Intraoperative Blood Loss
Conditions
Keywords
blood loss, Clinical Validation, Monitoring Equipment
Brief summary
This observational study aims to evaluate the practicality of a novel multifunctional intraoperative blood loss monitoring system in real-world surgical settings. The primary questions it seeks to address are: Using the direct measurement method as the reference standard, what is the magnitude of measurement error of the monitoring system, and does it tend to overestimate or underestimate blood loss? Does the monitoring system demonstrate superior accuracy compared with visual estimation, the gravimetric method, and the hemoglobin concentration-based method? During surgery, intraoperative blood loss will be measured simultaneously using five approaches: the novel multifunctional monitoring system, the direct measurement method, visual estimation, the gravimetric method, and the hemoglobin concentration method. These measurements will be conducted without interfering with the surgical procedure.
Interventions
None listed
Sponsors
Lanzhou University Second Hospital
Lanzhou University First Hospital
Study design
Observational model
CASE_ONLY
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Patients undergoing elective urological or general surgical procedures * Age 18 years or older * Preoperative hemoglobin concentration available * Intraoperative blood loss assessment required during surgery
Exclusion criteria
* Patients with incomplete intraoperative blood loss measurement data, * Severe hemolysis or other conditions that may affect hemoglobin measurement * Emergency surgery * Intraoperative blood loss assessment required during surgery 24 hours after surgery * Refusal to participate, when applicable
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Absolute error of the automatic intraoperative blood loss monitor compared with the direct measurement method | At the end of surgery | Absolute error is defined as the numerical difference between intraoperative blood loss measured by the automatic intraoperative blood loss monitor and intraoperative blood loss measured by the direct measurement method. A positive value indicates that the monitor overestimates blood loss compared with the direct measurement method, whereas a negative value indicates underestimation. Unit of Measure: Milliliters (mL) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Percentage error of the automatic intraoperative blood loss monitor compared with the direct measurement method | At the end of surgery | Percentage error is defined as the relative difference between intraoperative blood loss measured by the automatic intraoperative blood loss monitor and intraoperative blood loss measured by the direct measurement method, expressed as a percentage of the average value obtained by the two methods. A positive value indicates overestimation by the monitor, whereas a negative value indicates underestimation. Unit of Measure: Percentage |
| Absolute error of visual estimation compared with the direct measurement method | At the end of surgery | Absolute error is defined as the numerical difference between intraoperative blood loss estimated by visual estimation and intraoperative blood loss measured by the direct measurement method. A positive value indicates overestimation by visual estimation, whereas a negative value indicates underestimation. Unit of Measure: Milliliters |
| Absolute error of the gravimetric method compared with the direct measurement method | At the end of surgery | The accuracy of five methods (monitoring system, direct measurement, visual Absolute error is defined as the numerical difference between intraoperative blood loss estimated by the gravimetric method and intraoperative blood loss measured by the direct measurement method. A positive value indicates overestimation by the gravimetric method, whereas a negative value indicates underestimation. Unit of Measure: Milliliters |
| Absolute error of the hemoglobin concentration-based method compared with the direct measurement method | 24 hours after surgery | Absolute error is defined as the numerical difference between blood loss estimated by the hemoglobin concentration-based method and intraoperative blood loss measured by the direct measurement method. The hemoglobin concentration-based estimate is calculated using preoperative hemoglobin concentration, hemoglobin concentration measured 24 hours after surgery, and estimated blood volume. A positive value indicates overestimation by the hemoglobin concentration-based method, whereas a negative value indicates underestimation. Unit of Measure: Milliliters |
| Intraclass correlation coefficient between the automatic intraoperative blood loss monitor and the direct measurement method | At the end of surgery | The intraclass correlation coefficient is used to quantify agreement between intraoperative blood loss measured by the automatic intraoperative blood loss monitor and intraoperative blood loss measured by the direct measurement method. Higher values indicate stronger agreement between the two methods. Unit of Measure: Unitless coefficient |
| Bland-Altman mean bias between the automatic intraoperative blood loss monitor and the direct measurement method | Unit of Measure: Milliliters | Bland-Altman mean bias is defined as the mean difference between intraoperative blood loss measured by the automatic intraoperative blood loss monitor and intraoperative blood loss measured by the direct measurement method. A positive mean bias indicates systematic overestimation by the monitor, whereas a negative mean bias indicates systematic underestimation. |
| Bland-Altman limits of agreement between the automatic intraoperative blood loss monitor and the direct measurement method | At the end of surgery | Bland-Altman limits of agreement describe the range within which most differences between intraoperative blood loss measured by the automatic intraoperative blood loss monitor and intraoperative blood loss measured by the direct measurement method are expected to fall. Unit of Measure: Milliliters |
Countries
China
Outcome results
None listed