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

Abstract

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 (PaO 2 ) 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 (FiO 2 ) was set to 0.33, and arterial blood gas analysis was performed. The PaO 2 and ORi at the time of blood collection were recorded. After that, FiO 2 was changed to achieve an ORi around 0.5, 0.2, and 0, followed by arterial blood gas analysis. The relationship between ORi and PaO 2 was then investigated using the data obtained. Eighty datasets from the 20 patients were analyzed. When PaO 2 was less than 240 mmHg (n = 69), linear regression analysis showed a relatively strong positive correlation (r 2 = 0.706). The cut-off ORi value obtained from the receiver operating characteristic curve to detect PaO 2 ≥ 150 mmHg was 0.21 (sensitivity 0.950, specificity 0.755). Four-quadrant plot analysis showed that the ORi trending of PaO 2 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. KeywordsOxygen reserve index (ORi) • Arterial partial pressure of oxygen (PaO 2 ) • Hyperoxia • Hyperoxemia

The Use of Oxygen Reserve Index in One-Lung Ventilation and Its Impact On Peripheral Oxygen Saturation, Perfusion Index and Pleth Variability Index

“…[13][14][15][16] ORi is a parameter-driven from this device that is between 0 and 1 values, and it is sensitive to the changes in arterial oxygenation in the blood, with the range of 100 to 200 mmHg. [2,[8][9][10]13,[18][19][20][21] When oxygenation is in the moderate hyperoxic content showing an arterial blood oxygenation value of 100-240 mmHg in arterial blood gas analysis, the pulse oximeter SpO2 value remains 100%, whereas there is a decrease in the value of ORi. [2,[18][19][20][21] In our study, Figure 1 and Table 4 provides data on timedependent correlations between ORi with SpO2.…”

“…Furthermore, hyperoxemia is a potent vasoconstrictor stimulus to the coronary circulation, functioning at the level of the microvascular resistance vessels. [20,21] Tsuchiya et al demonstrated that the PVI could be used to evaluate anesthesia-induced hypotension in patients undergoing general anesthesia without age group classi cation. [23] This technique has been used in patients undergoing mechanical ventilation in the intensive care unit to detect uid responsiveness through respiratory patterns and peripheral perfusion changes.…”

“…Although it could be predicted that ORi would decrease before the decrease in SpO2 during left-sided OLV, the actual extent should be evaluated. [16,[18][19][20][21]When oxygenation is in the moderate hyperoxic range of PaO2 values between 100 and 240 mmHg, ORi decreases, but SpO2 does not. [20] 6.…”

ORi™: a new indicator of oxygenation

“…Vos et al investigated the correlation between PaO 2 and ORi during the administration of oxygen in 20 healthy volunteers, and they also reported that the two values have a strong positive correlation [24]. In addition, regarding the correlation between PaO 2 and ORi during anesthesia under oxygenation, when PaO 2 was less than 240 mmHg (n = 69), linear regression analysis showed a relatively strong positive correlation (r 2 = 0.706) [25].…”

“…In addition, hyperoxia can be detected by monitoring ORi in patients under general anesthesia, and thus the administration of unnecessarily high concentrations of oxygen can possibly be avoided. In fact, there are several reports demonstrating that the use of ORi in managing oxygen levels during and after surgery, and for patients in the intensive care unit (ICU) can prevent exposure to excess oxygen [25,48,49]. In general, high oxygen concentrations are more harmful to infants, children, and older patients than to adults [50].…”