Inspired Helium for Ischemic Protection During Knee Replacement Surgery

This group will be treated as any other patient would. Their anesthesia will be conducted as per routine with a target FiO2 of 0.25, (25%oxygen / 75%nitrogen) the only exception being that they will not be treated with inspired heliox.

This group will be treated with a single dose of inspired 75/25 heliox (75% helium 25% oxygen) breathed continuously for 15 minutes over any convenient window prior to the inflation of the surgical tourniquet. This will be the only change in their clinical care. Their anesthesia will be conducted as per routine and as the anesthesia team sees fit with a target FiO2 of 0.25, the only exception being that they will receive 75/25 heliox prior to the inflation of the tourniquet.

During the course of the operation a small muscle biopsy will be collected.