Clinical Validation of a Blood Loss Monitoring System

Prospective Multicenter Clinical Validation of a Novel Multifunctional Intraoperative Blood Loss Monitoring System

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.

Study Overview

• Status: Enrolling by invitation
• Conditions: Intraoperative Blood Loss

• Study Type: Observational
• Enrollment (Estimated): 120

Contacts and Locations

Study Locations

• China
  • Gansu
    • Lanzhou, Gansu, China, 730030
      • Lanzhou University Second Hospital
    • Lanzhou, Gansu, China, 730030
      • Lanzhou University Frist Hospital
    • Lanzhou, Gansu, China, 730030
      • Gansu Provincial People's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population will be recruited from adult patients undergoing elective urological and general surgical procedures at two tertiary hospitals in China, including Lanzhou University Second Hospital and Lanzhou University First Hospital. Participants will be selected from routine clinical practice settings where intraoperative blood loss monitoring is required. This population represents adult surgical patients managed under standard perioperative care, providing a real-world clinical context for evaluating intraoperative blood loss measurement methods.

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Self-controlled; This study includes a single self-controlled cohort of patients undergoing urological and general surgical procedures. All participants will undergo simultaneous intraoperative blood loss assessment using five different methods within the same surgical procedure: a novel multifunctional intraoperative blood loss monitoring system, the direct measurement method (reference standard), visual estimation, the gravimetric method, and the hemoglobin concentration-based method. No intervention is applied in this observational study. All measurements are performed according to a predefined protocol and do not interfere with the standard surgical workflow. The purpose of this design is to enable within-subject comparison of measurement accuracy across different methods under identical clinical conditions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Absolute error of the automatic intraoperative blood loss monitor compared with the direct measurement method	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)	At the end of surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage error of the automatic intraoperative blood loss monitor compared with the direct measurement method	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	At the end of surgery
Absolute error of visual estimation compared with the direct measurement method	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	At the end of surgery
Absolute error of the gravimetric method compared with the direct measurement method	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	At the end of surgery
Absolute error of the hemoglobin concentration-based method compared with the direct measurement method	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	24 hours after surgery
Intraclass correlation coefficient between the automatic intraoperative blood loss monitor and the direct measurement method	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	At the end of surgery
Bland-Altman mean bias between the automatic intraoperative blood loss monitor and the direct measurement method	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.	Unit of Measure: Milliliters
Bland-Altman limits of agreement between the automatic intraoperative blood loss monitor and the direct measurement method	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	At the end of surgery

Collaborators and Investigators

• Sponsor: Lanzhou University Second Hospital
• Collaborators: Lanzhou University First Hospital

Study record dates

Study Major Dates

• Study Start (Actual): September 10, 2025
• Primary Completion (Estimated): May 30, 2026
• Study Completion (Estimated): May 30, 2026

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 23, 2026
• First Posted (Actual): June 1, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: May 31, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: blood loss; Clinical Validation; Monitoring Equipment
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Hemorrhage
• Other Study ID Numbers: 2025A-987

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: The clinical data involves sensitive patient privacy. We are currently undecided on sharing the IPD, as it requires specific informed consent from the patients and authorization from the hospital's ethics committee.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No