Intra-operative Monitoring of Blood Loss

Study Overview
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Brief Summary
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Certain types of surgery are associated with occult blood loss, which is hard to detect intraoperatively by intermittent conventional, invasive Hb concentration measurements using the clinical standard of Hb monitoring by satellite laboratory analysis (Hbsatlab). The investigators want to see whether continuous non-invasive transcutaneous Hb measurement using a finger sensor (SpHb), (a) reduces the total time (area under the curve, AUC) a patient's Hb is below a predetermined transfusion threshold (HbAUC) for administration of red blood cell concentrate (RBC), and (b) prevents a decrease in total oxygen delivery (DO2) possibly associated with transfusion below a critical haemoglobin concentration. Furthermore, the investigators want to study if SpHb monitoring changes the timing of RBC administration and reduces the need for intra- and post-operative RBC transfusion.

Official Title
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Monitoring of Intraoperative Blood Loss: Benefit of Continuous Noninvasive Haemoglobin Monitoring?

Conditions
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Undetected Intraoperative Blood Loss

Intervention / Treatment
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* Procedure: blood transfusion, intermittent Hbsatlab measurement
* Procedure: blood transfusion, based on continuous SpHb readings


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients at the age of 18 years or older, planned for elective surgery at-risk for undetected blood loss. American Society of Anesthesiologists (ASA) classification I, II, III, IV Exclusion Criteria: Patient refusal Emergency surgery

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Hb group:15 patients<br>scheduled for elective surgery associated with undetected, i.e., difficult to reliably monitor intraoperative blood loss. | Procedure: blood transfusion, intermittent Hbsatlab measurement<br>* In the Hbsatlab group, RBC administration and its timing will be based on intermittent Hbsatlab measurement (routine care)<br>|
| SpHb group: 15 patients<br>scheduled for elective surgery associated with undetected, i.e., difficult to reliably monitor intraoperative blood loss. | Procedure: blood transfusion, based on continuous SpHb readings<br>* RBC administration and its timing will be based on continuous SpHb readings while Hbsatlab values, measured every 30 min. by an objective observer, will not be visible to the attending anaesthetist.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| HbAUC | the total time a patient's Hb is below a predetermined transfusion threshold (HbAUC) for administration of red blood cell concentrate | during operation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| blood transfusions | the number of perioperative blood transfusions | intra- and post operative up to 48h |