Skip to main content
 

Main menu

  • Home
  • Content
    • Current Issue
    • Editor's Commentary
    • Archives
    • Most-Read Papers of 2022
  • Authors
    • Author Guidelines
    • Submit a Manuscript
  • Reviewers
    • Reviewer Information
    • Create Reviewer Account
    • Reviewer Guidelines: Original Research
    • Reviewer Guidelines: Reviews
    • Appreciation of Reviewers
  • CRCE
    • Through the Journal
    • JournalCasts
    • AARC University
    • PowerPoint Template
  • Open Forum
    • 2023 Call for Abstracts
    • 2022 Abstracts
    • Previous Open Forums
  • Podcast
    • English
    • Español
    • Portugûes
    • 国语
  • Videos
    • Video Abstracts
    • Author Interviews
    • Highlighted Articles
    • The Journal

User menu

  • Subscribe
  • My alerts
  • Log in

Search

  • Advanced search
American Association for Respiratory Care
  • Subscribe
  • My alerts
  • Log in
American Association for Respiratory Care

Advanced Search

  • Home
  • Content
    • Current Issue
    • Editor's Commentary
    • Archives
    • Most-Read Papers of 2022
  • Authors
    • Author Guidelines
    • Submit a Manuscript
  • Reviewers
    • Reviewer Information
    • Create Reviewer Account
    • Reviewer Guidelines: Original Research
    • Reviewer Guidelines: Reviews
    • Appreciation of Reviewers
  • CRCE
    • Through the Journal
    • JournalCasts
    • AARC University
    • PowerPoint Template
  • Open Forum
    • 2023 Call for Abstracts
    • 2022 Abstracts
    • Previous Open Forums
  • Podcast
    • English
    • Español
    • Portugûes
    • 国语
  • Videos
    • Video Abstracts
    • Author Interviews
    • Highlighted Articles
    • The Journal
  • Twitter
  • Facebook
  • YouTube
Research ArticleOriginal Research

In Vitro Evaluation of Heat and Moisture Exchangers Designed for Spontaneously Breathing Tracheostomized Patients

Claudia Brusasco, Francesco Corradi, Maria Vargas, Margherita Bona, Federica Bruno, Maria Marsili, Francesca Simonassi, Gregorio Santori, Paolo Severgnini, Robert M Kacmarek and Paolo Pelosi
Respiratory Care November 2013, 58 (11) 1878-1885; DOI: https://doi.org/10.4187/respcare.02405
Claudia Brusasco
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • For correspondence: [email protected]
Francesco Corradi
Dipartimento Cardio-Nefro-Polmonare, Sezione Terapia Intensiva Cardiochirurgica, Azienda Ospedaliero Universitaria di Parma, Italy.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Maria Vargas
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
Dipartimento di Anestesia e Terapia Intensiva, Università di Napoli Federico II, Napoli, Italy.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Margherita Bona
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Federica Bruno
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Maria Marsili
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Francesca Simonassi
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Gregorio Santori
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Università Degli Studi di Genova, Istituto di Ricovero e Cura a Carattere Scientifico, Azienda Ospedaliera Universitaria San Martino, Genova, Italy.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Paolo Severgnini
Dipartimento Scienza ed Alta Tecnologia, Sezione Ambiente Salute Sicurezza Territorio, Università Degli Studi Dell'Insubria, Varese, Italy.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Robert M Kacmarek
Respiratory Care Services, Massachusetts General Hospital, Boston, Massachusetts.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Paolo Pelosi
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Sezione Anestesia e Rianimazione
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • References
  • Info & Metrics
  • PDF
Loading

Abstract

BACKGROUND: Heat and moisture exchangers (HMEs) are commonly used in chronically tracheostomized spontaneously breathing patients, to condition inhaled air, maintain lower airway function, and minimize the viscosity of secretions. Supplemental oxygen (O2) can be added to most HMEs designed for spontaneously breathing tracheostomized patients. We tested the efficiency of 7 HMEs designed for spontaneously breathing tracheostomized patients, in a normothermic model, at different minute ventilations (V̇E) and supplemental O2 flows.

METHODS: HME efficiency was evaluated using an in vitro lung model at 2 V̇E (5 and 15 L/min) and 4 supplemental O2 flows (0, 3, 6, and 12 L/min). Wet and dry temperatures of the inspiratory flow were measured, and absolute humidity was calculated. In addition, HME efficiency at 0, 12, and 24 h use was evaluated, as well as resistance to flow at 0 and 24 h.

RESULTS: The progressive increase in O2 flow from 0 to 12 L/min was associated with a reduction in temperature and absolute humidity. Under the same conditions, this effect was greater at lower V̇E. The HME with the best performance provided an absolute humidity of 26 mg H2O/L and a temperature of 27.8°C. No significant changes in efficiency or resistance were detected during the 24 h evaluation.

CONCLUSIONS: The efficiency of HMEs in terms of temperature and absolute humidity is significantly affected by O2 supplementation and V̇E.

  • tracheostomized patients
  • absolute humidity
  • inspiratory air temperature
  • air conditioning
  • heat and moisture exchangers

Introduction

The main functions of the upper airways are warming, humidifying, and filtering the inspired gas. In patients with tracheostomies the upper airway is bypassed, thus losing conditioning and filtering function. Breathing non-conditioned air for a prolonged time may damage the mucociliary function, resulting in a decrease in secretion clearance.1,2 Moreover, breathing cold and dry air results in heat loss and water loss by evaporation.1,2 Several animal and human studies have attempted to determine the “optimal” temperature and absolute humidity of inspired air when the upper respiratory tract is bypassed by an endotracheal tube or a tracheostomy.3–6 Since 1992 the American Association for Respiratory Care (AARC) clinical practice guidelines7 have recommended that inspired gases be warmed to 30°C and humidified to 30–33 mg H2O/L. Heat and moisture exchangers (HMEs) conserve a portion of the heat and humidity from the exhaled gas, conditioning the subsequently inspired gas.8–10 The use of HMEs in chronically tracheostomized spontaneously breathing patients can reduce retained secretions and improve quality of life.11,12 HMEs can also provide supplemental oxygen (O2) flow through a direct connection to an O2 delivery system. However, a dry and cold gas flow directly on the HME's membrane might reduce the amount of water and heat retained and transferred by the HME. In addition, a loss of HME efficiency during mechanical ventilation has been reported at high minute ventilation (V̇E).13,14 Our hypothesis was that additional O2 flow and different V̇E will affect the efficiency of HMEs designed for tracheostomized spontaneously breathing patients.

The aims of this study were to evaluate the effects of O2 flow at 3, 6, and 12 L/min and V̇E of 5 and 15 L/min on the performance (temperature and absolute humidity) of 7 commercially available HMEs, and to test their efficiency change over a 24 h period.

QUICK LOOK

Current knowledge

Heat and moisture exchangers (HMEs) are commonly used in chronically tracheostomized spontaneously breathing patients. Supplemental oxygen (O2) can affect the HME's performance.

What this paper contributes to our knowledge

The efficiency of HMEs used for spontaneously breathing patients with tracheostomy was decreased by increased O2 flow and increased minute ventilation. O2 flow of > 3 L/min was associated with important decreases in HME performance.

Methods

Experimental Protocol and Hygrometry

The experimental lung model consisted of a piston pump that was connected to one end of a breathing circuit, to simulate a spontaneously breathing patient (Fig. 1). The expiratory gas flow was heated and humidified (DAR HC 2000 HWH, Mallinckrodt/Covidien, Mansfield, Massachusetts) to mimic normothermic conditions (34°C).13,15 The HME was connected to the opposite end of the circuit and to O2 flow. A breathing circuit with 4 unidirectional valves to separate inspiratory and expiratory flows was inserted between the HME and the lung model. Two temperature probes, one dry and one wet (coated with cotton soaked with sterile water), were placed at both the inspiratory and expiratory sides of the circuit. The dry probe measured the actual gas temperature, while the wet one measured the temperature as lowered by evaporation. Since the wet probe measured a temperature proportional to gas dryness, the absolute humidity of the inspired and expired gases can be calculated from the temperature difference between the probes, with a formula previously reported.16,17 Temperatures were measured electronically, displayed on a screen and printed on a chart recorder (436004 uR 1000, Yokogawa, Tokyo, Japan). This psychrometric method is commonly used by clinicians and researchers interested in valuation of humidity.15,16 The system was considered stabilized after 1 h of ventilation without HME. The expiratory gas was maintained saturated at a temperature of 34°C. Once the lung model was stabilized, the HMEs were tested in a random order. Temperature and humidity output of the lung model were checked before each measurement.

Fig. 1.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig. 1.

Test setup. HME = heat and moisture exchanger.

Evaluation of Effects of O2 Flow and V̇E

Each HME was tested at 2 different V̇E (5 and 15 L/min, tidal volume 500 mL, and breathing frequencies of 10 and 30 breaths/min) and 4 O2 flows (0, 3, 6, and 12 L/min). For each combination of V̇E and O2 flow, 15 min after stabilization, 3 consecutive temperature measurements were taken and averaged. Room temperature and relative humidity were measured before each experiment and maintained constant throughout the experiment. Each pair of probes was calibrated by measuring room temperature, and the differences were always < 0.3°C. This value was used to correct all the measurements. All HMEs were tested on 4 different study days (a different HME was used each day) for assessment of reproducibility.

Evaluation After 24 Hours of Use

Each HME was studied for 24 consecutive hours with a V̇E of 10 L/min. A V̇E of 10 L/min was chosen, because it was midway between the 2 V̇E tested short-term, and represents a typical V̇E in critically ill patients. Temperature measurements were recorded at 0, 6, 12, and 24 h; resistance and weight of the HME were recorded at 0 and 24 h. Flow resistance was estimated from the pressure drop across the HME at 60 L/min flow. HME weight was measured by a precision balance, and the absolute change for each HME was determined.

The following commercially available HMEs were tested: HCH-6V (Mediflux, Croissy Beaubourg, France), HCH-6F (Mediflux, Croissy Beaubourg, France), Hydro-Trach T (Intersurgical, Woingham, Berkshire, United Kingdom), Edith Trach (GE Healthcare, Madison, Wisconsin), Tracheolife II (Mallinckrodt/Covidien, Mansfield, Massachusetts), Tracheal HME 9500/01S (Air Safety Limited, Lancashire, United Kingdom), and HME-D6 (DEAS, Castel Bolognese, Italy). Their main characteristics, according to the manufacturers, are described in Table 1.

View this table:
  • View inline
  • View popup
  • Download powerpoint
Table 1.

Characteristics of the Heat and Moisture Exchangers as Described by the Manufacturers

Statistical Analysis

Descriptive statistics are expressed as mean ± SD, median, minimum/maximum, 95% CI, and/or percentages. The coefficient of variation was calculated for the temperature and absolute humidity measurements. Normal distribution was evaluated with the Shapiro-Wilk normality test. Pearson correlation was performed to determine the degree of correlation between continuous variables. The values were compared as means of repeated measures by 2-way analysis of variance with the Tukey honest significant difference post hoc test. Homogeneity of variance was evaluated with the Fligner-Killeen test. Statistical significance was assumed by a 2-sided P value < .05. Statistical analysis was performed with statistics software (R 2.15.2, R Foundation, Vienna, Austria).

Results

Effects of O2 Flow and V̇E

Mean and median data for temperature and absolute humidity with each HME are presented, respectively, in Table 2 and Table 3. In all HMEs the progressive increase in O2 flow from 0 to 12 L/min was associated with a reduction in the temperature (P < .001) and absolute humidity (P < .001). Under the same conditions, this effect was greater at lower V̇E (5 vs 15 L/min) (P < .001) (Fig. 2). Comparing the average performance of all HMEs across all experimental settings, the minimum performance was a temperature of 24.6°C and an absolute humidity of 18.2 mg/L at V̇E 5 L/min and O2 flow 12 L/min, while the best performance was a temperature of 26.6°C and an absolute humidity of 23.4 mg/L at V̇E 15 L/min and O2 flow 0 L/min.

View this table:
  • View inline
  • View popup
  • Download powerpoint
Table 2.

Descriptive Statistics of Temperature for the Tested Heat and Moisture Exchangers

View this table:
  • View inline
  • View popup
  • Download powerpoint
Table 3.

Descriptive Statistics of Absolute Humidity for the Tested Heat and Moisture Exchangers

Fig. 2.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig. 2.

Temperature and absolute humidity versus O2 flow and breathing frequency (f). The horizontal lines within the data bars represent the medians. The tops and bottoms of the data bars represent the interquartile ranges. The whisker bars represent the minimum and maximum values.

Effects of Different HMEs on Temperature and Absolute Humidity

All the HMEs showed a variable degree of O2 flow-dependence, with increasing differences between measured and expected performance in terms of temperature and absolute humidity as O2 flow increased and V̇E decreased (P < .001). The overall performance of all HMEs tested is presented in Table 4 and 5 and Figure 3. The Tracheolife II showed the best performance: absolute humidity 26 mg H2O/L and temperature 27.8°C.

View this table:
  • View inline
  • View popup
  • Download powerpoint
Table 4.

Temperature Comparisons

View this table:
  • View inline
  • View popup
  • Download powerpoint
Table 5.

Absolute Humidity Comparisons

Fig. 3.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig. 3.

Median temperature and absolute humidity with the tested heat and moisture exchangers (HMEs). The horizontal lines within the data bars represent the medians. The tops and bottoms of the data bars represent the interquartile ranges. The whisker bars represent the minimum and maximum values.

Effects of 24 Hours of Use on Performance, Air Flow Resistance, and Weight

No significant drop in absolute humidity was detected over the 24 h evaluation of any HME (P = .99). No changes in flow resistance or pressure drop were observed between baseline and 24 h for any HME, except for Tracheolife II, which showed a pressure drop at 60 L/min, from 0.2 cm H2O to 0.8 cm H2O, which was not statistically significant or clinically important. The increases in weight at 24 h were 1.46 g for HCH-6V, 0.39 g for HCH-6F, 0.22 g for Hydro-Trach T, 2.05 g for Edith Trach, 0.47 g for Tracheolife II, 0.37 g for Tracheal HME 9500/01S, and 0.47 g for HME-D6, without any significant correlation with flow resistance at 60 L/min (r2 = 0.33, P = .46).

Between the 4 study days, room temperature was 24°C ± 0.5, whereas relative humidity was 13% ± 11. The dynamics of daily room temperature and relative humidity did not significantly affect the results (P = .58).

Discussion

The main results of the present study are:

  • The addition of O2 to an HME inversely affected HME efficiency.

  • The efficiency of all the HMEs was better at higher V̇E.

  • The Tracheolife II was best able to maintain temperature and absolute humidity of inspired gases.

To the best of our knowledge this is the first study evaluating the effects of the addition of O2, various V̇E, and 24 h use on the efficiency of HMEs for tracheostomized spontaneously breathing patients. It is important to stress that none of the HMEs tested met the AARC clinical practice guideline standards for humidification: 30–33 mg/L and 30°C.7

Effect of O2 Flow and V̇E

The absolute humidity and temperature of inspired gases were significantly, inversely affected by the addition of O2 flow. The drop in efficiency from 0 to 12 L/min of O2 flow was higher for absolute humidity than for temperature, and these results were consistent for all HMEs. We found that Tracheolife II maintained an acceptable performance up to 6 L/min O2 flow, then demonstrated a fall at 12 L/min, while the other HMEs presented a more gradual reduction in efficiency as O2 flow increased.

Most HMEs commercially available have the capability of adding supplemental O2 flow to increase FIO2. However, to our knowledge there is no information in the manufacturers' literature discussing the effect of adding O2 on the efficiency of the HME. The decrease in efficiency of HMEs at increasing O2 flow should be considered by physicians trying to optimize the clinical condition of their patients. The interdependence of HME performance and supplemental O2 flow should be expected, since HMEs are characterized by a hygroscopic membrane that retains water and heat from the exhaled air and then returns it to inspired air. The addition of supplemental O2 dries and lowers the temperature of the hygroscopic material, thus negatively affecting HME performance. The method of O2 delivery may be one of the reasons for the different behavior of each HME to increasing O2 flows, since some HMEs allow O2 to travel to the patient without traversing the hygroscopic membrane, while others direct the added O2 flow through the hygroscopic membrane.

In general, considering all HMEs tested at the 2 different V̇E conditions, they provided better temperature and humidity output at higher V̇E. Previous studies, reported contradictory results on the effects of V̇E on HME performance during mechanical ventilation.13–15 In fact, Unal et al14 found better performance at lower V̇E, while Pelosi et al15 demonstrated better performance at higher V̇E, and Chiumello et al13 found the best performance at 10 L/min, with a decrease in performance both at higher and lower V̇E. However, contrary to our study, those authors did not test HMEs designed for tracheostomized patients during spontaneous breathing. Our results can be explained by the fact that at lower V̇E the hygroscopic membrane receives less conditioned exhaled air per minute, allowing more time to cool down, thus losing more water molecules and being less efficient in the subsequent inspiration. Moreover, the HMEs were tested at 2 different V̇E (5 vs 15 L/min) by modifying only the respiratory frequency (10 vs 30 breaths/min). The differences in efficiency may be a direct result of the fact that with a higher respiratory frequency there is less time for the hygroscopic membrane to cool down. This finding may be minimized by increasing tidal volume to increase V̇E instead of rate.

Effect of Different HMEs on Temperature and Absolute Humidity

The present study has shown significant differences in efficiency among the 7 HMEs evaluated. Comparing the temperature output and absolute humidity of the HMEs at 15 L/min V̇E and 0 L/min O2 flow, the best performance was by Tracheolife II, with 28.4 mg H2O/L and 29.2°C, respectively, while the worst performance was by HME-D6, with 18.4 mg H2O/L and 25.3°C, respectively. The optimal level of inspired air conditioning in tracheostomized patients is still debatable. To the best of our knowledge there are no specific guidelines on the levels of absolute humidity and temperature in spontaneously breathing tracheostomized patients. Some studies on tracheostomized dogs have defined the optimal range of humidity to be 100% saturation at 25–30°C (ie, absolute humidity 23.1–30.5 mg H2O/L).18,19 In addition, excessive heating and humidification are recognized as harmful to the airway mucosa.20–22 In normal conditions the temperature range of expired gases is 28–32°C, with an absolute humidity of 27–33 mg H2O/L, and thus an inspired-gas temperature range of 29–33°C and an absolute humidity of 28–35 mg H2O/L should be adequate.23 These guidelines7 might also apply to tracheostomized patients, even if the portion of the artificial airway above the carina is shorter than with an endotracheal tube. We found that only the Tracheolife II reached the levels recommended in all conditions except for low V̇E with 6 or 12 L/min O2 flow and high V̇E with 12 L/min. The structure of Tracheolife II is very different from that of the other HMEs. Tracheolife II does not contain a spongy material like the others, but instead has an embossed and pleated membrane, which allows substantially more hygroscopic surface and consequently a greater entrapment of water.

We found that the performance of HMEs designed for tracheostomized patients during spontaneous breathing was poorer than that reported for HMEs for mechanically ventilated patients under similar experimental conditions.13,15,24 HMEs for spontaneously breathing patients are inserted into an open breathing circuit, drawing air from the room, whereas HMEs for mechanically ventilated patients are used in a closed ventilatory circuit, so the heat and moisture are kept within the system. Furthermore, HMEs for spontaneously breathing patients, except for Tracheolife II, are hollow in the middle, and the membrane is displaced to the periphery, allowing the collection of secretions and minimizing the increase of airway resistance, while all HMEs for mechanically ventilated patients have the membrane throughout the device, promoting efficiency but increasing resistance.

Effects of 24 Hours of Use on Performance, Air Flow Resistance, and Weight

Absolute humidity and temperature output were not affected during the 24 h study period. Several investigations of HMEs for mechanical ventilation demonstrated that changing HMEs after 48 h25–27 or even 96 h28 did not influence efficiency nor the incidence of nosocomial pneumonia. HMEs for spontaneously breathing patients have not been tested for longer than 24 h use, and are marketed with directions to replace them every 24 h. They do not have an antibacterial filter and are hollow in the middle, avoiding an increase of airway resistance. Our in vitro data suggest that HMEs could be used for longer periods, but the safety of this procedure should be demonstrated in a large clinical trial.

The efficiency of the HMEs evaluated was independent of room temperature and relative humidity, at least within the conditions during the present study. Room temperatures were similar throughout the 4 study days (24 ± 0.5°C); however, room relative humidity was quite different, depending on outside temperature (13 ± 11%). Room dryness may play an important role in absolute humidity output at different V̇E.

Our study has some limitations that need to be addressed. First, the model we used only partially reproduced clinical conditions. Thus, our results cannot be directly extrapolated to the clinical scenario. However, since all the devices were evaluated under the same conditions, the comparative efficiency of the devices is accurate. Second, all of the HMEs commercially available worldwide were not evaluated. Thus, other devices may demonstrate different performances. Third, the performance at different O2 flows and V̇E was not evaluated during the entire 24-hour period. Fourth, V̇E variations were only obtained by changing breathing frequency. Differences in performance between lower and higher V̇E may be a direct result of altering breathing frequency.

Conclusions

The performance of different commercially available HMEs used in tracheostomized patients during spontaneous breathing is significantly affected by O2 flow and V̇E. The minimal O2 flow required according to the patient's clinical condition should always be administered. Especially if a tracheostomized patient needs O2 flows higher than 3 L/min, the clinician should be aware of the negative effect O2 flow has on HME performance. Most importantly, the performance differences among the evaluated devices should be considered when making the choice of HME in tracheostomized spontaneous breathing patients. Finally, none of the HMEs tested met the AARC clinical practice guideline standards for humidification: 30–33 mg/L and 30°C.7

Footnotes

  • Correspondence: Claudia Brusasco MD, Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Università Degli Studi di Genova, Largo Rosanna Benzi 8, 16132, Genova, Italy. E-mail: claudia.brusasco{at}gmail.com.
  • The authors have disclosed no conflicts of interest.

  • Copyright © 2013 by Daedalus Enterprises

References

  1. 1.↵
    1. Scheenstra RJ,
    2. Muller SH,
    3. Hilgers FJ
    . Endotracheal temperature and humidity in laryngectomized patients in a warm and dry environment and the effect of a heat and moisture exchanger. Head Neck 2011;33(9):1285-1293.
    OpenUrlPubMed
  2. 2.↵
    1. Thomachot L,
    2. Viviand X,
    3. Arnaud S,
    4. Vialet R,
    5. Albanese J,
    6. Martin C
    . Preservation of humidity and heat of respiratory gases in spontaneously breathing, tracheostomized patients. Acta Anaesthesiol Scand 1998;42(7):841-844.
    OpenUrlPubMed
  3. 3.↵
    1. Primiano FP Jr.,
    2. Saidel GM,
    3. Montague FW Jr.,
    4. Kruse KL,
    5. Green CG,
    6. Horowitz JG
    . Water vapour and temperature dynamics in the upper airways of normal and CF subjects. Eur Respir J 1988;1(5):407-414.
    OpenUrlAbstract/FREE Full Text
  4. 4.
    1. Tsu ME,
    2. Babb AL,
    3. Sugiyama EM,
    4. Hlastala MP
    . Dynamics of soluble gas exchange in the airways: II. Effects of breathing conditions. Respir Physiol 1991;83(3):261-276.
    OpenUrlCrossRefPubMed
  5. 5.
    1. Tabka Z,
    2. Ben Jebria A,
    3. Guenard H
    . Effect of breathing dry warm air on respiratory water loss at rest and during exercise. Respir Physiol 1987;67(2):115-125.
    OpenUrlCrossRefPubMed
  6. 6.↵
    1. Primiano FP Jr.,
    2. Montague FW Jr.,
    3. Saidel GM
    . Measurement system for respiratory water vapor and temperature dynamics. J Appl Physiol 1984;56(6):1679-1685.
    OpenUrlAbstract/FREE Full Text
  7. 7.↵
    1. Restrepo RD,
    2. Walsh BK
    American Association for Respiratory Care; Restrepo RD, Walsh BK. AARC Clinical Practice Guideline. Humidification during invasive and noninvasive mechanical ventilation: 2012. Respir Care 2012;57(5):782-788.
    OpenUrlAbstract/FREE Full Text
  8. 8.↵
    1. Wilkes AR
    . Heat and moisture exchangers. Structure and function. Respir Care Clin N Am 1998;4(2):261-279.
    OpenUrlPubMed
  9. 9.
    1. Wilkes AR
    . Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 1 - history, principles and efficiency. Anaesthesia 2011;66(1):31-39.
    OpenUrlCrossRefPubMed
  10. 10.↵
    1. Wilkes AR
    . Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients. Anaesthesia 2011;66(1):40-51.
    OpenUrlPubMed
  11. 11.↵
    1. Lorenz KJ,
    2. Maier H
    . [Pulmonary rehabilitation after total laryngectomy using a heat and moisture exchanger (HME)]. Laryngo-rhino- otologie 2009;88(8):513-522.
    OpenUrl
  12. 12.↵
    1. Hilgers FJ,
    2. Aaronson NK,
    3. Ackerstaff AH,
    4. Schouwenburg PF,
    5. van Zandwikj N
    . The influence of a heat and moisture exchanger (HME) on the respiratory symptoms after total laryngectomy. Clin Otolaryngol Allied Sci1991;16(2):152-156.
    OpenUrlCrossRefPubMed
  13. 13.↵
    1. Chiumello D,
    2. Pelosi P,
    3. Park G,
    4. Candiani A,
    5. Bottino N,
    6. Storelli E,
    7. et al
    . In vitro and in vivo evaluation of a new active heat moisture exchanger. Crit Care 2004;8(5):R281-R288.
    OpenUrlCrossRefPubMed
  14. 14.↵
    1. Unal N,
    2. Kanhai JK,
    3. Buijk SL,
    4. Pompe JC,
    5. Holland WP,
    6. Gultuna I,
    7. et al
    . A novel method of evaluation of three heat-moisture exchangers in six different ventilator settings. Intensive Care Med 1998;24(2):138-146.
    OpenUrlCrossRefPubMed
  15. 15.↵
    1. Pelosi P,
    2. Severgnini P,
    3. Selmo G,
    4. Corradini M,
    5. Chiaranda M,
    6. Novario R,
    7. et al
    . In vitro evaluation of an active heat-and-moisture exchanger: the Hygrovent Gold. Respir Care 2010;55(4):460-466.
    OpenUrlAbstract/FREE Full Text
  16. 16.↵
    1. Thiery G,
    2. Boyer A,
    3. Pigne E,
    4. Salah A,
    5. De Lassence A,
    6. Dreyfuss D,
    7. et al
    . Heat and moisture exchangers in mechanically ventilated intensive care unit patients: a plea for an independent assessment of their performance. Crit Care Med 2003;31(3):699-704.
    OpenUrlCrossRefPubMed
  17. 17.↵
    1. Martin C,
    2. Thomachot L,
    3. Quinio B,
    4. Viviand X,
    5. Albanese J
    . Comparing two heat and moisture exchangers with one vaporizing humidifier in patients with minute ventilation greater than 10 L/min. Chest 1995;107(5):1411-1415.
    OpenUrlCrossRefPubMed
  18. 18.↵
    1. Tsuda T,
    2. Noguchi H,
    3. Takumi Y,
    4. Aochi O
    . Optimum humidification of air administered to a tracheostomy in dogs. Scanning electron microscopy and surfactant studies. Br J Anaesth 1977;49(10):965-977.
    OpenUrlAbstract/FREE Full Text
  19. 19.↵
    1. Noguchi H,
    2. Takumi Y,
    3. Aochi O
    . A study of humidification in tracheostomized dogs. Br J Anaesth 1973;45(8):844-848.
    OpenUrlAbstract/FREE Full Text
  20. 20.↵
    1. Williams R,
    2. Rankin N,
    3. Smith T,
    4. Galler D,
    5. Seakins P
    . Relationship between the humidity and temperature of inspired gas and the function of the airway mucosa. Crit Care Med 1996;24(11):1920-1929.
    OpenUrlCrossRefPubMed
  21. 21.
    1. Williams RB
    . The effects of excessive humidity. Respir Care Clin N Am 1998;4(2):215-228.
    OpenUrlPubMed
  22. 22.↵
    1. Cinnella G,
    2. Giardina C,
    3. Fischetti A,
    4. Lecce G,
    5. Fiore MG,
    6. Serio G,
    7. et al
    . Airways humidification during mechanical ventilation. Effects on tracheobronchial ciliated cells morphology. Minerva Anestesiol 2005;71(10):585-593.
    OpenUrlPubMed
  23. 23.↵
    1. Selvaraj N
    . Artificial humidification for the mechanically ventilated patient. Nurs Stand 2010;25(8):41-46.
    OpenUrlPubMed
  24. 24.↵
    1. Pelosi P,
    2. Chiumello D,
    3. Severgnini P,
    4. De Grandis CE,
    5. Landi L,
    6. Chierichetti LM,
    7. et al
    . Performance of heated wire humidifiers: an in vitro study. J Crit Care 2007;22(3):258-264.
    OpenUrlPubMed
  25. 25.↵
    1. Djedaini K,
    2. Billiard M,
    3. Mier L,
    4. Le Bourdelles G,
    5. Brun P,
    6. Markowicz P,
    7. et al
    . Changing heat and moisture exchangers every 48 hours rather than 24 hours does not affect their efficacy and the incidence of nosocomial pneumonia. Am J Respir Crit Care Med 1995;152(5 Pt 1):1562-1569.
    OpenUrlCrossRefPubMed
  26. 26.
    1. Thomachot L,
    2. Vialet R,
    3. Viguier JM,
    4. Sidier B,
    5. Roulier P,
    6. Martin C
    . Efficacy of heat and moisture exchangers after changing every 48 hours rather than 24 hours. Crit Care Med 1998;26(3):477-481.
    OpenUrlCrossRefPubMed
  27. 27.↵
    1. Boisson C,
    2. Viviand X,
    3. Arnaud S,
    4. Thomachot L,
    5. Miliani Y,
    6. Martin C
    . Changing a hydrophobic heat and moisture exchanger after 48 hours rather than 24 hours: a clinical and microbiological evaluation. Intensive Care Med 1999;25(11):1237-1243.
    OpenUrlCrossRefPubMed
  28. 28.↵
    1. Thomachot L,
    2. Boisson C,
    3. Arnaud S,
    4. Michelet P,
    5. Cambon S,
    6. Martin C
    . Changing heat and moisture exchangers after 96 hours rather than after 24 hours: a clinical and microbiological evaluation. Crit Care Med 2000;28(3):714-720.
    OpenUrlCrossRefPubMed
PreviousNext
Back to top

In this issue

Respiratory Care: 58 (11)
Respiratory Care
Vol. 58, Issue 11
1 Nov 2013
  • Table of Contents
  • Table of Contents (PDF)
  • Cover (PDF)
  • Index by author
  • Monthly Podcast

 

Print
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for your interest in spreading the word on American Association for Respiratory Care.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
In Vitro Evaluation of Heat and Moisture Exchangers Designed for Spontaneously Breathing Tracheostomized Patients
(Your Name) has sent you a message from American Association for Respiratory Care
(Your Name) thought you would like to see the American Association for Respiratory Care web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
In Vitro Evaluation of Heat and Moisture Exchangers Designed for Spontaneously Breathing Tracheostomized Patients
Claudia Brusasco, Francesco Corradi, Maria Vargas, Margherita Bona, Federica Bruno, Maria Marsili, Francesca Simonassi, Gregorio Santori, Paolo Severgnini, Robert M Kacmarek, Paolo Pelosi
Respiratory Care Nov 2013, 58 (11) 1878-1885; DOI: 10.4187/respcare.02405

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero

Share
In Vitro Evaluation of Heat and Moisture Exchangers Designed for Spontaneously Breathing Tracheostomized Patients
Claudia Brusasco, Francesco Corradi, Maria Vargas, Margherita Bona, Federica Bruno, Maria Marsili, Francesca Simonassi, Gregorio Santori, Paolo Severgnini, Robert M Kacmarek, Paolo Pelosi
Respiratory Care Nov 2013, 58 (11) 1878-1885; DOI: 10.4187/respcare.02405
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Abstract
    • Introduction
    • Methods
    • Results
    • Discussion
    • Conclusions
    • Footnotes
    • References
  • Figures & Data
  • Info & Metrics
  • References
  • PDF

Related Articles

Cited By...

Keywords

  • tracheostomized patients
  • absolute humidity
  • inspiratory air temperature
  • air conditioning
  • heat and moisture exchangers

Info For

  • Subscribers
  • Institutions
  • Advertisers

About Us

  • About the Journal
  • Editorial Board

AARC

  • Membership
  • Meetings
  • Clinical Practice Guidelines

More

  • Contact Us
  • RSS
American Association for Respiratory Care

Print ISSN: 0020-1324        Online ISSN: 1943-3654

© Daedalus Enterprises, Inc.

Powered by HighWire