Comparison of Different Ventilator and Vaporizer Technologies to Study Economic and Environmental Implications

Low-flow Anesthesia: Cost-effectiveness of the FLOW-i Anesthesia Machine, a Comparison to Established Anesthesia Delivery Unit

The purpose of this study is to test whether or not the use of a low volume ventilator in an anesthesia machine reduces anesthetic costs significantly as compared to other high volume machines. The study will compare the a low-flow anesthesia machine to a traditional anesthesia machine during routine elective general surgery in patients with ASA ratings of 1-2 under general anesthesia receiving standard care.

Study Overview

• Status: Completed
• Conditions: Anesthetic Gas Consumption and Cost-Effectiveness
• Intervention / Treatment: Device: ICU certified ventilator; Device: Non-ICU certified ventilator

Detailed Description

The study member will screen for potential subjects using the UCIMC surgical schedule. If a subject is deemed ineligible based on the inclusion and exclusion criteria after reviewing the medical history, his/her record will be discarded. No records will be retained from ineligible subjects. After discussing with the patient's surgeon, study team member will initiate the informed consent process by approaching each eligible subject to explain the study and what it entails. The Lead Researcher will address all questions and concerns from the subject before asking the subject to sign the research consent form.

The GE anesthesia machines currently owned by the operating room will be used to serve as the comparator to the Flow-i machine. The high volume anesthesia machines do not use a low volume system. Subjects will be randomized by recruitment day. On a given recruitment day, all consented subjects will receive anesthesia from one of two groups:

(1) MAQUET FLOW-i device (2) GE anesthetic device

Time points for both groups include:

T0: Time of intubation, when volatile anesthetic are typically first delivered to the patient. We will use 15L/min fresh gas flow, while dictating tidal volumes of 6-8 mL/kg ideal body weight and a PEEP of 6 centimeters of water (cm H2O) in accordance with current best practices.

T1: Time of incision, which typically represents the time of reaching steady state conditions of volatile anesthetic delivery. We will reduce fresh gas flow to 2 L/min in accordance with local practice and weigh the vaporizer at this point, allowing us to measure comparative anesthetic consumption during this wash-in time period (T0-T1).

T2: Time of anesthetic weaning, typically the time when preparing for patient emergence begins by discontinuing the delivery of volatile anesthetics to the patient. The vaporizer will be re- weighed at this point, allowing us to measure comparative anesthetic consumption at steady state maintenance of anesthetic depth (T1-T2) Logically, we will also be able to use T0-T2 in order to understand total comparative anesthetic consumption.

Aside from the randomization to either Group 1 or Group 2, there will be no changes in the surgical or anesthetic procedure, including the medication or treatments given to the subjects as determined by the treating physician. All subjects will receive general anesthesia in accordance to local practice.

For this study, the vaporizer(s) will be weighed on a tared scale before research procedures commence, after induction, and when the gas is shut off during weaning of anesthesia in preparation for extubation to calculate the amount consumed during this time (grams/minute). In addition, the following variables will be recorded:

Subject weight (kg) Tidal Volume (TV) Respiratory Rate (RR) 9 of 24

Positive end-expiratory pressure (PEEP) Fresh Gas Flow Volume % gas End Tidal (%) Time of extubation Time when Aldrete score > 8

This is not a physician-blinded study being that the physical characteristics of the standard delivery units are distinguishable from the MAQUET FLOW-i machine.

All MAC concentrations are standard of care: After the surgical procedure, patient will be assessed for time to reach Aldrete score greater than 8, level of pain and time to extubation. Their medical records will be reviewed to determine need for times and adverse events. Patients will not be contacted for study-related follow-up after they are discharged from recovery.

No photographs or audio/video recording will be collected for this study.

Subject's Privacy:

The study team member will screen for potential subjects using the UCIMC surgical schedule. If a subject is deemed ineligible based on the inclusion and exclusion criteria after reviewing the medical history, his/her record will be discarded. No records will be retained from ineligible subjects.

Study team member will approach each eligible patient to explain the study and what it entails. The study team member will address all questions and concerns from the subjects before asking the patient to sign the research consent form.

• Study Type: Interventional
• Enrollment (Actual): 110
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Orange, California, United States, 92868
      • University of California, Irvine Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Age 18-65 years
• Undergo surgery under general anesthesia in UCI Medical Center
• Agree to sign the consent and HIPAA forms
• Subjects who are able to receive sevoflurane

Exclusion Criteria:

• Subjects under the age of 18
• Chronic Obstructive Pulmonary Disease (COPD)
• Body Mass Index (BMI) > 30
• ASA > 2
• Pregnant females
• Procedures less than 2 hours
• Those with known sensitivity to sevoflurane or other halogenated agents; those with known or suspected susceptibility to malignant hyperthermia
• Severe Cardiovascular Disease: Left Ventricular Ejection Fraction (LVEF) < 30%

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: ICU certified ventilator; Participants assigned to receive ventilation with the ICU certified ventilator	Device: ICU certified ventilator; Examine anesthetic consumption rates
Active Comparator: Non-ICU certified ventilator; Participants assigned to receive ventilation with the Non-ICU certified ventilator	Device: Non-ICU certified ventilator; Examine anesthetic consumption rates

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Primary Study Variable: Amount of Gas Vaporized Anesthetic Per Minute Anesthesia	The purpose of this study is to test whether or not the use of a low volume ventilator in an anesthesia machine reduces anesthetic costs significantly as compared to other high volume machines. The study will compare the FLOW-i anesthesia machine to a GE anesthesia machine during routine elective general surgery in patients with ASA ratings of 1-2 under general anesthesia receiving standard care.	Intraoperative (minimum of 2 hours of anesthesia)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Reach Aldrete > 8	Time it took for patient to be safely discharged from the post-anesthesia care unit (PACU). The Aldrete Score evaluates recovery after anesthesia and patient readiness to be discharged from PACU. The patient is assessed for consciousness, mobility, breathing, circulation, and color. The evaluation occurs immediately after surgery and then every (1) hour before the patient is deemed ready for discharge.	Up to 24 hours
Time to Extubation From Weaning	Time it took to remove patient from mechanical ventilation	Intraoperative (minimum of 2 hours of anesthesia)

Collaborators and Investigators

• Sponsor: University of California, Irvine
• Investigators: Principal Investigator: Robert R Field, MD, University of California, Irvine

Publications and helpful links

General Publications

• Avramov MN, Griffin JD, White PF. The effect of fresh gas flow and anesthetic technique on the ability to control acute hemodynamic responses during surgery. Anesth Analg. 1998 Sep;87(3):666-70. doi: 10.1097/00000539-199809000-00033.
• Choi SU, Shin HW, Jung HI, Park JY, Yoon SZ, Lee YS, Kim WY, Chang SH. Control of the haemodynamic response to surgical stimuli in semi-closed circuit or closed circuit anaesthesia using a multifunctional anaesthesia system. J Int Med Res. 2010 Sep-Oct;38(5):1637-44. doi: 10.1177/147323001003800508.

Study record dates

Study Major Dates

• Study Start (Actual): February 14, 2018
• Primary Completion (Actual): November 8, 2019
• Study Completion (Actual): November 8, 2019

Study Registration Dates

• First Submitted: April 30, 2018
• First Submitted That Met QC Criteria: April 16, 2021
• First Posted (Actual): April 20, 2021

Study Record Updates

• Last Update Posted (Actual): August 10, 2021
• Last Update Submitted That Met QC Criteria: July 16, 2021
• Last Verified: July 1, 2021

More Information

Terms related to this study

• Keywords: sevoflurane; general anesthesia; cost-effectiveness; fresh gas flow; anesthesia machines; low volume ventilator; anesthetic costs
• Other Study ID Numbers: UCIANES11 [HS# 2014-1248]

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes