Effectiveness of heat and moisture exchangers in preventing ventilator-associated pneumonia in critically ill patients: a meta-analysis.

Altacílio Aparecido Nunes,Maria Auxiliadora-Martins,Mayra Gonçalves Menegueti

doi:10.1186/1471-2253-14-115

Abstract

BackgroundPatients may acquire ventilator-associated pneumonia (VAP) by aspirating the condensate that originates in the ventilator circuit upon use of a conventional humidifier. The bacteria that colonize the patients themselves can proliferate in the condensate and then return to the airways and lungs when the patient aspirates this contaminated material. Therefore, the use of HME might contribute to preventing pneumonia and lowering the VAP incidence. The aim of this study was to evaluate how the use of HME impacts the probability of VAP occurrence in critically ill patients.MethodsOn the basis of the acronym "PICO" (Patient, Intervention, Comparison, Outcome), the question that guided this review was "Do critically ill patients under invasive mechanical ventilation present lower VAP incidence when they use HME as compared with HH?". Two of the authors of this review searched the databases PUBMED/Medline, The Cochrane Library, and Latin-American and Caribbean Literature in Health Sciences, LILACS independently; they used the following keywords: "heat and moisture exchanger", AND "heated humidifier", AND "ventilator-associated pneumonia prevention". This review included papers in the English language published from January 1990 to December 2012.ResultsThis review included ten studies. Comparison between the use of HME and HH did not reveal any differences in terms of VAP occurrence (OR = 0.998; 95% CI: 0.778–1.281). Together, the ten studies corresponded to a total sample of 1077 and 953 patients in the HME and HH groups, respectively; heterogeneity among the investigations was low (I2 < 50%). Information about the outcome mortality was available in only eight of the ten studies. The use of HME and HH did not afford different results in terms of mortality (OR = 1.09; 95% CI: 0.864–1.376). The total sample size was 884 and 762 patients, respectively. Heterogeneity among the studies was low (I2 = 0.0%).ConclusionCurrent meta-analysis was not sufficient to definitely exclude an associate between heat and moisture exchangers and VAP. Despite the methodological limitations found in selected clinical trials, the current meta-analysis suggests that HME does not decrease VAP incidence or mortality in critically ill patients.

Highlights

Patients may acquire ventilator-associated pneumonia (VAP) by aspirating the condensate that originates in the ventilator circuit upon use of a conventional humidifier
In the particular case of Brazil, nosocomial pneumonia is the primary cause of infection among critically ill patients admitted to the intensive care units (ICU), which is associated with increased hospital costs [1,2,4,5,6] and mortality [3,6]
Study selection This review only considered controlled randomized clinical assays that evaluated the use of HME as compared with HH to prevent VAP in critically ill patients

Summary

Introduction

Patients may acquire ventilator-associated pneumonia (VAP) by aspirating the condensate that originates in the ventilator circuit upon use of a conventional humidifier. In the particular case of Brazil, nosocomial pneumonia is the primary cause of infection among critically ill patients admitted to the ICU, which is associated with increased hospital costs [1,2,4,5,6] and mortality [3,6]. This type of pneumonia occurs more frequently in patients submitted to mechanical ventilation for over 48 h, so it is commonly designated ventilator-associated pneumonia (VAP) [7]. Mortality due to VAP varies between 24 and 50% and may reach rates as high as 76% in patients with comorbidities such as COPD, diabetes and other chronic lung diseases [8]

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