Analysis of the Effectiveness of Arytenoidectomy and Posterior Cordectomy with the Use of CFD Airflow Measurements in Patients with BVFP: A Retrospective Study.

Purpose: Bilateral vocal fold paralysis (BVFP) is a rare larynx disease manifested by dyspnea, which often requires surgical treatment. The aim of the study is to determine the effectiveness of unilateral arytenoidectomy with posterior cordectomy in the treatment of BVFP using the computational fluid dynamics (CFD) method. Methods: This study included 33 patients with BVFP who underwent unilateral laser arytenoidectomy with posterior cordectomy. Glottis area measurements and spirometry, as well as a self-assessment of respiratory efficiency were performed before the surgery and after the recovery period. Using the CFD method, computer models of the glottis were made. Then, changes in air pressure gradient and maximum air velocity at the level of glottis were calculated, and local fields of pressure and air velocities were obtained. Results: The values of glottal surface area (S), spirometry parameters (forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF)), inlet air velocity at the glottal level as well as patients self-assessment of respiratory efficiency turned out to be significantly higher after the operation. The values of maximum velocity at the glottal level, pressure gradient at the glottal level turned out to be significantly lower after the surgery. We observed that the greater the increase in glottal surface area, the greater the decrease in self-assessment scales (visual analogue scale (VAS) and Medical Research Council (MRC)). Increased levels of spirometry parameters after the surgery correlated with smaller decrease of PEF-dependent pressure gradient at the glottal level (PEFΔP CFD). Conclusion: Unilateral laser arytenoidectomy with posterior cordectomy is an effective method for the treatment of BVFP. CFD is a useful tool to determine and visualize the effectiveness of surgical treatment in BVFP.

Computational fluid dynamics in the assessment of patients' postoperative status after glottis-widening surgery.

BACKGROUND: Computational fluid dynamics (CFD), a rapidly developing instrument with a number of practical applications, allows calculation and visualization of the changing parameters of airflow in the upper respiratory tract. OBJECTIVES: The aim of this study was to demonstrate the advantages of CFD as an instrument for noninvasive tests of the larynx in patients who had undergone surgical treatment due to bilateral vocal fold paralysis. MATERIAL AND METHODS: Surface measurements of the glottic space were made during maximum adduction of the vocal folds. Additionally, the following spirometric parameters were determined: forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and peak expiratory flow (PEF) rate. Based on the measurements, commercial mesh generation software was used to develop a geometrical model of the glottic space. The computations were carried out using a general purpose CFD code. The analysis included patients who were surgically treated for BVFP in the authors' department between 1999 and 2012. The study group consisted of 22 women (91.67%) and 2 men (8.33%). RESULTS: It was observed that the pressure drop calculated for free breathing depends on the area of the glottis and is independent of its shape. Importantly, for areas below approx. 40 mm2, a sudden rise occurred in the resistance to flow; for the smallest glottic areas studied, the pressure drop was almost 6 times higher than for an area of 40 mm2. Consequently, in cases of areas below 40 mm2 even minor enlargement of the glottic opening can lead to a marked improvement in breathing comfort. CONCLUSIONS: Computational fluid dynamics is a useful method for calculating and visualizing the changing parameters of airflow in the upper respiratory tract.

Facile and scalable synthesis of nanoporous materials based on poly(ionic liquid)s.

A simple, fast, sustainable, and scalable strategy to prepare nanoporous materials based on poly(ionic liquid)s (PILs) is presented. The synthetic strategy relies on the radical polymerization of crosslinker-type ionic liquid (IL) monomers in the presence of an analogous IL, which acts as a porogenic solvent. This IL can be extracted easily after polymerization and recycled for further use. The great advantages of this synthetic approach are the atom-efficiency and lack of waste. The effects of different monomer/porogen ratios on the specific surface area, porosity, and pore size have been investigated. Finally, the potential of the materials as CO2 sorbents has been evaluated.

Long-term results in patients after combined laser total arytenoidectomy with posterior cordectomy for bilateral vocal cord paralysis.

The problem of ventilation efficiency after total laser arytenoidectomy with posterior cordectomy due to bilateral vocal cord paralysis is discussed. There are a number of views on the usefulness and efficacy of different surgical procedures aimed at widening the glottis, but the studies concerning the long-term functional results are still lacking. The objective of the study is to evaluate the durability of ventilation results in patients after laser arytenoidectomy with posterior cordectomy based on the comparison between the early postoperative results and those assessed after a period of 5 years. Thirty patients (24 females, 6 males) aged between 30 and 80 (mean 58.5) with bilateral vocal cord paralysis after thyroid surgery, who underwent laser arytenoidectomy with posterior cordectomy, were analyzed. Ventilation tests were performed immediately after the operation and 5 years later with Body-Master Laab (Jaeger). The actual and predicted values of FVC, FEF(25), FEF(50), FEF(75), PEF, MMEF(75/25), AREA(Ex), sR(T0T), R(T0T) were compared and analyzed. Also, the values of the inspiratory parameters FIV(1), FIF(50), PIF and the coefficients FEF(50)/FIF(50) and FIV(1)/FEV(1) were assessed. Moreover, subjective evaluation was performed based on a questionnaire. The statistical analysis reveals a significant decrease in FIV(1), FIF(50), PIF and FIV(1)/FEV(1). FEF(50)/FIF(50) and sR(T0T) (actual and predicted values) increased significantly after 5 years from the operation. However, the patients did not complain nor was this tendency reflected in their answers to the questionnaire. The probable reasons for such ventilation results are discussed. The role of phoniatric rehabilitation and the time elapsed is emphasized. In general, it can be concluded that laser arytenoidectomy with posterior cordectomy is a durable and effective procedure, although the objective assessment does not fully match the patient's subjective impression.

The influence of laser arytenoidectomy on ventilation parameters in patients with bilateral vocal cord paralysis.

Bilateral vocal cord paralysis is a symptom that may lead to serious breathing problems. The treatment of patients with vocal cord paralysis presents a challenge to otolaryngologists. Many techniques have been developed in an attempt to improve the patient's airway insufficiency. The aim of the study was to evaluate the efficacy of the laser total unilateral arytenoidectomy with posterior cordectomy in patients with bilateral vocal cord paralysis. Thrity-six patients (33 females, 3 male) aged between 24 and 76 (mean 52) were treated by laser arytenoidectomy. The flow-volume loop and pletysmography were performed in all patients before and after the operation. Additionally, a group of 15 patients with unilateral vocal cord paralysis was introduced and analyzed as a special control. Based on the relative increase of the parameters after the surgery, the most useful of them were selected for the evaluation. Also, the character of the laryngeal obstruction was defined. Changes in the flow-volume loop before and after surgery were compared by planned comparison in univariate analysis ANOVA/MANOVA with an isolated control group. As the parameters AREA(EX), FEF50, FEF75, PEF and MMEF(75/25) increased most effectively, they appeared to be the most useful in the evaluation. FIV1/FEF1, FEF50/FIF50 and FEV1/FEV(0,5) allowed the definition of the obstruction as an extrathoracic dynamically variable quantity. The resistances measured during pletysmography diminished significantly after surgery. The introduction of the special control group with unilateral vocal cord paralysis showed that despite the significant improvement after surgery, the patients who had been operated on still had a laryngeal obstruction worse than that of patients from the control group. The laser arytenoidectomy is shown to be a useful and efficacious procedure for bilateral vocal cord paralysis.

[Aerodynamic model of ventilation efficacy in patients after laser arytenoidectomy]. / Aerodynamiczny model zmian wydolnosci wentylacyjnej u chorych po arytenoidektomii laserowej.

The treatment of bilateral vocal cord paralysis presents a challenge to otolaryngologists. All surgical procedures are designed to widen the lumen of the glottis without impairing vocal function and laryngeal closure during swallowing and respiration. The aim of the study was to evaluate the effectiveness of the laser arytenoidectomy by our own method. Based on the analysis of the results of 36 patients operated on due to bilateral vocal cord paralysis the aerodynamic model of ventilation efficacy changes was introduced and then verified. On the basis of the study an increase of the cross-sectional area of the glottis after laser arytenoidectomy can be combined with air flow improvement in upper airways. Thanks to this relation the postoperative ventilation efficiency may be predicted on the basis of its preoperative value and geometrical parameters of the glottis.