Leak during manual neonatal ventilation and its effect on the delivered pressures and volumes: an in vitro study

Sustained inflation: The lung recruitment maneuvers for neonates

Establishing effective respiration is vital in the transition from fetal to neonatal life. Respiratory support mainly facilitates and creates functional residual capacity and maintains adequate gas exchange. Sustained inflation (SI) delivers prolonged inflation and rapidly creates and establishes the functional residual capacity. The use of SI in preterm infants in the delivery room is still controversial. The optimum settings of SI remain unknown. Animal studies and clinical reports have demonstrated the advantages and disadvantages of SI. In this article, the current literature was reviewed to examine the efficacy of SI in infants.

Sustained Inflation vs Standard Resuscitation for Preterm Infants: A Systematic Review and Meta-analysis

IMPORTANCE

Most preterm infants require respiratory support to establish lung aeration after birth. Intermittent positive pressure ventilation and continuous positive airway pressure are standard therapies. An initial sustained inflation (inflation time >5 seconds) is a widely practiced alternative strategy.

OBJECTIVE

To conduct a systematic review and meta-analysis of sustained inflation vs intermittent positive pressure ventilation and continuous positive airway pressure for the prevention of hospital mortality and morbidity for preterm infants.

DATA SOURCES

MEDLINE (through PubMed), Embase, the Cumulative Index of Nursing and Allied Health Literature, and the Cochrane Central Register of Controlled Trials were searched through June 24, 2019.

STUDY SELECTION

Randomized clinical trials of preterm infants born at less than 37 weeks' gestation that compared sustained inflation (inflation time >5 seconds) vs standard resuscitation with either intermittent positive pressure ventilation or continuous positive airway pressure were included. Studies including other cointerventions were excluded.

DATA EXTRACTION AND SYNTHESIS

Two reviewers assessed the risk of bias of included studies. Meta-analysis of pooled outcome data used a fixed-effects model specific to rarer events. Subgroups were based on gestational age and study design (rescue vs prophylactic sustained inflation).

MAIN OUTCOMES AND MEASURES

Death before hospital discharge.

RESULTS

Nine studies recruiting 1406 infants met inclusion criteria. Death before hospital discharge occurred in 85 of 736 infants (11.5%) treated with sustained inflation and 62 of 670 infants (9.3%) who received standard therapy for a risk difference of 3.6% (95% CI, -0.7% to 7.9%). Although analysis of the primary outcome identified important heterogeneity based on gestational age subgroups, the 95% CI for the risk difference included 0 for each individual gestational age subgroup. There was no difference in the primary outcome between subgroups based on study design. Sustained inflation was associated with increased risk of death in the first 2 days after birth (risk difference, 3.1%; 95% CI, 0.9%-5.3%). No differences in the risk of other secondary outcomes were identified. The quality-of-evidence assessment was low owing to risk of bias and imprecision.

CONCLUSIONS AND RELEVANCE

There was no difference in the risk of the primary outcome of death before hospital discharge, and there was no evidence of efficacy for sustained inflation to prevent secondary outcomes. These findings do not support the routine use of sustained inflation for preterm infants after birth.

Delivery of Positive End-Expiratory Pressure Using Self-Inflating Bags during Newborn Resuscitation Is Possible Despite Mask Leak

BACKGROUND

Ventilation is the key intervention to resuscitate non-breathing newborns. Positive end-expiratory pressure (PEEP) may facilitate lung-liquid clearance and help establish functional residual capacity.

OBJECTIVES

The aim of this study was to describe how mask leak and ventilation rates affect delivered PEEP and tidal volumes during newborn resuscitations using a self-inflating bag with an integrated PEEP valve.

METHODS

This was an observational study including near-term/term newborns who received bag-mask ventilation (BMV) with a new self-inflating bag with a novel 6 mbar PEEP valve, without external gas flow, between October 1, 2016 and June 30, 2018 in rural Tanzania. Helping Babies Breathe-trained midwives performed most of the resuscitations. Pressures and flow were continuously measured and recorded by resuscitation monitors.

RESULTS

In total, 198 newborns with a median gestation of 39 weeks (25th, 75th percentiles 37, 40) and birth weight of 3,100 g (2,580, 3,500) were included. The median delivered PEEP and expired (tidal) volume at different levels of mask leak were 6.0 mbar and 11.3 mL/kg at 0-20% mask leak, 5.5 mbar and 9.3 mL/kg at 20-40%, 5.2 mbar and 7.8 mL/kg at 40-60%, 4.6 mbar and 5.0 mL/kg at 60-80%, and 1.0 mbar and 0.6 mL/kg at 80-100% mask leak. A high ventilation rate (>60/min) nearly halved expired volumes compared to <60/min for 0-60% leak. The BMV rate had a negligible effect on peak inflation pressure (PIP) and PEEP.

CONCLUSIONS

Mask leak up to 80% did not impair the provision of recommended PEEP or tidal volumes during BMV with a self-inflating bag. High or low ventilation rates did not significantly affect PIP or PEEP. Expired volumes were reduced at ventilation rates >60/min.

Use of a Mechanical Ventilator with Respiratory Function Monitoring Provides More Consistent Ventilation during Simulated Neonatal Resuscitation

INTRODUCTION

Positive pressure ventilation (PPV) with T-Piece and self-inflating bag (SIB) during neonatal resuscitation after birth is associated with variability in ventilation. The use of a ventilator with respiratory function monitoring (RFM) for PPV, however, has not been evaluated.

OBJECTIVE

To determine if ventilator + RFM can reduce ventilation variability compared to T-Piece and SIB in a preterm manikin at different combinations of target tidal volume (VT) and lung compliance (CL).

METHODS

Twenty clinicians provided PPV via mask and endotracheal tube (ETT) using SIB, T-Piece, T-Piece + RFM and Ventilator + RFM to a manikin with adjustable lung CL. Three combinations of CL and target VT: Low CL-Low VT, Low CL-High VT and High CL-Low VT were used in a random order.

RESULTS

The use of ventilator + RFM for PPV via ETT during High CL-Low VT period reduced the proportion of breaths with expiratory VT above target when compared to the other 3 devices (56 ± 35%, 85 ± 20%, 90 ± 25%, 92 ± 12% for ventilator + RFM, T-Piece + RFM, T-Piece, SIB, respectively; p < 0.05). During PPV via both mask and ETT, ventilator + RFM maintained the set Ti and rate, whereas SIB and T-Piece use resulted in higher rates, and T-Piece in higher proportion of breaths with prolonged Ti. During PPV via mask, ventilator + RFM reduced gas leakage compared to other devices.

CONCLUSION

In this simulation study, use of a mechanical ventilator with RFM led to an overall improvement in volume targeting at different settings of CL and reduced the gas leak during mask ventilation. The efficacy and safety of using this strategy to neonatal resuscitation in the delivery room needs to be evaluated.

Paramedics' Newborn Life Support Knowledge and Skills Before and After a Targeted Simulation-Based Educational Intervention

Objective: Resuscitation of neonates after birth in the out-of-hospital setting is challenging. Thus, we aimed to assess paramedics' newborn life support knowledge and skills before and after targeted simulation-based training. Methods: Voluntary paramedics were recruited from a single Red Cross division. During a 1-day simulation-based educational intervention, essential aspects of neonatal resuscitation were taught and practiced. Before and after simulation-based training, we assessed (1) knowledge of current European Resuscitation Council (ERC) guidelines using a 20-item-questionnaire and (2) the quality of simulated bag-valve-mask ventilation by measuring face mask leakage, using a respiratory function monitor (Standardized Measurement of Airway Resuscitation Training [SMART], GM Instruments Ltd., United Kingdom). Results: Forty-one paramedics participated in the initial survey and 12 took part in the simulation-based educational intervention. There was a significant increase in the number of correctly answered questions: median 62.1% (IQR 37.5-77.4%) vs. 91.7% (IQR 83.3-100%; p = 0.001). A total of 1,332 inflations were analyzed. The incidence of substantial mask leakage >75% decreased significantly after training (15.8 vs. 6.1%; p < 0.001), while median mask leakage was similar (17.0% [IQR 0.0-55.0%] vs. 18.0% [IQR 6.0-34.0%]; p = 0.414). Conclusions: Among paramedics, theoretical knowledge of current ERC guidelines was moderate in this study. Participation in a targeted simulation-based educational intervention was associated with a significant increase in theoretical knowledge. The initially high incidence of substantial mask leakage >75% was decreased after simulation-based training using respiratory function monitoring.

Delivery of positive end-expiratory pressure to preterm lambs using common resuscitation devices

BACKGROUND

In neonatal resuscitation, a ventilation device providing positive end-expiratory pressure (PEEP) is recommended. There is limited information about PEEP delivery in vivo, using different models of self-inflating bag (SIB) at different inflation rates and PEEP settings.

METHODS

We compared PEEP delivery to intubated preterm lambs using four commonly available models of paired SIBs and PEEP valves, with a T-piece, with gas flow of 8 L/min. Peak inspiratory pressure inflations of 30 cmH₂O, combined with set PEEP of 5, 7 and 10 cmH₂O, were delivered at rates of 20, 40 and 60/min. These combinations were repeated without gas flow. We measured mean PEEP, maximum and minimum PEEP, and its difference (PEEP reduction).

RESULTS

A total of 3288 inflations were analysed. The mean PEEP delivered by all SIBs was lower than set PEEP (P<0.001), although some differences were <0.5 cmH₂O. In 55% of combinations, the presence of gas flow resulted in increased PEEP delivery (range difference 0.3-2 cmH₂O). The mean PEEP was closer to set PEEP with faster inflation rates and higher set PEEPs. The mean (SD) PEEP reduction was 3.9 (1.6), 8.2 (1.8), 2 (0.6) and 1.1 (0.6) cmH₂O with the four SIBs, whereas it was 0.5 (0.2) cmH₂O with the T-piece.

CONCLUSIONS

PEEP delivery with SIBs depends on the set PEEP, inflation rate, device model and gas flow. At recommended inflation rates of 60/min, some devices can deliver PEEP close to the set level, although the reduction in PEEP makes some SIBs potentially less effective for lung recruitment than a T-piece.

Neopuff T-piece resuscitator: does device design affect delivered ventilation?

BACKGROUND

The T-piece resuscitator (TPR) is in common use worldwide to deliver positive pressure ventilation during resuscitation of infants <10 kg. Ease of use, ability to provide positive end-expiratory pressure (PEEP), availability of devices inbuilt into resuscitaires and cheaper disposable options have increased its popularity as a first-line device for term infant resuscitation. Research into its ventilation performance is limited to preterm infant and animal studies. Efficacy of providing PEEP and the use of TPR during term infant resuscitation are not established.

AIM

The aim of this study is to determine if delivered ventilation with the Neopuff brand TPR varied with differing (preterm to term) test lung compliances (Crs) and set peak inspiratory pressures (PIP).

DESIGN

A single operator experienced in newborn resuscitation provided positive pressure ventilation in a randomised sequence to three different Crs models (0.5, 1 and 3 mL/cmH₂O) at three different set PIP (20, 30 and 40 cmH₂O). Set PEEP (5 cmH₂O), gas flow rate and inflation rate were the same for each sequence.

RESULTS

A total of 1087 inflations were analysed. The delivered mean PEEP was Crs dependent across set PIP range, rising from 4.9 to 8.2 cmH₂O. At set PIP 40 cmH₂O and Crs 3 mL/cmH₂O, the delivered mean PIP was significantly lower at 35.3 cmH₂O.

CONCLUSIONS

As Crs increases, the Neopuff TPR can produce clinically significant levels of auto-PEEP and thus may not be optimal for the resuscitation of term infants with healthy lungs.

Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates--An In Vitro Study

Introduction

International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP.

Methods

Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH₂O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH₂O were studied. A second test was conducted with settings of PIP 40cmH₂O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO₂SMO⁺).

Results

Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25^th and 75^th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH₂O when set to 5cmH₂O and 6.1(4.9–7.1)cmH₂O when set to 10cmH₂O. Increasing the PIP from 20 to 40 cmH₂O led to a median (25^th and 75^th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH₂O and 4.3(3.2–4.8)cmH₂O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH₂O and 5.0(3.5–6.2)cmH₂O for both PEEP settings.

Conclusion

Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates.

Compression force on the upper jaw during neonatal intubation: mannequin study

AIM

Neonatal intubation is a technically challenging procedure, and pressure-related injuries to surrounding structures have been reported. The primary objective of this study was to determine the pressure exerted on the upper jaw during tracheal intubation using a neonatal mannequin.

METHOD

Multidisciplinary care providers working at a neonatal intensive care unit were requested to intubate a neonatal mannequin using the standard laryngoscope and 3.0-mm (internal diameter) endotracheal tube. Compression force exerted was measured by using pressure-sensitive film taped on the upper jaw before every intubation attempt. Pressure, area under pressure and time taken to intubate were compared between the different types of health-care professionals.

RESULTS

Thirty care providers intubated the mannequin three times each. Pressure impressions were observed on the developer film after every intubation attempt (n = 90). The mean pressure exerted during intubation across all health-care providers was 568 kPa (SD 78). The mean area placed under pressure was 142 mm(2) (SD 45), and the mean time taken for intubation was 14.7 s (SD 4.3). There was no difference in pressure exerted on the upper jaw between frequent and less frequent intubators. It was found that pressure greater than 400 kPa was inadvertently applied on the upper jaw during neonatal intubation, far exceeding the 250 kPa shown to cause tissue injury in animal models.

CONCLUSION

The upper jaw is exposed to a significant compression force during intubation. Although such exposure is brief, it has the potential to cause tissue injury. Contact of the laryngoscope blade with the upper jaw occurred in all intubation attempts with the currently used design of laryngoscope.

Accuracy of a disposable compared to a non-disposable infant T-piece resuscitator

Both disposable and non-disposable T-piece resuscitator (TPR) devices are used. Accuracy of the disposable and non-disposable infant TPR was compared. Peak inspiratory pressures (PIP) and positive end-expiratory pressures (PEEP) were measured during ventilation of a test lung. Measured PIP ±1 cmH2O and PEEP ±0.5 cmH2O of the desired pressures were considered acceptable. We tested the following: (A) Accuracy of setting pressures using built-in manometers of three disposable TPRs, (B) Minimal and maximal PIP and PEEP levels for the non-disposable and disposable TPR were measured using different gas flow rates, and (C) Accuracy of 25 caregivers setting pressures (PIP 25 cmH2O and PEEP 5 cmH2O). The results of the tests performed were as follows: (A) With pressures set: PIP 20, 25, 30, and 40 cmH2O and PEEP 5-8 cmH2O with 1 cmH2O stepwise increment, measured PIPs and PEEPs were in acceptable range. (B) At gas flow rates 5, 8, 10, and 15 L/min (disposable vs. non-disposable), min-max PIP were 4.0-43.2 vs. 2.9-77.1 cmH2O and min-max PEEP were 0.3-22.3 and 0.6-59.7 cmH2O. (C) Set PIP (cmH2O) by participants using disposable vs. non-disposable TPR was 25.8 (0.8) vs. 25.9 (1.3) (ns). PEEP was 5.4(0.5) vs. 4.7(0.5); p < 0.001.

CONCLUSION

The accuracy of the disposable TPR is comparable to that of the non-disposable TPR.