When Seconds Count, Buy More Time

Oxygen concentration titration guided by oxygen reserve index during pediatric laryngeal surgery with high-flow nasal cannula oxygen: a randomized controlled trial

PURPOSE

The objective of this study was to evaluate whether adjusting the oxygen concentration guided by the Oxygen Reserve Index (ORI) during pediatric laryngeal surgery with High Flow Nasal Cannula Oxygen (HFNO) could achieve postoperative PaO2 close to physiological levels while ensuring adequate oxygenation in surgery.

METHODS

Sixty pediatric patients undergoing laryngeal surgery or examination were randomly assigned to two groups. The ORI group received oxygen concentration adjustments every 5 min to maintain a target ORI value of 0.21, whereas the control group did not undergo any adjustments. Postoperative PaO2, time weighted average fraction of inspired oxygen (FiO2), and mean Peripheral Oxygen Saturation (SpO2) were compared between groups. Finally, some analyses were conducted to examine the relationship of ORI with PaO2.

RESULTS

In general, the postoperative PaO2 was 164.9 ± 48.8 mmHg in ORI group and 323.0 ± 87.7 mmHg in control group (P < 0.01). The time weighted average FiO2 in the ORI group was 85.9 [81.8-92.7] %. There was no significant difference in mean SpO2 between the two groups (ORI vs. control: 98.4 [97.7-99.2] vs. 98.8 [97.7-99.5]; P = 0.36). According to the analyses, the optimal cut value for ORI was determined to be 0.195 when PaO2 was 150 mmHg.

CONCLUSIONS

In pediatric laryngeal surgery with HFNO, reducing oxygen concentration guided by ORI helped achieve postoperative PaO2 levels closer to physiological norms without compromising intra-operative oxygenation.

Use of oxygen reserve index during bronchoscopic balloon dilation for subglottic stenosis in a patient with left ventricular assist device implantation -a case report

BACKGROUND

Monitoring the oxygenation status is crucial during general anesthesia to ensure patient safety. Although noninvasive pulse oximetry is commonly used to monitor percutaneous oxygen saturation (SpO2), it may not accurately reflect changes in oxygen partial pressure when the latter is excessively high or low. The oxygen reserve index (ORi) provides real-time information about the oxygen reserve status.

CASE

We present a case of successful management of subglottic stenosis using balloon bronchoscopy in an infant with a left ventricular assist device implantation under ORi monitoring to predict hypoxemia during the surgical procedure.

CONCLUSIONS

Utilizing ORi monitoring during anesthesia for procedures involving apnea in critically ill infants can help predict impending desaturation before a drop in SpO2 occurs, allowing anesthesiologists to effectively anticipate and manage the apnea period. Continuous ORi monitoring offers valuable insights during surgical procedures, especially in infants with compromised respiratory and cardiovascular functions.

Anesthetic management in a patient with severe tracheal stenosis by monitoring oxygen reserve index

Background

General anesthesia for tracheal stenting is challenging because of difficult ventilation and accompanying hypoxia. We report the use of oxygen reserve index (ORi™) during tracheal stenting.

Case presentation

Cauterization of an intratracheal tumor and tracheal stenting was scheduled in a patient. ORi decreased from 0.3 to 0.2 after starting cauterization using a flexible bronchoscope through a tracheal tube with 28% oxygen, while SpO₂ was maintained at 100%. ORi further decreased to 0, followed by a decrease of SpO₂ < 90%, and surgery was interrupted. SpO₂ was increased shortly after increasing FiO₂ to 1.0, but ORi remained 0 when surgery was resumed; it was increased after completion of cauterization. Both ORi and SpO₂ were maintained above 0.4 and 98%, respectively, during tracheal stenting through a rigid bronchoscope under intrapulmonary percussive ventilation.

Conclusion

ORi was useful for predicting a decrease of SpO₂ under general anesthesia for tracheal stenting.

The outcomes of using high oxygen concentration in pediatric patients

Oxygen reserve index, available as part of Masimo Rainbow SET pulse oximetry, is a noninvasive and continuous variable intended to provide insight into a patient's oxygen status in the moderate hyperoxic range (PaO₂ > 100 and ≤ 200 mm Hg), defined as a patient's oxygen "reserve". When used in conjunction with pulse oximetry, ORi extends the knowledge on a patient's oxygen status providing clinically important information helping to prevent hyperoxemia and hypoxemia. There are limited data on patients undergoing craniosynostosis surgery. Our primary goal was to evaluate the effects of different concentrations of inspiratory oxygen (FiO₂) on patient oxygenation status by monitoring ORi. Thirty patients scheduled for craniosynostosis were included in this observational cohort study. Patients were randomized into two equal groups: Group 1 received a fraction of inspired oxygen of 0.8 and group 2 received a FiO₂ of 0.6 during induction of anaesthesia. In addition to standard haemodynamic variables with ORi were recorded at baseline 1 min, 5 min, 60 min, and 120 min after intubation. Postoperative complications, length of stay in the intensive care unit and hospital were recorded. In total, 14 patients were evaluated in each group. Gender, age, BMI, ASA scores were similar between groups (p > 0.05). In Group 1, ORi values were significantly higher when compared to group 2 at baseline (0.86 ± 0.21 vs 0.45 ± 0.32, p = 0.001), one minute (0.61 ± 0.24 vs 0.27 ± 0.21, p = 0.001), and 5 min (0.34 ± 0.31 vs 0.10 ± 0.13, p = 0.033). High inspired oxygen concentration during induction of anesthesia in pediatric patients is associated with higher levels of ORi. Therefore, ORi may provide the means to safely reduce the inspired oxygen fraction during inhalational induction in paediatric patients.

Oxygen Reserve Index: Utility as an Early Warning for Desaturation in High-Risk Surgical Patients

BACKGROUND

Perioperative pulse oximetry hemoglobin saturation (Spo2) measurement is associated with fewer desaturation and hypoxia episodes. However, the sigmoidal nature of oxygen-hemoglobin dissociation limits the accuracy of estimation of the partial pressure of oxygen (Pao2) >80 mm Hg and correspondingly limits the ability to identify when Pao2 >80 mm Hg but falling. We hypothesized that a proxy measurement for oxygen saturation (Oxygen Reserve Index [ORI]) derived from multiwavelength pulse oximetry may allow additional warning time before critical desaturation or hypoxia. To test our hypothesis, we used a Masimo multiwavelength pulse oximeter to compare ORI and Spo2 warning times during apnea in high-risk surgical patients undergoing cardiac surgery.

METHODS

This institutional review board-approved prospective study (NCT03021473) enrolled American Society of Anesthesiologists physical status III or IV patients scheduled for elective surgery with planned preinduction arterial catheter placement. In addition to standard monitors, an ORI sensor was placed and patients were monitored with a pulse oximeter displaying the ORI, a nondimensional parameter that ranges from 0 to 1. Patients were then preoxygenated until ORI plateaued. Following induction of anesthesia, mask ventilation with 100% oxygen was performed until neuromuscular blockade was established. Endotracheal intubation was accomplished using videolaryngoscopy to confirm placement. The endotracheal tube was not connected to the breathing circuit, and patients were allowed to be apneic. Ventilation was resumed when Spo2 reached 94%. We defined ORI warning time as the time from when the ORI alarm registered (based on the absolute value and the rate of change) until the Spo2 decreased to 94%. We defined the Spo2 warning time as the time for Spo2 to decrease from 97% to 94%. The added warning time provided by ORI was defined as the difference between ORI warning time and Spo2 warning time.

RESULTS

Forty subjects were enrolled. Complete data for analysis were available from 37 patients. The ORI alarm registered before Spo2 decreasing to 97% in all patients. Median (interquartile range [IQR]) ORI warning time was 80.4 seconds (59.7-105.9 seconds). Median (IQR) Spo2 warning time was 29.0 seconds (20.5-41.0 seconds). The added warning time provided by ORI was 48.4 seconds (95% confidence interval [CI], 40.4-62.0 seconds; P < .0001).

CONCLUSIONS

In adult high-risk surgical patients, ORI provided clinically relevant added warning time of impending desaturation compared to Spo2. This additional time may allow modification of airway management, earlier calls for help, or assistance from other providers. The potential patient safety impact of such monitoring requires further study.

Oxygen reserve index, a new method of monitoring oxygenation status: what do we need to know?

The oxygen reserve index (ORI) is a new technology that provides real-time, non-invasive, and continuous monitoring of patients’ oxygenation status. This review aimed to discuss its clinical utility, prospect and limitations. A systematic literature search of PubMed, MEDLINE, Google Scholar, and ScienceDirect was performed with the keywords of “oxygen reserve index,” “ORI,” “oxygenation,” “pulse oximetry,” “monitoring,” and “hyperoxia.” Original articles, reviews, case reports, and other relevant articles were reviewed. All articles on ORI were selected. ORI can provide an early warning before saturation begins to decrease and expands the ability to monitor the human body's oxygenation status noninvasively and continuously with the combination of pulse oximetry so as to avoid unnecessary hyperoxia or unanticipated hypoxia. Although the technology is so new that it is rarely known and has not been applied to routine practices in hospitals, it shows good prospects for critical care, oxygen therapy, and intraoperative monitoring.

The oxygen reserve index (ORI): a new tool to monitor oxygen therapy

Supplemental oxygen is administered in the vast majority of patients in the perioperative setting and in the intensive care unit to prevent the potentially deleterious effects of hypoxia. On the other hand, the administration of high concentrations of oxygen may induce hyperoxia that may also be associated with significant complications. Oxygen therapy should therefore be precisely titrated and accurately monitored. Although pulse oximetry has become an indispensable monitoring technology to detect hypoxemia, its value in assessing the oxygenation status beyond the range of maximal arterial oxygen saturation (SpO₂ ≥97%) is very limited. In this hyperoxic range, we need to rely on blood gas analysis, which is intermittent, invasive and sometimes delayed. The oxygen reserve index (ORI) is a new continuous non-invasive variable that is provided by the new generation of pulse oximeters that use multi-wavelength pulse co-oximetry. The ORI is a dimensionless index that reflects oxygenation in the moderate hyperoxic range (PaO₂ 100-200 mmHg). The ORI may provide an early alarm when oxygenation deteriorates well before any changes in SpO₂ occur, may reflect the response to oxygen administration (e.g., pre-oxygenation), and may facilitate oxygen titration and prevent unintended hyperoxia. In this review we describe this new variable, summarize available data and preliminary experience, and discuss its potential clinical utilities in the perioperative and intensive care settings.