Comparing Devices Used To Humidify Respired Gases In Mechanical Ventilation

Objection To compare three humidifiers on humidifying efficiency and impact on respiratory mechanics and bacterial colonization in the respiratory tract.Methods Divide 90 patients treated by ventilator into 3 groups,respectively use the artificial noses,wick-type heated humidifiers and pass-over heated humidifiers as their different humidification devices.First,measure the inspired gas's temperature,relative humidity and absolute humidity and evaluate changes of airway secretions' characteristic of each group in the first three days using ventilator.Sencend,measure the different humidifiers' effects on the peak airway pressure,inspiratory resistance and dynamic compliance by vitro analog.At last,survey the peak airway pressure,inspiratory resistanceand dynamic compliance of every patient in each group and collect their airway secretions for bacteriological examination.Results①Inspired gas's temperature and absolute humidity of wick-type heated humidifier group is highest,followed by artificial nose group and pass-over heated humidifier group is lowest.②The relative humidity and absolute humidity of inspired gas in artificial nose group decrease with the increase of the time using ventilator.③With the days using ventilator increasing,the characteristics of airway secretions in wick-type heated humidifier group has not change significantly,while in artificial nose group and pass-over heated humidifier group has became thicker.④In vitro,heated humidifier has little impact on respiratory mechanics,but artificial nose make great impact on respiratory mechanics.⑤The rates of respiratory tract bacterial colonization of each group has no significant difference.Conclusion①Humidifying efficiency of wick-type heated humidifier is best,followed by artificial nose,pass-over heated humidifier is worst.②Impact of wick-type humidifier and pass-over heated humidifier on respiratory mechanics is little and that of artificial nose is great.③The rates of respiratory tract bacterial colonization of the three humidifier group have no significant difference.④We should select appropriate humidifier according to the different pathogenetic condition of different patients,and evaluate the characteristics of airway secretions regularly.