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Pre‐oxygenation in pregnancy: the effect of fresh gas flow rates within a circle breathing system *
Author(s) -
Russell E. C.,
Wrench I.,
Feast M.,
Mohammed F.
Publication year - 2008
Publication title -
anaesthesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.839
H-Index - 117
eISSN - 1365-2044
pISSN - 0003-2409
DOI - 10.1111/j.1365-2044.2008.05502.x
Subject(s) - medicine , oxygenation , anesthesia , elective caesarean section , tidal volume , entrainment (biomusicology) , oxygen , ventilation (architecture) , breathing , pregnancy , caesarean section , respiratory system , meteorology , chemistry , biology , rhythm , genetics , physics , organic chemistry
Summary We have investigated the effect of oxygen flow rate on pre‐oxygenation in pregnant patients at term using a circle system. Twenty patients presenting for elective Caesarean section maintained tidal volume breathing through a standard circle system for 3 min. Subjects were pre‐oxygenated using oxygen flow rates of 5 l.min −1 , 10 l.min −1 and 15 l.min −1 presented in random order. The mean (SD) fractional end‐tidal oxygen at the end of 3 min was 0.86 (0.07) for 5 l.min −1 , 0.92 (0.05) for 10 l.min −1 and 0.90 (0.09) for 15 l.min −1 (p < 0.001). Entrainment of air occurred in 22% of pre‐oxygenation sessions. Oxygen flow rates of 10 l.min −1 or above provide optimal pre‐oxygenation using a circle system in term parturients. In our study, entrainment of air occurred in a surprisingly high percentage of cases.