The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

HUMIDIFICATION AND AEROSOL DELIVERY DURING MECHANICAL VENTILATION USING CAPILLARY FORCE VAPORIZATION (C-FORCET)

M. Solomita, D.O. 1 and G.C. Smaldone, M.D.,PhD 1

1.Department of Pulmonary and Critical Care Medicine, SUNY at Stony Brook, Stony Brook, NY 11794

Background: To compare a device using capillary force vaporization (C-ForceT ; Pari Respiratory Equipment, Midlothian, VA) to conventional humidification systems during mechanical ventilation.

Methods:
The C-ForceT was integrated into a modified ventilator circuit to measure water vapor delivery. The device consists of a water pump and a heater plate designed to sit at the Y-piece. The heater plate was set at 130 °C. The water pump rate was adjusted to achieve a Y-piece temperature of 35 °C, as measured by a thermocouple from a conventional humidification system. A condenser tube was used to condense and measure some of the water vapor generated. Hygrometric measurements were made and used to determine the absolute humidity (AH) of the gas which escaped the condenser. Using the AH, the amount of water vapor which escaped the condenser was calculated. This allowed us to determine the amount of water delivered. The same was done for a non-heated wire (NHWH) and heated wire humidifier (HWH).  In addition, we measured the amount of water each device consumed from its water reservoir in order to determine device efficiency (water delivered / water consumed). Experiments were performed using three different ventilators (Drager 4 NeoFlow, Puritan Bennett 7200, T-Bird AVS III) and two different breathing patterns (TV=750, RR=15 and TV=400, RR=15). Aerosol delivery was determined by nebulizing radiolabeled albuterol with an Aerotech II nebulizer.  Each humidification device was evaluated with the PB7200 (breath actuated nebulization, TV=750, RR=15).  An inhaled mass (IM) filter was placed at the end of the ETT to determine the percentage of radioactivity, and therefore aerosol, that would be delivered to a patient.

Results:
C-ForceT delivered 15.0 ± 2.0, 15.7 ± 0.8, and 8.7 ± 0.5 mL water/hr at TV=400, and 30.7 ± 0.3, 28.9 ± 1.0, and 16.9 ± 1.2 mL water/hr at TV=750 using the Drager, PB7200, and T-bird ventilators respectively. The NHWH delivered 13.5 ± 0.3, 14.0 ± 0.8, and 13.6 ± 0.3 mL water/hr at TV=400, and 27.5 ± 0.6, 28.5 ± 0.5, and 23.3 ± 0.5 mL water/hr at TV=750 using the Drager, PB7200, and T-bird ventilators respectively. The HWH delivered 13.6 ± 0.8, 12.2 ± 0.5, and 10.9 ± 1.2 mL water/hr at TV=400, and 21.4 ± 1.2, 24.2 ± 1.0, and 18.1 ± 0.3 mL water/hr at TV=750 using the Drager, PB7200, and T-bird ventilators respectively. HWH and C- ForceT were more efficient than NHWH (HWH 67.8, 49.2, NHWH 36.7, 18.8, and CFV 66.4, 53.7% at TV=750 and TV=400 respectively). Efficiency was reduced when using the T-bird ventilator with each device. IM was 9.5 ± 1.6, 13.7 ± 0.9, and 16.0 ± 1.2 % for the NHWH, HWH, and C- ForceT respectively.

Conclusions:
C-forceT is an effective method for humidifying a ventilator circuit.  It eliminates inspiratory line condensation, uses sterile water efficiently, and has greater aerosol delivery during device use when compared to conventional systems. Humidification device performance is reduced due to bias flow (T-bird ventilator).


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