Self-inflating bags versus T-piece resuscitator to deliver sustained inflations in a preterm lamb model

Positive pressure ventilation at birth

OBJECTIVE

To review the current state of the art of positive pressure ventilation (PPV) during resuscitation FINDINGS: The frequency of PPV during delivery room resuscitation varies across settings and gestational age subgroups. Goal targets and parameters for delivery room PPV remain undefined. The T-piece resuscitator provides the most consistent pressures during PPV and may improve clinical outcomes. The laryngeal mask may be an important alternative interface for PPV, but more data are needed to identify the optimal role of the supraglottic airway during PPV. No objective monitors of PPV have conclusively demonstrated improved outcomes to date.

CONCLUSION

More information, including real-world data from population-based studies, is needed to provide data-driven guidelines for positive pressure ventilation during neonatal transition after birth.

Ventilation, oxidative stress and risk of brain injury in preterm newborn

Preterm infants have an increased risk of cognitive and behavioral deficits and cerebral palsy compared to term born babies. Especially before 32 weeks of gestation, infants may require respiratory support, but at the same time, ventilation is known to induce oxidative stress, increasing the risk of brain injury. Ventilation may cause brain damage through two pathways: localized cerebral inflammatory response and hemodynamic instability. During ventilation, the most important causes of pro-inflammatory cytokine release are oxygen toxicity, barotrauma and volutrauma. The purpose of this review was to analyze the mechanism of ventilation-induced lung injury (VILI) and the relationship between brain injury and VILI in order to provide the safest possible respiratory support to a premature baby. As gentle ventilation from the delivery room is needed to reduce VILI, it is recommended to start ventilation with 21–30% oxygen, prefer a non-invasive respiratory approach and, if mechanical ventilation is required, prefer low Positive End-Expiratory Pressure and tidal volume.

Validation of the disposable T-piece resuscitator (Neo-Tee): a bench study

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.

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.

Sustained lung inflation at birth: what do we know, and what do we need to know?

A sustained inflation has been advocated as a potential method of augmenting lung aeration at birth. Clinical trials have suggested that a sustained inflation may lead to a reduced need for intubation and ventilation in the first few days of life, without cardiovascular compromise or increased lung injury. Despite this, a sustained inflation is not currently a standard of practice, mainly due to a lack of clarity regarding the optimal delivery method. Animal trials have sought to refine delivery techniques. This review will outline current recommendations regarding a sustained inflation, discuss potential strategies for its optimal delivery and suggest priorities for future research.

Manual Ventilation and Sustained Lung Inflation in an Experimental Model: Influence of Equipment Type and Operator's Training

Aim

To compare the influence of devices for manual ventilation and individual experience on the applied respiratory mechanics and sustained lung inflation.

Methods

A total of 114 instructors and non-instructors from the Neonatal Resuscitation Program of the Brazilian Society of Pediatrics participated in this study. Participants ventilated an intubated manikin. To evaluate respiratory mechanics and sustained lung inflation parameters, a direct comparison was made between the self-inflating bag and the T-shaped resuscitator (T-piece), followed by an analysis of the effectiveness of the equipment according to the participants’ education and training.

Results

A difference between equipment types was observed for the tidal volume, with a median (interquartile range) of 28.5 mL (12.6) for the self-inflating bag and 20.1 mL (8.4) for the T-piece in the instructor group and 31.6 mL (14) for the self-inflating bag and 22.3 mL (8.8) for the T-piece in the non-instructor group. Higher inspiratory time values were observed with the T-piece in both groups of professionals, with no significant difference between them. The operator’s ability to maintain the target pressure over the 10 seconds of sustained lung inflation was evaluated using the area under the pressure-time curve and was 1.7-fold higher with the use of the T-piece. Inspiratory pressure and mean airway pressure applied during sustained lung inflation were greater with the self-inflating bag, as evaluated between the beginning and the end of the procedure.

Conclusion

The T-piece resulted in lower tidal volume and higher inspiratory time values, irrespective of the operator’s experience, and increased the ease of performing the sustained lung inflation maneuver, as demonstrated by the maintenance of target pressure for the desired period and a higher mean airway pressure than that obtained using the self-inflating bag.

How doctors learn and perform sustained inflations with a self-inflating bag: a manikin study with a newborn lung simulator

AIM

Sustained inflations during initial resuscitation may help a depressed infant make a more efficient transition to air-filled lungs. This study examined whether doctors could perform sustained inflations with a self-inflating bag in high and low compliance settings and with an open or blocked pressure-relief valve.

METHODS

We asked 43 doctors to carry out sustained inflations for more than 5-sec in a manikin connected to a newborn lung simulator with randomised compliance settings. Tidal volume, inflation time, peak and mean inflating pressure were measured, and 34 were retested 3 months later.

RESULTS

The majority of the doctors - 72% in the initial study and 62% in the retest - managed sustained inflations within three ventilation attempts, irrespective of lung compliance setting and years of work experience. Using a blocked pressure-relief valve produced higher tidal volume (27.8 versus 22.6 mL, p < 0.001), inflation time (8.9 versus 8.1 sec, p = 0.025), peak inflating pressure (34.0 versus 28.0 cmH2O; p = 0.012) and mean inflating pressure (28.1 versus 22.8 cmH2O; p < 0.001).

CONCLUSION

The majority of doctors could deliver sustained inflation with a self-inflating bag in a newborn lung simulator for more than 5-sec. Using a blocked pressure-relief valve resulted in higher inflation time, tidal volume and inflation pressure.

Unraveling the Links Between the Initiation of Ventilation and Brain Injury in Preterm Infants

The initiation of ventilation in the delivery room is one of the most important but least controlled interventions a preterm infant will face. Tidal volumes (V T) used in the neonatal intensive care unit are carefully measured and adjusted. However, the V Ts that an infant receives during resuscitation are usually unmonitored and highly variable. Inappropriate V Ts delivered to preterm infants during respiratory support substantially increase the risk of injury and inflammation to the lungs and brain. These may cause cerebral blood flow instability and initiate a cerebral inflammatory cascade. The two pathways increase the risk of brain injury and potential life-long adverse neurodevelopmental outcomes. The employment of new technologies, including respiratory function monitors, can improve and guide the optimal delivery of V Ts and reduce confounders, such as leak. Better respiratory support in the delivery room has the potential to improve both respiratory and neurological outcomes in this vulnerable population.