Arterial Elastance: A Predictor of Hypotension Due to Anesthesia Induction

Study Overview
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Brief Summary
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Hypotension is very common during and after anesthesia induction. A prolonged fasting period, a patient's underlying comorbidities, a sympathetic blockade by anesthetic agents, vasodilation, a reduction in preload, and cardiac contractility can cause post-induction hypotension.1,2 The relationship of even short-term hypotension with myocardial damage, renal injury, and stroke has been shown in many studies; therefore, it is very important to provide stable anesthesia induction.3 In current anesthesia practice, we can only intervene when hypotension occurs. If we can identify patients who may experience hypotension during anesthesia induction before it occurs, we can prevent possible postoperative organ dysfunctions by reducing the duration and depth of hypotension with prophylactic fluid and vasopressor administration. We hypothesized that arterial elastance (Ea) values before anesthesia induction could predict post-induction hypotension. To test our hypothesis, we aimed to investigate the reliability of the Ea value, which was monitored preoperatively using the pressure analytical recording method (PRAM) to predict the risk of hypotension that may occur after anesthesia induction.

Detailed Description
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Anesthesia induction-related hypotension is not uncommon and is still challenging for anesthesiologists to predict, despite advanced monitoring techniques. In current anesthesia practices, approximately 20-30% of patients develop hypotension during and after anesthesia induction. In large observational studies, the relationship between intraoperative hypotension and adverse cardiac, renal, and cerebral outcomes has been reported. Approximately one-third of intraoperative hypotension episodes occur during and after the induction of anesthesia, and most can be prevented if foreseeable. Therefore, we need quick and easy markers to predict patients at risk of hypotension to achieve the stable induction of anesthesia. Many studies have used noninvasive and invasive monitoring techniques for the preoperative prediction of hypotension after anesthesia induction. However, most studies evaluate the cardiovascular system with parameters that determine the preload and fluid responsiveness to predict the risk of post-induction hypotension, though the arterial system and its interaction with the ventricle are ignored.The heart and the arterial system are both anatomically and functionally interconnected and do not act independently. The major determinant of cardiovascular system performance and cardiac energetics is ventriculoarterial coupling (VAC). Ea is an indicator of cardiac afterload and arterial tone and can be calculated by the ratio of the end-systolic pressure (ESP) and stroke volume (SV) obtained from arterial wave analysis.Ea provides information about the ESP/SV relationship and dynamic afterload and gives the clinician the opportunity to evaluate VAC indirectly. We hypothesized that Ea values before anesthesia induction could predict post-induction hypotension. To test our hypothesis, we aimed to investigate the reliability of the Ea value, which was monitored preoperatively using the pressure analytical recording method (PRAM) to predict the risk of hypotension that may occur after anesthesia induction.

Official Title
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Arterial Elastance: A Predictor of Hypotension Due to Anesthesia Induction

Conditions
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Hemodynamic Instability, Anesthesia

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with ASA( American Society Of Anesthesiology) physical status 1-3 Underwent major elective surgery Required intra-arterial blood pressure monitoring before induction. Exclusion Criteria: Under 18 years of age Arrhythmia (atrial fibrillation, frequent premature beat) Severe pre-existing lung disease Severe valvular heart disease morbid obesity 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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterial elastance (Ea) measured before anesthesia induction was investigated whether is a predictive parameter for post-induction hypotension in patients undergoing general anesthesia. | Ea ((mmHg m-2ml-1)is an indicator of cardiac afterload and arterial tone and can be calculated by the ratio of the end-systolic pressure (ESP) and stroke volume (SV) obtained from arterial wave analysis. Ea was monitored using the uncalibrated pulse contour device MostCare (Vytech, Vygon, Padova, Italy) before the anesthesia induction | The duration of the study was defined from one minute before induction to 10 minutes after induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stroke volume variation (SVV), measured before anesthesia induction were assessed for prediction of post-induction hypotension in patients undergoing general anesthesia | Stroke volume variation (SVV,%), was monitored using the uncalibrated pulse contour device MostCare (Vytech, Vygon, Padova, Italy). SVV is a parameter used to asses cardiac preload and fluid responsiveness | The duration of the study was defined from one minute before induction to 10 minutes after induction | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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General anesthesia, Arterial elastance, Post-induction hypotension, Monitorization