Does Tourniquet Time or Pressure Contribute to Intracranial Pressure Increase following Tourniquet Application?

OBJECTIVE

The aim of this study was to determine whether an early increase in intracranial pressure (ICP) following the deflation of a tourniquet is related to the tourniquet time (TT) or tourniquet pressure (TP) and to identify a safe cut-off value for TT or TP.

MATERIALS AND METHODS

Patients who underwent elective orthopedic lower-extremity surgery under general anesthesia were randomized into 2 groups: group A (inflation with a pneumatic TP of systolic blood pressure + 100 mm Hg; n = 30) and group B (inflation using the arterial occlusion pressure formula; n = 30). The initial and maximum TPs, TT, and sonographic measurements of optic-nerve sheath diameter (ONSD) and end-tidal CO2 values were taken at specific time points (15 min before the induction of anesthesia, just before, and 5, 10, and 15 min after the tourniquet was deflated).

RESULTS

The initial and maximum TPs were found to be significantly higher in group A than in group B. At 5 min after the tourniquet deflation, there was a significant positive correlation between TT and ONSD (r = 0.57, p = 0.0001). When ONSD ≥5 mm was taken as a standard criterion, the safe cut-off value for the optimal TT was found to be < 67.5 min (sensitivity 87% and specificity 59.5%).

CONCLUSION

The ICP increase in the early period after tourniquet deflation was well correlated with TT but not with TP. TT of ≥67.5 min was found to be the cut-off value and is considered the starting point of the increase in ICP after tourniquet deflation.