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Neuroscience, cognitive science, and computer science are increasingly benefiting through their interactions. This could be accelerated by direct sharing of computational models across disparate modeling software used in each. We describe a Model Description Format designed to meet this challenge., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Doppler asymmetric spatial heterodyne (DASH) interferometry is a novel concept for observing atmospheric winds. This paper discusses a numerical model for the simulation of fringe patterns and a methodology to correct fringe images for extracting Doppler information from ground-based DASH measurements. Based on the propagation of optical waves, the fringe pattern was modeled considering different angular deviations and optical aberrations. A dislocation between two gratings can introduce an additional spatial modulation associated with the diffraction order, which was seen in laboratory measurements. A phase correction is proposed to remove phase differences between different row interferograms, which is the premise for calculating the average interferogram to improve the signal-to-noise ratio. Laboratory tests, simulation results, and Doppler velocity measurements indicate that a matrix determined in the laboratory can be applied to correct interferograms obtained from ground-based DASH measurements.

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 ( λ eff =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.

Measuring the aberrations of optical systems is an essential step in the fabrication of high precision optical components. Such a characterization is usually based on comparing the device under investigation with a calibrated reference object. However, when working at the cutting-edge of technology, it is increasingly difficult to provide an even better or well-known reference device. In this manuscript we present a method for the characterization of high numerical aperture microscope objectives, functioning without the need of calibrated reference optics. The technique constitutes a nanoparticle, acting as a dipole-like scatterer, that is placed in the focal volume of the microscope objective. The light that is scattered by the particle can be measured individually and serves as the reference wave in our system. Utilizing the well-characterized scattered light as nearly perfect reference wave is the main idea behind this manuscript., (© 2021. The Author(s).)

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.

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 ( λ eff ≈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.

In this paper a method for correcting the radial distortion of interferograms generated by a spatial heterodyne spectrometer system is presented. Instead of utilizing calibration patterns, the distortion model parameters are estimated based on the distorted fringe features generated by projecting the straight interference stripes onto the detector. Comparisons between polynomial models and division models indicate that division models can deliver competitive performance on the reconstructed image with fewer parameters. Simulated interferograms based on ray-tracing are used to demonstrate the correction of errors in the spatial, phase, and spectral domain caused by optical distortion.

This paper presents a method for wind velocity and Doppler temperature retrieval from interferograms of a Doppler asymmetric spatial heterodyne spectrometer. This method is based on the analytic representation of the signal and the subsequent algorithms. It turns out to be more robust than the conventional Fourier transform method at low SNR. The influence of optical dispersion on the accuracy of the retrieved parameters is also characterized. The effective optical path difference is suggested for use in wind and temperature retrieval routines. Computer simulations are used to characterize the accuracy of the proposed method, in particular regarding the influence of optical dispersion.

This paper presents a novel interferometric method for the simultaneous spatially resolved analysis of an object under test regarding the phase transmission function and the magnitude and orientation of the (uniaxial) birefringence. The measurement strategy is based on variations of the phase and polarization and processing the interference patterns so obtained. With this method, which is very similar to the classical phase-shifting interferometry, a complete analysis of birefringent properties of the object and its impact on the phase of the incoming light can be done in one measurement cycle. The theoretical description of the investigated methods and their experimental implementation are presented.

Interferometric speckle techniques are plagued by the omnipresence of phase singularities, impairing the phase unwrapping process. To reduce the number of phase singularities by physical means, an incoherent averaging of multiple speckle fields may be applied. It turns out, however, that the results may strongly deviate from the expected √N behavior. Using speckle-shearing interferometry as an example, we investigate the mechanism behind the reduction of phase singularities, both by calculations and by computer simulations. Key to an understanding of the reduction mechanism during incoherent averaging is the representation of the physical averaging process in terms of certain vector fields associated with each speckle field.

Optical components manipulating both polarization and phase of wave fields find many applications in today's optical systems. With modern lithography methods it is possible to fabricate optical elements with nanostructured surfaces from different materials capable of generating spatially varying, locally linearly polarized-light distributions, tailored to the application in question. Since such elements in general also affect the phase of the light field, the characterization of the function of such elements consists in measuring the phase and the polarization of the generated light, preferably at the same time. Here, we will present first results of an interferometric approach for a simultaneous and spatially resolved measurement of both phase and polarization, as long as the local polarization at any point is linear (e.g., for radially or azimuthally polarized light).

The homogeneity test of glass plates in a Fizeau interferometer requires the measurement of the glass sample in reflected as well as in transmitted light. For the measurement in transmitted light, the sample has to be inserted into the ray path of a Fizeau or Twyman-Green interferometer, which leads to a nested cavity setup. To separate the interference signals from the different cavities, we illuminate a Fizeau interferometer with an adaptive frequency comb. In this way, rigid glass plates can be measured, and linear variations in the homogeneity can also be detected. The adaptive frequency comb is provided by a variable Fabry-Perot filter under broadband illumination from a superluminescence diode. Compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher.

Optical components manipulating both polarization and phase of wave fields find more and more applications in today's optical systems. In particular, the polarization orientation may vary across the aperture. New measurement techniques and evaluation algorithms are needed to simultaneously characterize the properties of such elements. In this Letter, a general measurement algorithm for locally linear polarization distributions is presented, extending the methods of phase shifting interferometry to the simultaneous determination of polarization and phase. A class of evaluation algorithms is derived, and some example algorithms are described and tested for their resilience against systematic and stochastic stepping errors.

Measurements of wavefront deformations can be carried out with the help of lateral shearing interferometers. Here the focus is on a setup providing two shears along orthogonal directions simultaneously to generate the data needed for a reconstruction. We describe a diffractive solution using Ronchi phase gratings with a suppressed zeroth order for both the doubling of the wavefront under test and the bidirectional shearing unit. A series arrangement of the gratings offers an on-axis geometry, which minimizes the systematic errors of the test. For illumination, an extended incoherent monochromatic light source is used. High-contrast fringes can be obtained by tailoring the degree of coherence via a periodic intensity distribution.

Parallel two-step phase-shifting point-diffraction interferometry for microscopy based on a pair of cube beamsplitters is proposed. The first 45°-tilted cube beamsplitter splits object wave into two parallel copies: one copy is filtered by a pinhole in its Fourier plane to behave as reference wave, while the other one remains unchanged as object wave. The second cube beamsplitter combines the object and reference waves, and then split them together into two beams. Along with the two beams, two parallel phase-shifting interferograms are obtained in aid of polarization elements. Based on the proposed configuration, slightly-off-axis interferometry for microscopy is performed, which suppresses dc term by subtracting the two phase-shifting holograms from each other. The setup is highly stable due to its common-path configuration, and has been demonstrated to be suitable for measuring moving objects or dynamic processes.

Conventional optical imaging systems suffer from the presence of many imperfections, such as spherical aberrations, astigmatism, or coma. If the imaging system is corrected for spherical aberrations and fulfills the Abbe sine condition, perfect imaging is guaranteed between two parallel planes but only in a small neighborhood of the optical axis. It is therefore worth asking for optical systems that would allow for perfect imaging between arbitrary smooth surfaces without restrictions in shape or extension. In this Letter, we describe the application of transformation optics to design refractive index distributions that allow perfect, aberration-free imaging for various imaging configurations in R(n). A special case is the imaging between two extended parallel lines in R(2), which leads to the well-known hyperbolic secant index distribution that is used for the fabrication of gradient index lenses.

A new common-path and in-line point-diffraction interferometer for quantitative phase microscopy is proposed. The interferometer is constructed by introducing a grating pair into the point-diffraction interferometer, thus forming a common-path and in-line configuration for object and reference waves. Achromatic phase shifting is implemented by linearly moving one of the two gratings in its grating vector direction. The feasibility of the proposed configuration is demonstrated by theoretical analysis and experiments.

A simple algorithm for blind extraction of phase shifts is proposed for generalized phase-shifting interferometry from only three interferograms. Based on the statistical property of the object wave, the algorithm calculates approximately the involved phase shifts as initial values. The extraction is further improved by an iterative method, considering the fact that the closer the phase shifts approach their real values, the more uniform the reconstructed reference wave will become. The feasibility of this algorithm is demonstrated by both simulation and experiment.

Increasing accuracy requirements in aspheric metrology make the development of absolute testing procedures for aspheric surfaces important. One strategy is transferring the standard practice three-position test for spheres to aspherics. The three-position test, however, involves a cat's eye position and therefore has certain drawbacks. We propose an absolute testing method for rotationally symmetric aspherics where the cat's eye position is replaced with a radially sheared position. Together with rotational movements of the specimen, the surface deviations can be obtained in an absolute manner. To demonstrate the validity of the procedure, we present a measurement result for a sphere and compare it with a result obtained by the standard three-position test.

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.

We report on interferometric characterization of a deep parabolic mirror with a depth of more than five times its focal length. The interferometer is of Fizeau type; its core consists of the mirror itself, a spherical null element, and a reference flat. Because of the extreme solid angle produced by the paraboloid, the alignment of the setup appears to be very critical and needs auxiliary systems for control. Aberrations caused by misalignments are removed via fitting of suitable functionals provided by means of ray tracing simulations. It turns out that the usual misalignment approximations fail under these extreme conditions.

Aspheric optical surfaces are often tested using diffractive optics as null elements. For precise measurements, the errors caused by the diffractive optical element must be calibrated. Recently, we reported first experimental results of a three position quasi-absolute test for rotationally invariant aspherics by using combined-diffractive optical elements (combo-DOEs). Here we investigate the effects of the DOE substrate errors on the proposed calibration procedure and present a set of criteria for designing an optimized combo-DOE. It is demonstrated that this optimized design enhances the overall consistency of the procedure. Furthermore, the rotationally varying part of the surface deviations is compared with the rotationally varying deviations obtained by an N-position averaging procedure and is found to be in good agreement.

We have already reported a method for the quasi-absolute test of rotationally symmetric aspheres by means of combined diffractive optical elements (combo-DOEs). The combo-DOEs carry the information for the ideal shape of an aspheric surface under test as well as a spherical wave for the measurement at the cat's eye position. An experimental demonstration of the procedure is given. Measurements with two different designs of combo-DOEs have been conducted, and their relative advantages and disadvantages are discussed.

Cylindrical specimens may be tested advantageously by using grazing-incidence interferometry. A multiple positions test in combination with rotational averaging has recently been used to separate the surface deviations of the specimen from the interferometric aberrations. To reduce the measuring time and to check whether the results are reliable, a second procedure is now investigated, which uses the principle of the multiple positions test to determine quantities proportional to the difference quotients of the surface deviations. After numerical integration, the results can be compared with those obtained previously by rotational averaging. The measurement principle is described, and calibration results are presented.

Interferometry in grazing incidence can be used to test cylindrical mantle surfaces. The absolute accuracy of the resulting surface profiles is limited by systematic wavefront aberrations caused in the interferometer, in particular due to an inversion of the test wavefront in an interferometer using diffractive beam splitters. For cylindrical specimens, a calibration method using four positions has therefore been investigated. This test is combined with another method of optical metrology: the rotational averaging procedure. The implementation for grazing incidence is described and measurement results for hollow cylinders are presented. The gain in accuracy is demonstrated.

A diffractive grazing-incidence interferometer for the test of cylindrical lenses is described. Besides surface aberrations from the ideal shape, the interferometer allows for the simultaneous determination of the relative position and orientation of surfaces to another. The measurement principle as well as a classification of deviation types is given. Measurement results for planar concave lenses are presented.

One important feature of grazing-incidence interferometry is the anamorphotic distortion or the fore-shortened view of the interference pattern along the optical axis caused by the geometry of theinterferometer. To compensate for the consequential lower resolution along the optical axis, a setup was built in which the object plane is imaged onto a rectifying grating, ensuring sharp mapping of the whole specimen onto the detector. A volume hologram and a diffraction grating serve as rectifying elements and are applied to measure various types of planar objects such as mirrors and structured plastic samples. Accuracy, image sharpness, and residual distortion for both cases are discussed.

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., (Copyright 2001 Wiley-Liss, Inc.)

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

A 5-year-old boy with acute lymphatic leukemia in remission developed signs of malignant hyperthermia (MH) during general anesthesia for removal of a central venous access port. The anesthetic procedure for implantation of the port 17 months before had been uneventful despite use of the same triggering agents, halothane and succinylcholine. Meanwhile, the patient had received chemotherapy (COALL-03-85). The first sign of MH was masseter spasm following succinylcholine; then tachycardia, acidosis, myoglobinuria, and CPK elevation (8953 IU) appeared. There was only moderate temperature elevation to 37.8 degree C. Rapid improvement and complete recovery occurred after dantrolene i.v. The patient's father was found to have undiagnosed muscle pain and an elevated CPK level. An in vitro contracture test with halothane and caffeine revealed susceptibility to MH and supported the patient's diagnosis and genetic predisposition. Referring to several other cases in the literature concerning MH in patients with lymphomas and leukemias, a possible correlation between the two diseases is discussed. As the MH crisis in our patient was most probably genetic in origin, a common acquired cause such as a viral infection seems less probable. We do not believe the chemotherapy our patient received between the two anesthetics was the cause since about one-half of the patients in the literature had not had chemotherapeutic pretreatment at the time of the MH crisis. We believe that a common genetic predisposition is the most likely link between the two diseases. In any case, patients with leukemias and lymphomas should be monitored very carefully for symptoms of MH.(ABSTRACT TRUNCATED AT 250 WORDS)

This is a report on 35 cases of innominate artery compression of the trachea and its surgical correction by means of aortotruncopexy. Diagnostic procedures of choice were tracheoscopy and magnetic resonance imaging, which offers representative images of inspiration and expiration, shows the anatomical relations between aortic arch and trachea and reveals the extent of tracheal compression. Surgical treatment is indicated if narrowing of the tracheal lumen exceeds 70%. By fixation of the aortic arch and the proximal innominate artery to the back of the sternum, tracheal compression is relieved. There was no unsuccessful operation in the 35 children. One late death occurred from cardiac failure, unrelated to tracheal compression.

Magnetic Resonance Imaging of the pediatric chest was performed in 53 patients. All examinations were performed using a 1.0 and 1.5 Tesla superconducting MR imager. 80% of the children were examined using anesthesia with a ventilation of 20% inspiration and 80% expiration. After performing the MR examination in 55% of the cases an operation was performed. In 29 patients anomalies of the brachiocephalic trunc were found. In four patients MR detected a doubled aortic arch, in four patients we found a dilated arch. In eight children a dilated pulmonary artery was diagnosed. In combination with eight tracheobronchoscopy, MR imaging proved to be the diagnostic method of choice for the evaluation of anomalies of the mediastinum. New developments like fast imaging techniques and 3D acquisition promise a further diagnostic improvement in the mediastinum.

Magnetic resonance imaging of the trachea was performed in 21 children with congenital or acquired narrowing of the trachea or main bronchi. Diagnosis included aortic arch anomalies, innominate artery compression, pulmonary artery compression and tracheomalacia. All patients were examined after bronchoscopy. The demonstration of the trachea and the surrounding tissue and vessels on MR images enables the cause of tracheal compression and the degree and location of collapse to be evaluated. MRI is a modality well suited to characterizing tracheal narrowing without employing ionizing radiation or intravenous contrast medium. All MRI examinations were carried out with the patient under general anaesthesia so as not to risk pulmonary deterioration during sedation. In the cases presented MRI is the diagnostic step of choice after tracheobronchoscopy and broadens the diagnostic potential in extrinsic tracheal or bronchial stenosis in paediatric patients.

This is a report on five boys aged between 1 and 5 years who, after prolonged submersion in cold water, were treated at our department. On being taken out of the water, all the patients were clinically dead. After 1- to 3-hour successful cardiopulmonary resuscitation, with a rectal temperature of about 27 degrees C, they were rewarmed at a rate of 1 degree/hour. Two patients died within a few hours after the accident. One patient survived with an apallic syndrome, 2 children survived with no sequelae. In the event of a water-related accident associated with hypothermia, we consider suitable resuscitation to have preference over rewarming measures. The most important treatment guidelines and prognostic factors are discussed.

This is a report on 30 cases of innominate artery compression of the trachea and its operative correction by an aorto-truncopexy. Tracheoscopy is the most important examination for arriving at the diagnosis. Magnetic resonance imaging (MRI), which offers representative pictures of many moments of expiration and inspiration, shows the anatomic relationship between the innominate artery, the aortic arch and the trachea, also demonstrating the extent of the tracheal compression. Surgical treatment is indicated if narrowing of the lumen of the trachea is greater than 70%. By fixing the aortic arch and the proximal innominate artery at the back of the sternum the trachea is relieved of its compression. In 30 children there was no unsuccessful operation, and none of them died.

Three cases of male infants with hypoplasia and aplasia of the right lung and dextrocardia are reported. The infants developed increasing obstructive respiratory distress in the first 4 months of life. In all three cases, there was an opaque right hemithorax with overinflation of the left lung, a posterior deviation of the trachea with pulsatile stenosis, and a posteriorly located aortic arch. Hypoplasia (two cases) or aplasia (one case) of the right pulmonary artery and an absence or a remnant of the right main bronchus were also observed. Associated malformations were esophageal atresia with an abnormal high pouch of the proximal esophagus in case 1, and hypertelorismus syndrome in case 2. Because of severe respiratory distress in all three patients, an aortopexy was performed at the ages of 5 months (one infant) and 10 months (two infants). The obstructive respiratory signs disappeared postoperatively in the following weeks. It has been observed that tracheal stenosis in aplasia or hypoplasia of the right lung may be caused by the dislocated aortic arch. An aortopexy can release the airway compression in such cases. Because of associated malformations, a careful evaluation of the airway and vessels is recommended.