A reply.

Abstract

We thank all correspondents for their interest in our paper on supraglottic airway devices (SADs) 1. The objective of our study was to investigate the time to effective ventilation and ventilation quality of three different SADs in a manikin. Based on our results, we concluded that surf lifeguards can insert and successfully ventilate a manikin through a SAD. We are well aware of the limitations of manikin studies and acknowledge that great caution should be taken when extrapolating results from manikins to humans. As noted in the conclusion of our paper, we believe that our results should be confirmed in a clinical study. Baker and Webber have published an interesting case of a single resuscitation attempt following drowning. They report unsuccessful ventilation using two different SADs and therefore question the use of this type of device in drowning 2, but we suggest that this is insufficient to rule out the use of SADs in drowning. Their case report is of value in highlighting a number of issues. In their report, bag-valve-mask ventilation was interrupted during two attempts at inserting different SADs and ventilating through these, firstly an i-gel™ (Intersurgical, Wokingham, UK) and then an Ambu® AuraOnce™ (Ambu, Ballerup, Denmark), despite the lack of evidence to support the use of either, or indeed any, SAD in drowning. This led to unnecessary interruptions in bag-valve-mask ventilation, a method that has proven to be an effective ventilation technique for decades. New resuscitation equipment and techniques need to be introduced and used with caution, especially during real-life resuscitation, and the reader is left uncertain as to why their attempts failed: was the insertion of the device correct or impeded by ongoing chest compressions, for example? In the more controlled environment we created for our study, 40 surf lifeguards were able both to insert the i-gel and the Ambu AuraOnce devices, and achieve effective ventilation, in a manikin, both with and without ongoing chest compression 1. Secondly, sufficient expertise and skills are important when using new resuscitation equipment. Whether the rescuer in Baker and Webber's case report had experience of inserting and ventilating via the i-gel and Ambu AuraOnce devices on a regular basis is unknown, but practice in a manikin and experience in the clinical setting may have been helpful. Sufficient training and regular retraining is important to acquire and retain resuscitation skills. Thirdly, Baker and Webber report that an i-gel size 4 (for patients 50–90 kg) 3 and an Ambu AuraOnce size 5 (for patients 70–100 kg) 4 were used, for a patient weighing ~90 kg. Perhaps a size-5 i-gel (for a patient > 90 kg) 3 might have resulted in successful ventilation. Finally, Baker and Webber are correct to note that the pathophysiology of drowning may have increased airway resistance, making bag-valve-mask ventilation difficult using a SAD, but this is also a problem using other airway devices, including tracheal tubes, and ventilation methods. Importantly, if ventilation is unsuccessful using one device or ventilation method, another should be attempted. McKenna and Davis are correct to note that study results from manikins may differ from results obtained in patients 5. Results from manikin studies should be extrapolated to humans with caution, but we and others 6 think that manikin studies are of value, for example, when performing pilot evaluations of resuscitation techniques that might otherwise result in harming critically ill patients. As stated in our conclusions, we are planning a proof of concept study in humans on the use of SADs among surf lifeguards. Methods of ventilation used by surf lifeguards have not been studied extensively 7, 8, and more studies are needed. Currently, there is insufficient evidence to recommend any specific ventilation technique among surf lifeguards. However, there are potential benefits of using SADs including a reduced risk of aspiration and fewer interruptions in chest compressions during resuscitation. In the interim, we would encourage all lifeguard services that consider using SADs to do so only under rigorous conditions of operator training and systematic evaluation of use. We would welcome any data collected in the course of resuscitation, and would be pleased to collaborate on projects aiming to help improve survival from drowning.