The effects of inhalational anesthetics on regional cerebral oxygen saturation during the operation of lower extremities with pneumatic tourniquet


Background and goal of study
It is known that using a pneumatic tourniquet during lower extremity surgery cause the hemodynamic status changes and sometimes triggers severe complications such as neurological complications. 
Therefore, as we reported previously (2016 ESA), we investigated about the effects of sevoflurane and propofol anesthetics for regional cerebral oxygen saturation (rSO2) during the operation of lower extremities with pneumatic tourniquet.
Sevoflurane group indicated significantly higher levels of rSO2 than propofol group. 
Because of its effects of maintaining the cerebral blood flow leads to these results.
However, it was not certain how it would be when we use another inhalator anesthetics. 
The goal of this study was to determine whether rSO2 values differ between sevoflurane and desflurane anesthesia during lower extremity surgeries that require pneumatic tourniquet.

Material and Methods
Thirty-eight patients undergoing operation of lower legs were randomly divided into desflurane and propofol groups. 
The patients with The American Society of Anesthesiologists physiological status 1 or 2 and without past history of cerebral disease were included in this research. Physiological parameters and rSO2 were recorded under general anesthesia.
And these were recorded at 5 min before, and 5, 10 and 15 min after deflation of pneumatic tourniquet. We also performed arterial blood gas analysis at the same time points. Using the rSO2 value on 5min before the deflation as baseline, we compared every rSO2 data among the groups.
The patients were followed for a week after the operation to record complications.

Results
Sevoflurane group had significantly higher rSO2 values than desflurane group at 5min after the deflation. (p=0.002) Sevoflurane group indicated continuous increase in rSO2 after deflation. However, desflurane group showed decline in rSO2 values after deflation, though it regained within the recording period. Throughout the every time points, sevoflurane group indicated significant higher levels of cardiac index than desflurane group. There were no significant differences between the groups in terms of the post-operative complication. 

Discussion and Conclusion
There were significant differences among the inhalational anesthetics on rSO2 when the pneumatic tourniquet was deflated at 5min after the deflation. Even in the inhalator anesthetics, each anesthetic might have an inherent ability for cerebrovascular systems for the early phase of the deflation of tourniquet.

The effects of sevoflurane and desflurane anesthetics on regional cerebral oxygen saturation during the operation of lower extremities with pneumatic tourniquet