Ventilator-delivered mask ventilation compared with three standard methods of mask ventilation in a manikin model

Positive Pressure Ventilation in Preterm Infants in the Delivery Room: A Review of Current Practices, Challenges, and Emerging Technologies

BACKGROUND

A major proportion of preterm neonates require positive pressure ventilation (PPV) immediately after delivery. PPV may be administered through a face mask (FM) or nasal prongs. Current literature indicates that either of these are associated with similar outcomes.

SUMMARY

Nonetheless, FM remains the most utilized and the best choice. However, most available FM sizes are too large for extremely preterm infants, which leads to mask leak and ineffective PPV. Challenges to providing effective PPV include poor respiratory drive, complaint chest wall, weak thoracic muscle, delayed liquid clearance, and surfactant deficiency in preterm infants. Mask leak, airway obstruction, poor technique, and inappropriate size are correctable causes of ineffective PPV. Visual assessment of chest rise is often used to assess the efficacy of PPV. However, its accuracy is debatable. Though end tidal CO2 may adjudge the effectiveness of PPV, clinical studies are limited. The compliance of a preterm lung is highly dynamic. The inflating pressure set on T-piece is constant throughout the resuscitation, but the lung volume and dynamics changes with every breath. This leads to huge fluctuations of tidal volume delivery and can trigger inflammatory cascade in preterm infants leading to brain and lung injury. Respiratory function monitoring in the delivery room has potential for guiding and optimizing delivery room resuscitation. This is, however, limited by high costs, complex information that is difficult to interpret during resuscitation, and absence of clinical trials.

KEY MESSAGES

This review summarizes the existing literature on PPV in preterm infants, the various aspects related to it such as the pathophysiology, interfaces, devices utilized to deliver it, appropriate technique, emerging technologies, and future directions.

Newborn resuscitation devices: The known unknowns and the unknown unknowns

Infant resuscitation devices used at birth must be capable of delivering adequate and consistent ventilation in a controlled and predictable manner to a wide patient weight range, and combinations of transitional lung states. Manual inflation resuscitation devices delivering positive pressure lung inflation at birth can be classified broadly into two types: 1) flow generating, ie silicone self-inflating bags (SIB) also known as bag valve mask (BVM) and 2) flow dependent, ie anaesthetic flow inflating bag (FIB) and t-piece resuscitator (TPR) systems (eg: Neopuff, GE Panda and Draeger Resuscitaires). Globalization, lower production costs, and an expanding market need for devices, has led to a proliferation of brands (both reusable and single use) within a class type. T-piece resuscitators have become the dominant device particularly in high income countries. There remains a paucity of information on the performance characteristics of these devices and their ability to provide the required respiratory parameters for effective and safe ventilation across the full-expected weight range and lung states to which they will be applied. This review aims to inform current clinical practise on the biomechanical efficiency, reliability and efficacy of the most common devices used to apply PPV to newborns and infants ≤10 kgs.

European Resuscitation Council Guidelines 2021: Newborn resuscitation and support of transition of infants at birth

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

[Newborn resuscitation and support of transition of infants at birth]

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

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.

Delivery room emergencies: Respiratory emergencies in the DR

The majority of newborns transition to extra uterine life without support. However, respiratory emergencies in the delivery room are a common occurrence. Whilst some situations are predictable e.g. the anticipated birth of an extremely preterm infant, others are less so. In this chapter we address the most frequent scenarios that result in delivery room respiratory emergencies and discuss the latest recommendations for their management. We outline the need for a trained resuscitation team and appropriate equipment to provide respiratory support at every birth. We address the basic care that all infants should receive, the detailed application of non-invasive ventilation and the use of advanced airway techniques. We discuss the unique challenges presented by extreme prematurity including umbilical cord management, use of supplemental oxygen, initial modes of respiratory support and surfactant delivery. We will explore optimal techniques in the management of infants with lung hypoplasia, pneumothorax and meconium aspiration.

Neopuff T-piece resuscitator mask ventilation: Does mask leak vary with different peak inspiratory pressures in a manikin model?

AIM

The aim of this study was to compare mask leak with three different peak inspiratory pressure (PIP) settings during T-piece resuscitator (TPR; Neopuff) mask ventilation on a neonatal manikin model.

METHODS

Participants were neonatal unit staff members. They were instructed to provide mask ventilation with a TPR with three PIP settings (20, 30, 40 cm H₂ O) chosen in a random order. Each episode was for 2 min with 2-min rest period. Flow rate and positive end-expiratory pressure (PEEP) were kept constant. Airway pressure, inspiratory and expiratory tidal volumes, mask leak, respiratory rate and inspiratory time were recorded. Repeated measures analysis of variance was used for statistical analysis.

RESULTS

A total of 12 749 inflations delivered by 40 participants were analysed. There were no statistically significant differences (P > 0.05) in the mask leak with the three PIP settings. No statistically significant differences were seen in respiratory rate and inspiratory time with the three PIP settings. There was a significant rise in PEEP as the PIP increased. Failure to achieve the desired PIP was observed especially at the higher settings.

CONCLUSIONS

In a neonatal manikin model, the mask leak does not vary as a function of the PIP when the flow rate is constant. With a fixed rate and inspiratory time, there seems to be a rise in PEEP with increasing PIP.

Tidal Volume Delivery and Endotracheal Tube Leak during Cardiopulmonary Resuscitation in Intubated Newborn Piglets with Hypoxic Cardiac Arrest Exposed to Different Modes of Ventilatory Support

BACKGROUND

There are few data available on the interaction of inflations, chest compressions (CC), and delivery of tidal volumes in newborn infants undergoing resuscitation in the presence of endotracheal tube (ET) leaks.

OBJECTIVES

To determine the effects of different respiratory support strategies along with CC on changes in tidal volume and ET leaks in hypoxic newborn piglets with cardiac arrest.

METHODS

Asphyxiated newborn piglets, intubated with weight-adapted uncuffed ET, were randomized into three groups and resuscitated according to ILCOR 2010 guidelines: (1) T-piece resuscitator (TPR) group = peak inspiratory pressure (PIP)/positive end-expiratory pressure (PEEP) 25/5 cm H2O, rate 30/min, inflations interposed between CC (3:1 ratio); (2) self- inflating bag (SIB) group = PIP 25 cm H2O without PEEP, rate 30/min, inflations interposed between CC (3:1 ratio), and (3) ventilator group = PIP/PEEP of 25/5 cm H2O, rate 30/min. CC were applied with a rate of 120/min without synchrony to inflations.

RESULTS

We observed a significant increase of leak (average increase 11.4%) when CC was added to respiratory support (p = 0.0001). Expired tidal volume was larger in the SIB group than in the two other modes which both applied PEEP. However, tidal volumes caused by CC only were larger in the two groups with PEEP than in the SIB group (without PEEP).

CONCLUSIONS

There is interaction between lung inflations and CC affecting leak and delivery of tidal volume, which may be influenced by the mode/device used for respiratory support. Leak is larger in the presence of PEEP. However, CC cause additional tidal volume which is larger in the presence of PEEP.

The effectiveness of Ambu neonatal self-inflating bag to provide consistent positive end-expiratory pressure

BACKGROUND

The self-inflating bag (SIB) is the most common device used to resuscitate newborn infants worldwide. Delivering positive end-expiratory pressure (PEEP) may be important in infant resuscitation and limited research using one brand (Laerdal) SIB has led to international guidelines stating SIBs 'often deliver inconsistent positive end-expiratory pressure'.

AIM

To measure delivered PEEP using disposable and reusable Ambu SIBs fitted with Ambu PEEP valve and manometer comparing different rates of 20, 40 and 60 inflations per minute (IPM) and test lung compliance.

DESIGN

Three experienced neonatal medical staff provided positive pressure ventilation each using different disposable and reusable Ambu SIBs, targeting peak inflation pressure of 30-35 cm H2O at three different set PEEP levels of 5, 7.5 and 10 cm H2O on test lungs of compliance of 0.5 and 3.0 mL/cm H2O. Inflation data were captured with Florian Monitor and analysed by analysis of variance for repeated measures.

RESULTS

A total of 3265 inflations were analysed. The delivered PEEP was rate and lung compliance dependent. At set PEEP of 5 cm H2O, the adjusted measured PEEP was 3.6, 4.4 and 4.8 cm H2O at rates 20, 40 and 60 IPM, respectively, while at set PEEP of 10 cm H2O, the adjusted measured PEEP was 7.0, 8.8 and 9.8 cm H2O. The delivered PEEP was statistically higher with more compliant test lungs.

CONCLUSIONS

The Ambu SIB with Ambu PEEP valve can deliver consistent mean levels of PEEP close to the operator set PEEP. The performance of SIB with PEEP valves is likely brand specific and requires further evaluation.

Randomised comparison of two neonatal resuscitation bags in manikin ventilation

OBJECTIVE

To compare ventilation properties and user preference of a new upright neonatal resuscitator developed for easier cleaning, reduced complexity, and possibly improved ventilation properties, with the standard Laerdal neonatal resuscitator.

DESIGN

Eighty-seven Tanzanian and Norwegian nursing and medical students without prior knowledge of newborn resuscitation were briefly trained in bag-mask ventilation. The two resuscitators were used in random order on a manikin connected to a test lung with normal or low lung compliance. Data were collected with the Laerdal Newborn Resuscitation Monitor. The students graded mask seal and ease of air entry on a four-point scale ranging from 1 ('difficult') to 4 ('easy') and stated which device they preferred. (Equipment from Laerdal Global Health and Laerdal Medical).

RESULTS

For upright versus standard resuscitator and normal lung compliance, mean expiratory lung volume was 15.5 mL vs 13.9 mL (p=0.001), mean mask leakage 48% vs 58% (p<0.001), and mean airway pressure 20 cm H2O vs 19 cm H2O (p=0.003), respectively. For low lung compliance, mean expiratory lung volume was 8.6 mL vs 8.1 mL (p=0.045), mean mask leakage 53% vs 62% (p<0.001), and mean airway pressure 21 cm H2O vs 20 cm H2O (p=0.004) for upright versus standard. The upright resuscitator was preferred by 82% and 68% of students during ventilation with normal and low lung compliance, respectively (p=0.001).

CONCLUSIONS

Expiratory volumes were higher, mask leakage lower, and mean airway pressure slightly higher with upright versus standard resuscitator when ventilating a manikin. The majority of students preferred the upright resuscitator.

A metronome for pacing manual ventilation in a neonatal resuscitation simulation

AIM

During manual positive pressure ventilation (PPV), delivering a recommended respiratory rate (RR) is operator dependent. We tested the efficacy of a metronome as a standardised method to improve the accuracy of delivered RR during manual PPV in a neonatal resuscitation simulation.

METHODS

We conducted a blinded simulation in two consecutive stages. Using a self-inflating bag, 36 CPR trained operators provided PPV to a modified neonatal manikin via an endotracheal tube. Pressure and flow signals were captured by a respiratory function monitor. In the first standard stage, participants delivered RR as they would in delivery room. Prior to the second stage, they were asked about what their target RR had been and a metronome was set to that target. Subsequently, operators repeated PPV attempting to coordinate their delivered RR with the metronome. To evaluate accuracy we generated the variable RR Gap as the absolute difference between delivered and target RR. The primary outcome was the difference in RR Gap between stages.

RESULTS

Mean (SD) target RR was 50 (8.7) inflations/min. During the initial stage, median (IQR) RR Gap was 11.6 (4.7-18.3) inflations/min and 20/36 participants (55.5%) had a mean delivered RR beyond the recommended range. When paced by the metronome, RR Gap was reduced to 0.2 (0.1-0.4) inflations/min and 32/36 participants (89%) fell within the recommended range.

CONCLUSIONS

The use of a metronome improved the accuracy of delivered RR during manual PPV. Novel approaches to deliver an accurate RR during manual PPV need to be tested in more realistic scenarios.

Mask leak increases and minute ventilation decreases when chest compressions are added to bag ventilation in a neonatal manikin model

AIM

To determine changes in respiratory mechanics when chest compressions are added to mask ventilation, as recommended by the International Liaison Committee on Resuscitation (ILCOR) guidelines for newborn infants.

METHODS

Using a Laerdal Advanced Life Support leak-free baby manikin and a 240-mL self-inflating bag, 58 neonatal staff members were randomly paired to provide mask ventilation, followed by mask ventilation with chest compressions with a 1:3 ratio, for two minutes each. A Florian respiratory function monitor was used to measure respiratory mechanics, including mask leak.

RESULTS

The addition of chest compressions to mask ventilation led to a significant reduction in inflation rate, from 63.9 to 32.9 breaths per minute (p < 0.0001), mean airway pressure reduced from 7.6 to 4.9 cm H2 O (p < 0.001), minute ventilation reduced from 770 to 451 mL/kg/min (p < 0.0001), and there was a significant increase in paired mask leak of 6.8% (p < 0.0001).

CONCLUSION

Adding chest compressions to mask ventilation, in accordance with the ILCOR guidelines, in a manikin model is associated with a significant reduction in delivered ventilation and increase in mask leak. If similar findings occur in human infants needing an escalation in resuscitation, there is a potential risk of either delay in recovery or inadequate response to resuscitation.

Face mask ventilation--the dos and don'ts

Face mask ventilation provides respiratory support to newly born or sick infants. It is a challenging technique and difficult to ensure that an appropriate tidal volume is delivered because large and variable leaks occur between the mask and face; airway obstruction may also occur. Technique is more important than the mask shape although the size must appropriately fit the face. The essence of the technique is to roll the mask on to the face from the chin while avoiding the eyes, with a finger and thumb apply a strong even downward pressure to the top of the mask, away from the stem and sloped sides or skirt of the mask, place the other fingers under the jaw and apply a similar upward pressure. Preterm infants require continuous end-expiratory pressure to facilitate lung aeration and maintain lung volume. This is best done with a T-piece device, not a self-inflating or flow-inflating bag.

Testing of midwife neonatal resuscitation skills with a simulator manikin in a low-risk delivery unit

BACKGROUND

Expertise in neonatal resuscitation is essential for personnel involved in the care of newborns. In this observational cohort study the skills of 52 midwives in a simulated scenario were assessed.

METHODS

A total of 52 midwives in a low-risk unit and five specialist nurses in a high-risk unit were tested to establish their competence in newborn resuscitation. The 52 midwives were divided into groups 1 (n = 39; no pretest training) and 2 (n = 13; 1 day training prior to study). The video-recorded test scenario was a newborn with asphyxia. Thirty items were graded by a neonatologist and nursing team in real time. Using the Angoff method, a pass score was 18.71 for skills that were graded 0 or 1.

RESULTS

The average score of specialist nurses was 26 (range, 23-29). A total of 49% of midwives in group 1 and 92% in group 2 passed the test. The average score was 17.7 (range, 9-25) in group 1 and 21.9 (range, 17-27) in group 2. A total of 27% and 77% of midwives in groups 1 and 2, respectively, carried out ventilation at a frequency as per the algorithm. Mask leakage was higher in group 1 (44%) versus group 2 (23%). Five and three midwives in groups 1 and 2, respectively, overexpanded the lungs.

CONCLUSION

Many midwives had imperfect resuscitation skills. A 1 day course improved such skills. The standard scenario is an objective and useful performance marker in assessing and documenting improvements in competence in delivery room resuscitation.

A multi-parameter system for use in neonatal resuscitation research and training

Training staff in the resuscitation of neonates is an essential skill; resuscitation efficacy is difficult to quantify but critical to infant survival. Objective assessments of the efficacy of training methods, resuscitation techniques and devices have used concurrent measurements of air flow and air pressure in commercially available manikins. This system also simultaneously measures the force transmitted through the manikin head during simulated resuscitation, as applying excessive force may be deleterious to newborn infants. The overall accuracy of the force plate over the range 0-5 kg was 0.5%; the output was linear; the frequency response sufficiently high and there was no evidence of hysteresis. This system enables comparison of staff groups, resuscitation techniques and devices in an accurate and reproducible manner. Its use could improve training by offering a means of objective performance feedback through a range of parameters. Evaluation of clinical practice may also result in direct patient benefit.