Flow Resistance of Expiratory Positive-Pressure Systems

Pinsky, Michael R.; Hrehocik, Drew; Culpepper, Judith A.; Snyder, James V.

doi:10.1378/chest.94.4.788

Cited by 29 publications

(5 citation statements)

References 11 publications

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“…Peak expiratory flow is considered important by many physiotherapists for secretion clearance in intubated patients. It has been demonstrated previously that individual circuits and expiratory valves exhibit different resistive characteristics depending on the expiratory flow rates, and that variations exist between circuits 13,27,28 . Protocol 1 in this study resulted in the slowest PEFR and, despite the greatest variability in the volume delivered (±0.21 litres), the PEFR was the most consistent (±0.06 l/s).…”

Section: Discussionmentioning

confidence: 99%

The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

Maxwell

Ellis

2002

Anaesth Intensive Care

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Manual hyperinflation (MHI) is used by physiotherapists as a treatment technique in intubated patients. This study investigated the effect of three different MHI techniques using a Mapleson-C circuit configuration with a CIG Medishield valve on volume delivered (Vt), peak inspiratory (PIFR) and expiratory flow rates (PEFR), and peak airway pressure (PAP) in a test lung model. The protocols differed in the degree of valve closure and inclusion of an inspiratory pause.

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Section: Discussionmentioning

confidence: 99%

The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

Maxwell

Ellis

2002

Anaesth Intensive Care

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“…Modern CPAP valves are of a spring loaded, variable orifice design which open at a set pressure and should maintain constant upstream pressure as flow varies (flow independence). 5 The flow rate and FI O 2 generated by the Whisperflow are adjustable using uncalibrated dials. In theory, provided the flow into the breathing system exceeds the patient's peak inspiratory flow rate and the valves maintain flow independence, then the pressure in the breathing system and at the patient interface should remain constant at the required value throughout the respiratory cycle.…”

mentioning

confidence: 99%

Assessing the performance of the Whisperflow® continuous positive airway pressure generator: a bench study

Glover

Fletcher

2009

British Journal of Anaesthesia

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“…The inflation pressure was further attenuated by the CPAP interfaces, breathing circuits, and release from the water column during bCPAP. The bCPAP water-seal is considered a "pure threshold resistor" [28]. The LFAC flows that generated system pressures greater than the set point CPAP level (6 cm H 2 O) were diverted to the CPAP hoses and water column and released to the atmosphere.…”

Section: Safety and Efficacymentioning

confidence: 99%

Evaluation of a Novel Dry Powder Surfactant Aerosol Delivery System for Use in Premature Infants Supported with Bubble CPAP

DiBlasi,

Crandall,

Engberg

et al. 2023

Pharmaceutics

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Aerosolized lung surfactant therapy during nasal continuous positive airway pressure (CPAP) support avoids intubation but is highly complex, with reported poor nebulizer efficiency and low pulmonary deposition. The study objective was to evaluate particle size, operational compatibility, and drug delivery efficiency with various nasal CPAP interfaces and gas humidity levels of a synthetic dry powder (DP) surfactant aerosol delivered by a low-flow aerosol chamber (LFAC) inhaler combined with bubble nasal CPAP (bCPAP). A particle impactor characterized DP surfactant aerosol particle size. Lung pressures and volumes were measured in a preterm infant nasal airway and lung model using LFAC flow injection into the bCPAP system with different nasal prongs. The LFAC was combined with bCPAP and a non-heated passover humidifier. DP surfactant mass deposition within the nasal airway and lung was quantified for different interfaces. Finally, surfactant aerosol therapy was investigated using select interfaces and bCPAP gas humidification by active heating. Surfactant aerosol particle size was 3.68 µm. Lung pressures and volumes were within an acceptable range for lung protection with LFAC actuation and bCPAP. Aerosol delivery of DP surfactant resulted in variable nasal airway (0–20%) and lung (0–40%) deposition. DP lung surfactant aerosols agglomerated in the prongs and nasal airways with significant reductions in lung delivery during active humidification of bCPAP gas. Our findings show high-efficiency delivery of small, synthetic DP surfactant particles without increasing the potential risk for lung injury during concurrent aerosol delivery and bCPAP with passive humidification. Specialized prongs adapted to minimize extrapulmonary aerosol losses and nasal deposition showed the greatest lung deposition. The use of heated, humidified bCPAP gases compromised drug delivery and safety. Safety and efficacy of DP aerosol delivery in preterm infants supported with bCPAP requires more research.

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Flow Resistance of Expiratory Positive-Pressure Systems

Cited by 29 publications

References 11 publications

The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

Assessing the performance of the Whisperflow® continuous positive airway pressure generator: a bench study

Evaluation of a Novel Dry Powder Surfactant Aerosol Delivery System for Use in Premature Infants Supported with Bubble CPAP

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