In a recent randomized controlled trial, researchers compared lower tourniquet pressure and conventional tourniquet pressure in total knee arthroplasty (TKA).
Lower tourniquet pressure was defined as systolic blood pressure (SBP) + 120 mmHg, and conventional was SBP + 150 mmHg. Specifically, the researchers sought to determine whether lowering the tourniquet pressure was still effective at decreasing blood loss, and if lower pressure would mean fewer tourniquet-related complications.
“[Tourniquet] complications are commonly related to both the duration of its use and the inflation pressure,” the researchers wrote. “While a lower tourniquet pressure is safer, it may not provide a bloodless operative field. However, no consensus exists regarding the optimal target inflation pressure among orthopedic surgeons.”
- SBP > 200 mmHg
- Thigh circumference > 78 cm
- Anesthesia (not including spinal anesthesia)
- Peripheral vascular disease
- Unwillingness to participate in the study
Final analysis included 160 knees (124 patients) who were randomized to undergo TKA with conventional tourniquet pressure (n = 80) or lower tourniquet pressure (n = 80).
Median age was 71 years in the conventional group and 71.8 years in the lower pressure group, and both cohorts were mostly female (91% and 85%, respectively). Almost half (48%) of the conventional group underwent unilateral TKA, while 28% and 25% underwent first staged TKA and second staged TKA, respectively. In the lower pressure group, operation rates were: unilateral, 35%; staged first, 36%; and staged second, 29%. In both the conventional and low pressure groups, most patients received an e-motion PS Pro implant (71% and 80%, respectively); the remaining patients received a Genesis II implant. One surgeon performed all operations in both groups.
Bloodless surgical field rates were similar for the conventional (100%) and lower pressure (99%) groups. In the one patient who did not achieve a bloodless surgical field at initial exposure, the tourniquet pressure was increased by 30 mmHg. There were three instances of intraoperative blood oozing, one conventional patient and two lower pressure patients, due to a significant SBP increase; the maximum SBP in the conventional patient was 136 mmHg, and in the lower pressure patients was 143 and 194 mmHg.
“These patients required one instance of increase in the tourniquet pressure by 30 mmHg and achieved adequate control of hemostasis,” wrote the researchers, adding, “In addition, there was no difference in the hemoglobin drop on the 2nd and 5th day after surgery, drained volume and the calculated blood loss (all p > 0.05).”
The researchers concluded that outcomes were similar for conventional and lower pressure tourniquet techniques: “Therefore, we recommend using a tourniquet inflation pressure of 120 mmHg above the SBP during TKA.”