Background: The pneumatic tourniquet is frequently used in total knee arthroplasty. Tourniquet deflation may result in hypotension and tachycardia caused by the rapid shift of blood volume back to the ischaemic limb and a decrease in cardiac preload. Passive leg raising (PLR) represents a 'self-volume challenge' that can result in an increase in preload. Such a PLR-induced increase in preload was hypothesised to attenuate the decrease in preload resulting from tourniquet deflation.
Objective: To evaluate the effect of PLR on hypotension and tachycardia following tourniquet deflation.
Design: A randomised controlled trial.
Setting: Single medical centre.
Patients: Seventy patients who underwent unilateral total knee arthroplasty were randomised into two groups: tourniquet deflation with PLR (n = 35) or without PLR (control group, n = 35).
Intervention(s): Patients in both groups were administered a single dose of plain bupivacaine for spinal anaesthesia. The pneumatic tourniquet was inflated on the thigh and the surgery was performed. The study composed of four steps: for the PLR group, step 1 - inflation of the tourniquet while the patient was supine; step 2 - the patient's legs were raised to a 45° angle; step 3 - the tourniquet was deflated while the patient's legs were still raised; and step 4 - the legs were returned to the supine position. In the control group, the same perioperative procedure was used, but PLR was not conducted.
Main outcome measures: The patients' blood pressure and heart rate were measured before, during and after tourniquet deflation.
Results: After tourniquet deflation, the magnitude of the changes in blood pressure and heart rate was less in the PLR group than that in the control group. In addition, the blood pressure nadir also occurred later in the PLR group than in the controls.
Conclusion: Bilateral PLR is a simple, reversible manoeuvre that mimics rapid fluid loading. Bilateral PLR attenuates the severity of, and delays the time to, hypotension and tachycardia following deflation of a lower limb tourniquet.
Trial registration: ClinicalTrials.gov number NCT01592669.