In the UK, midwives working both in the community and the hospitals are taught a standardised approach to newborn resuscitation on the Newborn Life Support (NLS) Course (Richmond, 2011). Unfortunately, the techniques and recommended equipment for newborn resuscitation are neither always available nor practicable in the community.
Although midwives generally attend home deliveries in pairs, occasionally they are alone and two person techniques of resuscitation are not possible unless a member of the family is willing and able to help (Chua et al, 2012). A neighbouring Trust provides their community midwives with an i-gel® (Intersurgical UK), for this eventuality. As a consequence, the question was raised why this piece of equipment was not available for our own staff.
Although there has been no study supporting the use of either a Guedel oropharyngeal airway or an i-gel® in neonatal resuscitation, Guedel airways are used for airway management in newborn resuscitation and successful resuscitation of newborns has been reported using the Laryngeal Mask Airway (Schmölzer et al, 2013).
The i-gel® may be more suitable for single handed practitioners who undertake resuscitation infrequently. It is difficult to perform a single handed jaw thrust and impossible to perform a two handed jaw thrust and ventilate the lungs if attending a home birth as a lone midwife. We therefore chose to compare the use of these airway devices in an infant manikin.
Method
After obtaining approval from the Research and Development Committee, we invited 55 community midwives employed by Hull and East Yorkshire Hospitals NHS Trust to participate in this study during their continuing professional development (CPD) training time over a 4 month period. Twenty were able to participate.
All participants used the same equipment; Marshall Visionary Child Manual Resuscitator® 550ml bag, valve, mask, (Bag valve mask) with 40±5cm H2O pressure relief valve, an i-gel® (Intersurgical UK) and Guedel airways (Intersurgical UK). All of the equipment was supplied by the resuscitation department for the paediatric resuscitation trollies at Hull and East Yorkshire Hospitals NHS Trust and remained the same for each participant.
We decided that the time to first inflation breath was the most important clinical variable. This variable was chosen because aeration of the lungs is usually all that is required to resuscitate newborns (Richmond, 2011).
Based on our own data we expected the time to first breath with a bag valve mask and oral airway to be 30 seconds (data collected by observational studies during NLS courses). Any new technique would have to be substantially better than bag valve mask and oral airway in order to have potential clinical use.
A power analysis study showed that 12 candidates would be required to detect an improvement of at least 50% in time to first breath with the i-gel®, with a risk of a type 2 error of 20%.
Before participating in the study, a Resuscitation Council (UK) NLS instructor gave each participant individually a 20 minutes refresher training using the newborn algorithm. This included: inflation breaths using a bag valve mask device, laryngoscopy, suctioning of the oropharynx, sizing and insertion of the oropharyngeal airway. In addition, the instructor taught the participant to size, prepare and insert an i-gel® supraglottic airway.
An i-gel® supraglottic airway is a 2nd generation laryngeal mask. It is available in various sizes from 1 (3–5)kg used in this study to a size 5. It is produced from a thermo plastic polymer and is designed to make a non-inflatable anatomical seal. It is designed to be easily inserted (less than 5 seconds), offer greater stability and reduce the risk of tissue damage.
Immediately after the training, the participants were asked to manage two scenarios (Figure 1). These scenarios were run in the clinical skills centre using the newborn HAL® manikin system. A dedicated technician calibrated and operated the HAL® manikin and recorded relevant variables: the time taken to insert the oropharyngeal and i-gel® supraglottic airway and to deliver the first to fifth effective inflation breath, the duration of each inflation breath and the positive pressure generated. In addition any failures in either technique were recorded.
The midwives then completed a simple questionnaire (Appendix 1).
Results
Twenty of the 55 midwives that were approached participated.
All participants achieved chest rise with the oropharyngeal airway and bag valve mask but one candidate failed to achieve chest rise using positive pressure ventilation delivered through the i-gel® supraglottic airway. This measured failure rate of 5% in our study means the upper 95% confidence limit for the true failure rate is 25% (Newman, 1995).
There was no significant difference in the time to insert the oral airway or i-gel®, but the time to deliver the first inflation breath was significantly less with the i-gel® (Table 1).
| Oral airway + bag valve mask mean (SD) | i-gel® mean (SD) | P-value | |
|---|---|---|---|
| Insertion time in (seconds) | 13.2 (8.79) | 10.55 (3.48) | 0.13 |
| Time to first breath (seconds) | 26.1 (13.8) | 18.5 (4.9) | 0.02 |
| Time to fifth breath (seconds) | 41.7 (18.49) | 32.7 (11.66) | 0.07 |
The average improvement was 7.6 seconds and was maintained during the remaining 4 breaths measured during this study.
Due to the first inflation breath being achieved quicker with the i-gel® all inflation breaths were delivered in a shorter total period of time.
Table 2 compares the duration time of the inflation breaths during the two scenarios in relation to the recommended inflation time of 2–3 seconds. The table shows there was no statistical difference in the time taken to deliver each inflation P=o.29. Only one candidate managed to achieve a duration time of 2–3 seconds in the control scenario and only 4 candidates managed to achieve the recommended duration time in the i-gel® scenario
| Oral airway + bag valve mask mean (SD) | i-gel® mean (SD) | P-value | |
|---|---|---|---|
| Minimum time (seconds) | 0.94 (0.52) | 1.10 (0.48) | 0.52 |
| Maximum time (seconds) | 1.62 (0.62) | 1.80 (0.84) | 0.18 |
| Mean time (seconds) | 1.27 (7.46) | 1.49 (0.74) | 0.29 |
Table 3 compares the airway pressures generated using the two methods. There were significant differences in minimum pressures (P=o.oo62), maximum pressures (P=0.0022) and mean pressures (P=0.0030) between the two techniques. Participants using the i-gel® generated far greater inspiratory pressures than with the control. Forty percent of the midwives managed to maintain a mean airway pressure within the 30 cm H2O +/−5 using bag valve mask and oral airway. Only 19% of the participating midwives achieved a mean airway pressure within acceptable parameters using the i-gel®. Eighty-one percent of the participants generated pressures higher than the accepted parameters using the i-gel® and 53% using the bag valve mask and Guedel airway.
| Oral airway + bag valve mask mean (SD) | i-gel® mean (SD) | P-value | |
|---|---|---|---|
| Minimum pressure (cm H2O) | 29.52 (8.97) | 35.7 (9.77) | 0.0062 |
| Maximum pressure (cm H2O) | 38.7 (6.95) | 44.78 (4.82) | 0.0022 |
| Mean pressure (cm H2O) | 34.28 (7.46) | 40.19 (7.23) | 0.0030 |
The results from the questionnaire showed that five of the candidates stated they were not confident using the current recommended technique. All of the participants think that the i-gel® is better suited to the resuscitation of the newborn infant in the community than the current practice of bag valve mask and oropharyngeal airway.
Additional comments from the questionnaire
Discussion
Only 10 in 1000 babies >2.5kg require ventilatory support either bag valve mask or tracheal intubation at birth (Palme-Kilander, 1992). Of these, 80% respond to bag valve mask ventilation alone. Based on data from 2012–2013 from Hull and East Yorkshire Hospitals NHS Trust (5937 babies born in hospital, 49 at home and 100 born before arrival at hospital) approximately 59 babies may require ventilatory support in hospital and 2 per year in the community.
Although community midwives attend resuscitation updates each year and complete a NLS course every 4 years, deterioration of core practical skills is a major concern (Patel et al, 2012; Mosley et al, 2013).
Hull and East Yorkshire Hospitals NHS Trust provide i-gel® supraglottic airways on both the adult and paediatric resuscitation trolleys in hospitals for two reasons:
Although there are studies in which the authors assess the role and efficacy of LMAs in neonatal resuscitation within the hospital (Vadhera, 1997; Gandini, et al 1999; Zarnardo, 2010; Caldwell et al, 2011; Xiao-Yu, 2011) there are no documented studies specifically looking at the use of an i-gel® in newborn resuscitation within the community.
Our results support a previous study in which participants failed to achieve the recommended inflation time of 2–3 seconds using a Bag valve mask (Oddie et al,2005), the use of an i-gel® failed to improve this.
Our results (Table 3) also agreed with a previous study that showed the difficulty in maintaining pressures of 30 cm H2O using a bag valve mask and oral airway (Oddie et al, 2005).
All of the participants achieved effective chest rise using the bag valve mask and oral airway.
However, one of the participants failed to master i-gel® insertion. Five of the participants expressed a lack of confidence using the oropharyngeal airway and bag valve mask to inflate/ventilate a newborn and one of the participants felt confident within the study environment but wasn't convinced it would translate into practice. However, all 20 participants expressed the view they would be far more confident resuscitating a newborn using an i-gel®.
Our results show that there are problems with both techniques for providing ventilatory support by midwives in the community. The current recommended technique (Richmond, 2011) of Guedel airway and bag valve mask has the advantage of lower airway pressures although still above the recommended pressure of 30 cm H2O. However, it takes longer to achieve a seal and deliver an effective breath.
The i-gel® may offer a potential benefit, in that the time to first breath is significantly reduced. However, airway pressures were significantly higher.
The recorded inflation pressures for both techniques were often excessive which may cause barotrauma in the clinical setting.
Is the increased airway pressure seen in the study due to the pressure relief valve of the bag valve mask being set at 40 cm H2O, user technique or the volume of the bag valve mask? Was the excessive pressure generated using the i-gel® associated with an improved seal, reducing leakage?
We have collected some preliminary data that suggests using a 280 ml bag with an i-gel® may allow effective inflation/ventilation of the lungs and limit the airway pressures to within acceptable limits. We intend to make further formal studies of this. Another possibility is to use a pressure relief valve with a lower limiting pressure, and we intend to make formal studies of this.
Conclusions
In our manikin study, we identified one potential benefit using the i-gel® compared with the conventional Guedel airway and bag-mask ventilation, namely a much shorter time to obtain inflation of the chest. We intend to make further formal studies of this, and the use of a pressure relief valve with a lower limiting pressure.