Web site designed and maintained by Chris Cairns  © SICS EBM Group 2004                                  

Up
Martin, 1990
Roustan, 1992
Dreyfuss, 1995
Branson, 1995
Kirton, 1997
Boots, 1997
Kollef, 1998
Memish, 2001
Lacherdale, 2005

 

 

SICS EBM Group

 

Using heat and moisture exchange filters reduces the incidence of ventilator-associated pneumonia.

 

Dr David Swann on behalf of the SICS EBM Group.

 

Consultant, Intensive Care Unit, Royal Infirmary of Edinburgh

 

Correspondence to: d.g.swann@ed.ac.uk

 

SICS EBM web site December 2004 (Updated September 2005 & July 2006)

Citation

EBM Reviews. Scottish Intensive Care Society EBM Group. Swann D. Using heat and moisture exchange filters reduces the incidence of ventilator-associated pneumonia. 2004. (Updated 2005, 2006).

 Background

It has been standard practice to use heated water humidifiers (HWHs) in ventilated patients. While this achieves adequate heat and water content of inspired gases, it is not without potential hazard. Condensation of water vapour occurs in ventilator tubing and most circuits are colonised by bacteria within 24h. Inadvertent aspiration of contaminated water into the patient’s airway may be a cause of ventilator-associated pneumonia (VAP).

Heat and moisture exchange filters (HMEFs) have been developed with good performances with respect to the conservation of heat and humidity and the filtration of bacteria. Condensation and colonisation of the ventilator tubing is not a problem, so the incidence of VAP may be reduced.

 Objectives

Pooled analysis of well-conducted, prospective, randomised controlled trials (RCTs) that compared the incidence of VAP in patients receiving HWHs or HMEFs.

 Search strategy

Medline search using terms: Intensive care, critical care, mechanical ventilation, ventilator-associated pneumonia, nosocomial pneumonia, heat & moisture exchanger, heated humidifiers, controlled trial

 Selection criteria

RCTs with low risk of bias; two studies (6 & 7) were excluded from analysis because of a high risk of bias.

 Data collection and analysis

Study data were collated to calculate the relative and absolute risks of VAP in the two treatment groups. HWHs was considered the control intervention and HMEFs the experimental intervention. The number needed to treat with HMEFs to prevent one episode of VAP was calculated.

 Main results

20 patients need to be treated with HMEFs rather than HWHs to prevent one episode of VAP, with 95% CI of 11-103.

 Reviewer’s conclusions

Using heat and moisture exchange filters may reduce the incidence of ventilator-associated pneumonia.

Cautionary notes.

In pooling the results of these RCTs, there has been no testing for heterogeneity.

 The two RCTs with the most rigorous definition of VAP, using invasive respiratory sampling, failed to a significant difference in infection rates between the humidification systems.

 Perhaps the best justification for using HMEFs lies in the reduced cost.

Citation list with links to each CAT:

 

  1. Martin C, et al. Heat and moisture exchangers and vaporizing humidifiers in the intensive care unit Chest 1990; 97: 144-9. CAT.

  2. Roustan JP et al., Comparison of hydrophobic heat and moisture exchangers with heated humidifier during prolonged mechanical ventilation. Intensive Care Medicine 1992; 18: 97-100. CAT. 

  3. Dreyfuss D et al. Mechanical ventilation with heated humidifiers or heat and moisture exchangers: effects on patient colonization and incidence of nosocomial pneumonia. Am. J. Respir. Crit. Care Med, 1995; 151: 986-992. CAT.

  4. Branson R, et al. Comparison of 3 humidification techniques during mechanical ventilation: patient selection, cost and infection considerations. Respiratory Care 1995; 41: 809-16. CAT.

  5. Kirton OC et al. A prospective, randomized comparison of an in-line heater moisture exchange filter and heated wire humidifiers. Kirton OC et al., Chest 1997; 112: 1055-59. CAT. 

  6. Boots RJ et al. Clinical utility of hygroscopic heat and moisture exchangers in intensive care patients. Critical Care Medicine 1997; 25:1707-1712. CAT.

  7. Kollef MH. A Randomized Clinical Trial Comparing an Extended-Use Hygroscopic Condenser Humidifier With Heated-Water Humidification in Mechanically Ventilated Patients. Chest 1998; 113:759-67. CAT. 

  8. Memish Z et al. A randomized clinical trial to compare the effects of a heat and moisture exchanger with a heated humidifying system on the occurrence rate of ventilator-associated pneumonia. Am J Infect Control 2001; 29:301-5. CAT.

  9. Impact of Humidification Systems on Ventilator-associated Pneumonia. A Randomized Multicenter Trial. Lacherade et al., Am J Respir Crit Care Med 2005; 172: 1276–1282. CAT.


     Reviewed & Edited by BC & CC

 

Printer Friendly Version

 

© SICS EBM Group 2004