Hypoxaemia at induction is relatively common, with unsurprising independent risk factors (difficult preoxygenation, mask ventilation, and intubation).

pearl

• C Baillard, M Boubaya, E Statescu, M Collet, A Solis, J Guezennec, V Levy, and O Langeron.
• Department of Anesthesiology and Critical Care Medicine, Cochin University Hospital, Paris Descartes University, Assistance Publique-Hôpitaux de Paris, Paris, France. Electronic address: christophe.baillard@aphp.fr.
• Br J Anaesth. 2019 Mar 1; 122 (3): 388-394.

BackgroundThe incidence of hypoxaemia related to airway management is still a matter of concern. Our aim was to determine the factors that contribute to hypoxaemia during induction of anaesthesia after a standardised preoxygenation procedure.MethodsThe study was a multicentre and prospective observational trial. It evaluated the incidence of hypoxaemia at induction of anaesthesia in adult patients. The primary endpoint was the incidence of hypoxaemia defined as pulse oximetry of arterial oxyhaemoglobin saturation (SpO2) <95%.ResultsOf 2398 patients, hypoxaemia was observed in 158 (6.6%). We identified five preoperative independent risk factors: chronic obstructive pulmonary disease, hypertension, anticipated difficult mask ventilation and difficult tracheal intubation, and emergency surgery. There were also three pre-induction independent risk factors: difficult preoxygenation, difficult mask ventilation, and difficult tracheal intubation. We found a high negative predictive value of preoperative risk factors for difficult mask ventilation of 0.96 (0.95-0.96), and for difficult tracheal intubation (0.95 [0.94-0.96]). A total of 723 patients (30%) experienced difficult preoxygenation (FeO2 <90% at the end of preoxygenation). Male sex, chronic obstructive pulmonary disease, hypertension, emergency surgery, and predictable difficult mask ventilation were independent patient risk factors for difficult preoxygenation.ConclusionsDifficult mask ventilation and difficult tracheal intubation are risk factors for hypoxaemia at induction of general anaesthesia. Difficult preoxygenation was observed in 30% of patients and was also identified as a risk factor for hypoxaemia. This suggests that techniques improving preoxygenation should be implemented in daily practice.Copyright © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

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