Global Warming Impact and Clinical Effects of a Novel 'streamed-in' Nitrous Oxide Administration as a Carrier Gas During Sevoflurane General Anaesthesia: a Randomized Pilot Study

EC/05/22/2063

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)

2022-06-29

2023-04-22

2023-04-22

Completed

Early phase I

102

Inclusion Criteria: * 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 Exclusion Criteria: * 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

{'studyType': 'INTERVENTIONAL', 'phases': ['PHASE4'], 'designInfo': {'allocation': 'RANDOMIZED', 'interventionModel': 'PARALLEL', 'interventionModelDescription': "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.\n\nGroup 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.\n\nGroup 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 %.\n\nGroup 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).", 'primaryPurpose': 'BASIC_SCIENCE', 'maskingInfo': {'masking': 'DOUBLE', 'maskingDescription': '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.', 'whoMasked': ['PARTICIPANT', 'OUTCOMES_ASSESSOR']}}, 'enrollmentInfo': {'count': 102, 'type': 'ACTUAL'}}

2023-08-09