2001 OPEN FORUM Abstracts
EVALUATION OF THEWESTMED VIXONE NEBULIZER WITH THE MALLINCKRODT NELLCOR PURITAN BENNETT 840 VENTILATOR.
Erin Lichtenfels,BS, CRT; Gen Boas, BS; Douglas Oberly, MS, RRT. Hartford Hospital, Hartford,CT.
Background: The 840 ventilatoris a new model critical care ventilator developed by Mallinckrodt Nellcor PuritanBennett. The 840 was not designed to accommodate an in-line nebulizer, thuspractitioners are required to use metered dose inhalers or external gas powerednebulizers to deliver medications to patients. A simple calculation of AdditionalVolume = Ti x Flow (Lpm/60) is used to assist health care providers in determiningthe added inspiratory volume. The VixOne nebulizer is one of the newest wetnebulizers on the market manufactured by Westmed. This nebulizer operates at4 lpm as opposed to the typical 6 to 8 lpm recommended by other nebulizer manufacturers.Our goal was to determine the effects of additional gas flow through the 840ventilator and determine if the VixOne nebulizer can be used to deliver solutionbased medications.
Methods: The study was conductedby utilizing a Mallinckrodt 840 ventilator, VixOne nebulizer, Cosmo Plus RespiratoryProfile Monitor (Novametrix Medical Systems Incorporated), a heated-wire ventilatorcircuit (Airlife), and an adult test lung (Neditester). The Cosmo Plus devicewas placed in-line between the wye and the test lung to determine precise inspiratoryand expiratory volumes from the test lung. The VixOne nebulizer was placed onthe inspiratory line of the circuit 6 inches before the wye. The ventilatorwas set in volume control mode with a ramp waveform. A stiff compliance of 10ml/cmH20 was used. Inspiratory times were determined by tidal volume and flowrate. Saline was aerosolized in the nebulizer, powered by oxygen at variousflowrate intervals. Twenty-five exhaled tidal volumes were recorded at inspiratorytimes ranging from 0.2 to 2.0 seconds to determine an average tidal volume forcomparison. Subsequent liter flows ranging from 1 liter to 15 lpm were thentested.
Experience: When adding flowto a circuit during a nebulizer treatment there is an increase in measured expiratorytidal volume and it does not appear to be incremental. As inspiratory timesand flow rates increase, the tidal volumes became erratic. The flow rates rangedfrom 40 to 150 lpm and the tidal volumes ranged from 275 to 730 ml. At flowratesabove 8 lpm, we observed expiratory tidal volumes to plateau and high peak inspiratorypressures above 90 cmH2O. Ventilator failure occurred at 13 lpm causing a ?severeocclusion? message and the ventilator went into a safety ventilation mode.
Conclusion: Based on ourresearch, when adding flow from an external flowmeter during a nebulizer treatmentthere is an increase in measured expiratory tidal volume and it is extremelyvariable. The maximum added external flowrate that the 840 ventilator will tolerateis 12 lpm. However based on our observations, flowrates above eight liters perminute could produce less than adequate ventilation. Our data concludes thatthe additional volume added into the ventilator circuit affects the adequatemonitoring of exhaled tidal volumes. Health care practitioners utilizing the840 ventilator and nebulizers powered by external flowmeters need to be awareof the potential risk of a ventilator failure at flowrates above 8 lpm. The840 ventilator can tolerate the VixOne nebulizer operating at 4 lpm withoutany major malfunctions. Future study must be done to determine the efficacyof medication delivery with the VixOne nebulizer and the 840.