment. Results showed that intravascular obstructions could be removed, healing occurred, and vessels remained patent for up to 60 days.
