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

Overview

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.

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

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Screening
    • Masking: None (Open Label)
  • Study Primary Completion Date: October 30, 2018

Detailed Description

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.

Interventions

  • Diagnostic Test: hemodynamic parameters
    • vital signs on the monitor including heart rate, mean arterial pressure, peripheral oxygen saturation and End-tidal Carbon Dioxide
  • Diagnostic Test: arterial blood gase
    • 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.

Arms, Groups and Cohorts

  • Active Comparator: low-flow anesthesia
    • 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.
  • Active Comparator: normal-flow anesthesia
    • 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.

Clinical Trial Outcome Measures

Primary Measures

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

Secondary Measures

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

Participating in This Clinical Trial

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.

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 65 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Inonu University
  • Provider of Information About this Clinical Study
    • Principal Investigator: Sedat AKBAS, Asst. Prof. Dr. Sedat Akbas – Inonu University
  • Overall Official(s)
    • Sedat Akbas, Asst Prof, Study Director, Inonu University Medical Faculty

References

Nunn Geoffrey BA. Low-flow anaesthesia. Continuing Education in Anaesthesia Critical Care & Pain Volume 8, Issue 1, February 2008, Pages 1-4

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