The Science Journal of the American Association for Respiratory Care

1995 OPEN FORUM Abstracts

THE EFFECTS OF VARYING SET HUMIDIFIER TEMPERATURE AND VENTILATOR FLOW RATE ON THE RELATIVE HUMIDITY DELIVERED BY THE ANAMED HUMIDITUBE HEATED HUMIDIFIER SYSTEM.

Russell T. Reid, RRT, Mark Goldstein, RRT, Mercy San Juan Medical Center, Carmichael, California.

There is little data available regarding the humidity output of modern humidifiers. This study examined the effect of varying ventilator flow rate and set humidifier temperature on the relative humidity delivered by the Anamed Humiditube (Las) Vegas, Nevada) heated humidification system. This system is of a non-traditional design incorporating a heated wick that runs the entire length of the inspiratory tubing.

Methods: The Anamed Humiditube heated humidifcation system consisting of heater controller, pump and heated inspiratory wick was attached to a Hamilton Veolar (Reno, Nevada) mechanical ventilator. The mechanical ventilator was placed in the volume control mode with a square inspiratory flow wave form. A heated humidity chamber (HC), 37.2Cº (± 1.8Cº), was constructed to accommodate the probe of a capacitance type digital hygrometer (Curtin-Matheson Scientific, Brisbane, CA, Model # 244-355). Inspiratory gas passed through the HC for relative humidity measurement. A thermocouple thermometer (Baxter Inc, Duo Temp) continuously displayed the temperature adjacent to the Anamed humidifier temperature probe on the inspiratory side of the patient wye. Stabilized, repeat measures were collected at 1 minute intervals until 10 measurements at each variation of temperature and set ventilator flow rate were complete. Prior to testing all equipment was calibrated to the manufacturer's specifications.

Results: Data was analyzed using Analysis of Variance (ANOVA). Statistical significance existed within and between all groups pɘ.0001.

Set VentilatorHygrometerRelative Absolute Humidity

Temperature Flowrate Temperature Humidity (mg H_2O/L ±SD)

(Cº) (L/min)(Cº ±SD) (% ±SD)

32 40 31.93 (±0.05) 96.48 (±0.62) 32.60 (±0.20)

34 40 33.60 (±0.07) 98.84 (±0.42) 36.48 (±0.15)

36 40 35.58 (±0.19) 94.46 (±1.52) 38.61 (±0.59)

38 40 36.72 (±0.62) 86.74 (±0.66) 37.53 (±0.25)

32 60 31.79 (±0.02) 95.52 (±0.34) 31.80 (±0.11)

34 60 33.34 (±0.05) 98.85 (±0.23) 35.95 (±0.08)

36 60 34.92 (±0.15) 93.29 (±0.76) 36.77 (±0.28)

38 60 36.04 (±0.07) 86.32 (±0.05) 36.06 (±0.18)

32 80 31.57 (±0.03) 96.11 (±0.42) 31.76 (±0.13)

34 80 33.10 (±0.05) 98.92 (±0.32) 35.45 (±0.11)

36 80 34.57 (±0.10) 91.11 (±0.52) 35.39 (±0.18)

38 80 35.75 (±0.03) 86.51 (±0.27) 35.56 (±0.18)

32 10031.44 (±0.03) 96.21 (±0.18) 31.57 (±0.06)

34 10032.98 (±0.08) 98.57 (±0.22) 35.07 (±0.08)

36 10034.50 (±0.06) 91.11 (±0.49) 35.39 (±0.17)

38 10035.59 (±0.03) 87.53 (±0.21) 35.77 (±0.08)

Conclusion: The Anamed Humiditube met the American National Standards Institute (ANSI) heated humidifier output standard of 30 mg H_2O/L under all test conditions.

OF-95-159

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