Stroke
Conditions
Keywords
Cerebral oxygenation, Beach chair position, General anesthetic technique, Inspired oxygen fraction, End tidal carbon dioxide
Brief summary
The seated or beach chair position during surgery and general anesthesia decreases brain oxygen levels and can result in stroke. As such, poor neurological outcome following beach chair positioning is a growing concern. In the proposed study the investigators test the hypothesis that changes in ventilation strategy and anesthetic technique can affect cerebral oxygenation in anesthetized patients in the beach chair position.
Detailed description
This is a prospective cohort study with randomized nested design. Patients presenting for shoulder surgery will be randomized to receive desflurane or total intravenous anesthesia with propofol. Regional cerebral oxygenation will be measured using the INVOS 5100C monitor (Covidien, Boulder, CO). Depth of anesthesia will be maintained within a Bispectral Index range of 40-60. Following positioning, inspired oxygen fraction and minute ventilation will be sequentially adjusted. At each set point, regional cerebral oxygenation will be recorded and venous blood gas analysis performed. Statistical analysis will be repeated measures analysis of variance in which ventilation strategy is the within-subjects factor and anesthetic technique is the between-subjects factor; post hoc Tukey's correction will be used for multiple comparisons. If simple maneuvers of ventilation and anesthetic technique can prevent low brain oxygen levels, patient outcome may be improved.
Interventions
OTHERInspired oxygen fraction / end tidal carbon dioxide
Following induction of anesthesia, FIO2 and minute ventilation will be sequentially adjusted to achieve: 1. FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position. 2. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. 3. FIO2 100%, PETCO2 30mmHg - beach chair position. 4. FIO2 100%, PETCO2 45mmHg - beach chair position. 5. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position.
Sponsors
University of Michigan
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 85 Years
Healthy volunteers
No
Inclusion criteria
* scheduled for elective arthroscopic shoulder surgery in the beach chair position under general anesthesia with supplemental interscalene block
Exclusion criteria
* refusal to give consent * ineligible for interscalene block * history of cardiovascular disease * history of cerebrovascular disease * hypertension * respiratory failure * non-English speaker
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | duration of surgery, generally no more than 90 minutes total | rSO2 will be recorded as a snap shot. A mean value from right and left sides will be calculated for each patient at each study point. Set Point 1: FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position. Set Point 2: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. Set Point 3: FIO2 100%, PETCO2 30mmHg - beach chair position. Set Point 4: FIO2 100%, PETCO2 45mmHg - beach chair position. Set Point 5: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. With each set point, the value shown is the absolute change from baseline. |
| Regional Cerebral Oxygenation (rSO2) Values | duration of surgery, generally no more than 90 minutes total | Regional cerebral oxygenation (rSO2) values at the set ventilatory points of the study for each anesthetic choice. Set Point 1: FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position. Set Point 2: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. Set Point 3: FIO2 100%, PETCO2 30mmHg - beach chair position. Set Point 4: FIO2 100%, PETCO2 45mmHg - beach chair position. Set Point 5: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. |
Countries
United States
Participant flow
Pre-assignment details
Ten potential participants were excluded for not meeting inclusion criteria, declination to participate, and other reasons.
Participants by arm
| Arm | Count |
|---|---|
| Propofol Patients received total intravenous general anesthesia (TIVA) with propofol. Both have rSO2 measured and undergo identical changes in ventilation strategy.
Inspired oxygen fraction / end tidal carbon dioxide: Following induction of anesthesia, FIO2 and minute ventilation was sequentially adjusted to achieve:
1. FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position.
2. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position.
3. FIO2 100%, PETCO2 30mmHg - beach chair position.
4. FIO2 100%, PETCO2 45mmHg - beach chair position.
5. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. | 29 |
| Desflurane Patients received general anesthesia with desflurane. Both arms have rSO2 measured and undergo identical changes in ventilation strategy.
Inspired oxygen fraction / end tidal carbon dioxide: Following induction of anesthesia, FIO2 and minute ventilation was sequentially adjusted to achieve:
1. FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position.
2. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position.
3. FIO2 100%, PETCO2 30mmHg - beach chair position.
4. FIO2 100%, PETCO2 45mmHg - beach chair position.
5. FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. | 27 |
| Total | 56 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Determined to be ineligible | 0 | 1 |
| Overall Study | Misallocated to propofol intervention | 0 | 1 |
Baseline characteristics
| Characteristic | Propofol | Desflurane | Total |
|---|---|---|---|
| Age, Continuous | 51.3 years STANDARD_DEVIATION 10 | 49.3 years STANDARD_DEVIATION 13.3 | 50.34 years STANDARD_DEVIATION 11.6 |
| Region of Enrollment United States | 29 Participants | 27 Participants | 56 Participants |
| Sex: Female, Male Female | 11 Participants | 10 Participants | 21 Participants |
| Sex: Female, Male Male | 18 Participants | 17 Participants | 35 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 29 | 0 / 27 |
| other Total, other adverse events | 0 / 29 | 0 / 27 |
| serious Total, serious adverse events | 0 / 29 | 0 / 27 |
Outcome results
Primary
Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy
rSO2 will be recorded as a snap shot. A mean value from right and left sides will be calculated for each patient at each study point. Set Point 1: FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position. Set Point 2: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. Set Point 3: FIO2 100%, PETCO2 30mmHg - beach chair position. Set Point 4: FIO2 100%, PETCO2 45mmHg - beach chair position. Set Point 5: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. With each set point, the value shown is the absolute change from baseline.
Time frame: duration of surgery, generally no more than 90 minutes total
Population: Of the 29 participants initially randomized to receive desflurane treatment, one participant initially randomized to the desflurane arm was misallocated to the propofol arm and received propofol treatment, so is included in the propofol arm here.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Propofol | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 2: FIO2 30%; PETCO2 30mmHg (Beach Chair) | -15.48 Percent oxygen saturation | Standard Deviation 11.35 |
| Propofol | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 4: FIO2 100%; PETCO2 45mmHg (Beach Chair) | 5.46 Percent oxygen saturation | Standard Deviation 9.79 |
| Propofol | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 3: FIO2 100%; PETCO2 30mmHg (Beach Chair) | -8.31 Percent oxygen saturation | Standard Deviation 11.21 |
| Propofol | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 5: FIO2 30%; PETCO2 30mmHg (Beach Chair) | -9.00 Percent oxygen saturation | Standard Deviation 11.02 |
| Propofol | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 1: FIO2 30%; PETCO2 30mmHg (Supine) | -4.27 Percent oxygen saturation | Standard Deviation 8.43 |
| Desflurane | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 5: FIO2 30%; PETCO2 30mmHg (Beach Chair) | -3.59 Percent oxygen saturation | Standard Deviation 7.67 |
| Desflurane | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 1: FIO2 30%; PETCO2 30mmHg (Supine) | -0.70 Percent oxygen saturation | Standard Deviation 10.08 |
| Desflurane | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 2: FIO2 30%; PETCO2 30mmHg (Beach Chair) | -10.90 Percent oxygen saturation | Standard Deviation 7.03 |
| Desflurane | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 3: FIO2 100%; PETCO2 30mmHg (Beach Chair) | -3.14 Percent oxygen saturation | Standard Deviation 7.21 |
| Desflurane | Change in Regional Cerebral Oxygenation (rSO2) Before and 5 Minutes After Each Change in Ventilation Strategy | Set Point 4: FIO2 100%; PETCO2 45mmHg (Beach Chair) | 9.20 Percent oxygen saturation | Standard Deviation 7.01 |
Primary
Regional Cerebral Oxygenation (rSO2) Values
Regional cerebral oxygenation (rSO2) values at the set ventilatory points of the study for each anesthetic choice. Set Point 1: FIO2 30% (70% nitrogen), PETCO2 30mmHg - supine position. Set Point 2: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position. Set Point 3: FIO2 100%, PETCO2 30mmHg - beach chair position. Set Point 4: FIO2 100%, PETCO2 45mmHg - beach chair position. Set Point 5: FIO2 30% (70% nitrogen), PETCO2 30mmHg - beach chair position.
Time frame: duration of surgery, generally no more than 90 minutes total
Population: Of the 29 participants initially randomized to receive desflurane treatment, one participant initially randomized to the desflurane arm was misallocated to the propofol arm and received propofol treatment, so is included in the propofol arm here.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Propofol | Regional Cerebral Oxygenation (rSO2) Values | Set Point 2: Fio2 0.3 Petco2 30 mmHg | 59 Percentage cerebral oxygen saturation | Standard Deviation 13 |
| Propofol | Regional Cerebral Oxygenation (rSO2) Values | Set Point 4: Fio2 1.0 Petco2 45 mmHg | 74 Percentage cerebral oxygen saturation | Standard Deviation 12 |
| Propofol | Regional Cerebral Oxygenation (rSO2) Values | Set Point 3: Fio2 1.0 Petco2 30 mmHg | 64 Percentage cerebral oxygen saturation | Standard Deviation 14 |
| Propofol | Regional Cerebral Oxygenation (rSO2) Values | Set Point 5: Fio2 0.3 Petco2 30 mmHg | 64 Percentage cerebral oxygen saturation | Standard Deviation 14 |
| Propofol | Regional Cerebral Oxygenation (rSO2) Values | Set Point 1: Fio2 0.3 Petco2 30 mmHg | 67 Percentage cerebral oxygen saturation | Standard Deviation 13 |
| Desflurane | Regional Cerebral Oxygenation (rSO2) Values | Set Point 5: Fio2 0.3 Petco2 30 mmHg | 67 Percentage cerebral oxygen saturation | Standard Deviation 12 |
| Desflurane | Regional Cerebral Oxygenation (rSO2) Values | Set Point 1: Fio2 0.3 Petco2 30 mmHg | 69 Percentage cerebral oxygen saturation | Standard Deviation 11 |
| Desflurane | Regional Cerebral Oxygenation (rSO2) Values | Set Point 2: Fio2 0.3 Petco2 30 mmHg | 62 Percentage cerebral oxygen saturation | Standard Deviation 10 |
| Desflurane | Regional Cerebral Oxygenation (rSO2) Values | Set Point 3: Fio2 1.0 Petco2 30 mmHg | 67 Percentage cerebral oxygen saturation | Standard Deviation 11 |
| Desflurane | Regional Cerebral Oxygenation (rSO2) Values | Set Point 4: Fio2 1.0 Petco2 45 mmHg | 76 Percentage cerebral oxygen saturation | Standard Deviation 11 |
Comparison: P-values represent comparison of successive set points within anesthetic type (i.e.: Set Point 1 compared to Set Point 2, Set Point 2 compared to Set Point 3, etc.). This P-value was determined for each of set points 1, 2, 3, 4, and 5.p-value: <0.001ANOVA