Higher fraction of inspired oxygen in anesthesia induction does not affect functional residual capacity reduction after
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ORIGINAL ARTICLE
Higher fraction of inspired oxygen in anesthesia induction does not affect functional residual capacity reduction after intubation: a comparative study of higher and lower oxygen concentration Akihiro Kanaya • Daizoh Satoh • Shin Kurosawa
Received: 14 June 2012 / Accepted: 16 December 2012 / Published online: 18 January 2013 Ó Japanese Society of Anesthesiologists 2013
Abstract Background Low fraction of inspired oxygen (FIO2) reduces the atelectasis area during anesthesia induction. However, atelectasis may occur during laryngoscopy and endotracheal intubation because lungs can collapse within a fraction of a second. We assessed the effects of ventilation with 100 and 40 % oxygen on functional residual capacity (FRC) in patients undergoing general anesthesia. Methods Twenty patients scheduled for elective open abdominal surgery were randomized into 40 % oxygen (GI, n = 10) and 100 % oxygen (GII, n = 10) groups and FRC was measured. Preoxygenation and mask ventilation with 40 and 100 % oxygen were used in GI and GII, respectively. In both groups, 40 % oxygen was used for anesthesia maintenance after intubation. Bilateral lung ventilation was performed with volume guarantee and low tidal volume (7 ml/kg predicted body weight) using bilevel airway pressure. We measured FRC and blood gas in all patients during preoxygenation, after intubation, and during surgery. Results FRC decreased from during preoxygenation (GI 2380 ml, GII 2313 ml) to after intubation (GI 1569 ml, GII 1586 ml) and significantly decreased during surgery (GI
This study was presented at the Annual Meeting of the American Society of Anesthesiologists, Chicago, Illinois, October 17, 2011. A. Kanaya (&) S. Kurosawa Department of Anesthesiology and Intensive Care, Tohoku University Hospital, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan e-mail: [email protected] D. Satoh Department of Anesthesiology and Perioperative Medicine, Tohoku University Hospital, Sendai, Japan
1338 ml, GII 1417 ml) (P \ 0.05). PaO2/FIO2 decreased from during preoxygenation (GI 419 mmHg, GII 427 mmHg) to after intubation (GI 381 mmHg, GII 351 mmHg) and significantly decreased during surgery (GI 333 mmHg, GII 291 mmHg) (P \ 0.05). No significant differences were found between the groups in both parameters. Conclusions FRC significantly decreased from the awake state to surgery in both groups. FRC was not influenced by FIO2 elevation at anesthesia induction. Keywords Functional residual capacity Absorption atelectasis Oxygen concentration
Introduction Absorption atelectasis may occur with the use of high oxygen concentrations during preoxygenation, induction, and maintenance of general anesthesia [1]. This has been shown by chest computed tomography [1, 2]. However, preoxygenation using 100 % oxygen and replacement of all alveolar nitrogen with oxygen are advantageous when mask ventilation and intubation difficulties occur during induction of general anesthesia. Clinically, preoxygenation is considered adequate when the end-tidal oxygen (FE
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