Standard preoxygenation technique versus two rapid techniques in pregnant patients.
The aim of this study was to compare three different preoxygenation techniques in pregnant women by measuring end-tidal fractional oxygen concentration (FETO2): the traditional technique of 3min tidal volume breathing (VT x 3 min), 8 deep breaths (8 DB) and 4 deep breaths (4 DB). Twenty pregnant volunteers without pulmonary diseases were studied during the third trimester (36-38 weeks' gestation). Women were preoxygentated using a non-rebreathing respiratory circuit with a 3-L reservoir bag and a Capnomac Ultima calibrated before each patient to monitor FETO2 continuously. The three preoxygenation techniques were investigated in random order: VT x 3 min using an oxygen flow of 9 L min-1, 4 DB within 30s using an oxygen flow of 9 L min-1, and 8 DB within one minute using an oxygen flow of 15 L min-1. Between each technique, 5-min room air breathing was allowed to return to baseline FETO2 assessed by the Capnomac Ultima. An FETO2 >/= 90% was achieved more frequently with the VT x 3 min and the 8 DB techniques (76%) than with the 4 DB technique (18%) (P < 0.05). The average time required for obtaining an FETO2 >/= 90% was 107+/-37s. Both the VT x 3 min and the 8 DB techniques are therefore more effective for preoxygenation in pregnant patients than the 4 DB technique. In an acute obstetric emergency before rapid-sequence induction of general anaesthesia, 8 DB preoxygenation technique could be recommended.
Department of Anesthesia and Surgery, University Hospital, Tours, France.
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B
Chiron
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M
Laffon
M
M
Ferrandiere
J F
JF
Pittet
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H
Marret
C
C
Mercier
D000328:Adult; D000773:Anesthesia, Obstetrical; D005260:Female; D006801:Humans; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation / Q000379:methods*; D011247:Pregnancy; D012119:Respiration; D015656:Respiratory Mechanics; D013990:Tidal Volume