Abstract
BACKGROUND: The use of intraoperative pulse oximetry (Spo 2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo 2 may be reported as 98% when arterial partial pressure of oxygen (Pao 2) is as low as 70 mm Hg. Therefore, Spo 2 may not provide advance warning of falling arterial oxygenation until Pao 2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo 2 is >98%. This study evaluates the ORI to Pao 2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao 2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao 2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao 2 and ORI and for the unequal time intervals of Pao 2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao 2 of 100 and 150 mm Hg. ORI and Pao 2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao 2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao 2 relationship was stronger for Pao 2 to 240 mm Hg (r 2 = 0.536) than for Pao 2 over 240 mm Hg (r 2 = 0.0016). Measured Pao 2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao 2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao 2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019-0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao 2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040-0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao 2 ≥100 mm Hg when Spo 2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao 2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao 2 approaching 100 mm Hg when Spo 2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 626-633 |
| Number of pages | 8 |
| Journal | Anesthesia and Analgesia |
| Volume | 123 |
| Issue number | 3 |
| DOIs | |
| State | Published - Sep 1 2016 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Anesthesiology and Pain Medicine
Cite this
The Relationship between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen during Surgery. / Applegate, Richard Lee; Dorotta, Ihab L.; Wells, Briana; Juma, David; Applegate, Patricia.
In: Anesthesia and Analgesia, Vol. 123, No. 3, 01.09.2016, p. 626-633.Research output: Contribution to journal › Article
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TY - JOUR
T1 - The Relationship between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen during Surgery
AU - Applegate, Richard Lee
AU - Dorotta, Ihab L.
AU - Wells, Briana
AU - Juma, David
AU - Applegate, Patricia
PY - 2016/9/1
Y1 - 2016/9/1
N2 - BACKGROUND: The use of intraoperative pulse oximetry (Spo 2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo 2 may be reported as 98% when arterial partial pressure of oxygen (Pao 2) is as low as 70 mm Hg. Therefore, Spo 2 may not provide advance warning of falling arterial oxygenation until Pao 2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo 2 is >98%. This study evaluates the ORI to Pao 2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao 2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao 2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao 2 and ORI and for the unequal time intervals of Pao 2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao 2 of 100 and 150 mm Hg. ORI and Pao 2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao 2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao 2 relationship was stronger for Pao 2 to 240 mm Hg (r 2 = 0.536) than for Pao 2 over 240 mm Hg (r 2 = 0.0016). Measured Pao 2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao 2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao 2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019-0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao 2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040-0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao 2 ≥100 mm Hg when Spo 2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao 2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao 2 approaching 100 mm Hg when Spo 2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.
AB - BACKGROUND: The use of intraoperative pulse oximetry (Spo 2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo 2 may be reported as 98% when arterial partial pressure of oxygen (Pao 2) is as low as 70 mm Hg. Therefore, Spo 2 may not provide advance warning of falling arterial oxygenation until Pao 2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo 2 is >98%. This study evaluates the ORI to Pao 2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao 2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao 2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao 2 and ORI and for the unequal time intervals of Pao 2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao 2 of 100 and 150 mm Hg. ORI and Pao 2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao 2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao 2 relationship was stronger for Pao 2 to 240 mm Hg (r 2 = 0.536) than for Pao 2 over 240 mm Hg (r 2 = 0.0016). Measured Pao 2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao 2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao 2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019-0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao 2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040-0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao 2 ≥100 mm Hg when Spo 2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao 2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao 2 approaching 100 mm Hg when Spo 2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.
UR - http://www.scopus.com/inward/record.url?scp=84961392525&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84961392525&partnerID=8YFLogxK
U2 - 10.1213/ANE.0000000000001262
DO - 10.1213/ANE.0000000000001262
M3 - Article
VL - 123
SP - 626
EP - 633
JO - Anesthesia and Analgesia
JF - Anesthesia and Analgesia
SN - 0003-2999
IS - 3
ER -