Interferometric grazing incidence test of rough steep convex aspherics: full 3D reconstruction of the object.

A grazing incidence interferometric measurement procedure is applied to test rough convex steep rotationally symmetric aspherics. The measurement of rough surfaces is possible; i.e., without the need to polish the surfaces, due to the large effective wavelength (λeff=10µm) of the test. One measurement step using diffractive beam splitters and phase-shifting techniques delivers the surface information along one meridian. The full surface description can be stitched together from several phase results combined with appropriate object rotations. This publication includes, besides the short recapitulation of the measurement principle and experimental setup, a presentation of the simulated and measured data of an aspherical object under test. The data analysis of each meridian is focused on the elimination of the misalignment aberrations caused by specimen displacements. Finally, the stitching of multiple meridian regions to a 3D surface map of the specimen is shown.

Phase singularity reduction in speckle interferometry by tailoring the spatial coherence of light.

Reducing the number of phase singularities in speckle interferometry by physical means increases the quality of the phase deconvolution and enhances the separability of fringe systems, especially for highly dynamic fringe systems. The reduction is achieved by tailoring the spatial coherence of the light source at the entrance of the interferometer. The reduction mechanism is non-intuitive and rests on a change of size and of position of the speckle patterns as a result of the spatially shaped coherence. After demonstrating the amount of reduction that may be achieved, the reduction mechanism is explained theoretically and via simulations, and it is vindicated in an experiment using a Michelson-Mach-Zehnder interferometer hybrid.

Interferometric grazing incidence test of rough steep convex spherics: experimental data analysis.

Grazing incidence interferometry has been applied to plane, cylindrical, acylindrical, and general rod-like surfaces using diffractive beam splitters. Here, in a first step towards measuring aspherics, we demonstrate that also rough convex steep rotationally symmetric spherics can be measured along one meridian in a single step using diffractive beam splitters and phase shifting techniques. The measurement of rough surfaces is possible, i.e., without the need to polish the surfaces, due to the large effective wavelength (λeff≈10µm) of the test. We include, besides the short recapitulation of the measurement principle and experimental setup, a presentation of the measured data of one small meridian region for the special case of spherical objects under test. The subsequent data analysis combined with suitable simulations focuses on elimination of the misalignment aberrations from the results caused by specimen displacements in the setup.

Absolute testing of the reference surface of a Fizeau interferometer through even/odd decompositions.

Absolute testing of spherical surfaces is a technological necessity because of increased accuracy requirements. In a Fizeau setup, the main part of the interferometer deviations thereby comes from the reference surface. We demonstrate the validity of an absolute testing procedure for the reference surface that has been proposed earlier. The procedure relies on the decomposition of the surface deviations into odd and even parts and could be used in partially coherent illumination. The odd deviations are obtained from a basic and a 180 degree-rotated position of an auxiliary sphere, and the even deviations can be measured with the help of a cat's eye position in double pass using an opaque half screen in the interferometer aperture.

Metal airway stent implantation in children: follow-up of seven children.

Long segment malacia of the trachea or main stem bronchi in children is not always suitable for surgical correction; patients may therefore remain ventilator-dependent and/or experience severe obstructive crises. We treated 7 children (ages, 4 months to 9 years) with extreme structural central airway obstruction with stent implantations. Six were mechanically ventilated; 5 had frequent life-threatening obstructive spells requiring deep sedation or paralysis. Diagnoses were: syndrome-associated tracheobronchomalacia (n = 4), malignancy infiltrating the carina (n = 1), congenital tracheal stenosis (n = 1), and tracheobronchial compression by a malpositioned aorta (n = 1). Six tracheal and 13 bronchial stents were endoscopically placed. The prostheses included mesh titan (n = 5), the newer shape memory material nitinol (n = 13), and 1 Y-shaped carina stent. Follow-up was reported for 7 weeks to 72 months. All patients showed marked improvement of their respiratory obstruction. Six children were weaned at least temporarily from ventilation. No significant bleeding, stenosis, or perforation was observed. Seven stents were changed after up to 14 months. Three children are well and at home. In 2 children airway stabilization was successful, but they later died from causes unrelated to stent placement, and 2 children died due to generalized airway disease. Soft metal mesh airway stents can offer a therapeutic option in life-threatening inoperable obstruction of the trachea and main stem bronchi in children.

Bilateral bronchial balloon dilatation and Strecker stent implantation in a ventilated child with malignant carinal stenosis.

Tracheobronchial endoluminal reconstruction and stenting has become a valuable palliative tool in adults with intrathoracic tumors compromising the airways. Tracheobronchial balloon dilatation has been recently used in children and even neonates. We report a case of severe airway obstruction requiring emergency intubation and artificial ventilation in a 5-year-old child with intrathoracic recurrence of a rhabdomyosarcoma. Endoscopic balloon dilatation through the endotracheal tube with subsequent implantation of a non self-expanding metal mesh stent was used successfully, allowing extubation and discharge of the child from ICU.

[Fatal complications in tracheotomized children]. / Letale Komplikationen tracheotomierter Kinder.

BACKGROUND: Tracheotomy in the pediatric patient has become a routine procedure since the late 19th century, when it was used in treating diphtheria. Although underlying diseases have changed, the child with an artificial airway still faces numerous risks. This study investigates fatal complications in 280 patients with tracheostomy who were seen in the Dr. von Haunersches Kinderspital for laryngo-tracheo-bronchoscopy. METHOD: Data was acquired from patients' records of the Dr. von Haunersches Kinderspital and communications with other institutions. RESULTS: Nineteen deaths were investigated. Three patients died of acute cannula obstruction although hospitalized in different institutions. Two patients who died at home may also have suffered cannula obstruction, although this could not be verified. The majority of patients succumbed to the underlying disease. CONCLUSIONS: Permanent close supervision or monitoring at all times is critical to prevent cannular related deaths. Our results are compared with major series in other studies. In addition, we propose a booklet for the pediatric tracheotomy patient to document patient data and examination findings, e. g. type and size of cannula, duration of cannulation, laryngotracheometry, and complications. Its purpose will be to support communication between patients, parents, pediatricians, pediatric surgeons, and otolaryngologists. Furthermore, this booklet will help in evaluating risks, which may encounter pediatric tracheostomy patients, thereby enabling future studies.

Pulmonary sling: morphological findings. Pre- and postoperative course.

Pulmonary sling (PS) is a congenital condition in which the left pulmonary artery (LPA) arises from the right pulmonary artery (RPA), forming a sling around the trachea causing tracheal compression. The incidence is not so rare as initially thought. Symptoms of severe airway obstruction often begin in the newborn or young infant. Echo-colour-Doppler may reveal the PS but emphysema can mask the typical findings. Deviation of fluid-filled lungs may be detected prenatally. Chest radiographs show unusual air distribution, deviation of heart and mediastinum and altered tracheobronchial angles. Bronchography and bronchoscopy demonstrate the high incidence of associated tracheal anomalies such as cartilagenous rings and long tracheal stenosis. Anterior oesophageal indentation is not always seen in the oesophogram. Magnetic resonance imaging (MRI) and computed tomography (CT) reveal the PS, but cautious interpretation is necessary because of different levels of the anomalous LPA. PS and associated cardiovascular malformations can be clearly detected by angiography. Associated extrathoracic anomalies are common. Early diagnosis and therapy of PS is mandatory and consists of reimplantation of the LPA into the pulmonary trunk and division of the ligamentum arteriosum. The postoperative course may be cumbersome necessitating bronchological interventions. Tracheal resection may be necessary but restenosis is frequent. A one-stage repair has been proposed in such cases and was successfully done in a few reported cases. Relief of respiratory obstruction is often complete when there are no associated tracheobronchial anomalies. Late postoperative course is favourable but respiratory obstructive attacks may occur with decreasing incidence over time and tracheal growth.

[Risk score and postoperative complications in pediatric surgery]. / Risikoscore und postoperative Komplikationen in der Kinderchirurgie.

We have developed a risk score meeting the special demands of pediatric surgery. It conveys an objective impression of the patients' preoperative condition and enables us to predict their individual intra- and postoperative behavior. This study compiles the course of 1425 operations carried out between 1986 and 1990. They were divided into low, intermediate and high risk. In addition, the patients were classified into six different age groups. We demonstrate that the number of points assigned by our risk score is highly correlated with the rate of complications that occurred, that accompanying malformations and diseases are correctly picked up and weighed by the score as far as their importance for the postoperative course is concerned, that the score is suitable for ascertaining which patients have a high probability of developing complications: the specificity is close to 100% for more than 12 points on the score, and the proportion of correctly predicted lethal courses (sensitivity) is also close to 100%. The significance of the risk score lies first in the possibility of giving patients exact data on the intra- and postoperative risk, and secondly in the provision of an objective measure of quality control--which is legally prescribed in Germany--and comparison with other hospitals. Third, the risk score gives clear starting points for research aiming at improvement in the field of surgery in sick children, and lastly it forms the basis for reliable preoperative recognition of high-risk as needed patients for modern payment methodology of the per-cose costs and thus makes it possible to charge accordingly.

[Endoscopic, 3-dimensional measurement of neoplasms and stenoses of the larynx and trachea]. / Endoskopische, dreidimensionale Vermessung von Neubildungen und Stenosen des Larynx und der Trachea.

Calculating the exact measures of laryngeal tumours will be crucial for the next generation of the TNM System. Furthermore, cross-sectional area and length of a laryngotracheal stenosis are of major interest for clinical management. It is the aim of this study to assess these parameters endoscopically in a more detailed and exact manner. For this purpose a Hopkins Endoscope (Karl Storz, Tuttlingen, Germany) and a slide caliper are combined. This new instrument is called laryngometer (Fig. 1a u. b). It helps to measure the lengths of a stenosis or neoplasm. In addition it defines the level of a given object and provides a standard in a two-dimensional video sequence. Thus the laryngometer allows to digitally analyse cross-sectional areas and distances as well as to evaluate craniocaudal parameters.

[Surgical treatment of pediatric laryngeal stenosis in the area of the ring cartilage]. / Die chirurgische Behandlung der kindlichen Larynxstenose im Ringknorpelbereich.

In the past 15 years, infants and children with laryngeal stenosis have also been successfully treated with laryngotracheoplasty. From 1991 to 1993 we performed a surgical treatment in 20 pediatric patients with subglottic stenosis. The anterior cricoid split procedure should always be considered in children who cannot be extubated before undergoing tracheotomy, especially because in case of failure there are no disadvantages for any further operative measurements. By modifying the technique described by Cotton and Seid (1980), we performed an endoscopically controlled anterior cricoid split in 5 children via an endolaryngeal approach. 4 of these patients were extubated within 10 days after using a nasotracheal tube for splinting the cricoid level. In 14 patients with a tracheostoma we used a modification of Réthi's division of the posterior lamina of the cricoid by the placement of a autogenous costal cartilage graft. A 6-week-period of stenting is required for sufficient healing and stability of the reconstructed airway.

MRI in pre- and postoperative assessment of tracheal stenosis due to pulmonary artery sling.

OBJECTIVE: To evaluate the potential of MRI in the assessment of tracheal stenosis due to tracheal or vascular malformations, 45 children with severe respiratory distress were examined prospectively during a period of 1 year. Five of these children had tracheal stenosis due to a sling left pulmonary artery (SLPA). MATERIALS AND METHODS: Magnetic resonance examinations of the anesthetized children were performed with a 1.5 T Siemens MR imager using electrocardiographically gated T1-weighted SE sequences in transverse and sagittal slice orientations. Slice thickness was 3 mm and each sequence was repeated after shifting the slice position by 1 mm. Monitoring during the examinations included ECG, oscillatory blood pressure, respiratory rate, and oxygen concentration. Magnetic resonance findings were compared with esophagography, selective pulmonary angiography, bronchoscopy, Doppler sonography, and surgery. All examinations were repeated after surgical therapy to assess the improvement in tracheal stenoses and the patency of the ligated and reimplanted left pulmonary arteries. RESULTS: Magnetic resonance imaging clearly revealed the course of the SLPA and its topographic relationship to the trachea as well as the coexistence of cardiovascular and tracheobronchial or esophageal malformations. The degree and length of tracheal stenoses, which were measured in the pre- and postoperative axial slices and graphically displayed, as well as the angles of the right and left main stem bronchi, could be accurately determined. CONCLUSION: Magnetic resonance imaging in combination with bronchoscopy yielded the necessary and sufficient information for diagnosis and aided the surgeon in planning operative strategy and in postoperative follow-up.

[Life threatening late dislocation in chronic foreign body aspiration]. / Lebensgefährliche Spätdislokation bei chronischer Fremdkörperaspiration.

We report a case of a boy with a long-standing foreign body aspiration in the left main bronchus causing severe pneumonia of the left lung. During intravenous therapy with antibiotics there was a life-threatening event with acute dislocation of the foreign body into the right main bronchus, leading to acute respiratory insufficiency. We conclude that in chronic foreign body aspiration antibiotic therapy preceding bronchoscopy should only be performed in in-patients and with strict monitoring.

[Surgical complications caused by tracheobronchial foreign body in childhood]. / Chirurgische Komplikationen durch tracheobronchiale Fremdkörper im Kindesalter.

Four cases of tracheobronchial foreign body aspirations are described that necessitated surgical interventions. Bronchial rupture occurred in three cases and in one case the foreign body had to be removed via thoracotomy after endoscopic extraction had failed. The possible complications in case of a chronic tracheobronchial foreign body due to delayed diagnosis are pointed out. The purpose of this contribution is to provide the general practitioner with guidelines to suspect the presence of a foreign body well in time and to refer the patient quickly to a competent hospital for immediate treatment.

Severe lower tracheal stenosis in infancy.

16 infants with severe distal tracheal stenosis (TS) seen from 1978-1988 are reviewed. Diagnosis was established by endoscopy and confirmed by radiographic methods, including magnetic resonance imaging (MRI) in three cases. Types of TS ranged from segmental stenosis to complex lesions involving the carina and bronchi. Associated vascular anomalies were found in nine patients (56%). All patients needed long-term intubation or a tracheostomy (seven cases) for stenting of the airway. Patients with congenital TS (CTS) were treated by tracheal resection (two survivors), dilatation (one survivor, two non-survivors), or observation (two non-survivors). Patients with pulmonary artery sling (PAS) were treated by division of the vascular sling (three survivors, one non-survivor), or combined vascular and tracheal surgery (one non-survivor). One patient with dilated pulmonary arteries compressing both main bronchi died in spite of oxygen therapy. Two cases of compression by an anomalous aorta were managed with dilatation (one survivor, one non-survivor). One patient with a severe stricture after a tracheal resection was successfully treated by dilatation. The overall mortality was 50%. We conclude that 1. endoscopic examination of the tracheobronchial tree and thorough evaluation of associated anomalies is mandatory in symptomatic patients; 2. if indicated surgical correction is the treatment of choice for tracheal stenosis; 3. dilatation and stenting of the stenosis are invaluable tools in the management of these infants.

Treatment of congenital tracheoesophageal fistula by endoscopic laser coagulation: preliminary report of three cases.

Three newborns with congenital tracheoesophageal fistula were treated by endoscopic laser coagulation. After radiologic and endoscopic diagnosis, laser coagulation of the mucosal layer of the fistula followed using Nd:YAG laser light transferred through an uncovered quartz fiber of 600 microns diameter. The successful and uneventful course in two cases contrasts with the incomplete obliteration in one case caused by inadequate energy application and/or early localized instillation of contrast medium for radiologic control examination. The advantages of this method include elimination of an operative procedure, exclusion of operative complications, and the possibility of repetition in recurrent cases. Care must be taken to prevent esophageal and tracheal damage by use of this method.