The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

THE EFFECT OF FLOWRATE FROM AN IN-LINE NEBULIZER ON DELIVERED VOLUME AND PRESSURE WHILE USING THE LTV 1000 VENTILATING AN ELECTRONIC LUNG SIMULATOR

Candy Perry, Coby Steele, Lonny Ashworth MEd RRT. Boise State University, Boise, ID.

Background: Nebulizers are frequently used to administer medication to mechanically ventilated patients. If the ventilator does not have a built-in nebulizer, an external nebulizer must be added to the system. The effect of the additional flow on delivered volume and peak pressure was evaluated on the Pulmonetics LTV 1000 when ventilating an electronic lung simulator.

Methods: The LTV 1000 was connected to a Hans Rudolph Series 1101 Breathing Simulator (HR 1101). HR 1101 settings: rate 8/min, resistance 15 cmH20/L/sec, compliance 50 mL/cmH20. Five conditions were evaluated: Volume-targeted A/C; Pressure-targeted A/C; CPAP plus PSV with flow cycle percent set at 10%; CPAP plus PSV with flow cycle percent set at 25%; CPAP plus PSV with flow cycle percent set at 40%. Nebulizer flows were 0, 4, 6, 8 and 10 LPM. Five breaths were recorded in each of the five ventilator conditions at varying nebulizer flows; an average of the five breaths was the basis for evaluation.

Results: As nebulizer liter flow increased during Volume-targeted A/C, pressure increased from 19.7 to 28.4 cm H2O and VT increased from 579.5 to 752.6 mL. During Pressure-targeted A/C pressure remained constant at 20.2 cm H2O, but VT decreased from 603.8 to 510.1 mL. During CPAP with PSV pressure remained constant at 14.9 cm H2O, at all flow cycle percents. However, at flow cycle of 10% VT decreased from 502.3 to 282.4 mL; at 25% VT decreased from 448.6 to 269.6 mL; and at 40% VT decreased from 377.2 to 235.2 mL.

Conclusion: Adding an external nebulizer to the LTV 1000 during pressure-targeted A/C, volume-targeted A/C, or CPAP with PSV may change the delivered volume and/or pressure. These values must be closely monitored while ventilating patients receiving nebulized medications.

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