Assessing the Impact of Continuous Aerosolized Medications on Mechanical Ventilation When Filters and Expiratory Cassettes Become Compromised Due to Sodium Deposition

Background: Expiratory cassettes (EC) often play a vital role in mechanical ventilation (MV).ECs serve as the brain of the MV, measuring pressures and flows, among other functions after gas is exhaled from the patient. To protect the EC, filters are placed before it to prevent internal damage. Cases of filters creating PEEPtot (intrinsic PEEP) have resulted from the presence of sodium or aerosol medication deposition in the filters. The amount of time it takes for filter blockages or EC malfunction, however, has not been studied. Methods: Two ventilators were used side by side this bench study. Both used heated wire circuits and a filter attached to the EC according to the manufacturer’s recommendations. No filters were added to the inspiratory side. Sterilized ECs were used for the trial. MV settings were consistent for both ventilators: VC/AC, VT of 120 mL, frequency of 15, PEEP of 5 cm H2O and 1 s i-time were used in this bench study. Both MV circuits were attached to a 1 L max VT test lung. A continuous solution of 0.9% normal saline (NSS) was ran through a syringe pump at 10 mL/h using a vibrating mesh nebulizer. This was chosen to simulate continuous albuterol nebulization used for critical pediatric asthma exacerbations, as albuterol is mixed with NSS. The first ventilator (V1) received expiratory filter changes every 4 h, while the second ventilator (V2) had no filter changes throughout the study to determine its impact on the filters, EC readings, and the ability to ventilate. The following parameters were assessed every 4 h: Vti, Vte, PIP, PEEP actual, intrinsic PEEP (PEEPtot), expiratory airway resistance (Re), EC percentage of life expectancy. The trial ran for 6 days. Results: V1 had no significant change in Vti, Vte, PIP, PEEPtot, compliance (Ces), or Re over a 6-day period. V2 began to see changes in PEEPtot within 24 h. It was also subjectively reported that within 24 h the expiratory flow took significantly longer to get back to baseline. At 24, 48, and 72 h, values for PEEPtot in cm H2O (5.5, 12, 16), Re (11, 76, 452), PIP cm H2O (13, 18, 23). Conclusions: While running continuous albuterol mixed with NSS, ventilators that require EC filters, must be changed more frequently than at 24 h intervals, to prevent external factors of expiratory resistance. This may lead to caregivers mistaking airtrapping within the circuit of the ventilator for increased airway resistance in a patient who is at risk for severe airway resistance, ultimately leading to care mismanagement and potential patient harm.V2 no filter changesDatetimeNSS 10ml/hrsyringe changedVTIVTEMAPPIPPEEP actualPEEPTOTEC predicted life %AutoPEEP PresentCesRe5/130800yesno1211245.5134.64.683%no16.9165/131200yesno1201215.5134.64.783%no16.9165/131600yesyes1201215.6134.74.783%no17.2165/132000yesyes1201226.1134.9583%no18.2165/140001yesno1201236.51355.183%no18.3115/140400yesyes1201246.8135.15.383%no18.4115/140800yesno1211217.3135.25.583%yes18.4115/141200yesyes1211198145.76.183%yes18.4145/141600yesyes1211198.9146.4783%yes19.3195/142000yesno1211179.3146.87.583%yes20.3225/150001yesyes1211179.7157.27.983%yes20.6255/150400yesyes          5/150800yesno1211111318111283%yes24765/151200yesno1201161722151283%yes24765/151600yesyes1191142029151783%yes26.32445/152000yesno1191141928131683%yes10.5 5/160001yesno1211101620141683%yes29.84165/160400yesyes1201121621141683%yes33.22145/160800yesno1191111623141683%yes17.64525/161200yesno1191131827141683%yes10.722645/161600yesyes1191101929141683%yes9.222645/162000yesno1201112030141783%yes9.122645/170001yesyes1211172031141783%yes8.722645/170400yesyes1201152132151783%yes8.222645/170800yesno1201132132151783%yes7.222645/171200yesyes1211152133151783%yes7.422645/171600yesno1201182234151883%yes7.322645/172000yesno1201172235151883%yes7.422645/180001yesyes1201162335161883%yes7.32264V1 4 hour filter changesDateTimeNSS 10ml/hrSyringe changedVTIVTEMAPPIPPEEP actualPEEPTOTEC%Auto PEEPCesRe5/130800yesno1211175124.65.498%no19.4145/131200yesno1221226134.75.498%no19.9165/131600yesyes1221186134.75.498%no19.3165/132000yesyes1201196134.75.598%no20.9165/140001yesno1231196134.85.598%no20.5145/140400yesyes1221185124.75.498%no20.5145/140800yesno1211186134.75.498%no20.1155/141200yesyes1221226134.75.498%no20155/141600yesyes1221226134.75.598%no19.5155/142000yesno1231206134.75.598%no21.3155/150001yesyes1221216134.75.598%no21.1155/150400yesyes1221206134.75.598%no20.8145/150800yesno1231226124.75.498%no21.6135/151200yesno1221286134.85.498%no21.6145/151600yesyes1221195124.75.498%no21.3145/152000yesno1211246124.75.498%no21.4145/160001yesno1221246134.75.498%no22.4155/160400yesyes1231256134.75.498%no22.1145/160800yesno1221196124.75.497%no21145/161200yesno1221296124.75.497%no22.9145/161600yesyes1221225124.75.497%no21.7135/162000yesno1221235124.75.397%no22.6135/170001yesyes1221215124.75.597%no23.2135/170400yesy1221205124.75.597%no23.5135/170800yesno1221246124.85.497%no22.8145/171200yesyes1211246124.75.497%no21.9145/171600yesno1221226124.85.597%no21.7145/172000yesno1211226124.75.597%no22.3145/180001yesyes1211246124.75.597%no22.314