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N 2 O‐free low‐flow anesthesia technique for children
Author(s) -
Bozkurt P.,
Saygi Emir N.,
Tomatir E.,
Yeker Y.
Publication year - 2005
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2005.00741.x
Subject(s) - sevoflurane , medicine , anesthesia , oxygen , morphine , room air distribution , oxygen saturation , nitrous oxide , chemistry , physics , organic chemistry , thermodynamics
Background: The use of N 2 O during low‐flow anesthesia (LFA) causes difficulty in predicting inspired gas mixtures and oxygen concentration due to accumulation. An alternative technique, which uses a mixture of oxygen and air and a morphine infusion to replace N 2 O, has been evaluated in children during LFA, and the clinical effects and composition of gases in the system are presented here. Methods: Thirty‐five children aged 2–13 years undergoing major urogenital surgery were recruited into the study. Following a standardized induction, anesthesia was maintained with 2% sevoflurane in combination with a morphine infusion. After induction with 4 l min −1 , flow rates were reduced to 2 l min −1 and finally to 1 l min −1 at 10 min (0.5 l oxygen + 0.5 l air). The delivered oxygen concentration, oxygen saturation and the inspired and expired O 2 , sevoflurane and CO 2 concentrations were recorded from the start of induction to the end of anesthesia. Results: The duration of LFA was 132±89 min. The concentrat‐ion of oxygen delivered by the flow meters during this period was 55–60%. Although the changes in inspired and expired oxygen and sevoflurane and inspired CO 2 related to the duration of LFA were statistically significant ( P < 0.0001), they were not clinically relevant. All vital parameters were stable. Four patients required supplemental morphine and nine presented emergence agitation. Conclusion: We concluded that an N 2 O‐free LFA technique with 0.5 l min −1 of air and 0.5 l min −1 of O 2 supplemented by sevoflurane and a morphine infusion is safe and effective in children. The resulting high‐inspired oxygen concentration prevents occurrence of hypoxic gas mixtures, and the use of supplemental morphine compensates for the absence of N 2 O and overcomes the possibility of light anesthesia arising from a decrease in the inspired sevoflurane concentration.