Global Warming Impact of Nitrous Oxide

NCT05430750 | Completed Phase 4

• 1 other identifier: EC/05/22/2063
• Study Type: interventional
• Target: 102
• Locations: 1 country
• Sites: 1

Brief Summary

Environmental hazards of human activity are a topic of present day world, global warming being one of the leading concerns. Gases that contribute to this are greenhouse gases. Nitrous oxide (N2O) is a greenhouse gas that is commonly used in medical practice, mostly confined to provision of anaesthesia during surgical procedures in the operation theatre. N2O is not a potent anesthetic, and is used as a carrier for volatile anesthetic during general anaesthesia. This is to reduce the use of volatile anesthetics and other analgesic drugs while maintaining adequate depth of anaesthesia and analgesia. The N2O gas that is used during general anaesthesia is scavenged and released into the atmosphere without any processing. In the atmosphere it stays and produces deleterious greenhouse effect primarily owing to its long lifetime of 114 years. In addition, it also causes depletion of ozone layer. The green house effect of gases is evaluated and compared with the use of carbon-di-oxide equivalents (CDE). When the effects are considered for 20 years it is termed CDE20.The efforts to reduce these harmful effects can be directed towards reduction/cessation of N2O use, or its post anesthetic processing. The long history of its use in clinical practice and benefits such as analgesia for various procedures; makes it difficult to be completely taken out of usage in the present day anaesthesia practice. Though processing of N2O after use during GA is possible, it's impractical because of cost efficiency. We therefore, have directed our focus on further reducing its consumption while being used for GA. Low- flow anaesthesia has been in practice for the same reason (i.e. to reduce the wastage of gases). This study is aimed to reduce the N2O consumption even further by employing a novel 'streamed-in' technique of N2O administration during low-flow GA. Conventionally, N2O use is initiated during the initial high fresh gas flows (FGF) before shifting to low-flow ventilation. 'Streamed-in' N2O administration strategy employs initiation of N2O into FGF after the institution of low-flow anaesthesia. Hence, the participants are not exposed to an unconventional drug or a new route of its administration, but an alternate strategy to its conventional use. We aim to evaluate the novel technique of 'streamed-in' N2O during sevoflurane GA for its global warming effects (in terms of CDE20) and its clinical effects ( intraoperative general anaesthesia state, hemodynamic profile) and post operative effects( postoperative nausea vomiting -PONV, postoperative pain profile- numerical rating scale-NRS)

Conditions

Global Warming Effect of Nitrous Oxide

Keywords

nitrous oxide; sevoflurane; global warming

Outcome Measures

Primary Outcomes (1)

• Carbon-di-oxide equivalent -20 years (CDE20)

  Carbon-di-oxide equivalent -20 years of nitrous oxide \& sevoflurane will be calculated using the formula Mass of Anaesthetic used \*GWP20 (Global Warming Potential -20 years)

  From start of anesthesia till 5- minutes post extubation

Secondary Outcomes (9)

• Intraoperative End-tidal anaesthesia gas (ETAG) concentration

  From start of anesthesia till 5- minutes post extubation

• Intraoperative minimum alveolar concentration (MAC)

  From start of anesthesia till 5- minutes post extubation

• Intraoperative consumption of anesthetic gases

  From start of anesthesia till 5- minutes post extubation

• Changes in intra-operative heart rate (beats per minute)

  From start of anesthesia till 5- minutes post extubation

• Change in Intra-operative blood pressure - systolic , diastolic, and mean (mmHg)

  From start of anesthesia till 5- minutes post extubation

Study Arms (3)

Conventional' - N2O carrier gas group

ACTIVE COMPARATOR

Ventilation will be initiated with 2% Sevoflurane in O2-N2O (60 % FiO2) @3L/min to MAC 0.5. Once MAC reaches 0.5, the FGF will be decreased to 1.0L/min (Low flow) and allowed to reach MAC 1.0 before incision is allowed. At 20-minutes time point post induction if MAC 1.0 is not achieved at 2% sevoflurane then the sevoflurane vaporizer concentration will be adjusted to achieve MAC 1.0, before incision is allowed. Anaesthesia will be maintained at MAC 1.0 throughout. After surgery is over, the N2O - Sevoflurane will be stopped and FGF increased to 3.0L with 100% O2.

Drug: Nitrous oxide; Drug: Sevoflurane

'Streamed -in' N2O carrier gas group

ACTIVE COMPARATOR

Ventilation will be initiated with 2% Sevoflurane in O2 -Air (60 % FiO2) @3.0L/min to achieve a MAC of 0.5. Then, the FGF will be decreased to 1.0 L (low flow) and N2O will be 'streamed-in' @ 40 %. When MAC 1.0 is reached incision will be allowed. At 20-minutes time point post induction if MAC 1.0 is not achieved at 2% sevoflurane then the sevoflurane vaporizer concentration will be adjusted to achieve MAC 1.0, before incision is allowed. Anaesthesia will be maintained at MAC 1.0 throughout. After surgery is over, the N2O - Sevoflurane will be stopped and FGF increased to 3.0L with 100% O2.

Drug: Nitrous oxide; Drug: Sevoflurane

Non-N2O group

ACTIVE COMPARATOR

Ventilation will be initiated with 2% Sevoflurane in O2-Air (60 % FiO2 @ 3.0L/min) till the time it reaches MAC 0.5. Once MAC 0.5 reached, the FGF is decreased to 1.0L (Low-flow). The incision is allowed when MAC 1.0 is achieved .At 20-minutes time point post induction if MAC 1.0 is not achieved at 2% sevoflurane then the sevoflurane vaporizer concentration will be adjusted to achieve MAC 1.0, before incision is allowed. Anaesthesia will be maintained at MAC 1.0 throughout. After surgery is over, the O2 - Sevoflurane will be stopped and FGF increased to 3.0L with 100% O2.

Drug: Sevoflurane

Interventions

Nitrous oxide DRUG

In conventional nitrous oxide carrier group 2% Sevoflurane in O2-N2O (60 % FiO2) @3L/min will be delivered to achieve MAC 0.5.

Conventional' - N2O carrier gas group

Sevoflurane DRUG

Ventilation will be initiated with 2% sevoflurane in all the groups

'Streamed -in' N2O carrier gas group; Conventional' - N2O carrier gas group; Non-N2O group

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18-65 years
• ASA physical status I and II
• Patients undergoing elective non-laparoscopic surgeries of minimum 1 hour duration without use of adjuvant central neuraxial or peripheral nerve block under general anaesthesia

You may not qualify if:

• Failure to obtain consent
• Neurological disorders (previous neurosurgery , psychiatric disorders, autonomic system disorders - orthostatic hypotension, transient ischemic attacks )
• Cardiovascular disorders (uncontrolled hypertension, A-V block, sinus bradycardia, congenital heart disease, reduced LV compliance and diastolic dysfunction)
• Hepatorenal insufficiency
• Uncontrolled endocrine disorders (diabetes mellitus, hypothyroidism, hyperthyroidism)
• Electrolyte disturbances (hyponatremia, hypernatremia)
• Pulmonary dysfunction (restrictive /obstructive lung disease)
• Acute /chronic drug dependence /substance abuse
• Closed cavity surgeries (middle ear surgeries, eye surgeries)
• Previous h/o PONV

Sponsors & Collaborators

• Sir Ganga Ram Hospital: lead

Study Sites (1)

Sir Ganga Ram Hospital

New Delhi, National Capital Territory of Delhi, 110060, India

Location

MeSH Terms

Interventions

Nitrous Oxide; Sevoflurane

Intervention Hierarchy (Ancestors)

Nitrogen Oxides; Gases; Inorganic Chemicals; Nitrogen Compounds; Oxides; Oxygen Compounds; Methyl Ethers; Ethers; Organic Chemicals; Hydrocarbons, Fluorinated; Hydrocarbons, Halogenated; Hydrocarbons

Study Officials

• Amitabh Dutta, MD, PGDHR

  Sir Ganga Ram Hospital, New Delhi, INDIA

  STUDY CHAIR

• Nitin Sethi, DNB

  Sir Ganga Ram Hospital, New Delhi, INDIA

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: The patient will be blinded to the type of anesthesia intervention. The attending anesthesiologist will however not be blinded to the technique utilized to administer GA and recovery immediately after extubation inside the OR. The postoperative patient profile will be evaluated by an independent assessor blinded to the technique of GA.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor & Senior Consultant

Model Details: One hundred and two patients of either sex, and schedule for elective surgery under general anesthesia (GA) will be randomly divided into three groups of 34-each. Group 1('Conventional' N2O carrier gas group) Ventilation will be initiated with 2% Sevoflurane in O2-N2O (60 % FiO2) @3L/min to MAC 0.5. Once MAC reaches 0.5, the FGF will be decreased to 1.0L/min. Group 2 ('Streamed-in' N2O carrier gas group) Ventilation will be initiated with 2% Sevoflurane in O2 -Air (60 % FiO2) @3.0L/min to achieve a MAC of 0.5. Then, the FGF will be decreased to 1.0 L (low flow) and N2O will be 'streamed-in' @ 40 %. Group 3 (Non-N2O group) Ventilation will be initiated with 2% Sevoflurane in O2-Air (60 % FiO2 @ 3.0L/min) till the time it reaches MAC 0.5. Once MAC 0.5 reached, the FGF is decreased to 1.0L (Low-flow).

Study Record Dates

• First Submitted: June 18, 2022
• First Posted: June 24, 2022
• Study Start: June 29, 2022
• Primary Completion: April 22, 2023
• Study Completion: April 22, 2023
• Last Updated: August 9, 2023

Record last verified: 2023-08

Data Sharing

• IPD Sharing: Will not share

Locations

IN (1)