Hyperosmolar Saline Irrigation Fluid in Arthroscopic Knee Surgery

An isotonic solution, such as saline (0.9%, 300mOsm/L) or lactated ringer's (273 mOsm/L), is
commonly used and safely proven for joint irrigation during arthroscopy. Arthroscopic fluid
is usually pressurized to enable visualization through dilation of the joint or bursa and
prevent bleeding from the microvasculature. It has been recommended that this pressure be
maintained at 49mmHg or less below the systolic blood pressure to preserve the clarity of
view. The combination of large amounts of pressurized irrigation solution and lengthy
arthroscopic procedures may cause substantial tissue fluid retention. Thus, extravasation of
irrigation fluid into the periarticular tissues is inevitable and may create technical
difficulties as well as patient morbidity and complications. Previous investigators have
reported complications including tracheal obstruction, post-operative airway edema and
compromise leading to prolonged intubation, excess weight gain, neurologic injuries, skin
necrosis, and fluid overload associated with excessive fluid extravasation and tissue
retention. Furthermore, it has been shown that fluid accumulated during the operation is
slowly released back into the systemic circulation. Although there is not a rapid change in
circulating volume, there may be implications for elderly patients and those with multiple
comorbidities during prolonged arthroscopic surgery. Therefore the investigators seek to
determine if a hyperosmolar solution, similar to what is used in head trauma patients, can
reduce the degree of fluid extravasation in knee arthroscopy. The investigators also seek to
determine if a hyperosmolar solution has any effect on post-operative knee pain compared to
the standard isotonic solution. The third objective is to determine if a hyperosmolar
solution has any effect on post-operative pain medicine consumption compared to the standard
isotonic solution.