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Original article
Validation of the disposable T-piece resuscitator (Neo-Tee): a bench study
  1. Lizzy de Groene1,
  2. Anne P De Jaegere2,
  3. Olivier J Nijland2,
  4. Anton H van Kaam2,3
  1. 1 Department of Anaesthesiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
  2. 2 Department of Neonatology, Emma Children’s Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
  3. 3 Department of Neonatology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Lizzy de Groene, Department of Anaesthesiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands; l.degroene{at}vumc.nl

Abstract

Objective The Neo-Tee Infant T-piece resuscitator is a disposable T-piece resuscitator. The aim of this bench study was to assess the accuracy of the Neo-Tee using a measurement set-up and settings mimicking clinical practice.

Study design Nine Neo-Tee devices were tested using a face mask interface and a manikin. Pressures were set using the built-in manometer and simultaneously measured at the interface. Peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP) were studied under static conditions and positive pressure ventilation (PPV), using a wide range of clinically relevant flows and pressures. Pressures were measured without adjusting for a possible offset of PIP and PEEP after switching from static pressures to PPV. In an additional subset of measurements, PIP/PEEP offsets on the Neo-Tee manometer after starting PPV were adjusted.

Results Under static conditions, setting the PEEP level with the Neo-Tee manometer results in overestimation of the true PEEP applied at the airway opening, with a difference of approximately 1.5 cmH2O. When switching to PPV, this difference almost disappears. In contrast to PEEP, PIP levels measured at the airway opening were accurate.

Adjusting PIP and PEEP on the built-in manometer after starting PPV was necessary in all measurements, but this did not improve the accuracy of the targeted pressure delivery, especially for PEEP. A gas flow rate of 5 L/min was insufficient to reach commonly used PEEP levels of 5 cmH2O.

Conclusion The Neo-Tee T-piece resuscitator is accurate for delivering a static inflation and PPV, but not for delivering continuous positive airway pressure.

  • respiratory
  • resuscitation
  • neonatology
  • technology

https://doi.org/10.1136/archdischild-2018-315298

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    What is already known on this topic?

    • T-piece resuscitators provide the most consistent and accurate pressures during ventilation.

    • Non-disposable T-piece resuscitators require a significant financial investment to set up the equipment.

    • The Neo-Tee disposable T-piece resuscitator might be a cheaper solution, but data on its accuracy are limited.

    What this study adds?

    • The Neo-Tee delivers accurate pressures during positive pressure ventilation and a sustained inflation.

    • Continuous positive airway pressures (CPAP) delivered by the Neo-Tee are significantly lower as set on the built-in manometer.

    • A minimal gas flow of 8 L/min should be used in order to reach CPAP/PEEP levels of at least 5 cmH2O.

    Introduction

    T-piece resuscitators (TPRs) are often used in neonatal transition and resuscitation since these devices provide the most consistent and accurate peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP).1–7 In clinical practice, TPRs are used for applying one of three respiratory support modalities: continuous positive airway pressure (CPAP), sustained inflation or positive pressure ventilation (PPV).8 Most TPRs are non-disposable and therefore require a significant financial investment to set-up the equipment in every delivery room.

    The Neo-Tee Infant T-piece resuscitator (Mercury Medical, Florida, USA) is the first available disposable TPR. As shown in online supplementary figure 1, this single patient, flow-controlled and pressure-limited resuscitation device consists of a proximal controller, a tubing set and a distal built-in manometer near the T-connector. The proximal controller consists of an adjustable pressure relief valve, which offers the ability to apply a more consistent targeted PIP, which is limited at 40 cmH2O. The PEEP is adjusted trough the resistor, incorporated in the T-connector.

    The reliability of the Neo-Tee depends on both the consistency of the disposable pressure relief valve and the precision of the disposable built-in manometer. Variability of PIP and PEEP may result in delivery of either insufficient or excessive pressures. Studies including the Neo-Tee device are limited and only one study assessed the accuracy of the Neo-Tee pressure relief valve and manometer at different flow and pressure settings.9–12 However, this study only assessed the accuracy of the built-in manometer in a small range of pressure settings and only under dynamic conditions (ie, PPV). Static pressures mimicking CPAP or a sustained inflation were not tested. Furthermore, the authors only used three Neo-Tee devices and a test lung instead of a more clinically relevant face mask interface applied to a manikin.12

    Therefore, the aim of this bench study was to assess the accuracy of the Neo-Tee pressure relief valve and manometer in a broad range of pressures under both static and dynamic conditions and using a larger number of devices and a manikin set-up.

    Materials and methods

    Setting

    This bench study was performed at the neonatal intensive care unit of the Academic Medical Centre in Amsterdam, the Netherlands.

    Device and set-up

    As shown in online supplementary figure 2, the set-up consisted of a tube style 0–15 L/min air flow meter; a Neo-Tee TPR, a neonatal in-line pressure differential pneumotach (COSMOPLUS (CO2SMO+) model 8100, Novametrix Medical Systems, Connecticut, USA; flow range 0.25–28 L/min, pressure range −120 to +120 cmH2O13); a disposable face mask with a cushioned rim (Air Cushion Mask size 1, Medisize BV, Nederland) and a Laerdal Resusci manikin (Laerdal, Stavanger, Norway) with a 50 mL lung and a compliance of approximately 2 mL/cmH2O. The accuracy of the pressure measurement of the COSMOPLUS was tested using a 10 mL syringe and a glass bottle of 1000 mL filled with copper wool before each series of measurement. In addition, it was confirmed that the connection of the COSMOPLUS with the mask and the Neo-Tee was leak free. A total of nine Neo-Tee devices (part number 1050804, lot 11348) were tested.14 15

    Measurements and analysis

    The mask was fixed on the manikin with the left hand using the C-hand manoeuvre and the T-piece connector was occluded with the right hand. PEEP and PIP were set by adjusting the PEEP valve and the pressure controller, respectively.

    A broad range of settings were examined in random order over a 3-week period: three gas flow rates (5, 8 and 10 L/min), seven levels of PIP (10, 15, 20, 25, 30, 35 and 40 cmH2O) and three levels of PEEP (5, 6 and 8 cmH2O) in nine Neo-Tee patient circuits. First, the PIP and PEEP were studied under static conditions. Both PIP and PEEP were set separately using the Neo-Tee manometer and measured for 10 s with (PIPstat) and without (PEEPstat) occlusion of the PEEP valve. Next, a second measurement was started during which these pressures were used for PPV (PIPppv and PEEPppv). Mask ventilation was delivered by a single operator, during 2 min at a rate of 60/min guided by a metronome. The switch from static pressures to PPV was performed without interruption and a possible offset of PIP and PEEP from the target pressure was not corrected. All delivered pressures were also continuously recorded by the in-line pressure transducer (COSMOPLUS) and stored on a computer. In contrast to the Neo-Tee manometer readings, the researcher was blinded for the COSMOPLUS recordings.

    To assess the effect of a possible offset of PIP and PEEP after switching from static pressures to PPV on the accuracy of the Neo-Tee built-in manometer, we performed an additional set of measurements in three Neo-Tees. These measurements consisted of a limited range of commonly used PIP/PEEP combinations with a fixed flow rate of 8 L/min: PEEP 5 and 6 cmH2O combined with PIPs of 15, 20, 25 cmH2O; and PEEP 8 cmH2O combined with PIPs of 20, 25, 30 cmH2O. All measurements followed the same protocol as described above, with the exception that possible PIP/PEEP offsets visible on the Neo-Tee manometer were adjusted after starting PPV (PIPadj and PEEPadj).

    Data measured by the COSMOPLUS were exported with 100 Hz as comma separated values, using the software program Analyses Plus, and post-processed in Microsoft Excel 2010. The pressure purges initiated by the COSMOPLUS were manually removed. Each set of pressures was calculated separately: during the static phase, lowest pressure (CPAP) and highest pressure (sustained inflation) were averaged over 10 s respectively; during PPV, lowest (PEEP) and highest (PIP) pressures were averaged over 120 cycles (2 min).

    Statistics

    Statistical analysis was performed using SPSS (SPSS V.22.0 and V.24.0) software. Analysis of variance for repeated measures was used for analysing pressures measured by the Neo-Tee manometer and the in-line pressure transducer. Bonferroni corrections of estimates were made to adjust for multiple comparisons. The data are presented as mean (SD). P-values of <0.05 were considered statistically significant.

    Beyond statistical significant differences between the Neo-Tee and transducer pressure recordings, clinically relevant and acceptable deviations of PIP and PEEP were defined. Variations in PEEP ±0.5 cmH2O and PIP ±1 cmH2O of the desired pressures were considered acceptable, following the study by Krabbe et al.12

    Results

    In 726 of the intended 1161 measurements, the targeted PIP and PEEP could be reached. The number 1161 is calculated as follows: nine units, three flows, seven PIPs, three PEEPs and a static and dynamic (PPV) measurement makes 1134 measurements. In addition, we performed a set of measurements with three extra Neo-Tees with measurements in a limited range of commonly used PIP/PEEP combinations with a fixed flow rate of 8 L/min: PEEP 5 and 6 cmH2O combined with PIPs of 15, 20, 25 cmH2O and PEEP 8 cmH2O combined with PIPs of 20, 25, 30 cmH2O. Adding these 27 additional measurements to the first part of the experiment results in a total of 1161 measurements. A gas flow rate of 5 L/min proved to be insufficient to reach all PEEP levels. In addition, in the majority of measurements a gas flow rate of 8 L/min was insufficient to reach a PEEP level of 8 cmH2O.

    Positive end-expiratory pressure

    As shown in table 1, the static PEEP set with the Neo-Tee manometer resulted in a lower PEEP as measured by the pressure transducer, exceeding the clinically relevant threshold of ±0.5 cmH2O.12 After starting PPV, the mean PEEP measured at the airway opening increased to values close to the target PEEP.

    View this table:
    Table 1

    Mean static PEEP and mean PEEP during PPV

    As shown in figure 1, the level of PIP influenced the measured PEEP during PPV. In general, the PEEP level and its variability increased with increasing PIPs.

    Figure 1
    Figure 1

    The effect of applied peak inspiratory pressure (PIP) on measured positive end-expiratory pressure (PEEP).

    In all measurements (n=52) allowing for a Neo-Tee manometer-based adjustment of the PEEP after PPV was started, an adjustment had to be made. Table 2 shows that compared with the PEEPppv measurements the mean PEEPadj and its variability decreased.

    View this table:
    Table 2

    Adjusted PEEP measurements in a limited range of commonly used PIP/PEEP combinations at a fixed flow rate of 8 L/min

    The impact of flow on the measured mean PEEP level and its variability was limited (data not shown).

    Peak inspiratory pressure

    Table 3 shows the relationship between target PIP and the mean measured PIPstat and PIPppv at all target PEEP levels. PIPstat and PIPppv values were almost identical and within the predefined clinically relevant range of accuracy (±1 cmH2O), except for target PIP 30 and 40 cmH2O. Variability increased with increasing PIPs.

    View this table:
    Table 3

    Mean static PIP and mean PIP during PPV

    In contrast to the impact of the PIP level on the PEEPppv measurements, the level of PEEP did not impact the measured mean PIPppv (data not shown).

    Similar to PEEP, adjustment of PIP was also necessary in all (n=52) additional measurements that allowed for this. As a result, the PIP tended to deviate more from the target PIP compared with the unadjusted PIPppv, although these differences did not reach statistical significance (table 4).

    View this table:
    Table 4

    Adjusted PIP measurements in a limited range of commonly used PIP/PEEP combinations at a fixed flow rate of 8 L/min

    Similar to PEEP, the impact of flow on the measured mean PIP level and its variability was limited (data not shown).

    Discussion

    In this study, we evaluated the accuracy of the disposable Neo-Tee infant T-piece resuscitator in a bench set-up mimicking clinical application as much as possible. For this reason, we used both static application of PIP (ie, sustained inflation) and PEEP (ie, CPAP) as well as dynamic application (ie, PPV) across a broad range of clinically relevant pressure settings applied via a face mask interface to a newborn manikin.

    Our study shows that under static conditions, setting the PEEP level with the Neo-Tee manometer results in overestimation of the true PEEP applied at the airway opening, with on average a clinically relevant difference of approximately 1.5 cmH2O. Interestingly, when switching to PPV, this difference in PEEP set and applied almost disappears. This increase in PEEP under dynamic conditions is probably caused by inadvertent PEEP during PPV at a rate of 60/min. A recent study has shown that TPRs use a screw occlusion flow resistor that imposes substantial expiratory resistance, which is system inflow dependent.16 The finding that PEEP tended to increase more at higher PIP levels during PPV seems to support this assumption. It also showed that at low PIP setting (<20 cmH2O), the delivered PEEP still deviates >0.5 cmH2O from the target PEEP.

    In contrast to PEEP, PIP levels measured at the airway opening under static conditions were almost identical to the PIP set with the Neo-Tee manometer. Starting PPV had no relevant impact on the PIP level, nor did changes in PEEP. This is probably best explained by the fact that PIP, in contrast to PEEP, is not affected by air trapping. Furthermore, there might be a difference between the accuracy of the pressure controller (PIP) and the PEEP valve.

    Very similar to clinical practice, we used the static PEEP and PIP settings when transitioning to PPV. Anticipating a possible offset in delivered pressures during PPV, we performed additional measurements allowing for adjustment of the PIP and PEEP during PPV based on the manometer reading of the Neo-Tee. In all PPV measurements PIP and PEEP needed to be adjusted in order to match the manometer pressure with the target pressure. However, this did not improve the accuracy of the targeted pressure delivery, especially for PEEP. This suggests that the accuracy of the built-in manometer of the Neo-Tee is not optimal, especially at lower (PEEP) pressures.

    We also assessed the impact of gas flow on pressure delivery. The first and most important finding was that a gas flow rate of 5 L/min was insufficient to reach commonly used PEEP levels of 5 cmH2O. This inability of providing adequate PEEP levels at lower flows is also acknowledged in the manufacturer’s product specifications.15 At higher flows, most of the prespecified PEEP and PIP levels could be reached and different flows had limited impact on the accuracy of pressure delivery. To date, only one other bench study assessed the accuracy of the Neo-Tee infant T-piece resuscitator, but there were considerable differences with the present study: (1) the accuracy of PIP and PEEP delivery was only assessed during PPV using a smaller range of PIP levels; (2) pressure delivery under static conditions (ie, CPAP or sustained inflation) was not assessed; (3) the effect of gas flow on PIP and PEEP delivery during PPV was not assessed; (4) the number of Neo-Tee resuscitators (n=3) used in the study was relatively small and (5) they used a test lung and not a manikin with a face mask interface to assess accuracy. Their findings on accuracy during PPV are consistent with our study. Furthermore, they also reported that a gas flow of 5 L/min was insufficient to deliver a PEEP of 5 cmH2O.12

    Our study has several limitations that need to be addressed. First, the results of this study are based on a set-up using a manikin. Although this set-up is often used in delivery room research and certainly approaches real-life conditions, differences, such as the lack of spontaneous breathing, remain. The results may therefore be different when resuscitating a preterm infant. Second, accuracy of pressure delivery was only tested in a manikin with relatively normal lung mechanics. Results may differ under conditions of poor lung compliance. Finally, we did not systematically assess leak around the face mask and the manikin lung during pressure delivery as this was not the focus of our study. In fact, we wanted to mimic clinical conditions as much as possible and previous studies have indicated that some leak is present in most caregivers applying mask ventilation.17 However, similar to clinical practice, we made every attempt to minimise leak as much as possible. The fact that pressure tracings during the measurements were stable indicates that leakage was not a major issue.

    The results of this study have important clinical implications. Using the Neo-Tee infant T-piece resuscitator to apply PPV, results in accurate delivery of the PIP and PEEP set under static conditions. However, when applying CPAP, the delivered pressure is approximately 1.5 cmH2O lower than the set pressure and this may have clinical consequences when supporting pulmonary transition in the delivery room or a poor compliant lung in the neonatal intensive care unit. Furthermore, a gas flow of at least 8 L/min should be used to achieve a CPAP/PEEP level of 5 cmH2O. Finally, the Neo-Tee delivers accurate pressures during a sustained inflation manoeuvre.

    Conclusion

    The Neo-Tee Infant T-piece resuscitator is accurate for delivering a sustained inflation and PPV, provided a gas flow of at least 8 L/min is used. However, when applying CPAP, the delivered pressures at the airway opening are considerably lower than the set pressure on the built-in manometer.

    References

    1. ↵
      2. Perlman JM ,
      3. Wyllie J ,
      4. Kattwinkel J , et al
      . Part 7: neonatal resuscitation: 2015 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Circulation 2015;132:S204–S241.doi:10.1161/CIR.0000000000000276
      OpenUrlFREE Full Text
    2. ↵
      Nederlandse Vereniging voor Kindergeneeskunde. Richtlijn reanimatie van het kind bij de geboorte. 2014. http://www.nvk.nl/
    3. ↵
      2. Wyllie J ,
      3. Bruinenberg J ,
      4. Roehr CC , et al
      . European resuscitation council guidelines for resuscitation 2015: section 7. Resuscitation and support of transition of babies at birth. Resuscitation 2015;95:249–63.doi:10.1016/j.resuscitation.2015.07.029
      OpenUrlCrossRefPubMed
    4. ↵
      2. Thio M ,
      3. Dawson JA ,
      4. Moss TJ , et al
      . Self-inflating bags versus T-piece resuscitator to deliver sustained inflations in a preterm lamb model. Arch Dis Child Fetal Neonatal Ed 2014;99:F274–F277.doi:10.1136/archdischild-2013-305239
      OpenUrlAbstract/FREE Full Text
    5. ↵
      2. Dawson JA ,
      3. Gerber A ,
      4. Kamlin CO , et al
      . Providing PEEP during neonatal resuscitation: which device is best? J Paediatr Child Health 2011;47:698–703.doi:10.1111/j.1440-1754.2011.02036.x
      OpenUrlCrossRefPubMed
    6. ↵
      2. Kelm M ,
      3. Proquitté H ,
      4. Schmalisch G , et al
      . Reliability of two common PEEP-generating devices used in neonatal resuscitation. Klin Padiatr 2009;221:415–8.doi:10.1055/s-0029-1233493
      OpenUrlCrossRefPubMedWeb of Science
    7. ↵
      2. Roehr CC ,
      3. Kelm M ,
      4. Fischer HS , et al
      . Manual ventilation devices in neonatal resuscitation: tidal volume and positive pressure-provision. Resuscitation 2010;81:202–5.doi:10.1016/j.resuscitation.2009.10.008
      OpenUrlCrossRefPubMed
    8. ↵
      2. Roehr CC ,
      3. Gröbe S ,
      4. Rüdiger M , et al
      . Delivery room management of very low birth weight infants in Germany, Austria and Switzerland–a comparison of protocols. Eur J Med Res 2010;15:493–503.doi:10.1186/2047-783X-15-11-493
      OpenUrlCrossRefPubMed
    9. ↵
      2. Solevåg AL ,
      3. Haemmerle E ,
      4. van Os S , et al
      . Comparison of positive pressure ventilation devices in a newborn manikin. J Matern Fetal Neonatal Med 2017;30:595–9.doi:10.1080/14767058.2016.1180360
      OpenUrl
    10. ↵
      2. Solevåg AL ,
      3. Haemmerle E ,
      4. van Os S , et al
      . A novel prototype neonatal resuscitator that controls tidal volume and ventilation rate: a comparative study of mask ventilation in a newborn manikin. Front Pediatr 2016;4:129.doi:10.3389/fped.2016.00129
      OpenUrl
    11. ↵
      2. Perez SA ,
      3. Maldonado MJ ,
      4. Gamboa O , et al
      . Comparison of the efficacy of three positive pressure ventilation devices used by medical students on a neonatal resuscitation simulators. Clin Pract 2017;14:137–44.
      OpenUrl
    12. ↵
      2. Krabbe VB ,
      3. van Vonderen JJ ,
      4. Roehr CC , et al
      . Accuracy of a disposable compared to a non-disposable infant T-piece resuscitator. Eur J Pediatr 2014;173:1005–9.doi:10.1007/s00431-014-2280-z
      OpenUrl
    13. ↵
    14. ↵
      Mercury Medical. Manufacturers product specification. http://www.mercurymed.com/product-category/neo-tee-infant-t-piece-resuscitator/ (accessed Jul 2018).
    15. ↵
      Mercury Medical. Manufacturers product specification. http://mercurymed.com/pdf/neo-tee_peep_poster.pdf (accessed Jul 2018).
    16. ↵
      2. Hinder M ,
      3. McEwan A ,
      4. Drevhammer T , et al
      . T-piece resuscitators: how do they compare? Arch Dis Child Fetal Neonatal Ed 2019;104:F122–F127.doi:10.1136/archdischild-2018-314860
      OpenUrlAbstract/FREE Full Text
    17. ↵
      2. Kaufman J ,
      3. Schmölzer GM ,
      4. Kamlin CO , et al
      . Mask ventilation of preterm infants in the delivery room. Arch Dis Child Fetal Neonatal Ed 2013;98:F405–F410.doi:10.1136/archdischild-2012-303313
      OpenUrlAbstract/FREE Full Text

    Footnotes

    • Contributors Conception and study design: APDJ, LdG, AHvK. Collection, analysis and interpretation of data: APDJ, LdG, OJN. Drafting the manuscript for important intellectual content: APDJ, LdG, AHvK.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement All data used in this study are available to LdG, APDJ and AHvK.

    • Patient consent for publication Not required.