Adjustable breathing resistance for laryngectomized patients: Proof of principle in a novel heat and moisture exchanger cassette

Maximal cardiopulmonary exercise testing in laryngectomised patients using different heat and moisture exchangers - feasibility and exercise responses

OBJECTIVE

After laryngectomy, the breathing resistance of heat and moisture exchangers may limit exercise capacity. Breathing gas analysis during cardiopulmonary exercise testing is not possible using regular masks. This study tested the feasibility of cardiopulmonary exercise testing with a heat and moisture exchanger in situ, using an in-house designed connector. Additionally, we explored the effect of different heat and moisture exchanger resistances on exercise capacity in this group.

METHODS

Ten participants underwent two cardiopulmonary exercise tests using their daily life heat and moisture exchanger (0.3 hPa or 0.6 hPa) and one specifically developed for activity (0.15 hPa). Heat and moisture exchanger order was randomised and blinded.

RESULTS

All participants completed both tests. No (serious) adverse events occurred. Only four subjects reached a respiratory exchange ratio of more than 1.1 in at least one test. Maximum exercise levels using heat and moisture exchangers with different resistances did not differ.

CONCLUSION

Cardiopulmonary exercise testing in laryngectomees with a heat and moisture exchanger is feasible; however, the protocol does not seem appropriate to reach this group's maximal exercise capacity. Lowering heat and moisture exchanger resistance does not increase exercise capacity in this sample.

The Effects of a 'New Generation' of Heat and Moisture Exchangers in Laryngectomized Patients with Previous Heat and Moisture Exchanger Experience

Objectives: To evaluate the effects of a new generation of heat and moisture exchangers (NG-HMEs) on pulmonary rehabilitation, quality of life, patient satisfaction, and usage patterns. Methods: A prospective observational study on 23 laryngectomized patients with prior HME experience from June 1, 2021 to November 30, 2021. Patients were interviewed at inclusion, after 6 weeks and after 12 weeks after the introduction of NG-HMEs. Two validated questionnaires were used to report pulmonary complaints and quality of life: the Cough and Sputum Assessment Questionnaire (CASA-Q), the European Quality of Life 5 Dimensions Index Score (EQ-5D Index Score), and the European Quality of Life 5 Dimensions Visual Analog Scale (EQ-5D-VAS). Usage patterns and patient satisfaction were reported using study-specific questionnaires. Results: The patients had an average age of 65.7 ± 6.8 years, with 87% being male, on average 33.7 ± 35.3 months after total laryngectomy (TLE). NG-HMEs were used for a mean of 21.87 ± 4.63 hours/day (P = .034). After 12 weeks of use, patients reported the following changes in the CASA-Q domains: cough symptoms (+5; P = .663), cough impact (0; P = .958), sputum symptoms (+8; P = .13), and sputum impact (+3; P = .489). The EQ-5D index score increased (+0.024; P = .917) as well as the EQ-5D VAS (+0.8; P = .27). All patients rated their experience with NG-HMEs with ≥3 out of 5. The patients who used NG-HMEs as instructed (n = 13) reported more profound changes in the CASA-Q domains: cough symptom (+11; P = .129), cough impact (+7; P = .209), sputum symptom (+11; P = .123), and sputum impact (+10; P = .102). Conclusions: Our results show that NG-HMEs could have a positive clinical impact on pulmonary rehabilitation after TLE, even in HME-experienced patients. The use of NG-HMEs does not affect the quality of life. The possible effects of NG-HMEs require further evaluation in long-term studies to fully assess their efficacy.

Understanding and predicting the performance of passive heat and moisture exchangers using a numerical model

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.

Adjustable breathing resistance for laryngectomized patients: Proof of principle in a novel heat and moisture exchanger cassette

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.