Preoxygenation Is More Effective in the 25° Head-up Position Than in the Supine Position in Severely Obese Patients

Dixon, Benjamin J.; Dixon, John; Carden, Jennifer R.; Burn, Anthony J; Schachter, Linda M.; Playfair, Julie; Laurie, Cheryl; O'Brien, Paul Edmond

doi:10.1097/00000542-200506000-00009

Cited by 406 publications

(209 citation statements)

References 19 publications

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“…In one study, preoxygenated obese patients could sustain a longer DAWD in the 25°head-up position than they could in the supine position. 11 In another study, patients preoxygenated in a sitting position, as close to 90°a s possible, also had a longer DAWD (Table 3). 10 The advantages of the head-up position on oxygenation should be balanced against the possibility of a more difficult tracheal intubation and an increased incidence of hypotension at induction of anesthesia.…”

Section: Positionmentioning

confidence: 88%

“…Accordingly, there should be better oxygen reserves after preoxygenation in the upright position, which leads some authors to suggest a head-up position, 9 particularly in the obese. 10,11 The drawbacks of the upright position are a risk of hypotension and difficult tracheal intubation.…”

Section: Preoxygenation Techniquesmentioning

confidence: 99%

“…Ceci a incité certains auteurs à préconiser une position semi-assise, 9 plus particulièrement pour les patients obèses. 10,11 La position assise risque cependant d'accroître l'hypotension et de rendre l'intubation trachéale difficile.…”

Section: Les Techniques De Préoxygénationunclassified

“…Dans une étude, les patients obèses préoxygénés ont pu soutenir une PASD plus longue dans une position semi-assise à 25°qu'en décubitus dorsal. 11 Dans une autre étude, les patients pré-oxygénés en position assise, à un angle se rapprochant le plus possible de 90°, ont également présenté une PASD plus longue (Tableau 3). 10 Les avantages de la position semi-assise en matière d'oxygénation ne doivent pas faire oublier l'éventualité d'une intubation trachéale plus difficile et une incidence plus élevée d'hypotension à l'induction de l'anesthésie.…”

Section: Positionunclassified

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Optimizing preoxygenation in adults

Tanoubi

Drolet

Donati

2009

Can J Anesth/J Can Anesth

181

105

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Purpose Preoxygenation increases oxygen reserves and duration of apnea without desaturation (DAWD), thus it provides valuable additional time to secure the airway. The purpose of this Continuing Professional Development (CPD) module is to examine the various preoxygenation techniques that have been proposed and to assess their effectiveness in healthy adults and in obese, pregnant, and elderly patients. Principal findings The effectiveness of preoxygenation techniques can be evaluated by measuring DAWD, i.e., the time for oxygen saturation to decrease to\90%. Clinically, preoxygenation is considered adequate when end-tidal oxygen fraction is[90%. This is usually achieved with a 3-min tidal volume breathing (TVB) technique. As a rule, asking the patient to take four deep breaths in 30 sec (4 DB 30 sec) yields poorer results. Eight deep breaths in 60 sec (8 DB 60 sec) is equivalent to TVB 3 min. The DAWD is decreased in obese patients, pregnant women, and patients with increased metabolism. Obese patients may benefit from the head-up position and positive pressure breathing. A TVB technique is preferable in the elderly. Failure to preoxygenate is often due to leaks, which commonly occur in edentulous or bearded patients. In cases of difficult preoxygenation, directly applying the circuit to the mouth might be a useful alternative. Supplying extra oxygen in the nasopharynx during apnea might increase DAWD. Conclusion Since ventilation and tracheal intubation difficulties are unpredictable, this CPD module recommends that all patients be preoxygenated. The TVB 3 min and the 8 DB 60 sec techniques are suitable for most patients; however, the 4 DB 30 sec is inadequate. Continuing Professional Development objectivesAfter reading this review, the reader should be able to:• understand the physiological principles of preoxygenation;• describe the slow and fast techniques for preoxygenating patients; • apply the proper techniques in healthy adults with normal weight; • modify these techniques in obese patients, pregnant women, and the elderly; • briefly describe preoxygenation devices other than the face mask.The purpose of preoxygenation is to increase the oxygen reserves of the body, thus preventing hypoxia during a planned or unexpected period of apnea. The term ''denitrogenation'', indicating that nitrogen in the lungs is replaced by oxygen, is sometimes used instead of ''preoxygenation''. However, the latter is generally preferred because the primary goal is to provide oxygen, not to remove nitrogen. With adequate preoxygenation, patients can tolerate a longer period of apnea, and an increased margin of safety is created between induction of anesthesia and the moment the airway is secured. This extra time may prove particularly valuable if mask ventilation is difficult or contraindicated and if laryngoscopy and tracheal intubation are more difficult than expected.The purpose of this Continuing Professional Development (CPD) module is to summarize the physiological principles 123Can J Anesth/J Can Anesth (2009...

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Section: Positionmentioning

confidence: 88%