Michiel W. M. Brekel’s research while affiliated with University of Amsterdam and other places

Background: To improve the understanding of the thermodynamics and performance of small passive hygroscopic Heat and Moisture Exchangers (HMEs), a computer model simulating HME function is required. Methods: We developed a numerical HME model to calculate the HME's water and heat exchange. The model was tuned and verified with experimental data and validated by applying it to HME design variations. Results: Verification of the model's results to the experimental data shows that the tuned model yields reliable results. The mass of the core, which determines the HME's total heat capacity, is the most important parameter influencing the performance of passive HMEs. Conclusions: Increasing the HME's diameter is an effective way to improve an HME, as it yields higher performance and lowers breathing resistance. HMEs intended for use in warm or dry climates should contain more and those for use in cold humid climates should contain less hygroscopic salt.

Background: T4-classified squamous cell carcinoma (SCC) of external auditory canal (EAC) can potentially involve different anatomical structures, which could translate into different treatment strategies and survival outcomes within one classification. Our aim is to evaluate the clinical added value of T4-subclasses proposed by Lavieille and by Zanoletti. Methods: Retrospective data, including patients with primary operated cT4-classified EAC SCC, was obtained from 12 international hospitals. We subclassified according to the T4-subclasses. The treatment strategies, disease-free survival (DFS) and overall survival per subclass were calculated. Results: A total of 130 T4-classified EAC SCC were included. We found commonly used treatment strategies per subclass according to Lavieille and the DFS seems also to differ per subclass. Subclass according to Zanoletti showed comparable treatment strategies and survival outcomes per subclass. Conclusion: Our study suggests that the subclass according Lavieille might have added value in clinical practice to improve care of T4-classified EAC SCC.

Background Due to the heat and moisture exchanger's (HME) breathing resistance, laryngectomized patients cannot always use an (optimal) HME during physical exercise. We propose a novel HME cassette concept with adjustable “bypass,” to provide adjustment between different breathing resistances within one device. Methods Under standardized conditions, the resistance and humidification performance of a high resistance/high humidification HME (XM) foam in a cassette with and without bypass were compared to a lower resistance/lesser humidification HME (XF) foam in a closed cassette. Results With a bypass in the cassette, the resistance and humidification performance of XM foam were similar to those of XF foam in the closed cassette. Compared to XM foam in the closed cassette, introducing the bypass resulted in a 40% resistance decrease, whereas humidification performance was maintained at 80% of the original value. Conclusions This HME cassette prototype allows adjustment between substantially different resistances while maintaining appropriate humidification performances.

Background Squamous cell carcinoma (SCC) of the external auditory canal (EAC) is a rare disease, which is commonly classified with the modified Pittsburgh classification. Our aim was to evaluate the predictive performance of this classification in relation to disease‐free survival (DFS). Methods We examined retrospective data from a nationwide Dutch cohort study including patients with primary EAC SCC. These data were combined with individual patient data from the literature. Using the combined data, the predictive performances were calculated using the c‐index. Results A total of 381 patients were included, 294 for clinical and 281 for the pathological classification analyses. The c‐indices of the clinical and the pathological modified Pittsburgh classification predicting DFS were 0.725 (0.668‐0.782) and 0.729 (0.672‐0.786), respectively. Conclusion The predictive performance of the modified Pittsburgh classification system as such appears to be acceptable to predict the DFS of EAC SCC. Other factors need to be added to a future model to improve the predicted performance.