Evaluation of a prototype expiratory-phase aerosol controller during simulated pediatric volume-controlled ventilation.
BACKGROUND
Some methods of administering aerosolized medications during volume-controlled ventilation require adjustment of ventilator settings to avoid inadvertent increases in tidal volume (VT). Our bench evaluation of an expiratory-phase aerosol controller (EXPAC) sought to determine the differences (1) in aerosol delivery between continuous and EXPAC nebulization in pediatric and neonatal ventilator circuits and (2) in delivered VT with a 30-cm vs a 213-cm nebulizer supply line. DESCRIPTION OF DEVICE: An electrically powered EXPAC linked to the VIP Bird ventilator by a fiberoptic cable and driven by flow from an integral blender was developed to our performance specifications.


METHODS
In Phase 1, VT was measured at the patient connection under 3 conditions: (1) no nebulizer in-line, (2) a dry in-line nebulizer driven by EXPAC with a 30-cm supply line, and (3) Condition 2 with a 213-cm supply line. In Phase 2, we measured the aerosol delivered to a filter placed between the patient connector and the test lung. Aerosol delivery = filter wet weight-filter dry weight.


RESULTS
(1) When EXPAC was operated according to manufacturer's recommendations, no significant differences were found between VTS measured with EXPAC plus the 30-cm line and with no nebulizer in-line. VT increased significantly (p = 0.0001, 1-way ANOVA) in both circuits with the 213-cm supply line. (2) Mean (SD) aerosol delivery at the patient connection of the pediatric circuit was 1.5 (0.002)% with EXPAC and 1.7 (0.003)% with continuous nebulization (p = 0.23, t test) and of the neonatal circuit 1.6 (0.002)% with EXPAC and 1.5 (0.002)% with continuous nebulization (p = 0.45, t test).


CONCLUSIONS
EXPAC eliminated need for adjustment of ventilator settings and according to our data was as effective as continuous nebulization for delivering aerosol to the patient connection.
Primary Children's Medical Center, Salt Lake City, UT 84113.
J
J
Keenan
J W
JW
Salyer
D000280:Administration, Inhalation; D002648:Child; D003625:Data Collection; D005069:Evaluation Studies as Topic; D006776:Hospitals, Pediatric; D006801:Humans; D007231:Infant, Newborn; D009330:Nebulizers and Vaporizers / Q000592:standards*; D016544:Patient Simulation; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000592:standards; D014589:Utah