Nasal cavity airflow: Comparing laser doppler anemometry and computational fluid dynamic simulations.

Objective parameters to assess the physical flow conditions of breathing are scarce and decisions for surgery, e.g. nasal septum correction, mainly rely on subjective surgeon judgment. To define decision supporting parameters, we compare laser Doppler anemometry (LDA) and numerical computational fluid dynamic simulations (CFD) of the airflow velocity vector fields in the nasal cavity, including lattice Boltzmann (LB) and finite volume methods (FVM). The simulations are based on an anonymous patient CT dataset with septal deviation. LDA measurements are preformed using a 3D printed model. Nasal airflow geometry is randomly deformed in order to approximate surgical changes. The root-mean-square velocity error near the nasal valve of laser Doppler anemometry and lattice Boltzmann simulations is 0.071. Changes in geometry similarly affect both measurement and simulation.

Quantitative error analysis for computer assisted navigation: a feasibility study.

PURPOSE: The benefit of computer-assisted navigation depends on the registration process, at which patient features are correlated to some preoperative imagery. The operator-induced uncertainty in localizing patient features-the user localization error (ULE)-is unknown and most likely dominating the application accuracy. This initial feasibility study aims at providing first data for ULE with a research navigation system. METHODS: Active optical navigation was done in CT-images of a plastic skull, an anatomic specimen (both with implanted fiducials), and a volunteer with anatomical landmarks exclusively. Each object was registered ten times with 3, 5, 7, and 9 registration points. Measurements were taken at 10 (anatomic specimen and volunteer) and 11 targets (plastic skull). The active NDI Polaris system was used under ideal working conditions (tracking accuracy 0.23 mm root-mean-square, RMS; probe tip calibration was 0.18 mm RMS). Variances of tracking along the principal directions were measured as 0.18 mm(2), 0.32 mm(2), and 0.42 mm(2). ULE was calculated from predicted application accuracy with isotropic and anisotropic models and from experimental variances, respectively. RESULTS: The ULE was determined from the variances as 0.45 mm (plastic skull), 0.60 mm (anatomic specimen), and 4.96 mm (volunteer). The predicted application accuracy did not yield consistent values for the ULE. CONCLUSIONS: Quantitative data of application accuracy could be tested against prediction models with iso- and anisotropic noise models and revealed some discrepancies. This could potentially be due to the facts that navigation and one prediction model wrongly assume isotropic noise (tracking is anisotropic), while the anisotropic noise prediction model assumes an anisotropic registration strategy (registration is isotropic in typical navigation systems). The ULE data are presumably the first quantitative values for the precision of localizing anatomical landmarks and implanted fiducials. Submillimetric localization is possible for implanted screws; anatomic landmarks are not suitable for high-precision clinical navigation.

[Mass spectrometry in the verification of pyrimethamine poisoning]. / Pyrimethamin intoxikáció tömegspektrometriás igazolása.

A 17 years old male patient with Pyrimethamin therapy was released from our department by emphasising the necessity of continuous control. A month later the patient was accepted again with serious anaemia. Since the patient did not follow the instructions Pyrimethamin intoxication was presumed, but it had to be proved. At last the drug in the plasma was identified and quantified by mass spectrometry. The plasma concentration of Pyrimethamin was five times higher than the therapeutic level. The rapid analysis (4 hours after taking of blood) and adequate treatment resulted in rapid improvement with the concomitant decrease of plasma Pyrimethamin concentration. During clinical treatment the level of Pyrimethamin in the plasma was followed by mass spectrometry.

Myasthenia gravis: effect of immunoactive therapies.

New immunoactive therapies, plasmapheresis, intravenous steroid pulse infusion and intravenous immunoglobulins were examined for efficacy on the basis of large casuistics of myasthenia gravis. The best results were achieved with combination of these procedures. Indications of the new methods: (i) respiratory crisis of any character (myasthenic, cholinergic or mixed oscillating crisis); (ii) the patients' preparation for thymectomy; (iii) post-thymectomy therapy aimed at improving the patients condition, at avoiding relapses, at shortening the time of steroid therapy and at repressing cholinergic drug therapy; (iv) patients of old age in crisis-prone state. The new methods, together with thymectomy, steroid therapy and immunosuppression, represent a very efficient and promising new way toward modern therapy of myasthenia gravis.

[Therapy of adult respiratory distress syndrome]. / Therapie des respiratorischen Distress-Syndroms der Erwachsenen.

After a brief review of the pertaining literature, 10 patients treated for adult respiratory distress syndrome between 1974 and 1978 are reported. Eight patients died; in 4 cases the cause of death was some other irreversible lesion. Respirator treatment with the Bird-8 apparatus was supplemented with cardiac diuretic and antibiotic therapy. Improvement of the results can be hoped partly from prevention, partly from the early diagnosis of ARDS and its adequate treatment.