HPI Index With GDHT in Predicting Hypotension In General Anesthesia Patients

Study Overview
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Brief Summary
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The study will investigate whether the use of Goal Directed Hemodynamic Therapy implemented with the HPI algorithm using a treatment algorithm will reduce the incidence of hypotension and improve treatment of hypotension.

Detailed Description
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The perioperative period is characterized by hemodynamic instability. Intraoperative hypotension (IOH) can be caused by anesthesia drugs, surgical manipulations, hypovolemia or inhibition of the sympathetic nervous system and impairment of baroreflex regulatory mechanisms. In a retrospective analysis performed at the Cleveland Clinic, the risk for acute kidney injury (AKI) and myocardial injury (MI) increased when mean arterial pressure (MAP) was less than 55 mmHg. Further, even short durations of intraoperative hypotension were associated with AKI and MI. Salmasi and coll analyzed whether associations based on relative thresholds were stronger than those based on absolute thresholds regarding blood pressure. They found that there were no clinically important interactions between preoperative blood pressures and the relationship between hypotension and ΜΙ or ΑΚΙ at intraoperative mean arterial blood pressures less than 65 mmHg. Absolute and relative thresholds had comparable ability to discriminate patients with ΜΙ or ΑΚΙ from those without it. The authors concluded that anesthetic management can thus be based on intraoperative pressures without regard to preoperative pressure. In a retrospective cohort study Sun and coll conclude that an increased risk of postoperative stage I AKI occurs when intraoperative MAP was less than 60 mmHg for more than 20 min and less than 55 mmHg for more than 10 min. Hence it is fundamental for the management of any hemodynamically unstable patient the rapid assessment of the factors that determine the cardiovascular collapse, followed by prompt treatment and, ultimately, reversal of the responsible process. Recently a Hypotension Probability Indicator (HPI) algorithm has been developed from Edwards Lifesciences using continuous invasively-measured arterial waveforms to predict hypotension with high accuracy minutes before blood pressure actually decreases. The HPI algorithm can be integrated with a goal-directed hemodynamic treatment (GDHT) to achieve hemodynamic optimization by increasing global blood ﬂow and prevent organ failure. We developed a treatment protocol implementing HPI with GDHT that can be used in general anesthesia patients to guide clinical practice.

Official Title
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Is The Hypotension Probability Indicator With Goal Directed Haemodynamic Treatment Useful In Predicting And Treating Hypotension In General Anesthesia Patients?

Conditions
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Hypotension During Surgery

Intervention / Treatment
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* Device: Flotraq Sensor with EV1000 incorporating the HPI algorithm


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18 years or older Planned to receive general anaesthesia > 2h Planned to receive an arterial line during surgery Aim for MAP of ≥ 65 mmHg during surgery Being able to give written informed consent prior to surgery Exclusion Criteria: Aim for MAP other than 65 mmHg at discretion treating physician Significant hypotension before surgery defined as a MAP <65 Right- or left sided cardiac failure (e.g. LVEF<35%) Known cardiac shunts (significant) Known aortic stenosis (severe) Severe cardiac arrhythmias including atrial fibrillation Requiring dialysis Liver surgery with Pringle maneuver Vascular surgery with clamping of the aorta

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 |
| --- | --- |
| HPI + GDHT treatment<br>HPI + GDHT treatment using the FlowTraQ sensor and EV1000 monitor with the HPI algorithm incorporated following our protocol for hemodynamic treatment (fluids, vasopressors and inotropes) administered | Device: Flotraq Sensor with EV1000 incorporating the HPI algorithm<br>* The HPI algorithm is only available on the EV1000, Hemosphere and Flotrac monitoring systems and requires the use of a Flotrac sensor connected to an arterial line (Edwards Lifesciences Corp., Irvine, CA, USA). The Flotrac sensor has a splitter which enables the splitting of the arterial blood pressure signal to facilitate a blood pressure signal on both the anesthesia machine monitor (standard care) and the HemoSphere monitor (study). In the intervention arm we asked the anesthesiologist and anesthesia nurse to use the study treatment flowchart . If the HPI alarm goes off, which entails both a sound and a flickering light, we ask the anesthesiologist to act upon this alarm immedietaly. Use of the study treatment flowchart ensures that the anesthesiologist has to think about the underlying cause. The HemoSphere/EV1000 with HPI software has a second screen with variables that provide information about the underlying cause of the predicted hypotension.<br>|
| Control<br>Conventional treatment with invasive blood pressure monitoring. Administration of fluids and/or vasopressors are guided by standard hemodynamic parameters at the discretion of the attending physician. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TWA hypotension (measured with Flotrac sensor) | Time weighted average spent in hypotension, defined as MAP <65mmHg for ≥1min | intraoperative, starting 15 minutes after induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of hypotension (measured with Flotrac sensor) | Incidence of hypotension, defined as MAP <65mmHg for ≥1min | intraoperative, starting 15 minutes after induction | 
| Time spent in hypotension (measured with Flotrac sensor) | Time spent in hypotension, in minutes, defined as MAP <65mmHg for ≥1min | intraoperative, starting 15 minutes after induction | 
| Treatment choice (drugs/fluids) | Medication used to prevent/treat hypotension. A study member is present at the OR to make notes | intraoperative, starting 15 minutes after induction | 
| Treatment dose (drugs/fluids) | Dose of medication used to prevent/treat hypotension. A study member is present at the OR to make notes | intraoperative, starting 15 minutes after induction | 
| Time to treatment (drugs/fluids) | time to treatment of hypotension, defined as MAP <65mmHg for ≥1min. | intraoperative, starting 15 minutes after induction | 
| Diagnostic guidance protocol deviations | Diagnostic guidance protocol deviations, a study member is present at the OR to make notes of any protocol deviations. | intraoperative, starting 15 minutes after induction | 
| Postoperative Morbidity | Incidence of complications: cardiac, pulmonary, renal | postoperative, up to 30 days after surgery or until discharge from the hospital | 
| Postoperative Creatinine levels | Measurement if creatinine levels postoperatively | postoperative, up to 30 days after surgery or until discharge from the hospital | 
| Mortality | Incidence of mortality 30 days after surgery | postoperative, up to 30 days after surgery |