1998 OPEN FORUM Abstracts
HUMIDFICATION TECHNIQUES: EFFICIENCY AND COSTS
Humidification during mechanical ventilation can be accomplished with a variety of devices including:
* Heated humidifier with a conventional circuit (HH)
* Heated humidifier with a heated wire circuit (HH + HWC)
* Heat and moisture exchanger (HME)
* Active heat and moisture exchanger (AHME)
The choice of a humidification device should be based on patient lung health, duration of intended use, and goal of therapy. Heated humidification provides a wide range of temperature and humidity and is universal in its application. The use of heated wire circuits increases the initial cost, but eliminates condensate and decreases water usage. Studies have shown that over a three to four day period, the additional cost of the heated wire circuit is returned in reduced water usage.
Heat and moisture exchangers or 'artificial noses' are passive acting, portable, and inexpensive. Under appropriate circumstances, HME's represent the most cost efficient devices. Recent evidence suggests that HME's can be used for extended periods of time without incident (up to a week). Several recent papers have shown that a single use HME can be used 48-72 hrs without a decrease in efficiency of increase in resistance. However, there remain instances where HME use is inappropriate. These include hypothermic patients, patients with bloody secretions, patients with thick tenacious secretions, and those requiring therapeutic humidity. HME's with a large deadspace may be contraindicated in patients with small tidal volumes and those with respiratory muscle weakness. Problems during weaning may be exacerbated by HME use.
Recently, an active HME has been introduced. This device uses a HME and a secondary source of heat and moisture directed between the patient and the HME. This device further reduces water usage compared to HH and HH + HWC. This device is not limited in use because gas can be provided at alveolar conditions. However, deadspace remains an important issue and experience with this device is limited.
Humidification can be accomplished with an increasing array of devices. Therapists should understand the advantages, disadvantages, and use of each.
The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.