The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

COMPARING PRESSURE CHANGES AND AEROSOL DEPOSITION OF A STANDARD SMALL-VOLUME NEBULIZER AND A MINI-HEART LOW FLOW NEBULIZER DURING HFOV

Shane Cheney, Kevin Crezee, Tim Macknight, Jeff Wright; Respiratory Care Services, Primary Children’s Medical Center, Salt Lake City, UT

Introduction: Aerosolized medications are often administered to intubated neonates within the Newborn Intensive Care Unit at Primary Children’s Medical Center (PCMC). The standard as the means of delivery for aerosolized medications via the Sensormedics 3100A High Frequency Oscillator Ventilator (HFOV) has been an Metered Dose Inhaler (MDI). Previous bench lab studies conducted at PCMC showed that aerosol deposition was more effective via a Small Volume Nebulizer compared to an MDI in a neonatal lung model (Davidson et al, 2005). To build upon this information, we hypothesized that the efficiency of deposition would not be compromised and the turbulence / resistance to exhalation caused by the increased amount of flow at the closed suction catheter connection with the standard SVN setup could be minimized by using a Mini-HEART Low-Flow nebulizer (MHN). We further hypothesized that the post endotracheal tube (ETT) pressures would be higher than the set pressures on the HFOV with the standard SVN compared to a MHN with little or no change in aerosol deposition. Methods: To measure post ETT pressures, a neonatal lung model was attached to 2.5 - 4.0 ETT’s and ventilated with the HFOV. The MHN and standard SVN were connected to the suction port of the “Y” adapter and run at multiple settings. The post ET pressures were read and measured from the LifePort jet adapter connected to the Bunnell HFJV. To measure medication deposition, a lung model was used in conjunction with a MHN and SVN. The mini-heart dosage consisted of a pre-mixed unit dose of 2.5 mg (0.5ml) albuterol and 2.5 ml NS. Ventilator settings comparing aerosol deposition were as follows: Mean Airway Pressure (PAW)= 20 cmH20, Amp= 30 cmH20, Hz= 10. A wide spectrum of HFOV settings were used to test post-ET pressure differences with both types of nebulizers. Results: Mean Albuterol delivery for the MHN onto the filter was the following: 2.5 ET= 6.8%, 3.0 ET= 8.8%, 3.5 ET= 10.0%, 4.0 ET= 10.1%. The average of the above means was 9.2%. Mean PAW increase as measured post ET was 1.95 cmH20 using the standard SVN and 0.5 cmH20 using the MHN. When comparing post ET pressures the mini-heart consistently demonstrated lower post ET pressures. Conclusions: Post-ET pressures were minimized with the MHN, with similar deposition results of SVN aerosolized medication. Evidence suggests the MHN may provide the same benefit of an aerosolized medication without altering intrapulmonary pressures. Sponsored Research - None

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