Changing gas flow during neonatal resuscitation: A manikin study

Novel Neonatal Simulator Provides High-Fidelity Ventilation Training Comparable to Real-Life Newborn Ventilation

Face mask ventilation of apnoeic neonates is an essential skill. However, many non-paediatric healthcare personnel (HCP) in high-resource childbirth facilities receive little hands-on real-life practice. Simulation training aims to bridge this gap by enabling skill acquisition and maintenance. Success may rely on how closely a simulator mimics the clinical conditions faced by HCPs during neonatal resuscitation. Using a novel, low-cost, high-fidelity simulator designed to train newborn ventilation skills, we compared objective measures of ventilation derived from the new manikin and from real newborns, both ventilated by the same group of experienced paediatricians. Simulated and clinical ventilation sequences were paired according to similar duration of ventilation required to achieve success. We found consistencies between manikin and neonatal positive pressure ventilation (PPV) in generated peak inflating pressure (PIP), mask leak and comparable expired tidal volume (eV_T), but positive end-expiratory pressure (PEEP) was lower in manikin ventilation. Correlations between PIP, eV_T and leak followed a consistent pattern for manikin and neonatal PPV, with a negative relationship between eV_T and leak being the only significant correlation. Airway obstruction occurred with the same frequency in the manikin and newborns. These findings support the fidelity of the manikin in simulating clinical conditions encountered during real newborn ventilation. Two limitations of the simulator provide focus for further improvements.

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.

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.

An instructional video enhanced bag-mask ventilation quality during simulated newborn resuscitation

AIM

Approximately 20% of newborns infants need respiratory support at birth. This study evaluated whether video-based education could improve quality of positive pressure ventilation (PPV) performed by inexperienced staff during neonatal resuscitation.

METHODS

Fourth-year medical students were randomly paired and instructed to give PPV to a modified manikin as single-person resuscitators and as two-person-paired resuscitators using either an air cushion rim mask or a round mask before and after watching a self-instructional video. Airway pressure, gas flow, tidal volume and mask leak were recorded. PPV performance quality was analysed using video recording.

RESULTS

Mask leak was lower during one-person ventilation when using the air cushion rim mask (56 ± 16%) compared to the round mask (71 ± 19%). Round mask leak during one-person ventilation was significantly lower when using the two point top hold in contrast to the 'o.k.' rim hold (before training: 63 ± 22% vs. 72 ± 18%, after training: 57 ± 17% vs. 77 ± 12%). Watching a self-instructional video improved performance quality scores of both correct head positioning, and the quality of airway manoeuvres compared to baseline, however mask leak was not significantly reduced.

CONCLUSION

A self-instructional video significantly improved bag mask PPV performance in inexperienced providers but did not improve mask leak in a model of neonatal resuscitation.

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.

A review of carbon dioxide monitoring in preterm newborns in the delivery room

INTRODUCTION

The physiologic adaptation to extra uterine life during the immediate neonatal period is unique. Many newborns require assistance in this adaptive process. Recent evidence now supports titrating oxygen to guide resuscitation but no guidance is provided on utilizing exhaled CO2 measurements.

AIM

To review the current evidence relating to the use of CO2 monitoring in preterm newborns in the delivery room.

METHODS

Search was performed using the Cochrane Central Register of Controlled Trials, MEDLINE (1966-2014) and PREMEDLINE, EMBASE (1980-2014), CINAHL (1982-2014), Web of Science (1975-2014) and the Oxford Database of Perinatal Trials.

RESULTS

The search revealed 21 articles relating to CO2 detection, either quantitative or qualitative, in the newborn infant. The majority of these were observational studies, eight relating to CO2 detection as a means of confirming correct endotracheal tube placement in the newborn infant. The other indication is for mask ventilation, and there is one randomized control trial and four observational studies of CO2 detection during mask ventilation. The overall recommendation for CO2 detection for both clinical uses in the delivery suite is level B.

DISCUSSION

CO2 detection may be of particular benefit for preterm infants in the delivery suite. However there is a need for further research into CO2 detection, in particular capnography, as a means of confirming effective PPV in neonatal resuscitation.

Changes in positive end-expiratory pressure alter the distribution of ventilation within the lung immediately after birth in newborn rabbits

Current recommendations suggest the use of positive end-expiratory pressures (PEEP) to assist very preterm infants to develop a functional residual capacity (FRC) and establish gas exchange at birth. However, maintaining a consistent PEEP is difficult and so the lungs are exposed to changing distending pressures after birth, which can affect respiratory function. Our aim was to determine how changing PEEP levels alters the distribution of ventilation within the lung. Preterm rabbit pups (28 days gestation) were delivered and mechanically ventilated with one of three strategies, whereby PEEP was changed in sequence; 0-5-10-5-0 cmH₂O, 5-10-0-5-0 cmH₂O or 10-5-0-10-0 cmH₂O. Phase contrast X-ray imaging was used to analyse the distribution of ventilation in the upper left (UL), upper right (UR), lower left (LL) and lower right (LR) quadrants of the lung. Initiating ventilation with 10PEEP resulted in a uniform increase in FRC throughout the lung whereas initiating ventilation with 5PEEP or 0PEEP preferentially aerated the UR than both lower quadrants (p<0.05). Consequently, the relative distribution of incoming V_T was preferentially directed into the lower lobes at low PEEP, primarily due to the loss of FRC in those lobes. Following ventilation at 10PEEP, the distribution of air at end-inflation was uniform across all quadrants and remained so regardless of the PEEP level. Uniform distribution of ventilation can be achieved by initiating ventilation with a high PEEP. After the lungs have aerated, small and stepped reductions in PEEP result in more uniform changes in ventilation.

Human or monitor feedback to improve mask ventilation during simulated neonatal cardiopulmonary resuscitation

OBJECTIVE

To investigate if external chest compressions (ECC) increase mask leak, and if human or technical feedback improves mask ventilation during simulated neonatal cardiopulmonary resuscitation (CPR).

STUDY DESIGN

In this observational study, 32 participants delivered positive pressure ventilation (PPV) to a modified, leak-free manikin via facemask. Mask leak, tidal volume (VT), positive end expiratory pressure (PEEP) and respiratory rate (RR) were measured with a respiratory function monitor (RFM). Participants had to perform four studies. In the first study, participants performed PPV alone as baseline. Thereafter, three studies were performed in random order. In the PPV+ECC+manometer group, participants had to observe the manometer while the RFM was covered; in the PPV+ECC+RFM group, the RFM was used while the manometer was covered; and in the PPV+ECC+verbal feedback group, the RFM and manometer were covered while a team leader viewed the RFM and provided verbal feedback to the participants.

RESULTS

Median (IQR) mask leak of all studies was 15% (5-47%). Comparing the studies, PPV+ECC+RFM and PPV+ECC+verbal feedback had significantly less mask leak than PPV+ECC+manometer. Mean (SD) VT of all studies was 9.5±3.5 mL. Comparing all studies, PPV+ECC+RFM had a significantly higher VT than PPV and PPV+ECC+manometer. As well, PPV+ECC+verbal feedback had a significantly higher VT than PPV. PEEP and RR were within our target, mean (SD) PEEP was 6±2 cmH2O and RR was 36±13/min.

CONCLUSIONS

During simulated neonatal CPR, ECCs did not influence mask leak, and a RFM and verbal feedback were helpful methods to reduce mask leak and increase VT significantly.

Influence of the hand squeeze and mask distensibility on tidal volume measurements during neonatal mask ventilation

BACKGROUND

During mask ventilation, the mask volume can vary as it is pressurized or when it is squeezed. The change in volume of the mask may affect tidal volumes delivered and difference in inspired (Vti) and expired tidal volumes (Vte).

OBJECTIVES

To investigate whether hand squeeze and distensibility of the mask during ventilation influences tidal volume measurements.

METHODS

For both experiments, we ventilated a leak-free mask ventilation model using pressures of 25/5 cm H2O through a t-piece. Vti and Vte were measured. (A) Two consultants performed mask ventilation with (1) consistent hand squeeze, (2) release during inflation and squeeze during expiration, (3) squeeze during inflation, release during expiration, and (4) gentle squeeze.

RESULTS

(B) Thirty caregivers performed mask ventilation. Experiment A: Vti was different during consistent hold (1) 8.1 ml (0.4) and loose grip (4) 8.2 ml (0.3), compared to squeezing during inflation (2) 18.9 ml (1.9), or expiration (3) 6.4 ml (3.5). Variance in difference between Vti and Vte occurred only when the mask was squeezed during inflation (-47.4% (101.5)). Experiment B: volumes measured were consistent (intraindividual CV 3-5%, interindividual CV 9-10%). When comparing gas flow rate of 6-10 l/min, volumes increased by approximately 8%, differences in Vti and Vte were small with both flow settings (-0.9% (-3.9-1.4) and -0.6% (-3.3-1.8); n.s.).

CONCLUSION

Variation in mask hold during mask ventilation can influence volume measurement, but this hardly occurs when testing caregivers.