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  • Print publication year: 2010
  • Online publication date: January 2011

Chapter 9 - Facemasks and supraglottic airway devices

from Section 2 - Clinical


Hypoxaemic hypoxia (airway obstruction) is more damaging to cells than anaemic or stagnant hypoxia. In order to fully understand the classification of hypoxia, it is useful to consider the example of carbon monoxide poisoning. It is known that hypoxaemic hypoxia is of particular importance in the development of cellular hypoxia and it goes without saying that, in the context of the difficult airway, the principal cause of hypoxaemia is airway obstruction. It is important to understand the mechanisms by which hypoxaemia develops, and the factors which determine the rate of this process. Causes of hypoxaemia occurring during anaesthesia can be divided into the following three categories: problems with O2 supply, problems with O2 delivery from lips to lung, and problems with O2 transfer from lung to blood. Pre-oxygenation aims to increase body O2 stores to their maximum, so that periods of apnoea are tolerated for longer before critical desaturation occurs.

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Further reading

AsaiT, ShinguK. (2005). The laryngeal tube. British Journal of Anaesthesia, 95, 729–736.
BerckerS, SchmidbauerW, VolkT, et al. (2008). A comparison of seal in seven supraglottic airway devices using a cadaver model of elevated esophageal pressure. Anesthesia and Analgesia, 106, 445–448.
CaponasG. (2002). Intubating laryngeal mask airway. A review. Anaesthesia and Intensive Care, 30, 551–569.
Centre for Evidence-Based Purchasing. (2008). Buyers Guide. Laryngeal Masks. NHS Purchasing and suppliers agency. July, 2008.
CookTM. (2003). Spoilt for choice? New supraglottic airways. Anaesthesia, 58, 107–110.
CookTM, LeeG, NolanJP. (2005). The ProSeal laryngeal mask airway: A review of the literature. Canadian Journal of Anaesthesia, 52, 739–760.
EschertzhuberS, BrimacombeJ, HohlriederM, KellerC. (2009). The laryngeal mask airway Supreme–a single use laryngeal mask airway with an oesophageal vent. A randomised, cross-over study with the laryngeal mask airway ProSeal in paralysed, anaesthetised patients. Anaesthesia, 64, 79–83.
KellerC, BrimacombeJ, BittersohlP, LirkP, von GoedeckeA. (2004). Aspiration and the laryngeal mask airway: Three cases and a review of the literature. British Journal of Anaesthesia, 93, 579–582.
KellerC, BrimacombeJ, KleinsasserA, LoeckingerA. (2000). Does the ProSeal laryngeal mask airway prevent aspiration of regurgitated fluid?Anesthesia and Analgesia, 91, 1017–1020.
KellerC, BrimacombeJ, RädlerC, PühringerF. (1999). Do laryngeal mask airway devices attenuate liquid flow between the esophagus and pharynx? A randomized, controlled cadaver study. Anesthesia and Analgesia, 88, 904–907.
SchmidbauerW, BerckerS, VolkT, BoguschG, MagerG, KernerT. (2009). Oesophageal seal of the novel supralaryngeal airway device i-gel in comparison with the laryngeal mask airways Classic and ProSeal using a cadaver model. British Journal of Anaesthesia, 102, 135–139.
TheilerLG, Kleine-BrueggeneyM, KaiserD, et al. (2009). Crossover comparison of the laryngeal mask supreme and the i-gel in simulated difficult airway scenario in anesthetized patients. Anesthesiology, 111, 55–62.
VergheseC, BrimacombeJ. (1996). Survey of laryngeal mask airway usage in 11,910 patients: Safety and efficacy for conventional and non-conventional usage. Anesthesia and Analgesia, 82, 129–133.