SGA placement

Author: 
Mae Yap; Claas Siegmueller

 

INDICATIONS

SGAs are commonly used for airway management during general anesthesia. The NAP4 audit found that in more than 50% of all general anesthetics given in the UK the airway was a supraglottic one.

Especially with the introduction of second generation devices the role of SGAs has expanded from airway maintenance during routine low-risk surgery. SGAs are now...

  •  increasingly used for more obese or 'higher risk' patients (see discussion below),
  •  used for as a conduit for intubation, and
  •  used for airway management outside of the OR, for example during resuscitation/ cardiac arrest or in pre-hospital emergency care, where they might offer higher ventilation success rates compared to orotracheal intubation, particularly when providers are not well-trained to intubate.

Another very important indication for a supraglottic airway is as a rescue device in a CICO scenario.

CAUTION: While an SGA might work as a rescue device for an unanticipated difficult airway, where intubation and mask ventilation have failed, never consider an SGA as your plan A for an anticipated difficult airway, especially when you expect intubation to be difficult or impossible!

Advantages and disadvantages compared with endotracheal intubation

The classic laryngeal mask design was extensively investigated in comparison to the endotracheal tube for airway management, with most studies published in the 1990s (Brimacombe 1995). This early research comparing a SGA to the endotracheal tube 'gold standard' found that the laryngeal mask provides better haemodynamic stability at induction and during emergence compared with intubation and extubation. In addition, coughing is reduced during emergence with the classic design laryngeal mask. Anesthetic requirements for 'tolerating' the laryngeal mask are lower than for an ET tube, while oxygen saturation during emergence is higher. The incidence of a sore throat post-operatively is reduced with the classic laryngeal mask design.

SGAs are also easier to insert and are placed blindly requiring a comparatively low skillset, as opposed to endotracheal tubes which need at the very least a laryngoscope for placement and require more expertise to insert. The incidence of laryngospasm during emergence is also lower with SGAs (Yu et al, 2010).

On the other hand, SGAs have some major downsides compared to intubation with an endotracheal tube:

  • First and foremost, SGAs do not protect the lungs from aspiration as a cuffed endotracheal tube does. Even though second generation devices offer improved aspiration protection (read 'Supraglottic airways (SGAs)' on how they do that) compared to first generation devices, they do not offer the protection of an endotracheal tube.
  • Secondly, the cuff seal pressure achieved with an SGA is limited compared to that of an ET tube. Again, second generation devices fare better, often providing a seal up to 30- 35 cmH2O airway pressure. The cuff seal of an endotracheal tube on the other hand alllows for theoretically unlimited airway pressures. When an SGA is used with ventilation/ ventilator support, gas leakage around the cuff risks accidental gastric insufflation and consequently regurgitation/ aspiration, and of course causes reduced tidal volume delivery.

TECHNIQUE

Coming soon..


TIPS & TRICKS, TROUBLESHOOTING

    Coming soon...

    Bubble test

    Brimacombe technique


    REFERENCES

    Brimacombe, J. (1995): The advantages of the LMA over the tracheal tube or facemask: a meta-analysis. In Canadian Journal of Anaesthesia = Journal Canadien d'Anesthesie 42 (11), pp. 1017–1023. DOI: 10.1007/BF03011075.

    Uppal, V.; Fletcher, G.; Kinsella, J. (2009): Comparison of the i-gel with the cuffed tracheal tube during pressure-controlled ventilation. In British Journal of Anaesthesia 102 (2), pp. 264–268. DOI: 10.1093/bja/aen366.

    Metodiev, Yavor; Mushambi, Mary (2020): Supraglottic airway devices for Caesarean delivery under general anaesthesia: for all, for none, or for some? In British Journal of Anaesthesia 125 (1), e7-e11. DOI: 10.1016/j.bja.2020.02.012.

    Yao, Wei Yu; Li, Shi Yang; Yuan, Yong Jin; Tan, Hon Sen; Han, Nian-Lin R.; Sultana, Rehena et al. (2019): Comparison of Supreme laryngeal mask airway versus endotracheal intubation for airway management during general anesthesia for cesarean section: a randomized controlled trial. In BMC anesthesiology 19 (1), p. 123. DOI: 10.1186/s12871-019-0792-9.

    Yu, Seung H.; Beirne, O. Ross (2010): Laryngeal mask airways have a lower risk of airway complications compared with endotracheal intubation: a systematic review. In Journal of Oral and Maxillofacial Surgery: Official Journal of the American Association of Oral and Maxillofacial Surgeons 68 (10), pp. 2359–2376. DOI: 10.1016/j.joms.2010.04.017.

    Park, Sun Kyung; Ko, Geum; Choi, Geun Joo; Ahn, Eun Jin; Kang, Hyun (2016): Comparison between supraglottic airway devices and endotracheal tubes in patients undergoing laparoscopic surgery: A systematic review and meta-analysis. In Medicine 95 (33), e4598. DOI: 10.1097/MD.0000000000004598.

    Nicholson, Amanda; Cook, Tim M.; Smith, Andrew F.; Lewis, Sharon R.; Reed, Stephanie S. (2013): Supraglottic airway devices versus tracheal intubation for airway management during general anaesthesia in obese patients. In The Cochrane Database of Systematic Reviews (9), CD010105. DOI: 10.1002/14651858.CD010105.pub2.