2001 OPEN FORUM Abstracts
PERFORMANCE CHARACTERISTICSOF THE SERVO 345 USN IN PEDIATRIC MECHANICAL VENTILATION
William W. QuinnRRT RPFT, Regina Brzak, Cheryl Kennedy CRT, Cape Fear Valley Health SystemFayetteville, NC.
We sought to determinethe rate of medication consumption, efficiency of drug delivery, and quantityand concentration of residual medication in a bench model of pediatric volumeventilation while using the Servo 345 ultrasonic medication nebulizer (USN).
Methods: A Servo 300ventilator was attached to a 3.0 mm endotracheal tube, with a drip trap attachedto the end. An adapter containing a cotton ball was attached between this anda standard 1ml/cm H2O infant test lung. The USN was operated with 2.5 mg albuterolin 3 ml solution in a position 10 cm upstream from the patient wye for thirtyminutes. The USN was weighed before and after each run to determine rate ofnebulization. A fresh cotton ball was washed at the end of each run with 20ml saline. The washing was examined by spectrophotometry to determine albuterolcontent as a percent of albuterol placed in the USN. The residual medicationin the USN was also assayed. Ten trials were done in SIMV Volume Control firstwith a rate of 40, a 50 ml tidal volume, 33% I-time, 5 cm H2O PEEP and 100%O2. Then ten more were done with the rate turned down to 20.
Results (SD): Medicationnebulized in 30 minutes: Rate 40: 2.21ml(.23) Rate 20: 1.66ml(.20). Percentdrug delivered to test lung: Rate 40: 3.6% (.9) Rate 20: 3.2%(1.1) Concentrationof residual medication left in USN compared to original drug: Rate 40: +17%(5)Rate 20: +7%(7).
Conclusions: Underthe conditions tested the USN will leave residual medication which is more concentratedthan the original medication, in a manner very similar to a jet nebulizer. Thepercentage of drug delivered to the test lung is also similar to that reportedfrom similar tests using jet nebulizers. Finally, at a rate of 40 the rate ofnebulization of medication was .17 ml/min per 0.1 liter/sec flow (2.21 ml in30 min with 2 liter minute volume plus .67 liters expiratory bias flow), notthe .1 ml/min predicted by the USN operator?s manual