Active humidification in mechanical ventilation is not associated to an increase in respiratory infectious complications in a quasi-experimental pre-post intervention study

Abstract

Objective: There is controversy regarding the influence of humidification systems upon the incidence of respiratory infections associated to invasive mechanical ventilation (IMV). An evaluation was made of the differences in the incidence of pneumonia and tracheobronchitis associated to mechanical ventilation (VAP and VAT, respectively) with passive and active humidification. Design: A retrospective pre-post quasi-experimental study was carried out. Setting: A polyvalent ICU with 14 beds. Patients: All patients connected to IMV for >48h during 2014 and 2016 were included. Interventions: During 2014, passive humidification with an hygroscopic heat and moisture exchanger (HME) was used, while during 2016 active humidification with a heated humidifier (HH) and an inspiratory heated wire was used. Identical measures for the prevention of VAP were established (Zero Pneumonia Project). Main outcome measures: The incidence of VAP and VAT was estimated for 1000 days of IMV in both groups, and statistically significant differences were assessed using Poisson regression analysis. Results: A total of 287 patients were included (116 with HME and 171 with HH). The incidence density of VAP per 1000 days of IMV was 5.68 in the HME group and 5.80 in the HH group (p=ns). The incidence density of VAT was 3.41 and 3.26 cases per 1000 days of VMI with HME and HH respectively (p=ns). The duration of IMV was identified as a risk factor for VAP. Conclusions: In our population, active humidification in patients ventilated for >48h was not associated to an increase in respiratory infectious complications.