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Friday, July 27, 2012

Open Letter to: Respiratory Professionals

Dear Ladies and Gentlemen:

The Declaration of Independence was signed on August 2, 1776. In The Wizard of Oz, Dorothy wears silver shoes. Panama hats come from Ecuador. Alaska is the easternmost state in the United States.

Does not sound true, does it? And yet these are provable facts. The truth is: we've come to accept fallacies, falsehoods, misconceptions, and hearsay as genuine truth. Many times, we rarely demand substantiation. Below are some facts contrary to popular belief (and scientific research) in our profession.

This article is about the Clinical Practice Guidelines on Humidification. The CPG did not take the opportunity to correct some of the misconceptions that have kept reasonable clinicians from a decision to use what is arguably better therapy, even taking into account the normal contraindications to HME use. There are thousands of RCPs that have used HME devices to treat millions of patients and their judgment is disparaged by these continuing misconceptions.

We have approached researchers over the years to conduct studies on our device and continue that search today. In actuality, it is easy to see if our devices are working - secretions are watery to moderate and/or there is condensation between the device and the patient. These devices have now stood the test of time.

I appreciate your time in looking over this letter and the attached documents. To be fully informed, please read in the following order:

  • This letter
  • Siempos Impact of HME CCM 0712
  • Ricard LTR CCM 0712
  • Siempos RCP Ltr
  • BTT device report 6-11 to 5-12
  • Humidification CPG 2012
  • There are four continuing misconceptions about HME devices referenced in the CPG.

    1. Changing the HME at 48 hours does not increase VAP rates
    2. Breaking the circuit to change the HME may increase VAP rates
    3. Use of an HME is not recommended for LTV ventilation
    4. HMEs should be recommended for less than 96 hours use

    1. The documentation for changing the HME at 48 hours are from studies comparing VAP rates for 48 hour changes of the HME to non-heated wire circuits. As stated in 12.3, the condensate should be considered infectious waste and disposed of according to hospital policy, using strict universal precautions. Condensate that is collected in an HME is the same as condensate in the heated circuit. It is reasonable to conclude that it is wise to remove a potential source of infection inches from the ET tube. An HME changed at 24 hours has similar VAP rates as heated wire circuits - the condensate is the problem. It has been said: "Condensate is like dynamite; it is safe if handled properly." Condensate in the HME has colonized bacteria after 24 hours. There are no mechanisms to prevent bacterial growth in the warm moist environment of an HME device or a heated water circuit. HME devices changed at 24 hours and heated wire circuits have less condensate and consequently less colonization.

    2. Data on breaking the circuit is also derived from studies with heated water bath circuits with large amounts of condensation. Breaking a wet circuit with already contaminated condensate did lead to increased VAP rates. I am unaware of any study that directly links breaks in an HME circuit (dry) with increased VAP rates. Indeed, in 22 years of providing HMEs used from intubation to extubation, there has never been a report stating that switching to our devices caused an increase in VAP.

    3. LTV ventilation should have an appropriately sized HME device. Indeed, poorer performing devices than our standard device are acceptable. It is important to remember the ET tube bypasses some of the anatomical dead space an HME adds.

    4. Our therapeutic devices have proven an HME can be used from intubation to extubation if reasonable contraindications are followed. Hospitals as large as 1,000 beds have used our products continuously for more than 19 years. Indeed, we have never lost an account due to our product not performing as expected. We have zero ET or trach tube occlusion or pneumothorax reported to the FDA, the manufacturer or the company. The use of devices that meet the standards in 14.4 should be used as long as secretions remain watery to moderate or as long as there is sufficient condensation between the HME and the patient. The decision to continue using an HME should be a clinical one, not an arbitrary 96 hours.

    Class 1 HMEs have a significantly better safety record than heated humidification systems. The MAUDE database from the FDA shows 473 incidences for the category of heated humidification (BTT) in one year of which 376 were directly related to malfunctions in adult ICU use. (97 malfunctions reported were for NIV or neonatal humidification). In 10 years we have two – one of which was reported while we were utilizing a filter media no longer used. Our products have been used for millions of ventilator patient days. I am specific for our devices because poor performing HME devices do have incidences that have been reported to the FDA.

    By sections, these are factors that do not seem to have been considered.

    1.0 In the 6th paragraph, there is a reference to a study suggesting HME performance may not equal to the published ISO 9360. The study referenced was done in anesthesia with devices that are not designed for ICU usage. This is a common problem of faulting an HME regardless of the performance of the published device.

    4.3 The proper selection of an HME device with appropriate dead space within clinical guidelines for delivering humidification to a patient is acceptable for LTV patients. At low Vt, the device should still deliver 30mg H2O/L air and there are many devices capable of that performance.

    6.1.2 This is the most egregious error. The referenced article is for NON-invasive ventilation, a procedure where HME devices are not acceptable to be used. The guideline does not state the true status of the report.

    7.1 Modern HMEs provide humidification to maintain the mucociliary elevator and produce watery to moderate secretions. As long as the secretions are clinically acceptable, there is no reason to have an arbitrary limit.

    7.4 See attached review of the Siempos paper on VAP and humidification methods. This paper did an excellent review of humidification. There are differences between non-heated wire humidifiers and heated wire or HMEs. HMEs and heated wire humidifiers have less condensate and contribute less to the colonization of the circuit and have lower VAP rates.

    It is disheartening that advances in HME performance are still colored by prejudice and use of old information. Considering contraindications, proper use of HME devices that meet performance standards are arguably safer than and as therapeutic as heated humidification.

    Best regards,


    Hal Norris, President

    Direct: 404-373-8300 ext 210

    Humidity Fact and Fallacy Blog

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    Please comment on this missive below. If you have a horror story about HMEs and many do; make sure that you give all the relevant data, i.e. brand and model of HME, humidification performance (third party evaluation if possible), type of patient (if a low performing device was used on a patient with a high minute ventilation, you should expect a poor result). If you have a horror story on heated humidification, and many do, please provide the relevant data also. I will read and respond to all postings where appropriate. Anonymous posts are acceptable, but the captcha must be solved.


    Thank you for the letter. I have printed the document and will be sharing this with our students as I feel they need to be thorough in their assessment of practice.
    Dr. Kenny

    I like your comments regarding HME's However, do you have any studies to support your positon?? I would be very much interested.!

    Do you have documentation for using an HME on baby transports? We would like to do this but some are skeptical for us on preemies? Thank you


    We have a neonatal HME with and without O2 connection. While we are on solid ground in using an HME with adult patients, there is less information on using the device for preemies. RCPs use our device for transport frequently as it has low dead space 2.5ml and low resistance 0.35 cm H2O at 7.5 l/min. I am unaware of any studies on our device for its use in transport, but many believe it is better to add humidity and that is difficult with heated systems for transport.

    Thanks for your question. I wish I had a more definitive answer.

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