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This study will establish the feasibility and preliminary validity of real-time oxygen delivery index (DO₂i) monitoring using noninvasive hemoglobin (SpHb, Masimo) and minimally invasive cardiac output (FloTrac, Edwards) in cardiac surgery patients.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Cardiac surgery patients | The study uses a within-patient repeated-measures design, where each patient serves as their own control across the three timepoints. The following measures will be recorded:
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| SpHb monitor | Device | The SpHb monitor is an FDA approved device being used according to its approved indications. No additional invasive procedures, blood draws, or interventions are performed for research purposes. |
| Measure | Description | Time Frame |
|---|---|---|
| Agreement Between SpHb-Based and Pulmonary Artery Catheter Oxygen Delivery Index | Bias and 95% limits of agreement between monitor-derived DO₂i (calculated from continuous SpHb and FloTrac cardiac index) and pulmonary artery catheter DO₂i (calculated from arterial blood gas hemoglobin and Swan-Ganz cardiac index), analyzed using Bland-Altman method with mixed-effects modeling to account for repeated measures. Agreement is considered acceptable if percentage error is <30%. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post-protamine |
| Measure | Description | Time Frame |
|---|---|---|
| Directional Agreement for Changes in Oxygen Delivery Index | Four-quadrant concordance rate (with 15% exclusion zone) for directional changes in DO₂i between consecutive timepoints. Concordance is defined as agreement in direction of change (increase vs decrease) between monitor-derived and gold-standard DO₂i measurements. Scores range from 0- 100%, with higher percentages indicating better directional agreement. |
| Measure | Description | Time Frame |
|---|---|---|
| Major Adverse Cardiac Events (Exploratory) | Composite endpoint including all-cause mortality, myocardial infarction (elevated troponin with ECG changes or clinical symptoms), stroke (new neurologic deficit with imaging confirmation), or urgent revascularization. | Within 30 days of surgery |
| Acute Kidney Injury (Exploratory) |
Inclusion Criteria:
Exclusion Criteria:
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Adults undergoing cardiac surgery
| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Sherilyn Landree | Contact | (612) 282-3705 | landr184@umn.edu |
| Name | Affiliation | Role |
|---|---|---|
| Benjamin Gorbaty, MD | University of Minnesota | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Minnesota | Minneapolis | Minnesota | 55455 | United States |
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| Changes between consecutive intraoperative timepoints (baseline to post-heparin, post- heparin to post-protamine) during cardiac surgery |
| Correlation Between Oxygen Delivery Index and Arterial Lactate | Pearson or Spearman correlation coefficient between DO₂i (both monitor-derived and gold- standard) and simultaneously measured arterial lactate concentration. Correlation coefficients range from -1 to +1, with negative values indicating inverse relationship between DO₂i and lactate. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post- protamine |
| Agreement Between FloTrac and Swan-Ganz Cardiac Index | Percentage error between FloTrac arterial pressure-based cardiac index and Swan-Ganz thermodilution continuous cardiac index. Percentage error is calculated as (1.96 × SD of differences) / mean cardiac index × 100%. Agreement is considered acceptable if percentage error is <30%. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post- protamine |
| Impact of Baseline SpHb Calibration on Agreement | Comparison of limits of agreement before and after in vivo SpHb calibration (baseline- adjusted SpHb using first arterial blood gas hemoglobin value as reference). Measured as change in bias and 95% limits of agreement between uncalibrated and baseline-calibrated SpHb-based DO₂i compared to gold standard. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post- protamine |
| SpHb Signal Usability Rate | Percentage of planned timepoints with valid SpHb signal defined by perfusion index (PI) ≥ 0.5. Scores range from 0-100%, with 100% indicating valid signal at all timepoints. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post- protamine |
| Perfusion Index Threshold for Acceptable SpHb Accuracy | Minimum perfusion index value associated with acceptable SpHb accuracy, defined as SpHb bias within ±1 g/dL of arterial blood gas hemoglobin. Perfusion index values range from 0-20%, with higher values indicating better peripheral perfusion. | Three intraoperative timepoints during cardiac surgery: baseline, post-heparin, and post- protamine |
AKI defined and staged using KDIGO criteria based on postoperative serum creatinine changes: Stage 1 (1.5-1.9× baseline or ≥0.3 mg/dL increase), Stage 2 (2.0-2.9× baseline), Stage 3 (≥3× baseline or ≥4.0 mg/dL or initiation of renal replacement therapy). |
| Within 30 days of surgery |