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Does the use of heat and moisture exchangers rather than heated humidifiers affect the incidence of ventilator associated pneumonia?

 

Bottom: No significant difference in VAP rates between the groups.


Level of evidence: 1+

 

Citation:

Memish ZA, 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
 

Lead author's name and email: ZA Memish memish@ngha.med.sa

 

Three-part Clinical Question:

Patients: general intensive care patients requiring mechanical ventilation > 48h

Intervention: heat & moisture exchanger v. heated humidifier

Outcome: incidence of ventilator-associated pneumonia

 

Search Terms: Intensive care, critical care, mechanical ventilation, ventilator associated pneumonia, nosocomial pneumonia, heat & moisture exchanger, heated humidifiers, controlled trial

 

The Study: Randomised controlled trial, with unblinded analysis at trial completion.

 

The Study Patients: 243+ intensive care patients requiring mechanical ventilation > 48h


Control group 120 patients had heated humidifier (all analysed)


Experimental group 123+ patients had heat & moisture exchanger (123 analysed)

 

The Evidence:

 

Outcome

Time to Outcome

CER

EER

RRR

ARR

NNT

Pneumonia

Duration of mechanical ventilation

0.158

0.114

0.278

0.044

   NS

95% Confidence Intervals:

NS

NS

¥

 

Comments:


398 patients were randomised to the two treatment groups. 155 patients were excluded because they were not ventilated for > 48h or because they discontinued use of the heat & moisture exchanger. There were 75 exclusions in the control group and 80 in the experimental group. There was not an intention-to-treat analysis, but it seems reasonable to assume that there were few true drop-outs in the experimental group.

Both groups were similar at the start of the trial and were treated equally, apart from the experimental intervention.

A power calculation was done and appropriate statistical tests were made.

There was no significant difference in VAP rates between the two groups.

 

 

Appraised by: David Swann, ICU Consultant, Royal Infirmary of Edinburgh.
Email: d.g.swann@ed.ac.uk

 

Kill or Update By: December 2009

 

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© SICS EBM Group 2004