The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

THE EFFECTS OF HUMIDIFIER TEMPERATURE AND VENTILATOR FLOW RATE ON THE RELATIVE HUMIDITY DELIVERED BY THE FISCHER & PAYKEL MR-730 HUMIDIFICATION SYSTEM USING TWO HUMIDIFICATION CHAMBERS

Russell T. Reid, RRT CPFT, and Mark Goldstein, RRT. Mercy American River/San Juan Hospital, Carmichael, California

This study examined the effect of varying ventilator flow rate and set humidifier temperature on the relative humidity delivered by the F&P (Auckland, New Zealand) MR-730 heated humidification system using two different humidification chambers. Methods: A F&P MR-730 heated humidifier equipped with either a F&P MR-390 or MR-290 humidifcation chamber and Isothermal 72" heated wire circuit (Valencia, CA Model 1704-HO7) was attached to a Hamilton Veolar (Reno, NV) mechanical ventilator. The volume control mode with a square inspiratory flow wave form was used. A heated humidity chamber (HC), 37.7 C° (±1.8 C°), was constructed to accommodate the probe of a capacitance type digital hygrometer (CM Scientific, Brisbane, CA, Model #244-355) with integral thermistor. Inspiratory gas passed through the HC for relative humidity measurement. The heated wire controller was set for 0 C° differential. Five repeat, stabilized measures, were collected at 1 minute intervals at all combinations of flow rate and temperature. 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 p < 0.001.

Set Vent Hygrometer Hygrometer Absolute Absolute

Temp Flow Temp Temp Humidity Humidity

(Cº) Rate MR-390 MR-290 MR-390 MR-290

(L/min) (C/±SD) (C/±SD) (mg H2O/L ±SD) (mg H2O/L ±SD)

32 40 31.73(± 0.03) 31.99(± 0.07) 18.23(± 0.24)? 33.94(± 0.14)

34 40 33.19(± 0.31) 32.61(± 0.10) 33.37(± 0.42) 35.08(± 0.20)

36 40 34.68(± 0.15) 34.59(± 0.21) 34.93(± 0.41) 38.85(± 0.53)

38 40 36.22(± 0.75) 36.11(± 0.06) 38.92(± 1.65) 40.66(± 1.15)

32 60 31.64(± 0.04) 31.96(± 0.02) 19.35(± 0.17)? 33.79(± 0.00)

34 60 33.03(± 0.05) 32.85(± 0.10) 34.15(± 0.36) 35.48(± 0.00)

36 60 35.04(± 0.03) 34.76(± 0.12) 36.06(± 0.11) 39.13(± 0.35)

38 60 37.07(± 0.02) 35.94(± 0.05) 41.63(± 0.09) 42.05(± 0.00)

32 80 31.55(± 0.05) 31.72(± 0.18) 20.94(± 0.24)? 33.39(± 0.33)

34 80 33.07(± 0.04) 32.77(± 0.06) 33.43(± 0.16) 35.37(± 0.12)

36 80 34.80(± 0.41) 34.74(± 0.07) 37.32(± 0.66) 39.07(± 0.13)

38 80 37.00(± 0.59) 36.06(± 0.03) 41.85(± 1.29) 42.05(± 0.00)

32 100 31.41(± 0.10) 31.53(± 0.16) 26.59(± 0.41)? 33.10(± 0.27)

34 100 32.96(± 0.06) 32.43(± 0.26) 33.77(± 0.26) 34.72(± 0.57)

36 100 35.10(± 0.01) 34.77(± 0.05) 38.22(± 0.12) 39.24(± 0.33)

38 100 36.31(± 0.37) 35.95(± 0.47) 41.28(± 0.50) 41.41(± 1.21)

?-Did not meet the ANSI standards for heated humidification. Conclusion: The F&P MR-390 humidification chamber failed to meet the American National Standards Institute standard for heated humidifiers of 30 mg H2O/L for all flow rates at 32 C°

Reference: OF-96-092

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