Novel approaches to performance assessment of heat and moisture exchangers for pulmonary protection and rehabilitation in laryngectomized patients

Previous clinical research has provided sound knowledge about the effects of heat and moisture exchangers on clinical pulmonary functioning, clinical symptoms, and intra-tracheal climate changes in laryngectomized patients. The aim of this thesis was to further enhance our understanding of how an HME device functions, to develop new techniques and approaches to assess HME performance.
A newly developed, universally applicable ex vivo method that measures the HME water exchange performance, was introduced and validated. This method assesses the HME weight end-inspiratory and end-expiratory. A wide range of water exchange and humidity performances was found in 23 tested HME types. Next, we have found that the total water uptake of a hygroscopic HME during breathing is related to its humidity and water exchange performance. Loss of HME water uptake capacity was found after 24-hour tracheostoma application, however, the remaining water uptake was still clinically acceptable.
Tracheal mucus transport velocity and tracheal epithelial brush biopsies assessment were used to evaluate the effects of HME on mucociliary clearance. Significantly more ciliated cells were found in HME users than in non-HME users. The tracheal mucus transport velocity was not significantly higher in HME users than in non-HME users.
The incidence of pulmonary infections in laryngectomized patients shows a tendency that the number of tracheobronchitis and pneumonia episodes is lower in HME users than in non-HME users based on a retrospective clinical study and a European wide survey among head and neck surgeons.