Effects of Low-Flow Anesthesia on Hemodynamic Parameters and Oxygenation in Morbidly Obese Patients

Study Overview
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Brief Summary
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Low-flow anesthesia has been used for years with positive results, but its effects on hemodynamic parameters and oxygenation are not clearly known in high-risk morbidly obese patients who are prone to pulmonary dysfunction related to the obesity. Therefore, this prospective randomized study aimed to compare the effects of low-flow (0.75 L/min) and normal-flow (1.5 L/min) anesthesia on hemodynamic parameters and oxygenation in morbidly obese patients undergoing laparoscopic bariatric surgery.

Detailed Description
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Low-flow anesthesia has several potential benefits. It improves the flow dynamics of the inhaled air, increase mucociliary clearance, maintain body temperature, reduce fluid loss, result in savings of up to 75% and reduce greenhouse gas emissions and reduce treatment costs (10 - 13). However, it is necessary to examine whether the reduction of fresh gas flow affects the quality and safety of anesthesia management, especially during high-risk operations such as laparoscopic bariatric surgery. Low-flow anesthesia has been used for years with positive results, but its effects on hemodynamic parameters and oxygenation are not clearly known in high-risk morbidly obese patients who are prone to pulmonary dysfunction related to the obesity. Therefore, this prospective randomized study aimed to compare the effects of low-flow (0.75 L/min) and normal-flow (1.5 L/min) anesthesia on hemodynamic parameters and oxygenation in morbidly obese patients undergoing laparoscopic bariatric surgery.

Official Title
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Effects of Low-Flow Anesthesia on Hemodynamic Parameters and Oxygenation in Morbidly Obese Patients Undergoing Bariatric Surgery: A Prospective, Randomized Clinical Trial

Conditions
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Morbid Obesity, Hemodynamic Instability, Bariatric Surgery Candidate

Intervention / Treatment
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* Diagnostic Test: hemodynamic parameters
* Diagnostic Test: arterial blood gase


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Morbidly obese patients with American Society of Anesthesiology (ASA) scores of III-IV, Aged 18-65 years old, BMI>40 Exclusion Criteria: Pregnant Uncontrolled diabetes mellitus, Cardiovascular disease, Pulmonary disease, Cerebrovascular disease, Drug and alcohol addiction.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Screening
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: low-flow anesthesia<br>Patients in low-flow anesthesia receive a fresh gas flow of 4 L/min for the first 10 minutes and were then maintain with a fresh gas flow of 0.75 L/min. Patients will be monitored for hemodynamic parameters during the perioperative period. Arterial blood gase will be analyzed for the oxygenation. | Diagnostic Test: hemodynamic parameters<br>* vital signs on the monitor including heart rate, mean arterial pressure, peripheral oxygen saturation and End-tidal Carbon Dioxide<br>* Other names: End-tidal Carbon Dioxide;Diagnostic Test: arterial blood gase<br>* Arterial blood gas including partial oxygen pressure and partial carbon dioxide pressure is an important routine investigation to monitor the acid-base balance of patients, effectiveness of gas exchange, and the state of their voluntary respiratory control.<br>* Other names: partial carbon dioxide pressure;|
| Active Comparator: normal-flow anesthesia<br>Patients in normal-flow anesthesia received a fresh gas flow of 4 L/min for the first 10 minutes and were then maintained with a fresh gas flow of 1.5 L/min. Patients will be monitored for hemodynamic parameters during the perioperative period. Arterial blood gase will be analyzed for the oxygenation. | Diagnostic Test: hemodynamic parameters<br>* vital signs on the monitor including heart rate, mean arterial pressure, peripheral oxygen saturation and End-tidal Carbon Dioxide<br>* Other names: End-tidal Carbon Dioxide;Diagnostic Test: arterial blood gase<br>* Arterial blood gas including partial oxygen pressure and partial carbon dioxide pressure is an important routine investigation to monitor the acid-base balance of patients, effectiveness of gas exchange, and the state of their voluntary respiratory control.<br>* Other names: partial carbon dioxide pressure;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The level of partial oxygen pressure | The level of partial oxygen pressure is measured as mmHg in arterial blood gase analysis | From beginning of Anesthesia induction to the end of anesthesia (during perioperative period) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate | Heart rate is measured as beats/minute on the anesthesia monitor | From beginning of Anesthesia induction to the end of anesthesia (during perioperative period) | 
| Mean arterial pressure | Mean arterial pressure is measured as mmHg on the anesthesia monitor | From beginning of Anesthesia induction to the end of anesthesia (during perioperative period) | 
| Peripheral oxygen saturation | Peripheral oxygen saturation is measured as percentage (%) on the anesthesia monitor | From beginning of Anesthesia induction to the end of anesthesia (during perioperative period) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Morbidly obese patients, Bariatric surgery, Arterial blood analysis