ICU · Equipment, physics & clinical measurement

Humidification

Also known as Humidification · Heat and moisture exchanger · HME · Heated humidifier · Absolute humidity · Artificial nose · Mucociliary clearance · Isothermic saturation boundary · Relative humidity · Dew point · Rain-out · Ventilator circuit · High-flow nasal cannula

Humidification for the ICU First Part: the nose and turbinates warm, humidify, and filter inspired gas, conditioning it toward 37 degrees C and 100 per cent relative humidity (the guideline active-humidification upper target is 44 mg of water per litre); an endotracheal or tracheostomy tube bypasses this, so dry gas impairs mucociliary clearance and causes secretion retention and tracheal tube blockage. Absolute humidity (mg/L) is the measure that matters. A passive heat-and-moisture exchanger (HME, artificial nose) recaptures exhaled heat and water in a hygroscopic medium and should deliver at least 30 mg/L; heated humidification is superior to an HME for thick or copious secretions, and HMEs are not recommended in low-tidal-volume lung-protective ventilation, where added dead space can increase the ventilation requirement and PaCO2. An active heated humidifier targets 33 to 44 mg/L with gas at 34 to 41 degrees at the circuit Y-piece; active humidification is suggested for non-invasive ventilation, and high-flow nasal cannula (up to 60 L/min) was introduced with heated humidification systems. Ventilator circuits should not be changed routinely.

Checked against its sources on 1 Sept 2026