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Adjustment of oxygen reserve index (ORi™) to avoid excessive hyperoxia during general anesthesia

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The Oxygen Reserve Index (ORi™) is a non-invasive variable that reflects oxygenation continuously. The aims of this study were to examine the relationship between arterial partial pressure of oxygen (PaO2) and ORi during general anesthesia, and to investigate the usefulness of ORi as an indicator to avoid hyperoxia. Twenty adult patients who were scheduled for surgery under general anesthesia with arterial catheterization were enrolled. After induction of general anesthesia, inspired oxygen concentration (FiO2) was set to 0.33, and arterial blood gas analysis was performed. The PaO2 and ORi at the time of blood collection were recorded. After that, FiO2 was changed to achieve an ORi around 0.5, 0.2, and 0, followed by arterial blood gas analysis. The relationship between ORi and PaO2 was then investigated using the data obtained. Eighty datasets from the 20 patients were analyzed. When PaO2 was less than 240 mmHg (n = 69), linear regression analysis showed a relatively strong positive correlation (r2 = 0.706). The cut-off ORi value obtained from the receiver operating characteristic curve to detect PaO2 ≥ 150 mmHg was 0.21 (sensitivity 0.950, specificity 0.755). Four-quadrant plot analysis showed that the ORi trending of PaO2 was good (concordance rate was 100.0%). Hyperoxemia can be detected by observing ORi of patients under general anesthesia, and thus unnecessary administration of high concentration oxygen can possibly be avoided.

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  1. Pedersen T, Nicholson A, Hovhannisyan K, Moller AM, Smith AF, Lewis SR. Pulse oximetry for perioperative monitoring. Cochrane Database Syst Rev. 2014.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Collins JA, Rudenski A, Gibson J, Howard L, O’Driscoll R. Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve. Breathe. 2015;11:194–201.

    Article  PubMed  PubMed Central  Google Scholar 

  3. Aboab J, Jonson B, Kouatchet A, Taille S, Niklason L, Brochard L. Effect of inspired oxygen fraction on alveolar derecruitment in acute respiratory distress syndrome. Intensiv Care Med. 2006;32:1979–86.

    Article  Google Scholar 

  4. Damiani E, Adrario E, Girardis M, Romano R, Pelaia P, Singer M, Donati A. Arterial hyperoxia and mortality in critically ill patients: a systematic review and meta-analysis. Crit Care. 2014;18:711.

    Article  PubMed  PubMed Central  Google Scholar 

  5. Rincon F, Kang J, Maltenfort M, Vibbert M, Urtecho J, Athar MK, Jallo J, Pineda CC, Tzeng D, McBride W, Bell R. Association between hyperoxia and mortality after stroke: a multicenter cohort study. Crit Care Med. 2014;42:387–96.

    Article  PubMed  Google Scholar 

  6. Kallet RH, Matthay MA. Hyperoxic acute lung injury. Respir Care. 2013;58:123–41.

    Article  PubMed  PubMed Central  Google Scholar 

  7. Suzuki S, Eastwood GM, Peck L, Glassford NJ, Bellomo R. Current oxygen management in mechanically ventilated patients: a prospective observational cohort study. J Crit Care. 2013;28:647–54.

    Article  Google Scholar 

  8. de Graaff AE, Dongelmans DA, Binnekade JM, de Jonge E. Clinicians’ response to hyperoxia in ventilated patients in a Dutch ICU depends on the level of FiO2. Intensiv Care Med. 2011;37:46–51.

    Article  Google Scholar 

  9. Saugel B, Belda FJ. The oxygen reserve index in anesthesiology: a superfluous toy or a tool to individualize oxygen therapy? Minerva Anestesiol. 2018;84:1010–2.

    Article  PubMed  Google Scholar 

  10. Scheeren TWL, Belda FJ, Perel A. The oxygen reserve index (ORI): a new tool to monitor oxygen therapy. J Clin Monit Comput. 2018;32:379–89.

    Article  CAS  PubMed  Google Scholar 

  11. Szmuk P, Steiner JW, Olomu PN, Ploski RP, Sessler DI, Ezri T. Oxygen reserve index: a novel noninvasive measure of oxygen reserve—a pilot study. Anesthesiology. 2016;124:779–84.

    Article  CAS  PubMed  Google Scholar 

  12. Yoshida K, Isosu T, Noji Y, Hasegawa M, Iseki Y, Oishi R, Imaizumi T, Sanbe N, Obara S, Murakawa M. Usefulness of oxygen reserve index (ORi™), a new parameter of oxygenation reserve potential, for rapid sequence induction of general anesthesia. J Clin Monit Comput. 2018;32:687–91.

    Article  PubMed  Google Scholar 

  13. Niwa Y, Shiba J, Fujita H, Oka R, Takeuchi M. Oxygen reserve index (ORi™) contributes to prediction of hypoxemia and patient safety during tracheal stent insertion using rigid bronchoscopy: a case report. J Clin Monit Comput. 2018;1:2.

    Article  Google Scholar 

  14. Koishi W, Kumagai M, Ogawa S, Hongo S, Suzuki K. Monitoring the oxygen reserve index can contribute to the early detection of deterioration in blood oxygenation during one-lung ventilation. Minerva Anestesiol. 2018;84:1063–9.

    Article  PubMed  Google Scholar 

  15. Kanda Y. Investigation of the freely available easy-to-use software ‘EZR’ for medical statistics. Bone Marrow Transpl. 2013;48:452–8.

    Article  CAS  Google Scholar 

  16. Applegate RL 2nd, Dorotta IL, Wells B, Juma D, Applegate PM. The relationship between oxygen reserve index and arterial partial pressure of oxygen during surgery. Anesth Analg. 2016;123:626–33.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. Critchley LA, Lee A, Ho AM. A critical review of the ability of continuous cardiac output monitors to measure trends in cardiac output. Anesth Analg. 2010;111:1180–92.

    Article  Google Scholar 

  18. Vos JJ, Willems CH, van Amsterdam K, van den Berg JP, Spanjersberg R, Struys MMRF, Scheeren TWL. Oxygen reserve index: validation of a new variable. Anesth Analg. 2018.

    Article  Google Scholar 

  19. de Jonge E, Peelen L, Keijzers PJ, Joore H, de Lange D, van der Voort PH, Bosman RJ, de Waal RA, Wesselink R, de Keizer NF. Association between administered oxygen, arterial partial oxygen pressure and mortality in mechanically ventilated intensive care unit patients. Crit Care. 2008;12:R156.

    Article  PubMed  PubMed Central  Google Scholar 

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Correspondence to Keisuke Yoshida.

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The authors declare that they have no conflict of interest.

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This study was approved by the Ethics Committee of Fukushima Medical University (No. 2636) and has been performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

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Written informed consent was obtained from all individual participants included in the study.

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Yoshida, K., Isosu, T., Noji, Y. et al. Adjustment of oxygen reserve index (ORi™) to avoid excessive hyperoxia during general anesthesia. J Clin Monit Comput 34, 509–514 (2020).

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