Return of neonatal <scp>CPAP</scp> resistance – the Medijet device family examined using <i>in vitro</i> flow simulations

Falk, Markus; Donaldsson, Snorri; Jónsson, Baldvin; Drevhammar, Thomas

doi:10.1111/apa.13994

Cited by 11 publications

(15 citation statements)

References 13 publications

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“…The increased tubing resistance also leads to increased resistance to breathing (figure 3). This is expected and has been shown for other systems that generate CPAP using outflow resistance 29 30…”

Section: Discussionsupporting

confidence: 64%

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Basic principles of neonatal bubble CPAP: effects on CPAP delivery and imposed work of breathing when altering the original design

Baldursdottir

Falk

Donaldsson

et al. 2020

Arch Dis Child Fetal Neonatal Ed

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BackgroundThe original bubble continuous positive airway pressure (bCPAP) design has wide-bore tubing and a low-resistance interface. This creates a stable airway pressure that is reflected by the submersion depth of the expiratory tubing. Several systems with alterations to the original bCPAP design are now available. Most of these are aimed for use in low-income and middle-income countries and have not been compared with the original design.ObjectiveWe identified three major alterations to the original bCPAP design: (1) resistance of nasal interface, (2) volume of dead space and (3) diameter of expiratory tubing. Our aim was to study the effect of these alterations on CPAP delivery and work of breathing in a mechanical lung model. Dead space should always be avoided and was not further tested.MethodsThe effect of nasal interface resistance and expiratory tubing diameter was evaluated with simulated breathing in a mechanical lung model without interface leakage. The main outcome was delivered CPAP and imposed work of breathing.ResultsHigh-resistance interfaces and narrow expiratory tubing increased the work of breathing. Additionally, narrow expiratory tubing resulted in higher CPAP levels than indicated by the submersion depth.ConclusionOur study shows the significant effect on CPAP delivery and imposed work of breathing when using high-resistance interfaces and narrow expiratory tubing in bCPAP systems. New systems should include low-resistance interfaces and wide-bore tubing and be compared with the original bCPAP. Referring to all systems that bubble as bCPAP is misleading and potentially hazardous.

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Section: Discussionsupporting

confidence: 64%

“…This is expected and has been shown for other systems that generate CPAP using outflow resistance. 29 30 …”

Section: Discussionmentioning

confidence: 99%

Basic principles of neonatal bubble CPAP: effects on CPAP delivery and imposed work of breathing when altering the original design

Baldursdottir

Falk

Donaldsson

et al. 2020

Arch Dis Child Fetal Neonatal Ed

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“…The imposed work of breathing was calculated by integration of the pressure-volume loop for each breath (area within the loop). Measuring imposed work of breathing has been discussed by Banner [ 19 ] and the method has been used in our previous work [ 15 , 18 ].…”

Section: Methodsmentioning

confidence: 99%

“…Previous tests in mechanical lung models have shown large differences in in-vitro performance between systems [ 12 , 13 ]. Systems based purely on resistance (such as T-piece resuscitators) have consistently displayed unstable CPAP with high imposed work of breathing [ 12 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Infant CPAP for low-income countries: An experimental comparison of standard bubble CPAP and the Pumani system

2018

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IntroductionAccess to inexpensive respiratory support to newborn infants improves survival in low-income countries. Standard bubble continuous positive airway pressure (CPAP) has been extensively used worldwide for more than 30 years. One project aimed at providing affordable CPAP is the Pumani system developed by Rice 360°. Compared to standard bubble CPAP the system has an unconventional design. The aim was to compare the Pumani system with two traditional bubble CPAP systems, focusing on in-vitro performance and safety.MethodsThe Pumani system was compared to traditional bubble CPAP from Fisher & Paykel (Auckland, New Zealand) and Diamedica (Devon, United Kingdom). The systems were tested using static flow resistance and simulated breathing for a range of fresh gas flows and submersion levels.ResultsThere were large differences between the Pumani CPAP and the conventional bubble CPAP systems. The Pumani system was not pressure stable, had high resistance and high imposed work of breathing. It was not possible to use submersion depth to adjust CPAP without accounting for fresh gas flow.DiscussionThe Pumani design is novel and not similar to any previously described CPAP system. The main mechanism for CPAP generation was resistance, not submersion depth. The system should therefore not be referred to as bubble CPAP. The clinical consequences of its pressure instability and high imposed work of breathing are not known and trials on outcome and safety are needed.

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“…This reduction was significant (p < 0.001). The second generation Pumani bubble CPAP also reduces the iWOB below that of the Medijet nCPAP generator system [21,22]; it remains higher than that of the Diamedica and Fisher and Paykel bubble CPAP systems [22,23]. As iWOB is highly correlated with resistance, the significant reduction in resistance predicts this reduction in iWOB.…”

Section: Plos Onementioning

confidence: 97%

In vitro comparison of performance including imposed work of breathing of CPAP systems used in low-resource settings

et al. 2020

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Respiratory distress due to preterm birth is a significant cause of death in low-resource settings. The introduction of continuous positive airway pressure (CPAP) systems to treat respiratory distress significantly reduced mortality in high-resource settings, but CPAP was only recently introduced in low-resource settings due to cost and infrastructure limitations. We evaluated pressure stability and imposed work of breathing (iWOB) of five CPAP systems used in low resource settings: the Fisher and Paykel bubble CPAP, the Diamedica baby CPAP, the Medijet nCPAP generator, and the first (2015) and second (2017) generation commercially available Pumani CPAPs. Pressure changes due to fresh gas flow were evaluated for each system by examining the relationship between flow and pressure at the patient interface for four pressures generated at the bottle (0, 3, 5, and 7 cm H2O); for the Medijet nCPAP generator, no bottle was used. The slope of the resulting relationship was used to calculate system resistance. Poiseuille’s law of resistance was used to investigate significant contributors to resistance. Resistance ranged from 0.05 to 1.40 cmH2OL/min; three CPAP devices had resistances < 0.4 cmH2OL/min: the Fisher and Paykel system, the Diamedica system, and the second generation Pumani bubble CPAP. The other two systems, the Medijet nCPAP generator and the first generation Pumani bCPAP, had resistances >1.0 cmH2OL/min. Imposed WOB was measured using an ASL5000 test lung to simulate the breath cycle for an infant (5.5 kg), a term neonate (4.0 kg), and a preterm neonate (2.5 kg). Imposed WOB ranged from 1.4 to 39.5 mJ/breath across all systems and simulated infant sizes. Changes in pressure generated by fresh gas flow, resistance, and iWOB differ between the five systems evaluated under ideal laboratory conditions. The available literature does not indicate that these differences affect clinical outcomes.

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Return of neonatal CPAP resistance – the Medijet device family examined using in vitro flow simulations

Cited by 11 publications

References 13 publications

Basic principles of neonatal bubble CPAP: effects on CPAP delivery and imposed work of breathing when altering the original design

Basic principles of neonatal bubble CPAP: effects on CPAP delivery and imposed work of breathing when altering the original design

Infant CPAP for low-income countries: An experimental comparison of standard bubble CPAP and the Pumani system

In vitro comparison of performance including imposed work of breathing of CPAP systems used in low-resource settings

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