Anesthesia, General, Deep Sedation
Conditions
Keywords
depth of sedation, nitrous oxide, general anesthesia, anesthesia indices
Brief summary
The study hypothesizes that adding 60% nitrous oxide to a steady state sevoflurance or propofol anesthetic will lead to a decrease in both BIS and Entropy indices during a constant level of surgical stimulus
Detailed description
Nitrous oxide is a widely used general anesthetic pas. It is often used in addition to a second, more potent agent. BIS and Entropy are depth of anesthesia monitors in clinical use. There are conflicting reports about the usefulness of these monitors when nitrous oxide is used as a part of the anesthetic regimen. While some studies demonstrate a decrease in BIS and Entropy, this study aims to investigate the effects of adding nitrous oxide to a sevoflurane or a propofol based anesthetic on BIS and Entropy indices.
Interventions
Addition of 60% nitrous oxide for 20 minutes duration, then back to 1:1 oxygen/air mixture.
DRUGPropofol group
Addition of 60% nitrous oxide for 20 minutes duration, then back to 1:1 oxygen/air mixture.
Sponsors
University of Oklahoma
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
HEALTH_SERVICES_RESEARCH
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
No
Inclusion criteria
* Ages 18 to 55yrs * ASA status less than and equal to 2
Exclusion criteria
* Surgery on head and neck * ASA greater than 3 * Contraindication to nitrous oxide * Pregnant women * History of dementia and stroke, or other organic brain disorder * Prisoner * Ear surgery
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | From baseline to 20 minutes after the addition of 60% nitrous oxide | We planned this study to compare the effect of adding N2O on BIS and SE during an intravenous or an inhalation anesthetic. We hypothesized that neither BIS nor SE would decrease in response to the addition of N2O to a Propofol anesthetic. We also hypothesized that neither BIS nor SE would decrease in participants under Sevoflurane anesthesia if the inspired concentration of Sevoflurane were carefully and continuously adjusted to maintain a constant end-tidal concentration during the addition and discontinuation of N2O. BIS (0-100) and SE (0-92) are unitless, ordinal indices of anesthetic depth. Both indices are decreased when the depth of anesthesia is increased. |
Countries
United States
Participant flow
Recruitment details
Study includes patients aged 18 to 55 years who were classified as ASA physical status ≤2 and scheduled to have surgery under general anesthesia . Only patients for which intraoperative Entropy or BIS monitoring was planned were enrolled by speaking to the attending anesthesiologists working at the OU Presbyterian hospital.
Pre-assignment details
Patients were randomized into 2 groups that differ in the choice of the agent for the maintenance of general anesthesia: sevoflurane or propofol.
Participants by arm
| Arm | Count |
|---|---|
| Sevoflurane Group Sevoflurane based general anesthesia
Sevoflurane group: Addition of 60% nitrous oxide for 20 minutes duration, then back to 1:1 oxygen/air mixture. | 14 |
| Propofol Group Propofol based general anesthesia
Propofol group: Addition of 60% nitrous oxide for 20 minutes duration, then back to 1:1 oxygen/air mixture. | 14 |
| Total | 28 |
Baseline characteristics
| Characteristic | Total | Sevoflurane Group | Propofol Group |
|---|---|---|---|
| Age, Continuous | 38.7 years STANDARD_DEVIATION 9.7 | 39 years STANDARD_DEVIATION 10 | 38 years STANDARD_DEVIATION 9.6 |
| Body Mass Index (BMI) | 31.5 kg/m^2 STANDARD_DEVIATION 8 | 31 kg/m^2 STANDARD_DEVIATION 6 | 32 kg/m^2 STANDARD_DEVIATION 10 |
| Race (NIH/OMB) American Indian or Alaska Native | 1 Participants | 1 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 5 Participants | 2 Participants | 3 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 3 Participants | 2 Participants | 1 Participants |
| Race (NIH/OMB) White | 19 Participants | 9 Participants | 10 Participants |
| Region of Enrollment United States | 28 participants | 14 participants | 14 participants |
| Sex: Female, Male Female | 18 Participants | 8 Participants | 10 Participants |
| Sex: Female, Male Male | 10 Participants | 6 Participants | 4 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 14 | 0 / 14 |
| other Total, other adverse events | 0 / 14 | 0 / 14 |
| serious Total, serious adverse events | 0 / 14 | 0 / 14 |
Outcome results
Primary
The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE)
We planned this study to compare the effect of adding N2O on BIS and SE during an intravenous or an inhalation anesthetic. We hypothesized that neither BIS nor SE would decrease in response to the addition of N2O to a Propofol anesthetic. We also hypothesized that neither BIS nor SE would decrease in participants under Sevoflurane anesthesia if the inspired concentration of Sevoflurane were carefully and continuously adjusted to maintain a constant end-tidal concentration during the addition and discontinuation of N2O. BIS (0-100) and SE (0-92) are unitless, ordinal indices of anesthetic depth. Both indices are decreased when the depth of anesthesia is increased.
Time frame: From baseline to 20 minutes after the addition of 60% nitrous oxide
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Sevoflurane Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | Baseline BIS | 36 units on a scale | Standard Deviation 7 |
| Sevoflurane Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | 60% Nitrous Oxide BIS | 32 units on a scale | Standard Deviation 7 |
| Sevoflurane Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | Baseline SE | 37 units on a scale | Standard Deviation 10 |
| Sevoflurane Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | 60% Nitrous Oxide SE | 31 units on a scale | Standard Deviation 11 |
| Propofol Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | 60% Nitrous Oxide SE | 43 units on a scale | Standard Deviation 12 |
| Propofol Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | Baseline BIS | 40 units on a scale | Standard Deviation 10 |
| Propofol Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | Baseline SE | 43 units on a scale | Standard Deviation 11 |
| Propofol Group | The Effect of Nitrous Oxide on Bispectral Index (BIS) and State Entropy Index (SE) | 60% Nitrous Oxide BIS | 39 units on a scale | Standard Deviation 10 |