Ex vivo assessment and validation of water exchange performance of 23 Heat and

Moisture Exchangers for laryngectomized patients

Richard Branson MSc RRT FAARCProfessor of Surgery

University of Cincinnati

Authors Conflict of Interest

• The authors disclosed no COI.• This research project was partly funded by an unrestricted

research grant of the manufacturer of some of the tested HMEs, Atos Medical, Sweden. The study sponsor had no involvement in the study design, in the collection, analysis, and interpretation of data, in the writing of the manuscript or publication.

Background

• What is the research question?1. Determine ex vivo water exchange performance of commercially available HME’s for laryngectomy applications.2. Compare these measurements to absolute

humidity at end exhalation in volunteers.3. Determine the impact of hygroscopic treatment of the media on HME performance.

Background

• Is this research question relevant? – Comparison of device performance is difficult– Manufacturers use different test rigs and settings

to determine performance– Data is often expressed in different ways (water

loss, moisture output)– Testing is technically difficult and time consuming.

Not likely to be accomplished by clinicians

Background• What is known about this subject?• After total laryngectomy, breathing through the nose

is replaced by breathing through the permanent tracheostoma

Background• What is known about this subject?• Inspired air is no longer optimally conditioned before

reaching the trachea. • The colder and dryer inspired air leads to pulmonary

complaints such as increased mucus production, excessive coughing, and frequent airway infection

Background

• What is known about this subject?• The addition of an HME to tracheostoma valves

increase inspired moisture with little change in resistance.1

Grolman W, Blom ED, Branson RD, et al(1997) An efficiency comparison of four heat and moisture exchangers used in the laryngectomized patient. Laryngoscope 107:814–820.

Background

• What is known about this subject?• In randomized clinical trials, the use of an HME has

been proven to be effective in the reduction of pulmonary complaints and to significantly improve the quality of life after a total laryngectomy.

• Up to a 50% decrease in coughing episodes.

Ackerstaff AH. (1993) Improvements in respiratory and psychosocial functioning following total laryngectomy by the use of a heat and moisture exchanger. Ann Otol Rhinol Laryngol 102(11):878–883Bien S. (2010) The effect of a heat and moisture exchanger (Provox HME) on pulmonary protection after total laryngectomy: a randomized controlled study. Eur Arch Otorhinolaryngol 267(3):429–435Dassonville O. (2011) Randomised, multi-centre study of the usefulness of the heat and moisture exchanger (Provox HME(R)) in laryngectomised patients. Eur Arch Otorhinolaryngol 268(11):1647–1654Hilgers FJ. (1991) The influence of a heat and moisture exchanger (HME) on the respiratory symptoms after total laryngectomy. Clin Otolaryngol Allied Sci 16(2):152–156

Background

Manufacturer Information for the 23 Tested HMEs.

van den Boer, C. et al. Respir Care 2014;59:1161-1171

(c) 2012 by Daedalus Enterprises, Inc.

Methods• What is the study design?• Prospective evaluation of moisture output of 23

HME’s during breathing by a normal volunteer– Tidal, shallow and deep breathing

• Measurements– Weight of the media– Absolute humidity at end-inspiration and end-expiration– HME weight measurements were performed 25 times

alternating at the end of inspiration and at the end of expiration, using the different breathing patterns.

Test Set-up

van den Boer, C. et al. Respir Care 2014;59:1161-1171

(c) 2012 by Daedalus Enterprises, Inc.

Methods• Statistical methods• Assessment of the association between water exchange and

average breathing volume was determined using a linear mixed effects model for each HME type (three HMEs of one type together).

• The association between AHinsp and inspiratory breathing volume was determined using an exponential-decay nonlinear least-squares regression

• For the core weight experiments, weighted r2 were calculated using weighted Pearson correlations with inverse variances as weights.

• Aikake Information Criterion (AIC) was used to compare the associations between inspirational absolute humidity and both wet and dry core weights in two weighted linear regressions.

Results

• What are the main results? • There is a wide variation in performance of

devices• Hygroscopic devices performed best• Water exchange correlates well with end-

inspiratory absolute humidity

Model Estimate of Water Exchange Values and AHinsp at Volumes of 0.5 L and Standardized to a Reference Ambient Humidity of 5 mg/L.

van den Boer, C. et al. Respir Care 2014;59:1161-1171(c) 2012 by Daedalus Enterprises, Inc.

The observed (points) and estimated (lines) association between breathing volume and water exchange (weight change between inspiration and expiration) for different heat and moisture exchangers (HMEs), normalized to the chosen reference ambient humidity of 5 mg/L.21 Per

HME type, 63 data points were analyzed (21 per HME).

van den Boer, C. et al. Respir Care 2014;59:1161-1171(c) 2012 by Daedalus Enterprises, Inc.

Mean water exchange values (A) and end-inspiratory humidity (AHinsp) values (B) ranked at performance from high to low at a breathing volume 0.5 L and normalized to a reference

ambient humidity of 5 mg/L

van den Boer, C. et al. Respir Care 2014;59:1161-1171

(c) 2012 by Daedalus Enterprises, Inc.

Relation between wet core weight of the heat and moisture exchanger (HME) and end-inspiratory absolute humidity (AHinsp) for all HMEs and for HMEs with a simple cassette

van den Boer, C. et al. Respir Care 2014;59:1161-1171

(c) 2012 by Daedalus Enterprises, Inc.

Water uptake (weight increase between dry and wet heat and moisture exchanger [HME] core material) as function of HME water exchange performance.

van den Boer, C. et al. Respir Care 2014;59:1161-1171

(c) 2012 by Daedalus Enterprises, Inc.

Discussion• What do these findings mean? • There is a large deviation in device performance.• The impact of these differences is unclear but could

be clinically important.• How should these finding impact practice?• Cost, ease of use, resistance and moisture efficiency

should all be considered in a purchasing decision.

Discussion

• How do these findings related to previous findings from other studies?

• Many of these findings are novel.• Data are similar to previous findings with HME

devices used by mechanical ventilation (Ploysongsang Y, ARRD 1997)

• Data consistent with improved moisture output with hygroscopic salt treatment

Discussion

• What are the study limitations?• Exhaled moisture is likely different between mouth

breathing with a normal volunteer and a patient with a tracheostoma.

• Short period of observation• No insight into what is optimum for this population

to reduce complications• What additional work is needed in this area?• Clinical comparisons of devices over time

Conclusions

• What are the authors’ conclusions?• The results of this study can help establish a more

informed opinion about the performance of available HMEs for pulmonary rehabilitation in laryngectomized patients, and allow them to make an informed decision on which HME type to use.

• Hygroscopic salts attract a layer of water increasing media weight and moisture availability

Conclusions

• How do you think this should affect practice?• There are no known minimum standards for humidity in this

population. Although it seems that the highest humidity would provide the best comfort.

• Cost is an issue. How much would you pay for 15% more humidity

• What is the take-home message?• Select the best device for the patient based on comfort, ease

of use and cost.