OP Airways VS LMAs and ETI
According to research by Khosraven et al (2015) one of the main disadvantages of an OP airway is that its length, shape & lack of an inflatable cuff may cause oxygen to leak, leading to less oxygen than we might hope for entering the patient’s lungs.
- Khosraven et al (2015) studied 54 patients in Pakistan who had required use of an LMA or OP secondary to a failed endotracheal tube. They used paramedic reporting to help inform their results. Their results highlighted a concerning oxygen leak when using OP airways which could be corrected with the use of an LMA or ET tube. However, the ET tube required several attempts to insert. Perhaps surprisingly, this difficulty was noted when using OP airways too. Khosraven et al (2015) concluded that LMAs are preferential & researchers such as Jain et al (2016) have further argued this. Click on the ‘detail’ tab to read more about both studies & to understand the advantages and disadvantages of each airway adjunct. Remember that all adjuncts should be used where indicated, in line with guidelines.
‘Using OPA, patients maybe receive lower concentrations of oxygen and lower tidal volume’ (Khosraven et al, 2015). This may be due to where the OPA ends. It ‘opens at the pharnyx, consequently, oxygen leakage is inevitable’ (Khosraven et al, 2015). Comparatively, LMAs and endotracheal tubes cover these important areas either through an inflatable cuff or by simply being longer and larger. Furthermore, the shape of LMAs and endotracheal tubes may also prevent this problem.
However, Khosraven et al (2015) also highlighted that it takes longer to insert an endotracheal tube. Not only this, but more attempts are likely to be needed to correctly insert an endotracheal tube than for an OPA or LMA. This may even be true for an OPA when compared with an LMA (Brimacombe et al, 1998, cited in Khosravan et al, 2015). Khosraven et al (2015) noted how head/airway positioning become more important when using an endotracheal tube compared with an OP airway. Such disadvantages of LMA and ETI use make the OP airway appear more useful, despite its own problems.
To find any deciding differences between the airway adjuncts, Khosraven et al (2015) studied ‘airway management complications’ in the use of each adjunct. There were no significant differences between any of the airways used in this study.
The study was based in Iran and featured in the Pakistan Journal of Medical Sciences. It was conducted on 54 patients in a clinical trial where 37 patients who had undergone 2 failed intubations were treated with the use of an OPA or LMA – and this treatment was determined randomly. Khosravan et al (2015) used paramedic reports to inform the results and they concluded in favour of LMA use. LMAs would appear to have less disadvantages than the other two adjuncts studied and more advantages when used as indicated within the guidelines.
A more recent study by Jain et al (2016) also voted in favour of LMAs over other options as a means of reducing negative hemodynamic changes that can be observed in extubation. However, it should be noted that this study focused on anesthesia, not on the use of these devices in cardiac arrest settings prehospitally.
Fact check me – Khosravan, S. et al, 2015. ‘Comparing the effectiveness of airway management devices in pre-hospital care: A randomized clinical trial’, Pakistan Journal of Medical Sciences, 31 (4), pp. 946-949
Fact check me – Jain, S. et al, 2016. ‘A prospective randomized control study comparing classic laryngeal mask airway with Guedel’s airway for tracheal tube exchange and smooth extubation’, Anesthesia Essays and Research, 10 (3), pp552-556