Continuous Non-invasive Assessment of Blood Pressure in Bariatric Surgery

Study Overview
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Brief Summary
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Comparability of discontinuous non-invasive (sphygomanometric) and continuous semi-invasive and invasive (Masimo© ; Nexfin© Monitoring ; FloTrac© Edwards Lifesciences) beat to beat measurement methods for the determination of arterial blood pressure in patients undergoing bariatric surgery.

Detailed Description
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Comparison between non-invasive discontinuous blood pressure measurement using a sphygomanometric blood pressure cuff, and continuous non-invasive and invasive beat to beat blood pressure measurement methods(Nexfin© and FloTrac©). Bariatric patients show limitations regarding the conventional monitoring options with ECG derivation, pulse oxymetric oxygen saturation and sphygmomanometric blood pressure measurement. From a clinical point of view this results in an invasive arterial blood pressure monitoring . In addition to that, intraoperative extreme changes of the patients position on the table combined with the applied pneumoperitoneum during the minimally invasive laparoscopic surgery can significantly influence the cardiovascular parameters. An invasive arterial blood pressure monitoring is able to reproduce the blood pressure by stroke, but it does not give any information about the cardiac output. The sphygmomanometric blood pressure measurement also entails the risk of insufficient detection of a hypotonic phase in the measurement. Additional monitoring systems are currently available, which are capable of measuring completely non-invasive or semi-invasively different cardiovascular parameters such as cardiac output (CO) and fluid responsiveness. In this study, the investigators will compare continuous and discontinuous cardiovascular monitoring procedures and their parameters. The measurements take place at specific times, under defined changes in the body position with the additional influence of the pneumoperitoneum. These changes are recorded and compared at the same time during different measuring methods preoperatively, intraoperatively and postoperatively. The non-invasive Nexfin© Monitoring (Edwards Lifesciences) is to be evaluated and compared with further measurement methods (FloTrac© (Edwards Lifesciences)) as well as the sphygmomanometric upper arm blood pressure measurement. The investigators also compare the non-invasive and invasive continuous beat to beat blood pressure measurement with conventional, discontinuous sphygomanometric upper arm blood pressure measurement. The planned study is the comparison of 3 different hemodynamic monitoring procedures. For the evaluation the investigators use the method described by Bland and Altmann for calculating the mean deviation (bias) and the precision (mean value ± 2 standard deviations. In the case of multiple measurements , the modification of the Bland-Altman method is applied (repeated measurements). The number of cases was determined with n = 60 patients, followed by an intermediate evaluation. For a Bland-Altman analysis, the width w of the confidence interval for the Limits of Agreement is calculated as w = 6.79 • σ • 1 / √n, where n is number of cases and σ is the standard deviation. For a case count of n = 60, the result is w = 0.88 • σ and thus for this explorative study a sufficiently large number. In case of the dynamic variables, the percentage matching and the calculation of the kappa index are also used for the statistical evaluation.

Official Title
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Continuous Non-invasive Assessment of Blood Pressure in Comparison to the Invasive Gold-standard and to the Sphygmomanometer.

Conditions
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Bariatric Surgery, Arterial Blood Pressure

Intervention / Treatment
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* Procedure: baseline alert 1
* Procedure: Anti-Trendelenburg-position (ATB)
* Procedure: ATB in narcosis
* Procedure: baseline in narcosis 1
* Procedure: passive leg raising
* Procedure: volume bolus substitution
* Procedure: baseline in narcosis 2
* Procedure: start capnoperitoneum
* Procedure: ATB plus capnoperitoneum
* Procedure: ATB plus capnoperitoneum plus volume bolus substitution
* Procedure: ATB loss of capnoperitoneum
* Procedure: baseline
* Procedure: baseline alert 2
* Procedure: torso position rising 30° at the beginning
* Procedure: torso position rising 30° at the end


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Indication for bariatric surgery was made Classification according to the American Society of Anesthesiologists (ASA) 2-4 Age > 18 years Elective laparoscopic surgery Written declaration of consent Body Mass Index > 30 kg / m² Exclusion Criteria: atrial fibrillation cardiac arrhythmias aortic aneurysm > 4,5 cm Peripheral arterial occlusive desease grade 3-4 age < 18 years missing or incorrect patient consent form cognitive or linguistic barriers

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: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: bariatric surgery<br>baseline alert 1; Anti-Trendelenburg-position (ATB); Anti-Trendelenburg-position (ATB) in narcosis; baseline in narcosis 1; passive leg raising; volume bolus substitution (15 ml/kgKG Sterofundin balanced solution); baseline in narcosis 2; start capnoperitoneum; Anti-Trendelenburg-position (ATB) plus capnoperitoneum; ATB plus capnoperitoneum plus volume bolus substitution (15 ml/kgKG Sterofundin balanced solution); ATB loss of capnoperitoneum; baseline in narcosis; baseline alert 2; torso position rising 30° at the beginning; torso position rising 30° at the end | Procedure: baseline alert 1<br>* measurement in supine position<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: Anti-Trendelenburg-position (ATB)<br>* measurement under ATB<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: ATB in narcosis<br>* measurement under ATB in narcosis<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: baseline in narcosis 1<br>* measurement in supine position in narcosis<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: passive leg raising<br>* measurement under passive leg raising<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: volume bolus substitution<br>* measurement in supine position after volume bolus (15 ml/kgKG Sterofundin balanced solution intravenous)<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: baseline in narcosis 2<br>* measurement in supine position<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: start capnoperitoneum<br>* measurement in supine position<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: ATB plus capnoperitoneum<br>* measurement under ATB plus capnoperitoneum<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: ATB plus capnoperitoneum plus volume bolus substitution<br>* measurement in ATB plus capnoperitoneum after volume bolus (15 ml/kgKG Sterofundin balanced solution intravenous)<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: ATB loss of capnoperitoneum<br>* measurement under ATB<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: baseline<br>* measurement in supine position<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: baseline alert 2<br>* measurement in supine position<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: torso position rising 30° at the beginning<br>* measurement in the recovery unit<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;Procedure: torso position rising 30° at the end<br>* measurement in the recovery unit<br>* Other names: Nexfin© vs FloTrac© vs sphygmomanometric blood pressure;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Non-invasive arterial blood pressure measurement in comparison to invasive measurement in bariatric surgery | Accuracy of non-invasive beat-to-beat blood pressure measurement and sphygmomanometric measure in comparison to the invasive Gold standard. | From the beginning of surgery to admission to the PACU, approximately 4 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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limitation in conventional monitoring