The Impact of Intra-operative Fluid Infusion Rate on Microcirculation

Study Overview
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Brief Summary
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Intraoperative fluid therapy (IFT) is an integral part of anesthesia care during surgery. Its main indication is the optimization of oxygen supply to the tissues. For elective surgery that is not associated with higher blood loss and a long period of preoperative fasting, including fluids IFT is dosed to cover the basal daily need for fluids. However, it is not clear whether this fluid dose is optimal. Surgery is a stress factor that leads, among other things, to damage of the endothelial glycocalyx (EG). EG binds a significant amount of plasma, which is released during EG destruction and causes relative hemodilution. Isovolumic hemodilution is an established intraoperative procedure that serves to better control bleeding in procedures where bleeding is expected. However, partial hemodilution occurs even with standard IFT, and even when fluids are hardly given at all. Flow parameters in microcirculation have not yet been described depending on IFT conduction. The parameters of the microcirculation reflect its functioning, which will consequently affect the postoperative phase of the patient's moaning and clinical outcome.

Detailed Description
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Intraoperative fluid therapy (IFT) is an integral part of anesthesia care during surgery. Its main indication is the optimization of oxygen supply to the tissues. IFT is tailored to the surgical performance, blood loss, and patient (comorbidities, length of preoperative fasting, hydration level, volemia status). For elective surgery that is not associated with higher blood loss (< 200 ml) and a long period of preoperative fasting, including fluids (fluids per os < 2 hours before the procedure), IFT is dosed to cover the basal daily need for fluids (approx. 1-2 ml) /kg.hour-1). However, it is not clear whether this fluid intake is optimal. Surgery is a stress factor that leads, among other things, to damage of the endothelial glycocalyx (EG), which is a thin carbohydrate layer on the endoluminal side of endothelial cells, which is of fundamental importance for the physiology of microcirculation and tissue metabolism. EG also binds a significant amount of plasma (estimated up to 1.7 liters), which is released during EG destruction and causes relative hemodilution. Isovolumic hemodilution is an established intraoperative procedure that serves to better control bleeding in procedures where bleeding is expected (e.g. cardiac surgery using an extracorporeal circuit or vascular surgery). However, partial hemodilution occurs even with standard IFT, and even when fluids are hardly given at all. Flow parameters in microcirculation have not yet been described depending on IFT conduction. The parameters of the microcirculation reflect its functioning, which will consequently affect the postoperative phase of the patient's moaning and clinical outcome.

Official Title
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The Impact of Intra-operative Fluid Infusion Rate on Hemodilution and Microcirculation Prospective Observational Pilot Study

Conditions
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Fluid Therapy, Microcirculation, Hemodilution

Intervention / Treatment
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* Drug: Crystalloid Solutions


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: elective recumbent and laparoscopic surgery informed consent Exclusion Criteria: blood loss over 250 ml hemodynamic instability requiring noradrenaline infusion

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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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 10 % hemodilution<br>Recumbent surgery: infusion rate in first 20 minutes: 15 ml/kg/h infusion rate after 20 minutes: 2,6 ml/kg/h Laparoscopic surgery: infusion rate in first 20 minutes: 16 ml/kg/h infusion rate after 20 minutes: 0,8 ml/kg/h | Drug: Crystalloid Solutions<br>* Locally approved crystalloid solution will be given at the predefined infusion rate<br>|
| Experimental: 20 % hemodilution<br>Recumbent surgery: infusion rate in first 20 minutes: 26 ml/kg/h infusion rate after 20 minutes: 3,4 ml/kg/h Laparoscopic surgery: infusion rate in first 20 minutes: 28 ml/kg/h infusion rate after 20 minutes: 1,6 ml/kg/h | Drug: Crystalloid Solutions<br>* Locally approved crystalloid solution will be given at the predefined infusion rate<br>|
| Experimental: 30 % hemodilution<br>Recumbent surgery: infusion rate in first 20 minutes: 38 ml/kg/h infusion rate after 20 minutes: 5,1 ml/kg/h Laparoscopic surgery: infusion rate in first 20 minutes: 44 ml/kg/h infusion rate after 20 minutes: 2,4 ml/kg/h | Drug: Crystalloid Solutions<br>* Locally approved crystalloid solution will be given at the predefined infusion rate<br>|
| No Intervention: Standart care<br>Infusion rate based upon the standard care. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sublingual microcirculation profile | During one hour four measurements each 20 minutes will take place. Recordings will be assessed automatically by specialised software. Microcirculatory parameters of interest are: capillary density, De Backer score, perfused capillary density and proportion of perfused vessels. Capillary density comes in mm/mm2 and the higher number the better, there is not approved median number. De Backer score is derived from capillary density and it is without dimension. Perfused capillary density signifies a percent of perfused vessels and it is in %. Normal values in healthy adults are around 90 %. | 1 hour |