Heated Humidifier

Sunday August 20, 2006
Does heated humidifier reduces the risk of ventilator associated pneumonia (VAP) ?


Most of the VAP bundle guidelines does not include the type of humidifier to reduce the risk of VAP, although thats the first therapy in direct contact with respiratory tract.

In latest issue of Critical Care (ccforum.com) - The fully formatted PDF version not published yet but early version can be seen here - a study of 104 patients, who required mechanical ventilation more than 5 days, has been published. Patients were assigned either to heat and moisture exchangers (HME) (n = 53) or heated humidifiers (HH) (n = 51) * 1.

VAP was found in 8 of 51 (15.69 %) patients in the HH group and in 21 of 53 (39.62 %) in the HME group. The median time free of VAP were 20 days for HH and 42 days for HME group.

Study concluded that: The patients mechanically ventilated during more than 5 days developed a lower incidence of VAP with a heated humidifier than heat and moisture exchanger.


* HH: In the active humidifiers, called heated humidifiers (HH): the inspired gas passes across or over a heated water bath. In this study HH was provided at 37º C and 100 % relative humidity to the proximal airway (containing approximately 44 mg of water/L of gas).

HME: Passive humidifiers, called heat and moisture exchanger (HME), trap heat and humidity from the patient’s exhaled gas and returns some of that to the patient on the subsequent inhalation.


Related previous pearls:
Elevation of the head of the bed- 30 or 45 degrees ?
Intrahospital transport - a risk factor for VAP ? and
Oral care in ICU


Helpful links:
IHI's Implement the Ventilator Bundle and
7 strategies to prevent VAP: a look at the evidence (source: todayshospitalist.com)



Reference: click to get abstract

Ventilator-associated pneumonia using a heated humidifier or a heat and moisture exchanger - a randomized controlled trial - Critical Care 2006, 10:R116