Heat and Moisture Exchanger New Branded FREE SHIPPING (PACK OF 10 PIECES)


OVERVIEW

  • Heat and Moisture Exchanger (HME)
  • those in current use are generally combined with a microbiological filter, hence they are called HME filters (HMEF)
  • when passive humidification using an HME is use, the circuit is termed a “dry circuit” as a opposed to a “wet circuit” using active humidification.

USES

  • humidification, warming inspired gases and microbiological filtration
  • best used in patients with few secretions, who are not hypothermic, do not have large air leaks and do not have high airway resistance.

DESCRIPTION

  • Generally contains a layer of foam or paper embedded with a hydroscopic salt such as calcium chloride
  • Bacterial and viral filters ideally have filtration efficiency of >99.9%
  • HME with humidification efficiency >30mg.H2O/L
  • connects to a standard 15mm connector on an endotracheal tube
Heat-and-Moisture-Exchanger-1

METHOD OF INSERTION AND/OR USE

  • placed in line between Y-piece of breathing circuit and ETT

OTHER INFORMATION.


Benefits

  • ease of use
  • light
  • can retain their ability to humidify for up to 4 days with minimal change in resistance
  • less cumbersome during transport
  • lower staff workload
  • lower costs
  • decreases ventilatory acquired pneumonia (Kola et al, 2005)

Mechanism of heating and humidification

  • contains a layer of foam or paper embedded with a hygroscopic salt such as calcium chloride
  • expired gas cools as it crosses the membrane, resulting in condensation and release of the mass enthalpy of vaporisation to the HME layer
  • on inspiration absorbed heat evaporates the condensate and warms the gas, the hygroscopic salt releases water molecules when the vapor pressure is low
  • warming and humidification is thus regulated by the moisture content of the expired gas and patient’s core temperature
  • a filter layer is also present, either an electrostatically charged or a pleated hydrophobic layer, the latter helps return moisture to the gas as condensation and evaporation occurs between the pleats

Mechanism of filtration

  • Filtration is achieved for larger particles (>0.3 µm) by inertial impaction and interception
  • Smaller particles(<0.3 µm) are captured by Brownian diffusion.

COMPLICATIONS/DISADVANTAGES

  • inability to use with all patients (haemoptysis, tenacious secretions)
  • increased airways resistance
  • increased dead space
  • potential for unrecognized airway obstruction if filter blocks
  • less than full humidification and body temperature
  • drying of secretions
  • not appropriate for patients with large air leaks (e.g. bronchopleural fistulae) due extensive loss of inspired gas and inability to conserve heat and humidity