Preoxygenation in healthy volunteers: a graph of oxygen “washin” using end-tidal oxygraphy

Berry, Colin; Myles, Paul S.

doi:10.1093/bja/72.1.116

Cited by 96 publications

(56 citation statements)

References 3 publications

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“…[9][10][11][12] Leaks have been reported in 10 to 11.5% of subjects with no facial anomalies and normal dentition. 13,14 In real life, leaks probably occur even more frequently since we often preoxygenate patients who are edentulous, wear beards or mustaches, have a nasogastric tube in place, or cooperate poorly. When a leak is unavoidable, an imperfect preoxygenation is presumably better than none at all, but it is unclear which breathing method then yields the best results.…”

Section: Discussionmentioning

confidence: 99%

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When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing

Gagnon

Fortier

Donati

2006

Can J Anesth/J Can Anesth

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Purpose: Ideally, preoxygenation is performed using a tight fitting mask either by breathing normally for three to five minutes or with four to eight vital capacity (VC) breaths in 0.5 to one minute, but in practice leaks are frequent and sometimes unavoidable. This study was designed to determine which breathing method provided the best oxygenation in the presence of leak.Methods: Twenty volunteers were instructed to breathe from a circle circuit supplied with 6 L·min -1 of fresh oxygen. Each subject was tested under four situations selected in random order: 1) normal breathing for three minutes without leak; 2) normal breathing for three minutes with a leak; 3) four VCs in 30 sec without a leak; and 4) four VCs in 30 sec with a leak. The leak was created by a piece of size 18 French nasogastric tube, 5 cm long, taped under the face mask. Inspired and expired O 2 and CO 2 were sampled at the nostrils. Results: In the absence of a leak, the end-tidal oxygen fraction (F EO2 ) was greater after three minutes of tidal breathing (89 ± 3%; mean ± SD) in comparison with the response to four VCs (76 ± 7%; P < 0.001). Introduction of a leak decreased the F EO2 significantly (P < 0.001). With a leak, the F EO2 was similar with normal breathing (61 ± 8%) and after four VCs (59 ± 11%). Conclusion:Preoxygenation with tidal volume breathing for three minutes yields higher F EO2 in comparison to four VCs. If a small leak (4 mm internal diameter) is introduced, the F EO2 decreases significantly with both breathing methods to approximately 60%. Objectif

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Section: Discussionmentioning

confidence: 99%

“…We chose F EO2 since it has been shown to be an accurate, continuous and non-invasive measure of alveolar oxygen. 3,13,16 Furthermore, using F EO2 as an endpoint value in awake volunteers allowed us to study the subjects with the different preoxygenation techniques, with each subject serving as his/her own control.…”

mentioning

confidence: 99%

When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing

Gagnon

Fortier

Donati

2006

Can J Anesth/J Can Anesth

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“…With this concept Berry & Myles [40] produced alveolar denitrogenation with ventilation to a FIO 2 at 100%, and recorded FEO 2 (Fraction expiratory O 2 ) of 96% after 3 minutes exposure, this experiment shows that this process is rapid and probably happens in the same condition in the membrane oxygenator. Georgiads et al [41] subjected 185 patients who were mechanical valve carriers to ventilation with FIO 2 to 100% while he monitored microembolic events produced by cavitation valves with TCD.…”

Section: Fig 4 -Dynamics Of the Blood As It Travels The Pulmonary Camentioning

confidence: 62%

Gaseous microemboli in cardiac surgery with cardiopulmonary bypass: the use of veno-arterial shunt as a preventive method

Reis

Menezes

Justo

2012

Revista Brasileira De Cirurgia Cardiovascular

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Neurological complications are an important cause of morbidity in the postoperative period of cardiac surgery and its incidence reaches up to 75% of patients. An important cause of these events is the formation of microbubbles in the bloodstream during cardiopulmonary bypass. Integrative review was carried out on gaseous microemboli in cardiopulmonary bypass. This study analyzed studies with different methodological approaches, but that address the issue. The result suggests the denitrogenation of blood by hyperoxia dissolved microbubbles in the blood and venoarterial shunt can balance the respiratory parameters changed with hyperoxia.Descriptors: Extracorporeal circulation. Embolism, air. Cognition disorders. Cardiac surgical procedures. ResumoAs complicações neurológicas representam importante causa de morbidade no período pós-operatório de cirurgia cardíaca e sua incidência alcança até 75% dos pacientes. Uma importante causa desses eventos é a formação de microbolhas na corrente sanguínea durante a circulação extracorpórea. Realizou-se revisão integrativa sobre microembolia gasosa na circulação extracorpórea. Esse trabalho analisou estudos com abordagens metodológicas diferentes, mas que contemplam o tema. O resultado sugere que a desnitrogenação do sangue causada pela hiperoxia dissolve microbolhas formadas no sangue e o shunt venoarterial pode equilibrar os parâmetros respiratórios alterados pela hiperoxia.Descritores: Circulação extracorpórea. Embolia aérea. Transtornos cognitivos. Procedimentos cirúrgicos cardíacos.

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“…Recordings were obtained bilaterally over a total period of 1 hour (30 minutes of room air, 30 minutes of 100% oxygen). Since a previous study 17 had documented that it takes 3 minutes for complete denitrogenation of alveoli, TCD recordings were started 3 minutes after placing the patient on 100% oxygen. TCD data were reviewed by 2 blinded observers; in case of discordance, data were assessed by a third observer.…”

Section: Transcranial Dopplermentioning

confidence: 99%

Cerebral Microembolization After Bioprosthetic Aortic Valve Replacement

Al-Atassi

Lam²,

Forgie³

et al. 2012

Circulation

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Background-No human physiological data exists on whether aspirin only is as effective as warfarin plus aspirin in preventing cerebral microembolization in the early postoperative period after bioprosthetic aortic valve replacement (bAVR). Methods and Results-We prospectively enrolled 56 patients who had no other indication for oral anticoagulation, who underwent bAVR and received, in an open-label fashion, either daily warfarin (for INR 2.0 -3.0) plus 81 mg of aspirin (nϭ28) or 325 mg of aspirin only (nϭ28). Cerebral microembolization was quantified at 4 hours (baseline) and at 1 month postoperatively, by recording 1-hour bilateral middle cerebral artery (MCA) microembolic signals (MES). Platelet-function analysis (PFA) of closure times (CT) on collagen was also used as a marker of platelet-dependent activation. Follow-up to 1 year was complete. Preoperative demographics and baseline platelet function were equivalent in both groups. There was no mortality, stroke, or transient ischemic attack at 1 year in either group. No significant differences were found in the proportion of patients with MES among those receiving warfarin plus aspirin versus aspirin only, at baseline (68% versus 82%, respectively; Pϭ0.4) and at 1 month (46% versus 43%; Pϭ1.0) after bAVR. The total MES and PFA were also equivalent between groups, at baseline and follow-up. Conclusions-Early after bAVR, the effects of these 2 antithrombotic regimens on cerebral microembolization and platelet function are equivalent. These data bring new mechanistic support to the premise that aspirin only may safely be used early after bAVR in patients who have no other indication for oral anticoagulation.

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Preoxygenation in healthy volunteers: a graph of oxygen “washin” using end-tidal oxygraphy

Abstract: End-tidal oxygen fractions (FE'O2) have been measured in 40 healthy volunteers breathing 100% oxygen. On the assumption that FE'O2 is a good measure of alveolar oxygen, we have drawn a graph of oxygen washin vs time. Clinical applications are discussed.

Cited by 96 publications

References 3 publications

When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing

When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing

Gaseous microemboli in cardiac surgery with cardiopulmonary bypass: the use of veno-arterial shunt as a preventive method

Cerebral Microembolization After Bioprosthetic Aortic Valve Replacement

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